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1
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.
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2
Carlisle, C. „Atomic-scale imaging of adsorption, oxidation and co-adsorption on Ag{111}“. Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597289.
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The work presented in this thesis draws upon several uses of STM, from structural determination, when used in conjunction with theoretical simulations, to the observation of surface reactions and surface mediated interactions. Simulations have been used here for the first time to allow the complete structural determination of a complex reconstruction. The determination of the reconstruction's structure and composition has enabled further experiments involving the oxidation of the Ag{111} surface as well as adsorbate-oxygen interactions mediated by the surface. The source of inspiration for these studies has been the catalytic epoxidation of ethene on silver by atomic oxygen. Two 'surface' states of atomic oxygen have been observed. The first, denoted Oc, is considered to adsorb in interstitial sites within the top layer of AG{111}. Its adsorbate-adsorbate repulsive nature sees this species rapidly saturating at a coverage of just 0.05 ML, at which point the p(4x4)-O species becomes more stable and its growth is nucleated at step edges. On decomposition of the p(4x4)-O reconstruction, both Ag{111} triangular islands and fractures within the oxide appear across the terraces. Both features may play a significant role in the catalytic behaviour. Ethene adsorption on clean Ag{111} has provided information on the adsorption geometry, adsorption state and appearance in the STM image allowing confident interpretations of the coadsorbed ethene-oxygen system. Tip pulsing has been used to provide a controlled mechanism for the induced transition from the physisorbed intrinsic precursor state of ethene to that of the chemisorbed state. High-resolution images have enabled the direct observation of Friedel surface oscillations surrounding the chemisorbed state. To my knowledge, this is the first direct observation of such oscillations resulting from adsorbates.
3
Torabi, P., und M. T. Baei. „Electric Field Effect in CO Adsorption on the (6,0) Zigzag Single-walled Aluminum Nitride Nanotube: an Ideal Method for CO Adsorption“. Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35182.
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The behavior of the monoxide carbon (CO) adsorbed on the external surface of H-capped (6,0) zigzag
single-walled aluminum nitride nanotube was studied under the parallel and transverse electric fields
with strengths 0-140 × 10-4 a.u. by using density functional calculations. Geometry optimizations were carried
out at the B3LYP/6-31G* level of theory using the Gaussian 03 suite of programs. The binding energies
obtained from these calculations at different applied parallel and transverse electric field strengths
indicate that with increasing parallel electric field intensity, the binding energy values are increased, especially
in the higher parallel field strength, whereas the BE values for the applied transverse electric field
show a significant reverse trend. Results of this study indicate that with increasing parallel electric
field intensity the pristine AlNNT can be used as CO storage and the parallel electric field
effect is an ideal method for adsorption, storage, and fabrication of CO sensors.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35182
4
Maurin-Moulin, Marie-Hélène. „Adsorption et co-adsorption de l'ammoniac et de l'eau sur les poudres d'oxyde de magnésium“. Aix-Marseille 2, 1997. http://www.theses.fr/1997AIX22031.
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Au cours de ce travail nous nous sommes interesses a l'adsorption de l'eau et de l'ammoniac sur la surface de symetrie carree (100) de l'oxyde de magnesium sous forme de poudre. L'etude vibrationnelle des molecules (d'ammoniac ou d'eau) adsorbees sur la surface (100) de la poudre de mgo preparee par combustion de rubans de magnesium a l'air montre que l'ammoniac et l'eau sont essentiellement physisorbees sur la surface. Sur les defauts de surface la molecule d'eau est dissociee. Deux types de groupements hydroxyls sont presents en surface : les oh lies entre eux par une liaison hydrogene et les oh libres. Nous avons defini alors deux types d'hydroxyls libres. Lors de sa dissociation la molecule d'eau fournit un ion oh qui se fixe sur un cation mg#2#+ et un proton qui se fixe sur un anion o#2#-. L'adsorption de nh#3 sur mgo est fortement influencee par la presence de groupements oh de surface. Des experiences de co-adsorption d'eau et d'ammoniac ont montre que la molecule d'ammoniac reagit preferentiellement avec les hydroxyls lies aux cations de surface : mg#s-oh. La seconde partie de ce travail porte sur l'adsorption de la molecule d'ammoniac sur une poudre commerciale d'oxyde de magnesium. Elle met en evidence le role primordial de l'etat de surface sur la reactivite de surface de mgo. On a observe, pour la premiere fois, a notre connaissance, la formation de l'ion ammonium nh#+#4 sur la surface par reaction de l'ammoniac avec les hydroxyls de surface. Ces resultats montrent que l'analyse des vibrations de molecules adsorbees est une sonde tres fine pour l'etude de la reactivite de surface de substrats solides. En complement a cette etude, le reseau d'isothermes d'adsorption d'eau sur l'oxyde de magnesium, trace par gravimetrie d'adsorption a des temperatures proche de l'ambiante, a mis en evidence l'existence d'une bicouche d'eau sur la surface de mgo.
