To see the other types of publications on this topic, follow the link: Carbon monoxide – Absorption and adsorption.
Dissertations / Theses on the topic 'Carbon monoxide – Absorption and adsorption'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Carbon monoxide – Absorption and adsorption.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Christiaen, Anne-Claire. "Adsorption of water and carbon monoxide on Cu₂O(111) single crystal surfaces." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-11102009-020324/.
Full text
2
Winski, David Nathaniel. "Design and construction of a polarization modulated infrared reflection absorption spectrometer and validation with carbon monoxide adsorption on a platinum (100) surface." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 96 p, 2009. http://proquest.umi.com/pqdweb?did=1889078511&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Full text
3
Feltovich, Susanne D. "Influence of solvent on the infared spectrum of carbon monoxide adsorbed on platinum electrodes." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09292009-020247/.
Full text
4
Canard, Gabriel. "Matériaux hybrides organiques-inorganiques incorporant des métallocorroles de cobalt(III) : application à l'adsorption sélective du monoxyde de carbone." Dijon, 2004. http://www.theses.fr/2004DIJOS046.
Full text
5
Repper, Stephen. "Carbon monoxide absorption by copper(I) containing ionic liquids." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/7674/.
Full text
6
Kennedy, Sinead A. "Infrared studies of adsorption on model catalysts." Thesis, University of Reading, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250661.
Full text
7
Chamberlain, Jeffrey P. "The adsorption of carbon monoxide on silicon and gallium arsenide surfaces." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/29799.
Full text
8
Kalimtgis, Konstandinos. "ADSORPTION OF TRICHLOROETHYLENE AND CARBON TETRACHLORIDE ON SYNTHETIC AND NATURAL ADSORBENTS." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275355.
Full text
9
Rohmann, Christoph. "Carbon monoxide adsorption onto the metal oxides of α-Al2O3 and TiO2." Thesis, University of Auckland, 2011. http://hdl.handle.net/2292/9552.
Full textAbstract:
The aim of this study is to elucidate surface properties of α-Al2O3 and TiO2, such as; the number and accessibility of adsorption sites, forces governing the interaction of the surface with adsorbates and surface relaxation and reconstruction, using a combination of theory and experiment. Carbon monoxide was used as a probe molecule and its adsorption onto both clean and hydroxylated (0001) surfaces of α-Al2O3 was modelled using Density Functional Theory (DFT). Adsorption of CO onto α-Al2O3 and TiO2 (anatase and rutile) powders was investigated experimentally using infrared spectroscopy. In addition, Reflection-Absorption Infrared Spectroscopy (RAIRS) experiments were conducted to study the adsorption and photo-oxidation of CO to CO2 over the rutile TiO2(110) single crystal surface. Computational modelling of the adsorption of CO onto both dry and hydroxylated a-Al2O3(0001) surfaces was undertaken to investigate changes in binding conformations, surface relaxation effects & CO vibrational frequencies, with increasing adsorbate coverage. The adsorption of CO onto the (0001) surface begins with the C of CO approaching an Al adsorption site in a perpendicular fashion. Upon CO adsorption onto the dry and hydroxylated surfaces significant surface relaxations were noted, which were enhanced at hydroxylated surfaces. Generally, as the surface coverage increases, the CO adsorption energy and the CO vibrational frequency both decrease, except for highly hydroxylated surfaces, which do not tend to adsorb CO at all (?), as the surface hydroxylation causes the free Al adsorption sites to retreat into the bulk material. CO adsorption onto α-Al2O3 and TiO2 (anatase and rutile) powders have been studied by Fourier Transform Infrared (FTIR) spectroscopy to determine the CO vibrational frequency and heats of adsorption in order to compare those to the computed CO adsorption energies of the dry and hydroxylated (0001) surfaces of a-Al2O3 as well as to previously reported findings. The CO vibrational frequency was blue shifted (a shift to higher wavenumbers indicating a strengthening of the CO bond) compared to the free molecule in all cases, revealing a CO heat of adsorption being greatest for anatase followed by rutile while a-Al2O3 is exhibiting the weakest binding at the investigated powders. Reflection-Absorption Infrared Spectroscopy (RAIRS) has been successfully conducted for the first time to identify the CO adsorption site on well defined metal oxide single crystal surface, the (110) surface of TiO2 in this case. Therefore it is now possible to assign peaks observed on powder samples exactly to a crystal plane, enabling better comparison of computational and experimental results. RAIRS results revealed the presence of irreversibly adsorbed CO on top of five fold coordinated surface Ti atoms at 110K. Upon UV irradiation in the presence of molecular oxygen, a second band (attributed to physisorbed CO2) appeared and increased in intensity over time, while the CO adsorption band decreased. This photo-oxidation process (of CO to CO2) occurred.Whole document restricted until Nov. 2013, but available by request, use the feedback form to request access.
10
Predescu, Ligia. "Adsorption of nitrogen, methane, and carbon monoxide on aluminosilicate and aluminophosphate molecular sieves." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/10115.
Full textAbstract:
Considering the difficulties associated with the experimental determination of binary mixture adsorption isotherms, pure-gas adsorption information becomes vital in the prediction of these isotherms and the corresponding phase equilibria necessary in the design of adsorptive separation units. Experimental equilibrium isotherms describing the adsorption of pure N$\rm\sb2,\ CH\sb4,$ and CO in a natural aluminosilicate molecular sieve (clinoptilolite from Cuba) and two synthetic small-pore aluminophosphate molecular sieves (AlPO$\sb4$-17 and AlPO$\sb4$-18) have been determined using the volumetric method at 40$\sp\circ$C over a pressure range up to about 1000 mm Hg, and subsequently fitted with the Langmuir and Flory-Huggins Vacancy Solution Theory equations. Additional Langmuir and FH-VST fits of equilibrium isotherms previously measured over the same pressure range at room temperature and 40$\sp\circ$C to describe the equilibrium adsorption of the same three adsorbates in two aluminosilicate molecular sieves (natural clinoptilolite from Turkey and zeolite 5A), as well as in a medium-pore aluminophosphate molecular sieve AlPO$\sb4$-11 were also obtained. The Freundlich equation was found to yield a better fit than either the Langmuir or FH-VST equations for the experimental adsorption isotherms of N$\sb2$ and CO on AlPO$\sb4$-17. The higher observed capacities of the aluminosilicate molecular sieves, compared to the aluminophosphates, were attributed to the energetic heterogeneity conferred by the presence of framework-charge compensating cations. The model parameters obtained by fitting the experimental pure-component adsorption isotherms permitted the prediction of the mixture adsorption phase diagrams and the binary adsorption isotherms by the Extended Langmuir Model and the Flory-Huggins Vacancy Solution Model for the three possible binary mixtures at 101.3 kPa total pressure and the pure-component adsorption temperatures investigated. The Ideal Adsorbed Solution Theory was also applied with the explanation of the behaviour predicted by each model for each adsorption system was attempted. (Abstract shortened by UMI.)
11
Nolan, Peter Eugene 1958. "Separating carbon monoxide from carbon dioxide for Mars oxygen production using catalytic disproportionation or selective solid adsorption." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/558186.
Full text
12
Flemming, Christine Juliette Jane. "Impact and nature of open metal sites: a water and carbon monoxide adsorption study on MOF-74 isostructural MOFs." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/48992.
Full textAbstract:
In this work the magnesium, zinc, nickel and cobalt MOFs of the MOF-74 isostructural family are used to probe metal-dependent adsorbate interactions with water and with carbon monoxide because of their ability to generate open metal sites upon activation. An isostructural family is used so that the only variable from one MOF to another is the metal incorporated into the framework. For water adsorption isotherms with humidities up to 90%, the observed trend at 298K and 1 bar is Mg-MOF-74 > Zn-MOF-74 > Co-MOF-74 > Ni-MOF-74. This observed trend is due to Lewis acid-base interactions. When the weight effect is removed, differences are still observed, especially below 40% relative humidity, thereby confirming that there is a metal effect. These studies revealed that PXRD alone cannot indicate the level of structural decomposition and that none of the four isostructures fully retain their structural integrity on exposure to humidified air because of microstrain and/or the presence of oxygen; more studies examining the extent of structural decomposition need to be undertaken. For carbon monoxide adsorption the general observed trend for P < 4 bar and temperatures of 298, 313 and 333K is Co-MOF-74 > Ni-MOF-74 > Zn-MOF-74 > Mg-MOF-74. This trend is based on π-backbonding interactions. Here again, differences remain after removal of the weight effect, confirming the metal dependence. Notably, Co-MOF-74 has the highest CO loading at 298K and 1 bar reported so far. Both the Toth and Virial Isotherms were used to fit the CO adsorption data followed by the use of the Clausius-Clapeyron equation to find the isosteric heats of adsorption, qst. The results from the Toth isotherm are more reliable and showed that qst remains constant as loading increases for Mg-MOF-74, decreases for Zn-MOF-74 and increases with loading for Co-MOF-74 and Ni-MOF-74; Ni-MOF-74 had the highest heat of adsorption at all loadings. It appears that using the Clausius-Clapeyron equation to calculate qst is an inappropriate method for Ni-MOF-74 so other methods such as calorimetry are recommended. It is also recommended to model the data of all the MOFs with other isotherm models such as Sips equation and to investigate the possibility of chemisorption for the cobalt and nickel isostructures. Finally, Henry’s constant results reveal that Ni-MOF-74 has the highest affinity for CO at low coverages.
13
Eve, Jemimah Kate. "Adsorption and co-adsorption on metal single crystals at cryogenic temperatures." Thesis, University of York, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313949.
Full text
14
Gottfried, Jörg Michael. "CO oxidation over gold adsorption and reaction of oxygen, carbon monoxide, and carbon dioxide on an Au(110)-(1x2) surface /." [S.l. : s.n.], 2003. http://www.diss.fu-berlin.de/2003/133/index.html.
Full text
15
Michel, Anne-Charlotte. "Structure et réactivité en chimisorption et catalyse des alliages Pd8Ni92 (111) et (110)." Lyon 1, 2000. http://www.theses.fr/2000LYO10264.
Full textAbstract:
Ce travail vise à caractériser au mieux les surface d'alliage Pd8Ni92 (111) et (110), et à étudier les propriétés chimisorptives et réactives de ces faces afin de déterminer les facteurs (géométriques, électroniques. . . ) qui influencent les propriétés catalytiques de ces systèmes bimétalliques. Un très fort enrichissement en Pd (80 % atomique) dans l'ultime plan de surface a été mis en évidence pour les deux faces de l'alliage conduisant à une reconstruction de surface dans le cas de la face (110). L'étude de l'adsorption de CO par spectrométrie vibrationnelle (HREELS) et thermodésorption a montré que les propriétés chimisorptives des faces (110) et (111) de l'alliage sont modifiées par rapport aux faces correspondantes du Pd pur, celles de la face (110) étant toutefois moins altérées que la face (111) : une diminution de l'énergie d'adsorption de CO a pu être observée sur les alliages et les sites d'adsorption ont pu être caractérisés (sites linéaires, pontés ternaires, Pd, Ni ou mixtes PdNi). Les mesures de réactivité en hydrogénation du butadiène indiquent que le Pd présent à la surface de l'alliage est beaucoup plus actif que le Pd pur et ceci d'autant plus sur la face (110), l'alliage étant vingt fois plus actif que le palladium. Contrairement à la face (110), la face (111) se désactive au cours de la réaction. L'étude de la chimisorption du butadiène par HREELS a permis de montrer une adsorption de type di-π sur la face (110) de l'alliage, identique à celle observée sur Pd (110). Sur la face (111), le butadiène se modifie par réaction de surface.
16
Zein, Eddin Mohamed Yahia. "Caractérisation de catalyseurs bimétalliques cobalt-manganèse issus de carbonyles, actifs en hydrogénation du CO." Lyon 1, 1989. http://www.theses.fr/1989LYO10094.