5
Boily, Jean-François. „Experimental study of Cd-citrate Co-adsorption on corundum“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ29659.pdf.
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6
Su, Lun Wei. „Cobalt adsorption and/or co-precipitation onto ferric oxyhydroxide“. Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/36252.
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The Caron process was developed in the 1920s. In this process, the ore is dried and milled, then roasted in a reducing atmosphere to convert nickel and cobalt to their metallic form. Nickel and cobalt are then leached in ammoniacal solution but some losses occur due to adsorption and co-precipitation with iron oxide or hydroxide precipitates. The effects of various parameters on iron precipitation in the Caron process leach were studied. The parameters studied include pH, temperature, contact time with iron and its precipitates and initial ferrous concentration. The adsorption of otherwise soluble Co onto freshly precipitated ferric hydroxide was measured at four different temperatures between 20ºC and 35ºC. The percentage of cobalt adsorbed onto iron precipitates was directly related to the initial iron concentration but the effect of temperature was less clear. The amount of cobalt adsorbed depended on the pH. Solution contact time with iron precipitates had a very small effect on cobalt adsorption (2-3% difference). The highest adsorption of cobalt (99%) was obtained with an initial concentration of 0.2 M ferrous sulfate at pH 7 after 2 hours of contact time. The main iron precipitate was ferrihydrite. X-ray analysis revealed the characteristic “2 line” ferrihydrite (Fe₅HO₈4H₂O) with no goethite being observed in any of the precipitates. TEM revealed an amorphous structure, which is also indicative of ferrihydrite. SEM showed a preponderance of poorly resolved precipitates, which did not appear to be crystalline. Traces of cobalt were measured in the ferrihydrite particulate by EDX.
7
Chihara, Kazuyuki, Shingo Ito, Hideo Nagashima, Masayuki Hikita und Ryosuke Suzuki. „Adsorption of organics on MSC5A in supercritical CO 2“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-185835.
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Chromatographic measurements were made for the adsorption of benzene, toluene and m-xylene on molecular sieving carbon (MSC) in a supercritical fluid CO2 mixed with organics. A supercritical chromatograph packed with MSC was used to detect pulse responses of the organics. Adsorption equilibria and adsorption dynamic parameters for organics were obtained by moment analysis of the response peaks. Dependences of adsorption equilibrium constants, K*, and micropore diffusivity, D, on the amount adsorbed were examined. The dependencies of adsorption equilibrium constants, K*, and micropore diffusivities, D, for benzene, toluene and m-xylene, on the molarity of benzene over a range of temperature and pressure were obtained. Experimental results were simulated using the “Stop & Go” method as well as by molecular simulation.
8
Yasui, Yoshimi. „CO adsorption and CO oxidation on the Pd(110)c(2×4)-O surface“. 京都大学 (Kyoto University), 1998. http://hdl.handle.net/2433/182450.
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9
Seitsonen, Ari Paavo. „Theoretical investigations into adsorption and co-adsorption on transition metal surfaces as models to heterogeneous catalysis“. [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=963831291.
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10
Schlapka, Andreas. „Adsorption von CO und O2 auf Pt-Ru(001)- Bimetalloberflächen“. [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=966110072.
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11
Abbassi, Maria. „Selective CO Adsorption Separation from CO2 via Cu-modified Adsorbents“. Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42151.
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CO2 capture and conversion appears to be a prominent solution to mitigate greenhouse gas
emissions (GHG) and global warming issue. Among different CO2 conversion approaches,
CO2 hydrogenation via reverse water gas shift (RWGS) reaction is one of the most promising
technology to convert CO2 to CO. Subsequently, CO is transformed to value added chemicals
or liquid fuels. To improve the overall CO2 conversion for RWGS reaction, product separation
and recycling is being proposed.