Full textAbstract:
Des catalyseurs au cobalt et au cobalt manganese, prepares par impregnation d'alumine par les metaux carbonyles et le carbonyle mixte comn(co)9 en solution ont ete etudies par spectroscopie ir, chimisorption du co et mesures magnetiques. Les especes subcarbonyles formees resultant de l'action des groupements superficiels de l'alumine et dependent de la teneur en cobalt. Cependant, des 60#oc aucune difference n'est obtenue pour les carbonyles du cobalt de nuclearite differente. Les melanges co2(co)8 et mn2(co)10 ne donnent lieu a aucune reaction entre especes de comn(co)9 n'est pas detruit lors de cette fixation. L'etude des catalyseurs mixtes a permis de mettre en evidence un site d'adsorption du co particulier caracterise par une frequence ir du co adsorbe elevee. La position de cette bande a pu etre correlee a l'activite catalytique de ces solides en synthese de fischer-tropsch. L'utilisation du carbonyle mixte permet d'obtenir des particules de cobalt tres fines (2,5 nm) en interaction etroite avec le manganese et tres actives pour la meme reaction
17
Krauth, Oliver. "Investigation of the surface enhanced infrared absorption in the case of carbon monoxide on iron thin films." [S.l. : s.n.], 1999. http://deposit.ddb.de/cgi-bin/dokserv?idn=961929510.
Full text
18
Gertenbach, Rosalind May. "Methane and carbon dioxide sorption studies on South African coals." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1919.
Full textAbstract:
Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2009.Sequestration of carbon dioxide, CO2, has received large interest as a viable option for mitigating the high atmospheric concentrations of this greenhouse gas. Each year 25 gigatons of anthropogenic CO2 (7.3 GtC/yr) are released into the earth’s atmosphere with the combustion of fossil fuels being the major contributing source. Research in the field of sequestration technology involves evaluating various geological structures as possible reservoirs, determining adsorption capacities of natural formations and developing methods for carbon dioxide injection and the monitoring thereof. Identified potential CO2 reservoirs for geological carbon sequestration (GCS) include saline formations, depleted oil and gas fields and deep coal seams. Carbon dioxide sequestration in coal seams provides the economic opportunity of enhanced coalbed methane (CH4) recovery (ECBM). In South Africa, some coal seams are considered a viable option for long term CO2 sequestration projects as they are abundant and closely situated to South Africa’s largest concentrated CO2 point sources. Many studies have been conducted to determine the sorption capacities for methane and carbon dioxide gases on various coals from around the world; however, similar data have not been recorded for South African coals. The objectives of this study are to determine the adsorption capacities for methane and carbon dioxide of three South African coals over a pressure range of 0 – 50 bar. In the study, single-component gas adsorption experiments were conducted and the absolute adsorption capacities are reported. Isothermal adsorption experiments were conducted using both the volumetric and gravimetric methods with the volumetric apparatus pressure range extending up to 50 bar and the gravimetric apparatus up to 20 bar. Carbon dioxide adsorption capacities are much higher than the methane adsorption capacities, which are expected. Gravimetric experiments produce greater adsorption capacities than the volumetric method. However, the relative CO2/CH4 ratios for each coal, as well as the relative CO2/CO2 ratios between coals, remain almost identical. The difference in adsorption capacity is attributed to the strength of the vacuum pump used on each apparatus. The gravimetric apparatus makes use of a much stronger vacuum pump which can thus evacuate the coal pores more adequately than in the volumetric apparatus. The methane and carbon dioxide adsorption capacities of the three moisture-free coals compare well with literature data. The adsorption isotherms fit conventional adsorption models (the Langmuir and Freundlich adsorption equations) extremely well thus indicating that monolayer adsorption takes place. Since no internationally recognised testing standards are in place regarding adsorption procedures on coal, it is very difficult to compare adsorption results presented in the literature. Respective researchers determine their own experimental conditions for the many variables in coal adsorption studies. It is recommended that international testing standards be set in place to make coal research comparable. Such efforts would aid the development of a coal adsorption database, another recommendation, which would advance sequestration technology exchange and eliminate duplication of research efforts. The objectives of the project were achieved by determining the absolute adsorption capacities for carbon dioxide and methane gas of the three South African coals within a pressure range of 0 – 50 bar. Further work is required to investigate adsorption capacities of South African coals under supercritical conditions (above 73 bar abs and 31.1 oC).
19
Gallaba, Gallaba Mudiyanselage Dinuka Harshana. "AN EXPERIMENTAL STUDY OF STRUCTURAL DEFORMATION AND “GATE OPENING” OF ZEOLITIC IMIDAZOLATE FRAMEWORK-8 UPON GAS SORPTION: THERMODYNAMIC AND KINETIC EVIDENCE." OpenSIUC, 2020. https://opensiuc.lib.siu.edu/dissertations/1858.
Full textAbstract:
Volumetric adsorption experiments were conducted over three sorbates in Zeolitic Imidazolate Framework – 8 (ZIF-8). The sorption isotherms were measured at low temperatures. The study included carbon monoxide sorption in ZIF-8, xenon in ZIF-8, and methane sorption in ZIF-8. As a metal-organic framework that has been investigated thoroughly for its remarkable characteristics, ZIF-8 interactions with the above three sorbates has revealed some new features. Each of these systems offered a unique opportunity to study the physical properties of the sorbate and ZIF-8 and the thermodynamic responses of the system for its unique characteristics. The fundamental understating of sorbents-sorbate not only reveals some of the remarkable properties but also opens up new frontiers for researches in practical applications such as gas storage separation and other sorption-based fields of interest. The investigation into CO-ZIF-8 system has confirmed some of the predictions made on a similar system and analysis on the ZIF-8 structure. The measured adsorption isotherms have confirmed the existence of three pre-saturation subs steps, which were explained in terms of effects from the structural transition and polarity of the sorbate. The behavior of isosteric heat of adsorption and the equilibration time revealed a strong connection between steps in the isotherm and the structural changes of ZIF-8 due to organic linker rotation and volume expansion, also known as “Gate-Opening” in some cases. In both Xe-ZIF-8 and CH4 -ZIF-8 systems, the sorption isotherms revealed two substeps before the saturation. This is the first time such a feature was resolved experimentally in these systems although many previous studies have predicted the feature. The experimental observations on characteristics of the Xe -ZIF-8 system are also verified by computer simulations. Unlike the CO-ZIF-8 system, Xe-ZIF-8 interactions do not trigger the organic linker rotation of ZIF-8 structure, but it influenced the expansion of the ZIF-8 structure. In CH4 – ZIF-8 system the isotherms’ substeps were not as steep as Xe system but the loading dependence of isosteric heat of adsorption and equilibration time revealed features that are similar to CO. The lack of sorption-combined structural analysis of CH4-ZIF-8 prevent us from concluding the actual nature of the changes occurring which are related to the substeps and other thermodynamic and kinetic features. In all three systems, our measurements of the adsorption kinetics, we observed a non-monotonic behavior of the equilibration time as a function of sorbent loading. For CO the loading dependence of equilibration time exhibit peaks at loadings that correspond to the intermediate and higher loading sub-steps, and CH4 showed similar behavior at the loading corresponds to its intermediate substep region. The sharp peaks can be interpreted as packing rearrangement of adsorbed phase molecule in both cases and for CO there may be some contributions from the linker flipping and structural transition. The structural effect of kinetics is yet to be confirmed by a structural analysis for the CH4 system.
20
Ager, Patrick. "Mobilizationpurging of aqueous metal ions into supercritical carbon dioxide." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=20553.
Full textAbstract:
The technology of supercritical fluid extraction (SFE) offers the opportunity to efficiently extract both relatively non-polar analytes as well as ionic materials (such as metal ions) that can be mobilized with the addition of complexing reagents. The nebulizer of a conventional flame atomic absorption spectrometer (FAAS) was modified to extend the range of metals amenable to on-line detection. The flow injection thermospray-FAAS (FI-TE-FAAS) interface provided efficient detection for a variety of less volatile elements (Co, Cr(III), Cr(VI), Fe, Ni, Mn and Al) present as ions in aqueous media or as complexes in the supercritical fluid (SC-CO2) carrier phase. The range of possible metal analytes that can be monitored has been increased over the nine elements (Ag, As, Cd, Cu, Hg, Mn, Pb, Se and Zn) that could be detected with an all-silica interface. The acetylacetonate complexes offered considerable potential for metal detection in an SC-CO2 carrier phase. Limits of detection (LODs) were used to compare the instrument responses to different metals. (Abstract shortened by UMI.)
21
Wilson, Sean M. W. "Adsorption Separation of CO2 from CO in Syngas: Improving the Conversion of the Reverse Water Gas Shift Reaction." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33169.
Full textAbstract:
In this research project, adsorption is considered for the separation of CO2 from CO for applications such as industrial syngas production and in particular to improve the conversion of the Reverse Water Gas Shift (RWGS) process. The use of adsorption technology for these applications requires an adsorbent that can effectively separate out CO2 from a gas mixture containing CO2, CO, and H2. However, adsorption of H2 is insignificant when compared to both CO2 and CO, with only CO2 and CO being the adsorbed species. The adsorption of CO2 and CO was investigated in this work for four major types of industrial adsorbents which include: activated aluminas, activated carbons, silica gels, and zeolites. Zeolites, with their ability to be fine tuned many parameters which may affect adsorption, were investigated in terms of the effect of the cations present, SiO2/Al2O3 ratios, and structure to determine how to optimize adsorption of CO2 while decreasing adsorption of CO. This will help to determine a promising adsorbent for this separation with focus on maximizing the selective adsorption of CO2 over CO.
To investigate this separation three scientific experimental methods were used; gravimetric adsorption isotherm analysis, volumetric adsorption isotherm analysis, and packed bed adsorption desorption breakthrough analysis. Gravimetric and volumetric methods allow for testing the adsorbent with the individual species of CO2 and CO. This investigation will let us determine the pure component adsorption capacity, heats of adsorption, regenerability, and basic selectivity. Packed bed adsorption breakthrough experimentation was then carried out on promising adsorbents for the CO2 separation from a mixture of CO2, CO, and H2. These experiments used a gas mixture that would be comparable to that produced from the RWGS reaction to determine the multicomponent gas mixture behaviour for adsorption. Temperature swing adsorption (TSA) with a purge gas stream of H2 was then used to regenerate the adsorbent.
22
Knöfel, Christina. "Synthesis, characterisation and evaluation of porous materials for the adsorption of carbon dioxide." Aix-Marseille 1, 2009. http://www.theses.fr/2009AIX11005.
Full textAbstract:
In this work, mesoporous oxides, namely silica, titania and zirconia were synthesised using a triblock copolymer as structure directing agent. Further, the silica and the titania materials were functionalised with different aminosilane molecules. Characterisation of the prepared materials was carried out using various methods including nitrogen sorption, ATR infrared spectroscopy and X-ray diffraction. The materials were tested for their carbon dioxide adsorption properties using mainly microcalorimetry. In-situ infrared measurements and theoretical DFT calculations were carried out to help understand the microcalorimetric adsorption results in certain cases. With respect to the different carbon dioxide adsorption, it was highlighted that the functionalisation of amine sites on silica materials significantly improved the adsorption capacities. A comparison of the different oxides has shown that the adsorption properties mainly depend on the strength of the metal-oxygen bond within the oxides but also on the textural characteristics, such as porosity of the investigated materialsDans ce travail, des oxydes mesoporeux, tels que silice, oxyde de titane et oxyde de zircone ont été synthétisés en utilisant un copolymère à triblock comme agent structurant. De plus, la silice et l’oxyde de titane ont été fonctionnalisés avec différentes molécules d'aminosilane. La caractérisation des matériaux préparés a été effectuée par diverses méthodes, telles que la sorption d'azote, la spectroscopie infrarouge (ATR) et la diffraction des rayons X. Les matériaux ont été examinés pour leurs propriétés d'adsorption du dioxyde de carbone utilisant principalement la microcalorimétrie. Dans certains cas, des mesures de spectroscopie IR in-situ et des calculs théoriques de DFT ont été effectués pour mieux comprendre les résultats obtenus par microcalorimétrie d’adsorption. En ce qui concerne les différentes propriétés d'adsorption nous avons mis en évidence que la functionalisation des emplacements d'amine sur les matériaux de silice a amélioré de manière significative les capacités d'adsorption. Une comparaison des différents oxydes a confirmé que les propriétés d'adsorption dépendent principalement de la force du lien du métal-oxygène dans les oxydes mais également des caractéristiques de texture, telles que la porosité
23
Naumann, d'Alnoncourt Raoul. "The coverage dependent adsorption of carbon monoxide on copper catalysts studied by a combination of adsorption microcalorimetry, temperature programmed desorption and Fourier transform infrared spectroscopy." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975763873.