In this research, adsorption separation technology has been explored to selectively separate
CO from CO2 in RWGS using pressure swing adsorption (PSA) process. To investigate the
adsorption capacity and selectivity of CO, different porous materials have been identified for
CO separation. In this research, activated carbons, ordered mesoporous silica, and metal
organic framework materials were studied. Equilibrium isotherms of CO and CO2 were
measured in a gravimetric system at a temperature of 25 °C for pressures up to 20 bar.
Preliminary adsorption isotherm results had shown an insufficient CO uptake and low
selectivity level compared to CO2, thus not justifying their application for CO separation.
Herein, to improve the CO adsorption capacity and selectivity, Cu-based adsorbents were
developed using copper (II) chloride (CuCl2) as a precursor to synthesize six different
adsorbents. The adsorbents were prepared using two different synthesis methods; the modified
polyol method for reduction and nanoparticle deposition of Cu (I) ions, and thermal monolayer
auto-dispersion method. Furthermore, different copper (II) loadings were investigated to
determine the monolayer dispersion capacity of CuCl2 on the support.
The modified adsorbents by copper salt exhibited significantly high CO uptake with large
CO/CO2 selectivity, reversing the results obtained before adsorbent modification. Thus, Cubased adsorbents are promising materials for CO separation and recovery from a gaseous mixture containing CO2.
12
Lively, Ryan P. „Hollow fiber sorbents for post-combustion CO₂ capture“. Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43758.
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As concerns mount about the rise in atmospheric CO₂ concentrations, many different routes to reduce CO₂ emissions have been proposed. Of these, post-combustion CO₂ capture from coal-fired power stations is often the most controversial, as the CO₂ capture system will remove generating capacity from the grid whereas many of the other solutions involve increasing the generating capacity of the grid with low CO₂-emission plants. Despite this, coal-fired power stations represent a major point source for CO₂ emissions, and if a consensus is reached on the need to reduce CO₂ emissions, a low-cost method for capturing and storing the CO₂ released by these power plants needs to be developed. The overarching goal of this research is to design and develop a novel hollow fiber sorbent system for post-combustion CO₂ capture.
To achieve this goal, three objectives were developed to guide this research: i) develop a conceptual framework for hollow fiber sorbents that focuses on the energetic requirements of the system, ii) demonstrate that hollow fiber sorbents can be created, and a defect-free lumen layer can be made, iii) perform proof-of-concept CO₂ sorption experiments to confirm the validity of this approach to CO₂ capture. Each of these objectives is addressed in the body of this dissertation.
Work on the first objective showed that fiber sorbents can combine the energetic advantages of a physi-/chemi-sorption process utilizing a solid sorbent while mitigating the process deficiencies associated with using solid sorbents in a typical packed bed. All CO₂ capture technologies--including fiber sorbents--were shown to be highly parasitic to a host power plant in the absence of effective heat integration. Fiber sorbents have the unique advantage that heat integration is enabled most effectively by the hollow fiber morphology: the CO₂-sorbing fibers can behave as "adsorbing heat exchangers."
A dry-jet, wet-quench based hollow fiber spinning process was utilized to spin fibers that were 75wt% solid sorbent (zeolite 13X) and 25wt% support polymer (cellulose acetate). The spinning process was consistent and repeatable, allowing for production of large quantities of fibers. The fibers were successfully post-treated with an emulsion-based polymer (polyvinylidene chloride) to create a defect-free lumen side coating that was an excellent barrier to both water and gas permeation. A film study was conducted to elucidate the dominant factors in the formation of a defect-free film, and these factors were used for the creation of defect-free lumen layers. The work discussed in this thesis shows that the second objective of this work was definitively achieved.
For the third objective, sorption experiments conducted on the fiber sorbents indicated that the fiber sorbents CO₂ uptake is simply a weighted average of the support material CO₂ uptake and the solid sorbent uptake. Furthermore, kinetic experiments indicate that CO₂ access to the sorbents is not occluded noticeably by the polymer matrix. Using the fiber sorbents in a simulated rapid thermal swing adsorption cycle provided evidence for the fiber sorbents ability to capture the sorption enthalpy released by the CO₂-13X interaction. Finally, a slightly more-pure CO₂ product was able to be generated from the fiber sorbents via a thermal swing/inert purge process.
13
Liao, Kristine. „Calorimetry study of the adsorption of diatomic molecules on Co{110}“. Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610142.
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14
Peter, Matthias. „Oxygen and CO adsorption on supported Pd nanoparticles and Pd(111)“. Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://dx.doi.org/10.18452/16896.
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Um die Korrelation zwischen Partikelgröße und Reaktivität von Pd Nanopartikeln auf Eisenoxid zu untersuchen wurde die experimentelle Methode Einkristalladsorptionskalorimetrie mit der Präparation von Modellsystemen kombiniert. Da diese Systeme mit mikroskopischen Methoden untersucht wurden, liegen detaillierte strukturelle Informationen vor. Es konnte gezeigt werden, dass die Adsorptionsenergie auf 3.4 nm großen Pd Nanopartikeln um 69 kJ/mol höher ist als auf Pd(111). Dieser Effekt resultiert aus der Änderung des Adsorptionsplatzes von Facettenplätzen auf Pd(111) zu Kantenplätzen auf Pd Nanopartikeln. Die Änderung der Partikelgröße im Bereich 3.4 nm - 1.9 nm führt zu einer Verringerung der Adsorptionsenergie um 70 kJ/mol. Eine Reduktion der Adsorptionsenergie auf kleineren Nanopartikeln wurde auch für CO gemessen. Die Differenz in der Pd-O Bindungsenergie zwischen den verschiedenen Systemen verringert sich bei erhöhter Adsorbatbedeckung. Die Anzahl adsorbierter Sauerstoffatome auf frisch präparierten Pd Nanopartikeln bei 300 K ist um drei bis vier mal höher als die Anzahl an Sauerstoffatomen welche Pd Oberflächenplätze sättigen können. Diese Beobachtung kann mit Sauerstoffdiffusion in die Nanopartikel oder in den Träger erklärt werden. Die Wechselwirkung zwischen Sauerstoff und CO auf Pd(111) und Pd Nanopartikeln verschiedener Größen wurde als Funktion der Bedeckung studiert. Aufgrund der CO-O Wechselwirkung verringert sich die CO Adsorptionsenergie um ~40 kJ/mol auf sauerstoffvorbedeckten Pd(111) und Pd Nanopartikeln der Größen 2.9 nm und 3.4 nm.To determine the correlation between the particle size and the reactivity of Pd nanoparticles, which are supported on iron oxide, the experimental method single crystal adsorption calorimetry has been combined with the preparation of model systems. Detailed structural information on the supported systems is available from previous structural studies. It was found that the oxygen adsorption energy is 69 kJ/mol higher on 3.4 nm sized Pd nanoparticles compared to Pd(111) due to a change of the local adsorption site from threefold hollow to low coordinated sites. A reduction of the particle size in the range 3.4 nm - 1.9 nm was found to lead to a decrease of the adsorption energy by 70 kJ/mol. A reduction of the adsorbate binding energy has also been found for CO. The difference in the Pd-O binding energy between the different systems decreases with increasing coverage. It was demonstrated that the number of adsorbed oxygen atoms on freshly prepared Pd nanoparticles at 300 K is three to four times higher than the amount of oxygen atoms which saturate the Pd surface sites. This observation can be explained with oxygen diffusion either into the nanoparticles or into the support. The interaction between oxygen and CO has been studied on Pd(111) and Pd nanoparticles of different sizes as a function of the coverage. Due to CO-O interaction, the CO adsorption energy is reduced by ~40 kJ/mol on oxygen precovered Pd(111) and Pd nanoparticles of 2.9 nm and 3.4 nm.
15
Sclauzero, Gabriele. „Modeling CO adsorption on Pt and Au monatomic chains and nanocontacts“. Doctoral thesis, SISSA, 2010. http://hdl.handle.net/20.500.11767/4143.