Full text
24
Daoudi, Abdelali. "Systèmes Métal-CO comme modèles de chimisorption : interaction de configuration et orbitales naturelles." Paris 11, 1988. http://www.theses.fr/1988PA112050.
Full textAbstract:
Nous nous sommes intéressé à l'étude de la nature des interactions entre un métal de transition de le 1ère série- M = Cu, fe et Ti - et une molécule de monoxyde de carbone CO. Ce travail porte d'abord sur les molécules triatomiques MCO, pour lesquelles il existe certaines données expérimentales, mais concerne aussi le domaine de la chimisorption et éventuellement le domaine de la réactivité catalytique. Les calculs de self consistance (SCF) suivis d'une interaction de configuration (IC) nous ont permis, après une recherche systématique, l'attribution de l’état fondamental et des premiers états excités qui sont inconnus pour les molécules MCO et considérées. Les structures électroniques, courbes de potentiel, géométries d’équilibre, champs de force harmoniques complets et vibrations sont présentés et discutés pour l'état fondamental et le premier excité trouvés pour ces systèmes. Ces calculs nous ont permis de déterminer les ressemblances, les différences ainsi que les facteurs influençant la liaison C-0 et la liaison M-C lorsqu'on se déplace dans la série 3d des métaux de transition. Ces calculs théoriques ont nécessité des outils de travail appropriés : un traitement SCF plusieurs couches ouvertes et un traitement d'IC capable de récupérer une partie importante de la corrélation et de tenir compte des problèmes de quasi dégénérescence. Pour les systèmes étudiés ici l'approximation de Hartree-Fock conduit souvent à des résultats insuffisants ; d'importants effets de corrélation apparaissent non seulement dans la détermination des paramètres structuraux, mais aussi dans la description de l’interaction entre M et CO. Dans le traitement de corrélation par variation-perturbation, l'emploi des orbitales naturelles joints à un hamiltonien monoélectronique à nombres d'occupation variables s'avère très efficace pour la convergence du développement d'IC. En plus de leur intérêt pour cette fin, les orbitales naturelles facilitent l'analyse des fonctions d'onde IC ainsi obtenues. D’après les résultats obtenus dans ce travail, nous avons mis en évidence des lois sur la donation et la rétrodonation sous forme explicite et même sous forme qualitative à des fins prédictives.
25
Foster, Paul J. "Continuous Co-Separation by Liquid Absorption in Aqueous Cuprous Chloride (CuCl) and Magnesium Chloride (MgCl2) Solution." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1789.pdf.
Full text
26
Austin, Lydia B. "The feasibility of using airborne carbon dioxide flux measurements for imaging the rate of biomass production /." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65452.
Full text
27
Venkatachalam, Sri Saran. "Polymer-derived carbon materials for terahertz wave absorption." Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10013.
Full textAbstract:
L’objectif de ce travail de thèse est de développer des absorbants large bande et un détecteur thermique à base de matériaux carbonés issus de la pyrolyse de polymères, pour des applications dans le domaine terahertz. Deux types de polymères précurseurs ont été utilisés: un polymère organique (polyimide) et un hybride organique-inorganique (organopolysiloxane). La conversion thermique sous atmosphère inerte a été suivie par diverses techniques d’analyse : la thermogravimétrie couplée à la spectrométrie de masse, les spectroscopies Infrarouge et Raman. Les matériaux issus du polymère organique sont constitués principalement de carbone graphitique avec des rendements à la pyrolyse de 55% en poids. En revanche, la pyrolyse des organosiloxanes conduit à des matériaux céramiques de type composite dans lesquels des domaines de graphène sont répartis dans un réseau oxycarbure de silicium, avec des rendements de 85% en poids. L’absorption THz de 78%, sur une large bande 0.2-3 THz, a été obtenue sur l’échantillon d’épaisseur 0.95 mm, issu de la pyrolyse à 1500 °C du polymère organosilicé. Le principal avantage de l’utilisation de polymères réside dans la facilité de leur mise en forme pour obtenir des formes complexes aux dimensions souhaitées, grâce au procédé par coulage. Comme preuve de concept, la fabrication d’un micro-bolomètre, utilisant le matériau carboné céramique à structure pyramidale comme absorbant THz à large bande, a permis d’atteindre une sensibilité SV de 0.76V/W, une constante de temps de 180ms et un seuil de détection de puissance de 2 nW/Hz1/2, valeur avoisinant, voire meilleure, que celle des dispositifs actuellement disponibles sur le marchéThe aim of this work is the development of broadband absorbers and thermal detectors, based on carbon materials issued from pyrolysis of polymers and devoted to terahertz (THz) applications. Two types of polymer, organic (polyimide) and hybrid organic-inorganic polysiloxane, have been used. The progress of thermal conversion of these polymers in inert atmosphere was followed by thermogravimetric analysis coupled with mass spectrometry, and IR and Raman spectroscopies. The pyrolysis of polymers up to 1200 °C left black residues materials.Organic-derived materials are composed of mainly graphitic-carbon with a yield of about 55 wt%, while organosiloxane polymers result in a ceramic composite material, in which free carbon domains are embedded into an oxycarbide network, with a yield of 85 wt%.It has been found that the presence of sp2 carbon is necessary but not sufficient in and itself for the absorption of terahertz radiations. Carbon must be at least partially ordered into a few stacked-graphene layers. The THz absorbance of up to 78% over the broadband of 0.2-3 THz was obtained for a 0.95 mm thick sample resulting from pyrolysis of organosiloxane polymer at 1500 °C. The main advantage of using polymers lies in their ability to form complex small parts in a near net-shape by the casting process.Finally, using net-shaped pyramidal ceramic structures as absorbers, a proof of concept was achieved with the fabrication of a broadband terahertz micro-bolometer, with a responsivity of 0.76 V/W, time constant of 180 ms, and noise equivalent power of 2 nW/Hz1/2, thus putting it in fair competition with commercial thermal detectors
28
Shinall, Brian Darnell. "The use of layered double hydroxides as adsorbents for carbon dioxide." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/10156.
Full text
29
Karra, Jagadeswarareddy. "Development of porous metal-organic frameworks for gas adsorption applications." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45751.
Full textAbstract:
Metal-organic frameworks are a new class of porous materials that have potential applications in gas storage, separations, catalysis, sensors, non-linear optics, displays and electroluminescent devices. They are synthesized in a "building-block" approach by self-assembly of metal or metal-oxide vertices interconnected by rigid linker molecules. The highly ordered nature of MOF materials and the ability to tailor the framework's chemical functionality by modifying the organic ligands give the materials great potential for high efficiency adsorbents. In particular, MOFs that selectively adsorb CO₂ over N₂, and CH₄ are very important because they have the potential to reduce carbon emissions from coal-fired power plants and substantially diminish the cost of natural gas production. Despite their importance, MOFs that show high selective gas adsorption behavior are not so common.
Development of MOFs for gas adsorption applications has been hindered by the lack of fundamental understanding of the interactions between the host-guest systems. Knowledge of how adsorbates bind to the material, and if so where and through which interaction, as well as how different species in adsorbed mixture compete and interact with the adsorption sites is a prerequisite for considering MOFs for adsorptive gas separation applications. In this work, we seek to understand the role of structural features (such as pore sizes, open metal site, functionalized ligands, pore volume, electrostatics) on the adsorptive separation of CO₂, CO and N₂ in prototype MOFs with the help of molecular modeling studies (GCMC simulations). Our simulation results suggest that the suitable MOFs for CO₂ adsorption and separation should have small size, open metal site, or large pore volume with functionalized groups.
Some of the experimental challenges in the MOF based adsorbents for CO₂ capture include designing MOFs with smaller pores with/without open metal sites. Constructing such type of porous MOFs can lead to greater CO₂ capacities and adsorption selectivities over mixtures of CH₄ or N₂. Therefore, in the second project, we focused on design and development of small pore MOFs with/without open metal sites for adsorptive separation of carbon dioxide from binary mixtures of methane and nitrogen. We have synthesized and characterized several new MOFs (single ligand and mixed ligand MOFs) using different characterization techniques like single-crystal X-ray diffraction, powder X-ray diffraction, TGA, BET, gravimetric adsorption and examined their applicability in CO₂/N₂ and CO₂/CH₄ mixture separations. Our findings from this study suggest that further, rational development of new MOF compounds for CO₂ capture applications should focus on enriching open metal sites, increasing the pore volume, and minimizing the size of large pores.
Flue gas streams and natural gas streams containing CO₂ are often saturated by water and its presence greatly reduces the CO₂ adsorption capacities and selectivities. So, in the third project, we investigated the structural stability of the developed MOFs by measuring water vapor adsorption isotherms on them at different humid conditions to understand which type of coordination environment in MOFs can resist humid environments. The results of this study suggest that MOFs connected through nitrogen-bearing ligands show greater water stability than materials constructed solely through carboxylic acid groups.
30
Loffreda, David. "Modélisation théorique de l'adsorption et de la réactivité de la molécule NO sur les surfaces de catalyseurs à base de palladium, de rhodium et d'alliages palladium-manganèse." Lyon 1, 1999. http://www.theses.fr/1999LYO10295.
Full textAbstract:
Les pots catalytiques assurent le traitement des gaz d'echappement par des catalyseurs trois-voies composes de rhodium, actif vis-a-vis de la reduction du monoxyde d'azote no, de palladium et de platine, actifs vis-a-vis de l'oxydation du monoxyde de carbone co et des hydrocarbures residuels. Cette difference entre les metaux est encore mal elucidee. Afin de comprendre la specificite du rh, l'etude des sites d'adsorption et de l'activite des surfaces metalliques envers la dissociation de no est realisee au moyen de calculs quantiques utilisant la theorie de la fonctionnelle de la densite. Dans une premiere etape, les differents sites d'adsorption moleculaire de no et de co sont caracterises par leurs proprietes geometriques, electroniques et vibrationnelles, sur les surfaces de pd et de rh (100), (111) et (511), et d'alliage palladium-manganese pd 3mn (100) et (111). La relation entre les modes d'adsorption et les frequences d'elongation n-o et c-o est etablie. Les sites ternaires sont preferentiels sur les surfaces (111). Ceci contraste avec l'interpretation usuelle des spectres infrarouges experimentaux qui conclut a l'existence de sites pontes. De nouvelles gammes de frequences sont donc proposees pour ameliorer l'analyse vibrationnelle experimentale. Dans une seconde etape, les proprietes thermodynamiques, cinetiques et vibrationnelles de la reaction de dissociation de no sont modelisees sur ces surfaces. L'energie d'activation de la reaction depend fortement du chemin reactionnel emprunte lors de la decomposition de la molecule. Sur les surfaces pd (100), pd et rh (111), le chemin reactionnel est long, l'energie d'activation est grande et la cinetique est tres lente a temperature ambiante. Sur les surfaces pd (511), rh (100) et (511), pd 3mn (100), le chemin reactionnel est plus court car l'etat de transition a une geometrie proche de l'etat stationnaire de depart. L'energie d'activation est nettement abaissee et la cinetique est, par consequent, plus rapide.
31
Leclerc, Hervé. "Caractérisation par spectroscopie infrarouge de solides organiques inorganiques de type MOF (Metal Organic Framework) : Thèse soutenue sur un ensemble de travaux." Caen, 2011. http://www.theses.fr/2011CAEN2017.