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Nanotechnology has become a word of common use and is attracting a lot of interest since it promises revolutionary applications and technological breakthroughs in many areas, from electronics to medicine, from information and communication technology to environmental and energy solutions, and several others. The term itself has acquired a broad meaning and encompasses a wide range of elds in many disciplines, but a common denominator of whatever falling within the scope of nanotechnology exists: it concerns the design, characterization and production of structures, devices and systems by controlling their shape and size at the nanometer scale. Many nanotechnology applications have already been realized or are on their way. Some examples are nanomaterials, materials which acquire novel properties and desired functionalities thanks to an atomic scale processing (obtained for instance by \functionalization" of coatings or paintings with nanoparticles); nanolithography in electronics; nanomedicine (nanosensors, drug delivery procedures); bottom-up approaches such as molecular self-assembly for DNA technology, and so on.
16
Bollini, Praveen P. „Amine-oxide adsorbents for post-combustion CO₂ capture“. Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52908.
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Amine functionalized silicas are promising chemisorbent materials for post-combustion CO₂ capture due to the high density of active sites per unit mass of adsorbent that can be obtained by tuning the synthesis protocol, thus resulting in high equilibrium CO₂ adsorption capacities. However, when compared to physisorbents, they have a few disadvantages. Firstly, oxidative degradation of the amine groups reduces the lifetime of these adsorbent materials. Furthermore, rapid heat release following the reaction between amines and CO₂ results in large local temperature spikes which may adversely affect adsorption equilibria and kinetics. Thirdly, there is a lack of fundamental understanding of CO₂-amine adsorption thermodynamics, which is key to scaling up these materials to an industrial-scale adsorption process. In this dissertation the qualitative and quantitative understanding of these three critical aspects of aminosilica adsorbents have been furthered so these materials can be better evaluated and further tuned as adsorbents for post-combustion CO₂ capture applications.
17
Piccolo, Laurent. „Réactivité d'agrégats de palladium supportés sur MgO(100) : adsorption du NO, réactions CO+NO et CO+O2“. Phd thesis, Université de la Méditerranée - Aix-Marseille II, 1999. http://tel.archives-ouvertes.fr/tel-00445979.
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Les agrégats métalliques de taille nanométrique possèdent, par rapport aux matériaux massifs, des propriétés chimiques singulières, et constituent des modèles pour l'étude de la catalyse hétérogène. La réactivité d'agrégats de palladium, élaborés par croissance épitaxique sur MgO(100) et caractérisés par microscopie électronique en transmission, a été étudiée. Des expériences d'adsorption de NO et de réactions CO+NO et CO+O2 ont été réalisées sous ultravide par une technique de jet moléculaire pulsé. Avant de se chimisorber sur les agrégats, les molécules de monoxyde d'azote peuvent diffuser sur le support. Nous avons mesuré la probabilité de physisorption de NO sur MgO, et quantifié ce phénomène de diffusion-capture. Une fois adsorbé sur le palladium, le NO se dissocie, produisant de l'azote, ou se désorbe. L'énergie d'activation de désorption du NO est de 32 kcal/mol. Une influence de la température et de la morphologie des agrégats sur leur capacité à adsorber et dissocier le NO a été mise en évidence. La réaction de réduction de NO par CO produit essentiellement CO2 et N2. A pressions de réactifs égales, l'activité catalytique est maximale à environ 260°C. Les étapes limitantes de la réaction sont, à basse température, la dissociation du NO et, à haute température, l'adsorption du CO. La prise en compte de la diffusion des réactifs sur le support permet de déterminer précisément l'influence de la taille des agrégats sur leur activité catalytique, et révèle une corrélation avec les expériences d'adsorption de NO. Enfin, la cinétique de la réaction d'oxydation du CO a été analysée en régime transitoire, à l'aide de simulations simples. En deçà d'environ 200°C, la vitesse de la réaction est limitée par l'inhibition de l'adsorption de l'oxygène par le CO fortement chimisorbé sur les arêtes des agrégats. Au-delà de 200°C, c'est l'existence d'un état précurseur de la chimisorption de CO à fort recouvrement en oxygène qui réduit la vitesse de production de CO2.
18
Piccolo, Christian-Laurent. „Réactivité d'agrégats de palladium supportés sur MgO(100) : adsorption du NO, réactions CO+NO et CO+O2“. Aix-Marseille 2, 1999. http://www.theses.fr/1999AIX22075.
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Les agrégats métalliques de taille nanométrique possèdent, par rapport aux matériaux massifs, des propriétés chimiques singulières, et constituent des modèles pour l'étude de la catalyse hétérogène. La réactivité d'agrégats de palladium, élaborés par croissance épitaxique sur MgO(100) et caractérisés par microscopie électronique en transmission, a été étudiée. Des expériences d'adsorption de NO et de réactions CO+NO et CO+O2 ont été réalisées sous ultravide par une technique de jet moléculaire pulsé. Avant de se chimisorber sur les agrégats, les molécules de monoxyde d'azote peuvent diffuser sur le support. Nous avons mesuré la probabilité de physisorption de NO sur MgO, et quantifié ce phénomène de diffusion-capture. Une fois adsorbé sur le palladium, le NO se dissocie, produisant de l'azote, ou se désorbe. L'énergie d'activation de désorption du NO est de 32 kcal/mol. Une influence de la température et de la morphologie des agrégats sur leur capacité à adsorber et dissocier le NO a été mise en évidence. La réaction de réduction de NO par CO produit essentiellement CO2 et N2. A pressions de réactifs égales, l'activité catalytique est maximale à environ 260°C. Les étapes limitantes de la réaction sont, à basse température, la dissociation du NO et, à haute température, l'adsorption du CO. La prise en compte de la diffusion des réactifs sur le support permet de déterminer précisément l'influence de la taille des agrégats sur leur activité catalytique, et révèle une corrélation avec les expériences d'adsorption de NO. Enfin, la cinétique de la réaction d'oxydation du CO a été analysée en régime transitoire, à l'aide de simulations simples. En deçà d'environ 200°C, la vitesse de la réaction est limitée par l'inhibition de l'adsorption de l'oxygène par le CO fortement chimisorbé sur les arêtes des agrégats. Au-delà de 200°C, c'est l'existence d'un état précurseur de la chimisorption de CO à fort recouvrement en oxygène qui réduit la vitesse de production de CO2.
19
Maurer, Ronald W. „Competitive Adsorption of Poly(1-vinylpyrrolidone-co-styrene) and Kymene onto Wood Fibers: the Improved Effect of Sequential Adsorption“. Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14075.
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Non-ionic copolymers, such as poly(1-vinylpyrrolidone-co-styrene), are used in the production of filtration membranes and fibers because of their ability to provide both hydrophilic and hydrophobic character. However, their non-ionic character and solubility in water prevents inexpensive recovery from waste streams. Wood fibers show potential as recovery agents because they are inexpensive, environmentally friendly, and have a large surface area per unit mass (200 m2/g). However, due to the anionic nature of the fiber surface, their adsorptive behavior is often limited to cationic species. We have shown that low-dosage application of a cationic polyamide epichlorohydrin resin, Kymene 557H®, using a sequential adsorption process can alter the fiber surface charge so as to provide more neutral surface area for the non-ionic polymer to adsorb; furthermore, the adsorbed Kymene 557H® does not block the approach of poly(1-vinylpyrrolidone-co-styrene). Single-component adsorption of poly(1-vinylpyrrolidone-co-styrene) was on the order of 10-3 g/g; with Kymene 557H® adsorbed on the fiber, the adsorption increased one order of magnitude to 10-2 g/g. This significant increase is caused by neutralization of fiber surface charge via Kymene 557H® adsorption, creating a surface more favorable for adsorption and recovery of non-ionic species.
20
Marcos, Carla Abregú, Abraham Sopla Maslucán, Miguel Cano Lengua und José C. Alvarez. „Co-authors Networks in Adsorption Refrigeration and Air-Conditioning with Solar Energy“. Universidad Peruana de Ciencias Aplicadas (UPC), 2021. http://hdl.handle.net/10757/653778.
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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.The refrigeration and air conditioning systems by adsorption with solar energy are a very interesting option to replace the conventional compression systems because they save energy, are noiseless and use non-aggressive ozone layer refrigerants; however, there are scarcities of studies at this topic. The acquisition of knowledge and positioning in research on this topic by new research groups could be facilitated by knowing the context, trends, and collaborations that emerge in the subject. A map of collaborative co-authors between the greatest authors on the subject was drawn up, the same one that is done using Gephi software. From the analysis of these maps, the centrality degree and collaboration between the authors were determined.