Full textAbstract:
Ce travail rapporte la caractérisation par spectroscopie infrarouge in situ d’une famille iso-structurale de quatre solides poreux organiques-inorganiques de type MOF (MOF : Metal Organic Framework) dénommés MIL-100(X) (MIL pour Matériaux de l’Institut Lavoisier) avec X= Al3+, Fe3+, Al3+ et V3+. Les caractérisations des centres métalliques et des propriétés acido-basiques ont été réalisées pour différentes températures d’activation des matériaux par ajouts ou non de molécules sondes telles que CO, CO2, CD3CN, pyridine et propyne. La première partie, portant sur l’étude du MIL-100(Cr), révèle l’absence de sites basiques de force notable, mais la présence de centres acides de Lewis Cr3+ localisés sur les trimères. L’adsorption d’eau ou d’alcools transforme ces sites en sites acides Bronsted dont la force dépend de la nature de l’adsorbat et du complexe formé. La deuxième partie est consacrée à l’étude du MIL-100(Fe). Elle révèle d’abord l’existence de sites Fe3+ susceptibles de se réduire en sites Fe2+ par chauffage sous vide, puis démontre l’existence d’un phénomène de rétrodonation qui accroit les interactions entre les sites Fe2+ insaturés et des molécules telles que le CO, le propène et le propyne. L’étude spectroscopique du MIL-100(Al), présentée en troisième partie, rapporte pour la première fois une caractérisation fine de sites Al3+ insaturés en conformation pentaédrique et présents en grande quantité dans un environnement cristallographique bien défini. Le dernier chapitre présente une caractérisation du MIL-100(V) pour différentes température d’activation : nature des espèces extra réseaux et des centres métalliques insaturésThis study reports the characterization by in situ infrared spectroscopy of an isostructural family of four porous MOFs (MOF: Metal Organic Framework) denoted MIL-100(X) (MIL: Material from the Institute Lavoisier) with X: Al3+, Fe3+, Al3+ and V3+. The characterizations of the metallic centers and acido-basic properties have been performed at different temperature of activation by adsorption or not of probe molecules such as CO, CO2, CD3CN, pyridine and propyne. The first part devoted to the MIL-100(Cr), reveals the lack of any significant basic sites but the occurrence of Cr3+ Lewis acid sites located on the trimers. Adsorption of water or alcohols transforms the Lewis sites into Bronsted acid sites whose strength depends on the nature of the adsorbate and of the complex formed. The second part is dedicated to the study of the MIL-100(Fe) material. It reveals first the presence of Fe3+ sites able to be reduced into Fe2+ sites by thermal treatment under vacuum and secondly demonstrates the occurrence of a pi-back donation effect which increases the interactions between Fe2+ unsaturated sites and molecules such as CO, propene and propyne. The spectroscopic study of MIL-100(Al) presented in the third part reports for the first time a precise characterization of unsaturated pentahedral Al3+ sites present in a large amount and in a well defined crystallographic environment. The last chapter presents the characterization of MIL-100(V) activated at different temperatures: nature of the extra framework species and of unsaturated metallic sites
32
Dotse, Charles Kafui. "ELECTROCHEMICAL AND SURFACE-ENHANCED RAMAN SPECTROSCOPIC STUDIES OF FORMIC ACID OXIDATION, CARBON MONOXIDE AND 1, 4-PHENYLENEDIISOCYANIDE ADSORPTION ON METAL NANOPARTICLES." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1451993102.
Full text
33
Rodolfo, Barron Jimenez. "Application of an all-solid-state diode-laser-based sensor for carbon monoxide detection by optical absorption in the 4.4 4.8 µm spectral region." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1509.
Full textAbstract:
An all-solid-state continuous-wave (cw) laser system for mid-infrared absorption measurements
of the carbon monoxide (CO) molecule has been developed and demonstrated. The single-mode, tunable
output of an external-cavity diode laser (ECDL) is difference-frequency mixed (DFM) with the output of a
550-mW diode-pumped cw Nd:YAG laser in a periodically-poled lithium niobate (PPLN) crystal to
produce tunable cw radiation in the mid-infrared. The wavelength of the 860-nm ECDL can be coarse
tuned between 860.78 to 872.82 nm allowing the sensor to be operated in the 4.4 4.8 µm region. Results
from single-pass mid-IR direct absorption experiments for CO concentration measurements are discussed.
CO measurements were performed in CO/CO2/N2 mixtures in a room temperature gas cell that allowed the
evaluation of the sensor operation and data reduction procedures. Field testing was performed at two
locations: in the exhaust of a well-stirred reactor (WSR) at Wright-Patterson Air Force Base and the
exhaust of a gas turbine at Honeywell Engines and Systems. Field tests demonstrated the feasibility of the
sensor for operation in harsh combustion environments but much improvement in the sensor design and
operation was required. Experiments in near-adiabatic hydrogen/air CO2-doped flames were performed
featuring two-line thermometry in the 4.8 µm spectral region. The sensor concentration measurement
uncertainty was estimated at 2% for gas cell testing. CO concentration measurements agreed within 15%
of conventional extractive sampling at WSR, and for the flame experiments the repeatability of the peak
absorption gives a system uncertainty of 10%. The noise equivalent CO detection limit for these
experiments was estimated at 2 ppm per meter, for combustion gas at 1000 K assuming a SNR ratio of 1.
34
Aufdenkampe, Anthony Keith. "The role of sorptive processes in the organic carbon and nitrogen cycles of the Amazon River Basin /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/10968.
Full text
35
Peredo, Mancilla Joselin Deneb. "Adsorption and Separation of Carbon Dioxide for Biomethane Production : The Use of Activated Carbons." Thesis, Pau, 2019. http://www.theses.fr/2019PAUU3012/document.
Full textAbstract:
Le biométhane est une source d'énergie verte qui, de part son coût et son faible impact environnemental, peut être considéré comme une alternative au gaz naturel et au diesel. La production d'énergie primaire par l'Union Européenne, à partir du biométhane, a été multipliée par 23 en cinq ans (2011-2016), ce qui rend nécessaire et urgent la recherche de nouvelles solutions performantes pour l’épuration du biogaz, notamment la séparation du dioxyde de carbone (CO2) du méthane (CH4).Dans ce contexte, l’objectif de ce travail doctoral porte sur la détermination des indicateurs de performances (capacité d’adsoprtion, sélectivité) de charbons actifs (CAs) dans le contexte de la séparation méthane/dioxyde de carbone pour la production de biométhane. A cette fin, les isothermes d'adsorption de CH4 et CO2 ont été déterminées à partir d’un dispositif manométrique d’adsorption. Les mesures ont été effectuées à des températures de 303 et 323 K pour des pressions variant de 0.1 à 3 MPa. Dans un premier temps, l’étude a porté sur 5 échantillons commerciaux de CA différents. Les résultats montrent une corrélation entre la surface spécifique et la quantité de dioxyde de carbone adsorbée. En outre, le volume microporeux a un impact significatif lors des processus d'adsorption du CO2 tandis que le volume des mésopores n'a pas d’effet direct.Par ailleurs, l'étude complémentaire d'isothermes d'adsorption du CH4 et du CO2 purs à l’aide de trois charbons actifs, issus de noyaux d’olive, activés par différentes méthodes de synthèse, révèle que la méthode d'activation est déterminante pour modifier les propriétés chimiques et structurales des charbons actifs et donc accroitre leurs propriétés d'adsorption.En outre, la sélectivité des CAs commerciaux pour la séparation CH4/ CO2 a été calculée à partir des isothermes d'adsorption du mélange équimolaire CH4/ CO2 à une température de 303 K et pour des pressions jusqu'à une pression de 3 MPa. Les résultats obtenus montrent qu’une surface spécifique élevée (< 1500 m2 g-1) facilite l'adsorption du CO2 mais réduit le facteur de sélectivité. En parallèle, une forte porosité conduit à une séparation moins efficace des deux gaz alors que la présence de groupes basiques en surface favorise les phénomènes d’adsorption du CO2.L'ensemble des résultats montre que les charbons actifs, étudiés dans ce travail de recherche, possèdent des propriétés d'adsorption comparables à celles des charbons actifs commerciaux et sont des matériaux compétitifs pour l'épuration du biogazBiomethane is a proven source of clean energy, it is one of the most cost-effective and environment-friendly substitute for natural gas and diesel. The European Union primary energy production from biomethane has folded by ~23 times in a 5 years time period (2011-2016) making necessary to find new and improved solutions for the separation of methane (CH4) and carbon dioxide (CO2), main components of biogas. In this context, the objective of this doctoral thesis is the determination of performance indicators such as the adsorption capacity and selectivity of activated carbons (ACs) for the CH4/ CO2 separation. This work focuses on the adsorption properties of activated carbons for the methane/carbon dioxide separation. To this end, CH4 and CO2 pure gas experimental adsorption isotherms of activated carbons were obtained on a pressure range of 0.1 to 3 MPa) and temperatures ranging from 303 to 323 K. The first part of this thesis project consisted in the analysis of the CH4 and CO2 pure gas adsorption properties of 5 commercial activated carbons Using a set of five commercial activated carbons a linear relationship between the adsorbent surface area and the CO2 adsorption capacity was determined. The micropore volume also showed a direct influence on the adsorption capacity. The second part of this work consisted in the study of the carbon dioxide and methane adsorption behavior of biomass-based activated carbons. Using a series of 3 ACs that had been obtained from olive stones by different activation methods, the activation technique proved to be of mayor importance as it determines the textural and chemical properties of the adsorbent and thus its gas adsorption capacity.Lastly, the CH4/CO2 adsorption selectivity of the 5 commercial activated carbons was calculated from the equimolar mixture adsorption isotherms. The selectivity factor was proven to be dependent on the sum of textural and chemical properties of the samples. Although, activated carbons with high average pore sizes and surface areas depicted higher adsorbed quantities it was on detriment of their selectivity. The selectivity was found to be better for the activated carbon showing an intermediate surface area and a narrow pore size distribution. In addition, the presence of sulfur functionalities was also found to improve the adsorption selectivity. Overall, this work shows that activated carbons are competitive materials for the upgrading of biogas, displaying adsorption properties comparable to those of other commercially available materials
36
Lozinska, Magdalena Malgorzata. "Investigation of inorganic porous solids as adsorbents for the separation of carbon dioxide from flue gas." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3964.
Full textAbstract:
Porous inorganic solids including mesoporous silicas, zeolites and silicoalumnio-phosphates have been investigated as adsorbents for carbon dioxide, particularly in relation to uptake from flue gases at 0.1 bar and ca. 298 K, but also at higher pressures. The mesoporous silicas SBA-1 and SBA-2, with mesocages separated by narrower windows, have been prepared, calcined at various temperatures and also nitrided with ammonia at high temperature. Nitridation has resulted in framework nitrogen incorporation, but this gave only small increases in the uptake of CO₂ of these mesoporous silicas, which are very low (< 0.2 mmol g⁻¹) at flue gas conditions (0.1 bar, 298 K). A series of cationic forms of the small pore zeolites, chabazite, ZK-5 and Rho, have been prepared by exhaustive cation exchange (and pre-calcination of the as-prepared form of Rho). In addition, a series of ultrastabilised zeolite Rho samples has been prepared to investigate the influence of extra-framework aluminium species on CO₂ uptake. For comparison, the silicoaluminophosphate versions of ZK-5 (SAPO STA-14) and Rho (SAPO(RHO)) have been prepared. Adsorption on Li-, Na-, K- and Ca-forms of chabazite (Si/Al = 3.0) has been related to the crystal structures of their dehydrated forms, as determined by Rietveld refinement against powder X-ray diffraction data (PXRD). For Na- and K-chabazite the structure has been measured in situ by PXRD during CO₂ adsorption. Li-chabazite has the highest uptake from all chabazite cationic forms (4.3 mmol g⁻¹). PXRD of K-chabazite reveals cation migration from eight-membered ring sites to six-membered ring sites upon CO₂ adsorption. Na-chabazite shows partial transformation from rhombohedral to monoclinic symmetry upon prolonged evacuation at high temperature, with resultant non-Type I CO₂ adsorption behaviour. Li-, Na- and K-forms of ZK-5 (Si/Al = 4.16) show high CO₂ uptakes at 0.1 bar and 298 K (Li-ZK-5, 4.7 mmol g⁻¹, which is the highest of the solids measured here). Like all H-forms, H-ZK-5 shows weaker uptake. None of the ZK-5 forms show high selectivity for CO₂ over small hydrocarbons, because cations do not block eight-membered ring windows and the structures do not distort upon dehydration. Uptake of CO₂ on univalent cation forms of zeolite Rho has been studied at low (up to 1 bar) and high (up to 10 bar) pressures. All cationic forms (but not H-Rho) show distortion (Im3̅m to I4̅3m) upon dehydration. Forms of zeolite Rho in which cations occupy window sites in the eight-membered rings between α-cages show hysteresis in their CO₂ isotherms, the magnitude of which (Na⁺,NH₄⁺ < K⁺ < Cs⁺) correlates with the tendency of cations to occupy double eight-membered ring sites rather than single eight-membered ring sites. Additionally, reversible CO₂ uptake using the Zero Length Column method on fully and partially cation exchanged samples has been measured. In situ synchrotron PXRD of CO₂ adsorption on Na-Rho indicates Na cations remain in window sites on the time average, indicating CO₂ uptake must occur by a 'trapdoor mechanism' by which Na cations move away from the windows to allow CO₂ to adsorb. In addition, in situ PXRD reveals the adsorption sites of CO₂ bound cations. Adsorption of small hydrocarbons does not occur on Rho, even at high pressure, indicating that adsorption is selective, and depends on the degree of interaction with the adsorbate rather than simply on the molecular size. Na-Rho is therefore a selective adsorbent for CO₂ over CH₄ with selectivities of 150–25 at 1–9 bar and 298 K, predicted from the single component isotherms, and an uptake of 3.07 mmol g⁻¹ at 0.1 bar. High ‘selectivities' are also observed over K-, Cs- and Ca-forms, examples of a novel type of adsorption selectivity.
37
Du, Preez Louis Jacobus. "The reactive absorption of CO2 into solutions of MEA/2-propanol." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4192.
Full textAbstract:
Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: The discovery that the reaction of CO2 with primary amines in both aqueous and non-aqueous media provides a viable chemical method for determining the effective interfacial mass transfer area for separation column internals has lead to an increase in the interest of studying the reaction kinetics and determining the governing reaction rate expressions. For the absorption studies conducted on these systems, many authors assumed that power rate law reaction kinetics govern the reaction rate, which simplified the derivation of absorption correlations. This has already been proven to be an over simplifying assumption, since many authors suggest a non-elementary rate expression based on the pseudo-steady state hypothesis for the reactive zwitterion intermediate to be valid. An evaluation of the existing reaction rate expressions for the homogeneous liquid phase reaction of CO2 and mono-ethanolamine (MEA) in a 2-propanol solvent system was performed. The reaction rate profiles of CO2 and MEA at 25ºC, 30ºC and 35ºC, and relative initial concentrations of [MEA]i = [CO2]i, [MEA]i = 2.5[CO2]i, [MEA]i = 4[CO2]i were determined by means of an isothermal CSTR set-up. Scavenging of the unreacted MEA with benzoyl chloride provided the means to be able to stop the reaction in the product stream. This in turn allowed for the construction of concentration- and reaction rate profiles. The reaction rate data was modelled on various rate expressions by means of a MATLAB® non-linear estimation technique, employing the Levenberg-Marquard algorithm for minimizing the loss function. It was concluded that the rate expressions proposed in literature are insufficient and a rate expression derived fundamentally from first principals is proposed: [ ][ ] [ ] [ ][ ] [ ]2 MEA 1 2 2 -r = k CO RNH - k2 Z + k3 Z RNH2 - k4 S where ki are the reaction rate constants, Z is the zwitterion reactive intermediate and S the salt product of the overall reaction mechanism. In order to be able to determine the effective interfacial mass transfer area, the absorption rate per unit area or specific rate of absorption for the solute gas as a rate expression function of species concentration must firstly be determined. This is achieved by performing experimental absorption runs on a gas-liquid contactor of known surface area. This study incorporated the well known wetted wall experimental set-up. The aim was to construct and implement a wetted wall set-up and conduct absorption experiments for a gas side CO2 concentration range stretching from pure CO2 to diluted gas mixtures absorbing into solutions of varying MEA concentrations. Validation of the set-up was done by performing experiments at similar conditions to a previous study. The study then proceeded to determine the absolute and specific absorption rates at CO2 mass percentages of 100%, 78%, 55% and 30% into solutions of MEA concentrations of 0.25 and 0.3 mol/L. These runs were conducted at 25ºC and 30ºC. The wetted wall was designed to facilitate absorption studies at column heights of 60, 90 and 105mm. This allowed the investigation of the effect that surface area and column height has on the absolute rate of absorption as well as the CO2 and MEA concentrations in the liquid phase It was found that the specific absorption rate is independent of contact time, which is consistent with the rapid nature of the reaction. It was furthermore found that an increase in MEA concentration caused an increase in the absorption rate. The effect of temperature is linked with the solubility of CO2 in the solution. As the temperature increases, the solubility of CO2 decreases, but the absorption rate increases. The result is that it seems as if a change in temperature has no effect on the absorption rate, when in actual fact it does. An increase in the amount of CO2 absorbed is noticed for an increase in wetted wall surface area. This is expected and indicates that there is an increase in the amount of CO2 absorbed as the column length increases. Stopping the absorption reaction by means of MEA scavenging with benzoyl chloride at various column heights will allow for the construction of a concentration profile for both CO2 and MEA as a function of column height. These profiles will allow for the derivation of a non-elementary rate expression governing the specific absorption rate. This has been identified as ‘n area of great interest for future investigation.
AFRIKAANSE OPSOMMING: ‘n Groot navorsingsbelangstelling in die reaksiekinetika van CO2 en monoethanolamien (MEA) het ontstaan sedert die ontdekking dat hierdie reaktiewe sisteem ook ‘n goeie metode is vir die bepaling van die effektiewe massaoordragsoppervlakte van gestruktureerde pakkingsmateriaal. Die klem val op die bepaling van eerstens die mees geskikte en akkurate model om die reaksiekinetika te beskryf wat dan gebruik kan word om die absorbsiekinetika deeglik te karaktariseer. Sommige van die vorige navorsers het vereenvoudigende aannames gemaak rakende die reaksiekinetika ten einde die bepaling van geskikte absopsievergelykings te vergemaklik. Ander het gevind dat die nie-elementêre, pseudo-gestadigde toestand hipotese gebasseer op die reaktiewe zwitterioon tussenproduk van die reaksie ‘n meer verteenwoordigende kinetiese model is. Hierdie studie is eerstens gemik op die evaluasie van die bestaande reaksiekinetikavergelykings deur die homogene vloeistoffase reaksie van CO2 met mono-etanolamien (MEA) in die oplosmiddel, 2-propanol te ondersoek. Die studie is uitgevoer in ‘n isoterme CSTR sisteem by onderskeidelik 25ºC, 30ºC en 35ºC en MEA konsentrasies van [MEA]i = [CO2]i, [MEA]i = 2.5[CO2]i en [MEA]i = 4[CO2]i. Die voorgestelde reaksiekinetikavergelykings was gemodelleer met ‘n nie-lineêre datapassingstegniek verskaf deur die sagtewarepakket, MATLAB® wat die Levenberg- Marquard algoritme gebruik om die resfunksie te minimeer. Uit die teorie en datapassing word die volgende vergelyking voorgestel: [ ][ ] [ ] [ ][ ] [ ]2 MEA 1 2 2 -r = k CO RNH - k2 Z + k3 Z RNH2 - k4 S waar ki die reaksietempokonstante voorstel, Z die zwitterioontussenproduk en S die soutproduk. Die eerste stap in die bepaling van die effektiewe massaoordragsarea van gestruktureerde pakkingsmateriaal is om ‘n geskikte vergelyking of korrelasie vir die spesifieke absorpsie van die gas te bepaal. Dit word gedoen deur absoprsie eksperimente te doen op toerusting van bekende oppervlakarea. Hierdie studie het die reeds bekende ‘wetted wall’ opstelling gebruik. Die hoof doelwit van hierdie absorpsiestudie was om ‘n werkende opstelling te bou en absorpsie eksperimente vir CO2 konsentrasies wat strek van suiwer CO2 tot verdunde mengsels uit te voer. Die konsentrasie MEA is ook gevarieër. Die geskiktheid van die opstelling is eerstens getoets deur eksperimentele lopies uit te voer by soorgelyke toestande as ‘n vorige studie. Die doel van die studie is om die absolute en spesifieke absorpsietempos van CO2 by gasfase massapersentasies van 100%, 78%, 55% en 30% in MEA/2-propanol oplossings met MEA konsentrasies van 0.25 en 0.3 mol/L te bepaal. Die lopies is uigevoer by beide 25ºC en 30ºC. Die opstelling is ook ontwerp om absorpsie eksperimente by verskillende kolomhoogtes uit te voer. Hierdie hoogtes is 60, 90 en 105mm. Hierdie studie het tweedens gefokus op die effek wat absorpsiearea en kolomhoogte op die absorpsietempo van CO2 het. Die resultate van die studie toon dat die absorpsietempo onafhanklik is van kontaktyd. Dit stem saam met die vinnige reaksietempo. ‘n Toename in MEA konsentrasie het ‘n toename in spesifieke absorpsietempo tot gevolg, terwyl die effek van temperatuur gekoppel kan word aan die oplosbaarheid van CO2. Soos die temperatuur toeneem, neem die absolute absorpsietempo toe, maar die oplosbaarheid van CO2 neem af, dit het beide ‘n toenemende en afnemende effek op die spesifieke absorpsietempo. Die hoeveelheid CO2 geabsorbeer neem toe met ‘n toename in kolomhoogte. Die konsentrasie MEA in die uitlaatvloeistof toon ‘n skynbare eksponensiële afname met ‘n toename in kolomhoogte. ‘n Studie gemik om die konsentrasieprofiele van CO2 en MEA as ‘n funksie van kolomhoogte te bepaal, word voorgestel. Absorpsiemodelle en korrelasies kan dan afgelei word uit hierdie profiele, wat die berekening van die effektiewe massaoordragsarea akkuraat sal maak. Dit sal deel vorm van toekomstige navorsing.
38
Azevêdo, Geraldo Gilvan de. "Simulação e projeto de uma coluna de absorção com reação química : sistema 'C'O IND2'/monoetanolamina." [s.n.], 1996. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267526.
Full textAbstract:
Orientador: Sandra Lúcia da CruzDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-17T06:22:43Z (GMT). No. of bitstreams: 1 Azevedo_GeraldoGilvande_M.pdf: 2284902 bytes, checksum: 216506a853501999f43bb1c95f73333a (MD5) Previous issue date: 1996
Resumo: Absorção é o processo utilizado para a separação de um ou mais componentes de uma corrente gasosa, através do contato com um solvente líquido, podendo ocorrer ou não reação química entre eles.Um dos processos industriais mais importantes é a remoção de dióxido de carbono, utilizando-se soluções aquosas de monoetanolamina. Trata-se de uma reação rápida e o CO2 pode estar combinado sob a forma de íon carbamato, carbonato ou bicarbonato. Processos de absorção com reação química, quando comparados àqueles de absorção física apenas, apresentam dificuldades para o seu projeto. Na realidade, os projetos de empresas de grande porte são verdadeiras "caixaspretas" e, no Brasil, pouco tem sido publicado a respeito. No presente trabalho, apresenta-se a modelagem de uma coluna de pratos perfurados para a absorção de CO2 em soluções de monoetanolamina (MEA) e, através da simulação em computador, calcula-se o número de estágios da coluna necessários para realizar uma dada separação, analisando-se diversos parâmetros envolvidos no processo.
Abstract: Absorption is a process where the componentsof a gaseous stream are separated, through a liquid solvent. The process may be simply physical or being follo ed by a chemical reaction. In industry, one of the most important absorption processes is the remova I of carbon dioxide, by using aqueous solutions of monoethanolamine (MEA). The reaction between CO2 e MEA is considered fast and CO2 can be combined in different ways: carbamate, carbonate or bicarbonate ions. Comparing the design of chemical and physical absorbers, the former is more difficult than laUer. In fact, the designs carried out by large companies are truly "back-boxes". In addition, there is not almost anything published in Brazil about this subject. In this work, we present the mathematical modeling of a perforated-tray column for the absorption of CO2 in monoethanolamine (MEA) solutions. A computer program was developed in order to calculate the number of stages necessary to reach a given specification, as 1611 as the severa I relevant parameters involved in the processo.
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestre em Engenharia Química
39
Johansson, Emil. "Synthesis and Characterisation of Potential Hydrogen Storage Materials." Doctoral thesis, Uppsala universitet, Fysik III, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4509.