Revisión por pares
21
Rashchi, Fereshteh. „Adsorption on silica in Pb- and Ca-SO¦4-CO¦3 systems“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ29625.pdf.
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22
Küpper, David. „Gas adsorption effects on magnetism and structure of ultrathin Co-based films“. Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612263.
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23
Zhu, Yibing. „CO2 Adsorption on amine-coated elastomers: an IR study“. University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1522426264764055.
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24
Wang, Jiamin. „Exploring Strategies to Break Adsorption-Energy Scaling Relations in Catalytic CO Oxidation“. Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/96537.
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An atomistic control of chemical bonds formation and cleavage holds the key to making molecular transformations more energy efficient and product selective. However, inherent scaling relations among binding strengths of adsorbates on various catalytic materials often give rise to volcano-shaped relationships between the catalytic activity and the affinity of critical intermediates to the surface. The optimal catalysts should bind the reactants 'just right', i.e., neither too strong nor too weak, which is the Sabatier's principle. It is extremely useful for searching promising catalysts, but also imposes serious constraints on design flexibility. Therefore, how to circumvent scaling constraints is crucial for advancing catalytic science. It has been shown that hot electrons can selectively activate the chemical bonds that are not responsive to phonon excitation, thus providing a rational approach beyond scaling limitation. Another emerging yet effective way to break the scaling constraint is single atom catalysis. Strong interactions of supported single atoms with supports dramatically affect the electronic structure of active sites, which reroutes mechanistic pathways of surface reactions. In my PhD research, we use CO oxidation reaction on metal-based active sites as a benchmark system to tailor mechanistic pathways through those two strategies 1) ultra-fast laser induced nonadiabatic surface chemistry and 2) oxide-supported single metal catalysis, with the aim to go beyond the Sabatier activity volcano in metal catalysis.Doctor of Philosophy
Catalysis is the process of increasing the chemical reaction rate by lowering down the activation barrier. There are three different types of catalysis including enzyme, homogeneous, and heterogeneous catalysis. Heterogeneous catalytic reactions involve a sequence of elementary steps, e.g., adsorption of reactants onto the solid surface, transformation of adsorbed species, and desorption of the products. However, the existing scaling relations among binding energies of reaction intermediates on various catalytic materials lead to volcano-shaped relationships, which show the reaction activity versus the binding energy of critical intermediates. The optimal catalysts should bind the reaction intermediates neither too strong nor too weak. This is the Sabatier's principle, which provides useful guidance for searching promising catalysts. But it also imposes the constraint on the attainable catalytic performance. How to break the constraint to further improve the catalytic activity is an emerging problem. The recent studies have shown that the hot surface electrons on the metal surfaces induced by the ultra-fast laser can selectively activate the chemical bonds, thus providing a rational approach beyond scaling constraints. Another way to break the scaling constraint is single atom catalysis. The metal oxides are frequently used as the support to stabilize the single metal atoms. The strong interaction between the single metal atoms and the support affects the electronic structure of the catalysts. Thereby catalytic reactions on the single metal atoms catalyst are very different from that on metal surfaces. In my PhD research, we use CO oxidation reaction as a benchmark system, to tailor reaction pathways through those two strategies on 1) Ru(0001) under ultra-fast laser pulse and 2) Ir single metal atoms supported on spinel oxides, to go beyond Sabatier activity volcano in metal catalysis.
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Delachaux, Florine. „Étude de la faisabilité d'un procédé d’adsorption gaz-solide pour le traitement des NOx et CO en présence d'eau : application aux émissions de moteurs diesel en espaces confinés“. Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0273/document.