Full textAbstract:
The dissociative and non-dissociative hydrogen uptake in carbon nanostructures and metallic films were investigated by measurements and analysis of solubility isotherms. The total, non-dissociative, uptake for multi-walled nano-barrels and amorphous nanoporous carbon was determined to be 6.2 and 4.2 wt. % respectively at 77 K and the adsorption energies (at lowest coverage) -7.2 and -4.2 kJ/mol. At 298 K the H-uptake was negligible. At low concentrations the H-uptake of Nb-films is strongly affected by the film thickness. For thicknesses less then about 31 nm, the absorption energy was found to be temperature dependent. Such changes have not been observed in Nb films before. The presence of multiple absorption energies was shown to limit the possibility to obtain relevant absorption and interaction energies by traditional Sievert's and van 't Hoff analysis. The Mg1-xNix system (0<0.43) was investigated with respect to the hydrogen uptake. For Mg2Ni the hydrogen uptake, at an external hydrogen pressure of 1 bar, is close to 1.33 H/M (Mg2NiH4). The enthalpy of formation is smaller in the film as compared to bulk material. The changes in the absorption energy are caused by the adhesion to the substrate as well as the nanocrystallinity of the absorbing layers. The optical band gap of Mg2NiH4 was determined to be 2.4 eV. In Mg1-xYx (0<0.17) it was found that the Y-concentration limits the hydrogen uptake at 1 bar. However, the kinetics of the uptake improves substantially with a minimum of 7 at.% of Y. For Mg-Y the optical band gap (3.6 eV) is independent of Y concentration within the concentration range investigated, while the transmittance decreases with increasing Y content.
40
Nickerl, Georg. "Synthese metallorganischer Gerüstverbindungen und poröser Polymere für den Einsatz in der Katalyse, Sensorik und Stofftrennung." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-151847.
Full textAbstract:
Poröse Materialien zeichnen sich durch hohe spezifische Oberflächen bzw. hohe spezifische Porenvolumina aus. Dies macht sie zu geeigneten Kandidaten für die Gasspeicherung, Stofftrennung und die heterogene Katalyse, die Hauptanwendungsgebiete poröser Materialien. Um poröse Materialien hinsichtlich der eben genannten Anwendungsfelder zu optimieren ist es von entscheidender Bedeutung, sie hinsichtlich ihrer jeweiligen Anwendung maßzuschneidern.
Eine Klasse hochporöser Materialien, bei der das Maßschneidern der Poren möglich ist, ist die der metallorganischen Gerüstverbindungen [engl. Metal-Organic Frameworks (MOFs)]. MOFs zeichnen sich durch einen modularen Aufbau aus, der ein systematisches Design der Poren erlaubt. Auch poröse Polymere können durch Funktionalisierung der entsprechenden Monomere hinsichtlich verschiedener Anwendungsgebiete gezielt synthetisiert werden.
Ein Ziel dieser Arbeit war die Integration des Metalls Rhodium als knotenbildendes Element in ein MOF. Dazu wurde Rhodium(II)-acetat, welches bereits das Schaufelradmotiv enthält, mit den trifunktionellen Carbonsäuren Trimesinsäure und 4,4´,4´´ Benzen-1,3,5-triyl-tribenzoesäure zu den MOFs DUT 82 und DUT 83 umgesetzt. Das Schaufelradmotiv als sekundäre Baueinheit in DUT-82 konnte durch röntgenabsorptionspektroskopische Untersuchungen nachgewiesen werden. Nach überkritischem Trocknen gefolgt von thermischer Aktivierung zeigten DUT-82 und DUT-83 eine permanente Porosität mit spezifischen BET-Oberflächen von bis zu 1150 m2g-1.
Weiterhin konnte für DUT-82 eine sehr hohe Affinität zu Kohlenmonoxid, die selten für MOFs beobachtet wird, nachgewiesen werden. Berechnungen der Adsorptionsenthalpie ergaben bei niedrigen Beladungen einen Wert von ungefähr 50 kJmol-1, was für eine Chemisorption von Kohlenmonoxid an DUT-82 bei niedrigen Drücken spricht. Weiterhin zeigten katalytische Untersuchungen, dass sich DUT-82 als heterogener Hydrierkatalysator eignet. In einer Modellreaktion konnte Styrol erfolgreich zu Ethylbenzen umgesetzt werden.
In einem weiteren Teil der Arbeit sollte ein MOF synthetisiert werden, das Stabilität und eine hohe Kapazität für Schwefelwasserstoff miteinander vereint. Eine Klasse bereits bekannter MOFs mit hoher Stabilität basiert auf dem [Zr6O4(OH)4]12+-Cluster. Durch Kombination des [Zr6O4(OH)4]12+-Clusters mit Bipyridindicarboxylat konnte das MOF UiO-67(bipy) hergestellt werden, welches isostrukturell zu UiO 67 ist. Untersuchungen an UiO 67(bipy) zeigten, dass das unbeladene Netzwerk keinen Schwefelwasserstoff adsorbiert. Die Bipyridinfunktionalität wurde anschließend für die permanente Integration weiterer Metallzentren (Metall = Cu, Ni, Co) genutzt. Dazu wurde UiO-67(bipy) zu wässrigen oder ethanolischen Metallsalzlösungen gegeben und es kam zur Adsorption der Metallsalze aus der Flüssigphase. Durch die postsynthetische Integration der Metallsalze konnte die Adsorptionskapazität der resultierenden Metallsalz@UiO-67(bipy)-Materialien für Schwefelwasserstoff bis auf 8 Gew.% gesteigert werden.
Neben Adsorption und Katalyse ist die Sensorik ein weiteres Anwendungsfeld von MOFs. Eine organische Einheit, die sich als sensitive Komponente für eine Integration in ein MOF anbietet, ist Dihydro-1,2,4,5-tetrazin, das zu 1,2,4,5-Tetrazin oxidiert werden kann. Das bemerkenswerte Merkmal dieser Reaktion ist der radikale Farbwechsel von Gelb nach Pink. Nach erfolgreicher Synthese der Dihydro-1,2,4,5-tetrazindicarbonsäure sollte sie durch Kombination mit dem [Zr6O4(OH)4]12+-Cluster zu einem UiO-66 analogen Netzwerk in ein stabiles Netzwerk integriert werden. Da die direkte Syntheseroute eines UiO-66 analogen Netzwerks nicht zum Erfolg führte, wurde die mildere Variante des Linkeraustauschs gewählt. Über diese Route konnte das Dihydro-1,2,4,5-tetrazindicarboxylat erfolgreich partiell in das UiO-66 Netzwerk integriert werden. Anschließende Untersuchungen zeigten, dass die in das Netzwerk eingebaute Dihydro-1,2,4,5-tetrazin-Einheit sowohl in der Flüssig- als auch in der Gasphase erfolgreich oxidiert werden kann, was durch UV/vis-Messungen belegt werden konnte.
Eine weitere Klasse poröser Materialien, die hervorragende chemische Stabilität aufweist, ist die der konjugierten Triazin-Netzwerke. Sie entstehen durch Cyclotrimerisierung multifunktioneller Nitrile. Durch geschickte Wahl der Monomere ist eine Funktionalisierung der Triazin-Netzwerke möglich.
Um ein chirales Triazin-Netzwerk zu synthetisieren, wurde Spirobiindan erfolgreich mit Nitrilgruppen funktionalisiert. Die Umsetzung des Monomers in einer Zinkchlorid-Schmelze führte zu porösen Polymeren mit spezifischen BET-Oberflächen von bis zu 1180 m2g 1. Dabei konnte die Porengrößenverteilung des Triazin-Netzwerkes durch Variation des Verhältnisses von Zinkchlorid zu Monomer gezielt eingestellt werden. Die Polymersynthese erfolgte mit einer racemischen Mischung des Monomers und führte somit zu einem achiralen Polymer. Erste Untersuchungen zeigten, dass eine Trennung des racemisch vorliegenden Monomers mittels Hochleistungsflüssigchromatographie möglich ist.
Die Imidazoliumgruppe ist eine weitere Baueinheit, die in Triazin-Polymere integriert werden sollte, da sie leicht in ein N-Heterocyclisches Carben überführt werden kann. N-Neterocyclische Carbene können direkt als Katalysator bzw. als Ligand für eine Vielzahl von Metallen zur Generierung eines Katalysators genutzt werden. Über mehrstufige Synthesen konnten zwei nitrilfunktionalisierte Imidazoliumsalze hergestellt werden. Die anschließende Cyclotrimerisierung führte zu porösen Polymeren mit spezifischen BET-Oberflächen von bis zu 680 m2g-1. Erste katalytische Untersuchungen zum Einsatz dieser Triazin-Netzwerke in Umpolungsreaktionen von Zimtaldehyd mit 2,2,2 Trifluoracetophenon zeigten jedoch lediglich einen geringen Umsatz zum gewünschten Produkt.
41
Kothawala, Dolly N. "Controls on the soil solution partitioning of dissolved organic carbon and nitrogen in the mineral horizons of forested soils." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115565.
Full textAbstract:
Note:The soil-solution partitioning of dissolved organic carbon (DOC) withinmineral soil horizons is primarily controlled by processes of adsorption and desorption. These abiotic processes largely occur within a short equilibration time of seconds to minutes, which generally occur faster than microbial processes. To characterise the adsorption of DOC to mineral soils, I used the Langmuir adsorption isotherm, which holds several advantages to the commonly used linear initial mass (IM) isotherm. One advantage to using the Langmuir isotherm is anestimation of the maximum DOC adsorption capacity (Qmax). The Qmax estimates the number of remaining DOC binding sites available on the mineral soil particle surfaces. I modified the traditional Langmuir isotherm in order to estimate the DOC desorption potential of native soil organic matter (SOC).[...]
Le partitionnement entre les solutions de sols du carbone organiquedissous (COD) dans les horizons des sols minéraux est essentiellement contrôle par les processus d'adsorption et de désorption. Ces processus abiotiques se déroulent normalement dans un bref temps d'équilibration variant de quelques secondes a quelques minutes, ce qui est en général plus rapide que les processus microbiens. Pour caractériser Fadsorption de COD aux sols minéraux, nous avons utilise l'isotherme d'adsorption de Langmuir. Cette isotherme présente plusieurs avantages par rapport a Fisotherme de masses initiales (IM) linéaires couramment utilisée, en particulier F estimation de la capacité d'adsorption maximale du COD (Qmax). Le Qmax estime le nombre de sites de liaison de COD restants a la surface du sol minéral. Nous avons aussi modifie Fisotherme de Langmuir traditionnelle afin d'évaluer le potentiel de désorption de COD de la matière organique du sol indigène (MOS).[...]
42
Kothawala, Dolly N. 1972. "Controls on the soil solution partitioning of dissolved organic carbon and nitrogen in the mineral horizons of forested soils." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115858.
Full textAbstract:
The soil-solution partitioning of dissolved organic carbon (DOC) within mineral soil horizons is primarily controlled by processes of adsorption and desorption. These abiotic processes largely occur within a short equilibration time of seconds to minutes, which generally occur faster than microbial processes. To characterise the adsorption of DOC to mineral soils, I used the Langmuir adsorption isotherm, which holds several advantages to the commonly used linear initial mass (IM) isotherm. One advantage to using the Langmuir isotherm is an estimation of the maximum DOC adsorption capacity (Qmax). The Qmax estimates the number of remaining DOC binding sites available on the mineral soil particle surfaces. I modified the traditional Langmuir isotherm in order to estimate the DOC desorption potential of native soil organic matter (SOC).Sorption characteristics were derived for a broad range of52 mineral soils collected from 17 soil profiles spanning across Canada from British Columbia to Quebec. Mineral horizons with the greatest Qmax included the Fe-enriched B horizons of acidic Podzols and Volcanic soils, followed by B horizons not enriched in Fe, followed by A and C horizons. Podzol B horizons were distinct from all other horizons due to significantly higher desorption potential. Soil properties predicting the adsorption characteristics of DOC also predicted the adsorption characteristics of dissolved organic nitrogen (DON). Adsorption of DOC and DON was tightly coupled (R 2 = 0.86), however the ratio of DOC:DON in the final equilibrium solution lowered for 48 out of 52 minerals horizons. These results suggest that DON may be slightly more mobile than DOC.
A short-term (32 day) incubation was perform to establish the fate of indigenous soil C, relative to newly adsorbed soil C to four mineral soils with different adsorption characteristics. Soil columns were leached periodically and sampled for DOC and CO2 production. Two Fe-enriched mineral horizons with high adsorption capacity released low amounts of old SOC, yet released almost all of the newly adsorbed SOC. In contrast, two B horizons without Fe-enrichment released greater amounts of old SOC, and retained a greater fraction of the newly adsorbed SOC than the Fe-enriched horizons. These results identify a contrast between the fate of indigenous and newly adsorbed SOC on mineral soils with differing Qmax.
The final component of this study examined changes to the molecular structure of DOC after equilibration with mineral soils. Multiple techniques were used to assess changes in the molecular composition of DOC, including the analysis of aromatic content by specific UV absorbance (SUVA) and fluorescence spectroscopy, analysis of molecular weight distribution (MWD) with high performance size exclusion chromatography (HPSEC) and functional group analysis with Fourier transform infra-red spectroscopy (FTIR). The solution phase DOC generally showed a reduced aromatic content, along with the removal of organic compounds with carboxyl groups. The MWD of DOC was reduced after equilibration to mineral soils, and the reduction in average molecular weight was related to the Qmax of mineral soils.
The various components of this thesis have contributed to the overall understanding of controls on the adsorption of DOC and DON species to mineral soils of the Canadian temperate and boreal forest.
43
Demir-kivrak, Hilal. "Synthesis And Characterization Of Ethanol Electro-oxidation Catalysis." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12613887/index.pdf.
Full textAbstract:
ABSTRACT
SYNTHESIS AND CHARACTERIZATION OF ETHANOL ELECTRO-OXIDATION CATALYSIS
Demir-Kivrak, Hilal
Ph.D., Department of Chemical Engineering
Supervisor : Prof. Dr. Deniz Üner Co-supervisor : Dr. Sadig Kuliyev October 2010, 196 pages In this study, the role of defects, the role of Sn in relation to defects, and the role of oxide phase of tin in ethanol electro-oxidation reaction were investigated. Firstly, adsorption calorimetry measurements were conducted on monometallic (1%Pt, 2%Pt, and 5%Pt) and bi-metallic (5% Pt-Sn) &gamma
-Al2O3 supported Pt catalysts. It was observed that while saturation coverage values decreased, intermediate heats remained same for Pt-Sn catalysts by the increasing amount of tin. The effect of particle size was investigated on Pt/C (pH=5), Pt/C (pH=11) catalysts at different scan rates. At high scan rates (quite above diffusion limitations), current per site activities were nearly the same for 20% Pt/C (E-Tek), Pt/C (pH=11), and Pt/C (pH=5) catalysts, which explained as electro-oxidation reaction takes place at the defects sites. Furthermore, the effect of support on ethanol electro-oxidation was investigated on CNT supported Pt catalyst. Results indicate that only the metal v dispersions improved ethanol electro-oxidation reaction and support did not have any effect on ethanol electro-oxidation reaction. Results on the 20% Pt-Sn/C (15:1 to 1:1 Pt: Sn atomic ratios) and 20% Pt-SnO2/C (6:1 and 1:1) catalysts indicated that ethanol electro-oxidation activity increased by increasing tin amount. For 20% Pt-Sn/C catalysts, Pt-Sn (6:1)/C indicated best activity. On the other hand, 20% Pt-SnO2 (6:1)/C catalyst was better than Pt-Sn (6:1)/C in terms of ethanol electro-oxidation activity due to the fact that there was low contact between Pt and tin oxide particles.
44
Anghel, Clara. "Studies of transport in oxides on Zr-based materials." Licentiate thesis, Stockholm, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-366.
Full text
45
Yu, Zhewei. "Equilibrium and kinetics studies of hydrogen storage onto hybrid activated carbon-metal organic framework adsorbents produced by mild syntheses." Thesis, Nantes, Ecole des Mines, 2016. http://www.theses.fr/2016EMNA0236/document.
Full textAbstract:
Depuis une quinzaine d’années, les matériaux poreux de type Metal Organic Frameworks (MOFs) offrent de nouvelles perspectives dans le cadre du stockage d’hydrogène par adsorption. Ces matériaux possèdent une structure et un réseau de pores particulièrement bien adaptés à l’adsorption des gaz. Ainsi, le téréphtalate de Chrome (III) (MIL-101(Cr)), composé chimiquement très stable, possède une grande capacité de stockage de l’hydrogène, du dioxyde de carbone et du méthane. Afin de renforcer sa capacité de stockage d’hydrogène, un dopage au charbon actif (AC) du matériau a été envisagé. Les synthèses des matériaux dopés et non-dopés ont été réalisées et, pour cela, différents agents minéralisants (acide fluorhydrique, acide acétique et acétate de sodium) ont été testés. Les matériaux synthétisés furent caractérisés par diffraction des rayons X (DRX), par microscopie électronique à balayage (MEB), par analyses thermogravimétriques (ATG) et par adsorption d’azote à 77K. Les capacités de stockage d’hydrogène de ces matériaux à 77 K et 100 bar ont été évaluées par mesures des isothermes d’adsorption d’hydrogène, réalisées par méthodes volumétrique et gravimétrique. Les résultats obtenus par ces deux méthodes sont en parfait accord et le matériau composite affiche une capacité d’adsorption de 13.5 wt%, qui est supérieure à celle du matériau non dopé (8.2 wt% dans les même conditions expérimentales). Les cinétiques d’adsorption ont été mesurées à 77 K par méthode volumétrique. Les résultats obtenus ont été comparés au modèle de la force motrice linéaire, Linear Driving Force (LDF). Un modèle de diffusion dépendant de la température a été développé afin de tenir compte des variations de températures qui se produisent durant le processus d’adsorptionSince the last 15 years, the porous solids such as Metal-Organic Frameworks (MOFs) have opened new perspectives for the development of adsorbents for hydrogen storage. The structure and the pore networks of these materials are especially adapted to the adsorption of gases. The chromium (III) terephthalate-based MIL-101(Cr) is a very stable material which exhibits good adsorption uptakes for hydrogen (H2), carbon dioxide (CO2) and methane (CH4).In this study, syntheses were carried out by different ways and several mineralizing agents such as hydrofluoric acid (HF), acetic acid (CH3COOH) and sodium acetate (CH3COONa) have been tested. Moreover, Activated Carbon (AC) has been introduced in the framework to create an AC incorporated composite material with an enhanced specific surface area. Conventional techniques such as powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and nitrogen (N2) adsorption isotherms at 77 K were used for materials characterizations.In the aim to evaluate hydrogen storage capacities of these materials, hydrogen adsorption isotherms were measured at 77 K via both volumetric and gravimetric methods, and the obtained results are in good agreement. A hydrogen uptake value of 13.5 wt% has been measured at 77 K and 100 bar for the composite material which shows a great improvement of hydrogen capacity compared to the pristine MIL-101(Cr) (8.2 wt%).Finally, hydrogen adsorption kinetics has been measured at 77 K using volumetric method. The obtained results were compared to the Linear Driving Force (LDF) and a temperature dependent diffusion model was also considered to take into account the temperature variations which occur during the adsorption process
46
Du, Preez Louis Jacobus. "Reactive absorption kinetics of CO2 in alcoholic solutions of MEA: fundamental knowledge for determining effective interfacial mass transfer area." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86656.
Full textAbstract:
Thesis (PhD)--Stellenbosch University, 2014.ENGLISH ABSTRACT: The reactive absorption rate of CO2 into non-aqueous solvents containing the primary amine, mono-ethanolamine (MEA) is recognised as a suitable method for measuring the effective interfacial mass transfer area of separation column internals such as random and structured packing. Currently, this method is used under conditions where the concentration of MEA in the liquid film is unaffected by the reaction and the liquid phase reaction is, therefore, assumed to obey pseudo first order kinetics with respect to CO2. Under pseudo first order conditions, the effect of surface depletion and renewal rates are not accounted for. Previous research indicated that the effective area available for mass transfer is also dependent upon the rate of surface renewal achieved within the liquid film. In order to study the effect of surface depletion and renewal rates on the effective area, a method utilising a fast reaction with appreciable depletion of the liquid phase reagent is required. The homogeneous liquid phase reaction kinetics of CO2 with MEA n-Propanol as alcoholic solvent was investigated in this study. A novel, in-situ Fourier Transform Infra-Red (FTIR) method of analysis was developed to collect real time concentration data from reaction initiation to equilibrium. The reaction was studied in a semi-batch reactor set-up at ambient conditions (T = 25°C, 30°C and 35°C, P = 1 atm (abs)). The concentration ranges investigated were [MEA]:[CO2] = 5:1 and 10:1. The concentration range investigated represents conditions of significant MEA conversion. The reaction kinetic study confirmed the findings of previous research that the reaction of CO2 with MEA is best described by the zwitterion reactive intermediate reaction mechanism. Power rate law and pseudo steady state hypothesis kinetic models (proposed in literature) were found to be insufficient at describing the reaction kinetics accurately. Two fundamentally derived rate expressions (based on the zwitterion reaction mechanism) provided a good quality model fit of the experimental data for the conditions investigated. The rate constants of the full fundamental model were independent of concentration and showed an Arrhenius temperature dependence. The shortened fundamental model rate constants showed a possible concentration dependence, which raises doubt about its applicability. The specific absorption rates (mol/m2.s) of CO2 into solutions of MEA/n-Propanol (0.2 M and 0.08 M, T = 25°C and 30°C, P = ±103 kPa) were investigated on a wetted wall experimental setup. The experimental conditions were designed for a fast reaction in the liquid film to occur with a degree of depletion of MEA in the liquid film. Both interfacial depletion and renewal of MEA may be considered to occur. The gas phase resistance to mass transfer was determined to be negligible. An increase in liquid turbulence caused an increase in the specific absorption rate of CO2 which indicated that an increase in liquid turbulence causes an increase in effective mass transfer area. Image analysis of the wetted wall gas-liquid interface confirmed the increase in wave motion on the surface with an increase in liquid turbulence. The increase in wave motion causes an increase in both interfacial and effective area. A numerical solution strategy based on a concentration diffusion equation incorporating the fundamentally derived rate expressions of this study is proposed for calculating the effective area under conditions where surface depletion and renewal rates are significant. It is recommended that the reaction kinetics of CO2 with MEA in solvents of varying liquid properties is determined and the numerical technique proposed in this study used to calculate effective area from absorption rates into these liquids. From the absorption data an effective area correlation as a function of liquid properties may be derived in future.
AFRIKAANSE OPSOMMING: Die reaktiewe absorpsie van CO2 in nie-waterige oplossings van die primêre amien, monoetanolamien (MEA) word erken as ‘n geskikte metode om die effektiewe massaoordragsarea van gepakte skeidingskolomme te bepaal. Tans word die metode gebruik onder vinnige pseudo eerste orde reaksietoestande met betrekking tot CO2. Die pseudo eersteorde aanname beteken dat die konsentrasie van MEA in die vloeistoffilm onbeduidend beïnvloed word deur die reaksie en effektief konstant bly. Onder pseudo eerste orde toestande word oppervlakverarming- en oppervlakvernuwingseffekte nie in ag geneem nie, juis as gevolg van die konstante konsentrasie van MEA in die vloeistoffilm. Daar is voorheen bevind dat oppervlakverarming en oppervlakvernuwing ‘n beduidende invloed het op die beskikbare effektiewe massaoordragsarea. Hierdie invloed kan slegs bestudeer word met ‘n vinnige reaksie in die vloeistoffilm wat gepaard gaan met beduidende oppervlakverarming van die vloeistoffase reagens. Die homogene vloeistoffase reaksiekinetika van CO2 met MEA in die alkohol oplosmiddel, n- Propanol, is in hierdie studie ondersoek. ‘n Nuwe, in-situ Fourier Transform Infra-Rooi (FTIR) metode van analiese is ontwikkel in hierdie ondersoek. Die reaksie is ondersoek in ‘n semienkelladings reaktor met MEA wat gevoer is tot die reaktor om met die opgeloste CO2 te reageer. Die FTIR metode meet spesiekonsentrasie as ‘n funksie van tyd sodat die konsentrasieprofiele van CO2, MEA en een van die soutprodukte van die reaksie gebruik kan word om verskillende reaksiesnelheidsvergelykings te modelleer. Die reaksie is ondersoek onder matige toestande (T = 25°C, 30°C and 35°C, P = 1 atm (abs)). Die konsentrasiebereik van die ondersoek was [MEA]:[CO2] = 5:1 en 10:1. Hierdie bereik is spesifiek gebruik sodat daar beduidende omsetting van MEA kon plaasvind. Die reaksiekinetieka studie het, ter ondersteuning van bestaande teorie, bevind dat die reaksie van CO2 met MEA in nie-waterige oplosmiddels soos alkohole, beskyf word deur ‘n zwitterioon reaksiemeganisme. Die bestaande reaksiesnelheids modelle (eksponensiële wet en pseudo gestadigde toestand hipotese) kon nie die eksperimentele data met genoegsame akuraatheid beskryf nie. Twee nuwe reaksiesnelheidsvergelykings, afgelei vanaf eerste beginsels en gebaseer op die zwitterioon meganisme, word voorgestel. Hierdie volle fundamentele model het goeie passings op die eksperimentele data getoon oor die volledige temperatuur en konsentrasiebereik van hierdie studie. Die reaksiekonstantes van die fundamentele model was onafhanklik van konsentrasie en tipe oplosmiddel en het ‘n Arrhenius temperatuurafhanklikheid. Die verkorte fundamentele model se reaksiekonstantes het ‘n moontlike konsentrasieafhanlikheid gewys. Dit plaas onsekerheid op die fundamentele basis van hierdie model en kan dus slegs as ‘n eerste benadering beskou word. Die spesifieke absorpsietempos (mol/m2.s) van CO2 in MEA/n-Propanol oplossings (0.2 M en 0.08 M MEA, T = 25°C and 30°C, P = ±103 kPa) is ondersoek met ‘n benatte wand (‘wetted wall’) eksperimentele opstelling. Die eksperimentele toestande is gekies sodat daar ‘n vinnige reaksie in die vloeistoffilm plaasgevind het, met beide beduidende en nie-beduidende MEA omsetting. Die doel met hierdie eksperimentele ontwerp was om die invloed van intervlakverarming en intervlakvernuwing op die spesifieke absorpsietempo te ondersoek. Gas fase weerstand was nie-beduidend onder die eksperimentele toestande nie. Beide intervlakverarming en intervlakvernuwing gebeur gelyktydig en is waargeneem vanuit die eksperimentele data. ‘n Beeldverwerkingstudie van die gas-vloeistof intervlak van die benatte wand het bevind dat daar ‘n toename in golfaksie op die vloeistof oppervlak is vir ‘n toename in vloeistof turbulensie. Hierdie golfaksie dra by tot oppervlakvernuwing en ‘n toename in effektiewe massaoordragsarea. ‘n Numeriese metode word voorgestel om die effektiewe area van beide die benatte wand en gepakte kolomme te bepaal vanaf reaktiewe absorpsietempos. Die metode gebruik die fundamentele reaksiesnelheidsvergelykings, bepaal in hierdie studie, in a konsentrasie diffusievergelyking sodat oppervlakverarming en vernuwing in ag geneem kan word. Daar word voorgestel dat die reaksiekinetika van CO2 met MEA in oplossings met verskillende fisiese eienskappe (digtheid, oppervlakspanning en viskositeit) bepaal word sodat die numeriese metode gebruik kan word om ‘n effektiewe area korrelasie as ‘n funksie van hierdie eienskappe te bepaal.
47
Lintis, Laura. "Étude des phénomènes de sorption de l’eau sur des aérosols solides émis lors d’un incendie : identification des paramètres physico-chimiques d’influence." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0304/document.
Full textAbstract:
Au cours d’un incendie dans une installation nucléaire de base (INB), les filtres à très haute efficacité (THE) sont colmatés par un dépôt (ou « gâteau ») de suies (des agrégats de nanoparticules carbonées). L’effet de l’humidité, observée au niveau du gâteau de suies par la présence d’un condensat, n’est pas encore pris en compte dans les modèles de colmatage développés dans la communauté scientifique. Dans ce contexte, la présente étude vise à mieux comprendre le phénomène de sorption de l’eau sur les suies. Pour ce faire, des suies dites « analytiques » ont été produites avec différents combustibles isolés, ceci à différentes teneurs en dioxygène, et des suies « d’incendie » ont été produites à partir d’essais de feux à grande échelle, ceci à différentes ventilations et avec des combustibles réalistes (boîte à gants, câbles électriques, huile hydraulique). Les propriétés physico-chimiques de ces suies (morphologie, porosité, surface spécifique, composition chimique et élémentaire) ont été déterminées parallèlement à l’obtention des isothermes de sorption d’eau, pour des suies sous forme de pastilles et de poudres non tassées. Les paramètres obtenus avec le modèle Dubinin-Serpinski pour une première catégorie de suies hydrophobes ont permis de proposer une modélisation pertinente des isothermes caractéristiques des suies analytiques. Par ailleurs, les isothermes de sorption de l’eau sur des gâteaux de suies dites hydrophiles et essentiellement issues de combustibles et situations réelles d’incendie, ont été modélisées à l’aide de l’équation de D’Arcy et Watt (DW). Pour cette seconde catégorie de suies, les paramètres du modèle DW apparaissent relativement dispersés, comparés à ceux obtenus pour les suies analytiques. Cette relative dispersion s’explique par des propriétés très variables des suies d’incendie et notamment par la présence importante d’oxygène et d’halogènes (chlore, phosphore). Cette étude a donc permis de mettre en évidence une adsorption plus importante pour les suies d’incendie, conduisant à la condensation capillaire, cette dernière étant favorisée pour les suies sous forme de pastilles. In-fine, la composition chimique et élémentaire des suies apparaît ainsi comme le paramètre prépondérant du phénomène de sorption de l’eau sur les suiesDuring a fire in a nuclear plan, the high efficiency particle air (HEPA) filters are clogged by a deposit (or “cake”) of soot, the latter corresponding to carbonaceous nanoparticles aggregates. The effect of humidity, observed on the filters by the presence of condensed water, is still not considered in the clogging models developed in scientific community. In this context, the aim of this study consists on a better understanding of the water sorption on the soot. The experimental approach was first the production of “analytical” soot with different isolated fuels and at different dioxygen concentrations, and of “fire” soot at large scale with different ventilations and complex elements (glove boxes, electrical cables, hydraulic oil). The physicochemical properties (morphology, porosity, specific surface area, elemental and chemical composition) and the water sorption isotherms, for samples at compacted pellet and powder state, have been determined. The parameters from the model of Dubinin-Serpinski, obtained for a first class of hydrophobic soot, enabled to propose a relevant model, characteristic of the analytical soot. Furthermore, water sorption isotherms on soot cake, coming from realistic fires and fuels, have been modeled with the D’Arcy and Watt (DW) equation. For this second class of hydrophilic soot, the DW parameters appear relatively more dispersed. This relative dispersion is due to the different properties of the fire soot and especially to the presence of high amounts of oxygen and halogens (chlorine, phosphor). This study enabled to highlight a more significant water adsorption on fire soot, leading to the capillary condensation, which is favored for soot compacted into pellet. Soot chemical a and elemental composition appeared to be the most influencing parameter on water sorption phenomenon
48
Armellini, Victor Antonio de Deus 1986. "Modelagem matemática e simulação computacional do processo de absorção de CO2 em módulos de membrana." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266939.
Full textAbstract:
Orientador: Sergio Persio RavagnaniDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-16T22:22:20Z (GMT). No. of bitstreams: 1 Armellini_VictorAntoniodeDeus_M.pdf: 4894836 bytes, checksum: 94bbcb586bf0955c10788e44b96533de (MD5) Previous issue date: 2010
Resumo: A emissão de dióxido de carbono (CO2) na atmosfera, quando realizada em larga escala, é considerada como a mais séria causa de problemas ambientais a nível mundial. Devido à atual conscientização mundial em torno do assunto, as indústrias responsáveis estão reduzindo a emissão mediante a captura do gás, normalmente realizada através da absorção do poluente em solventes específicos. Os equipamentos mais comuns, que permitem o contato entre o gás e o solvente, são as colunas de borbulhamento, spray ou recheio. Porém, seu uso apresenta desvantagens que comprometem sua operação, tais como, formação de espuma e dispersão das fases. Frente às desvantagens existentes nos equipamentos convencionais, foram desenvolvidos os módulos de membrana, considerados equipamentos mais adequados para o contato e captura do CO2 pelos solventes. Devido à ausência de trabalhos em condições operacionais mais realistas utilizando módulos de membrana, o presente estudo buscou realizar a modelagem e simulação do processo de absorção de CO2 em módulos de membrana, utilizando como solventes o 2-amino-2-metil-1-propanol (AMP), dietanolamina (DEA) e metildietanolamina (MDEA). A modelagem matemática foi concebida através da adaptação das equações de balanço de massa, capazes de representar numericamente o processo em estudo. Com a intenção de resolver numericamente as equações foi aplicado o método das diferenças finitas de Crank-Nicholson, por fim, buscou-se a implementação de um algoritmo computacional, baseado em linguagem Fortran, para resolver o problema e simular o processo de absorção química de CO2 em módulos de membrana. Inicialmente as simulações foram conduzidas com o intuito de avaliar a estabilidade do método numérico adotado, quanto ao processo em estudo. Após a constatação da estabilidade do método proposto, foi conduzido um estudo para determinar a quantidade ideal de pontos a serem utilizados na discretização. Os resultados obtidos através da simulação tem um comportamento condizente com valores previstos pela teoria. Finalmente, o processo de absorção foi simulado utilizando AMP, DEA e MDEA, onde se verificou que as maiores taxas de absorção de CO2 foram obtidas com o uso de AMP como solvente reativo
Abstract: The emission of carbon dioxide (CO2), when performed on a large scale, is considered the most serious cause of environmental problems worldwide. Due to the current global awareness around the subject, the industries are responsible for reducing emissions by capturing the gas, usually performed by absorption of the pollutant by specific solvents. The most common equipment, which allow contact between gas and solvent are the bubble, spray or fixed bed columns. However, its use has disadvantages that undermine its operation, such as foam formation and phase dispersion. Due the disadvantages existing in conventional equipment, were developed membrane modules, considered the most appropriate equipment for the contact and capture of CO2 by solvents. Due to lack of work in more realistic operating conditions using membrane modules, this study sought to do the modeling and simulation of the process of absorption of CO2 in membrane modules, using the solvent as 2-amino-2-methyl-1-propanol (AMP), diethanolamine (DEA) and metildietanolamina (MDEA). The mathematical model was designed by adjusting the balance equations of mass, capable to represent numerically the process under study. To solve numerically the equations was applied the method of finite difference Crank-Nicholson, finally, we sought to implement an algorithm based on Fortran, to solve the problem and simulate the process of chemical absorption of CO2 into modules membrane. Initially the simulations were conducted in order to assess the stability of the numerical method adopted. After verifying the stability of the proposed method, we designed a study to determine the ideal amount of points to be used in the discretization. Soon after, the validity of the simulator was verified by comparing its results with values predicted by theory. Finally, the absorption process was simulated using AMP, DEA and MDEA, and the highest rates of CO2 absorption were calculated, with the use of AMP as a reactive solvent
Mestrado
Ciencia e Tecnologia de Materiais
Mestre em Engenharia Química
49
Clowes, Steven Kenneth. "Experimental studies of surface-adsorbate interactions and surface magnetism." Thesis, University of York, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323531.
Full text
50
Massart, Thierry-Jean. "Soudage par diffusion en vue de la realisation de jonctions heterogenes : utilisation du procede de decapage-activation." Paris, ENMP, 1987. http://www.theses.fr/1987ENMP0037.
Full textAbstract:
Sondage par diffusion teste sur une jonction astroloy (nk17cdat) et in100 (nk15cat) a teneurs en carbone et en titane differentes. Ces jonctions presentent des problemes de segregation sur les surfaces libres