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Depuis 2012, les gaz d’échappement diesel sont considérés comme cancérigènes, ce qui représente un risque pour les travailleurs quotidiennement exposés à ces fumées. Cette étude s’intéresse plus particulièrement aux oxydes d’azotes (NOx) et au monoxyde de carbone (CO) présents dans l’échappement diesel. Actuellement, des solutions catalytiques permettent de réduire la concentration de sortie de ces composés mais elles ne sont pas viables pour les véhicules non routiers fonctionnant de façon discontinue et pour solutionner la problématique du « cold start ». La thèse s’est alors orientée vers l’adsorption sur des zéolithes. Dans un premier temps, sept zéolithes ont été choisies et l’étude de l’adsorption des corps purs en dynamique a montré qu’elles étaient peu efficaces dans la capture de NO et de CO mais qu’elles avaient de bonnes capacités d’adsorption vis à vis de NO2. L’étude plus poussée sur trois d’entre elles, Na Y, NH4 Y et H Y, a montré qu’en présence d’O2 et/ou de vapeur d’eau dans le flux gazeux, des réactions chimiques se produisent, conduisant notamment à la formation de NO2 et/ou de NO qui doivent alors être également adsorbé. Le rôle de la température d’adsorption a également été étudié sur la zéolithe Na Y. Son influence est importante à la fois sur la capacité d’adsorption et sur les cinétiques des réactions chimiques. Les capacités de rétention maximales des NOx sur la zéolithe Na Y sont obtenues à 30°C en présence d’O2 dans le flux gazeux et en absence totale d’eau. Afin d’améliorer la capture de NO et CO, il est possible d’estimer les capacités d’adsorption d’autres zéolithes en utilisant la modélisation moléculaire par Density Functional Theory (DFT) afin de calculer les chaleurs isostériques d’adsorptionSince 2012, diesel exhaust gases are considered to be carcinogenic, which is a risk to workers who are exposed to these fumes on a daily basis. This study focuses on nitrogen oxides (NOx) and carbon monoxide (CO) present in the diesel exhaust. Currently, catalytic solutions can reduce the outlet concentration of these compounds, but they are not viable for non road vehicles operating intermittently and to solve the problem of “cold start”. The thesis was then focuses on adsorption on zeolites. As a first step, seven zeolites were selected and the study of the adsorption of pure components in dynamics showed that they were ineffective in the uptake of NO and CO but they had good adsorption capacities for NO2. The further study on three of them, Na Y, NH4 Y and H Y, showed that in the presence of O2 and/or water vapor in the gaseous stream, chemical reactions occur, leading in particular to the formation of NO2 and/or NO which must then also be adsorbed. The role of adsorption temperature has also been studied on zeolite Na Y. Its influence is important on the adsorption capacity and on the kinetics of the chemical reactions. The maximum retention capacities of NOx on zeolite Na Y are obtained in presence of O2 in the gaseous mixture and in absence of water. In order to improve the uptake of NO and CO, it is possible to estimate the adsorption capacities of other zeolites by using molecular modeling by Density Functional Theory (DFT) to calculate the isosteric heats of adsorption
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Pöttinger, Leo [Verfasser], und Thomas [Akademischer Betreuer] Bürgi. „Spectroscopic characterization of dye sensitized TiO₂ with CO₂ co-adsorption and visible light excitation / Leo Pöttinger ; Betreuer: Thomas Bürgi“. Heidelberg : Universitätsbibliothek Heidelberg, 2014. http://d-nb.info/1177810808/34.
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Cariem, Muhammad Junaid. „Adsorption of K and KO on Hägg iron carbide surfaces and its effect on the adsorption of CO: a DFT study“. Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/18476.
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Includes bibliographic references.The Fischer-Tropsch synthesis catalysed by iron is a well-established process, used for the conversion of syngas (a mixture of CO and H₂ ) to long chain hydrocarbons. Potassium is typically added as a promoter in iron-based Fischer-Tropsch to improve activity, selectivity and product distribution. The mechanism behind potassium promotion has in the past been explained as a combination of electron donation and electrostatic interaction. However, despite the importance of potassium as a promoter, the nature of the potassium species on the surface; whether it is present as metallic potassium (K) or is present as another species has received relatively little investigation. No research has been published as of yet as to the effects of potassium adsorption on a Hägg iron carbide surface or the effects on CO adsorption when co-adsorbing CO with potassium on a Hägg iron carbide surface. In this study density functional theory (DFT) has been used to investigate * The adsorption of CO on the Fe₅C₂(100)₀.₀₀ and Fe₅C₂(100)₀.₀₈₉ surfaces. * The adsorption of K, O and KO on the Fe₅C₂(100)₀.₀₀ and Fe₅C₂(100)₀.₀₈₉ surfaces. * The co-adsorption of K, O or KO with CO on the Fe₅C₂(100)₀.₀₀ and Fe₅C₂(100)₀.₀₈₉ surfaces. A thermodynamic analysis was done to investigate the stability of K versus the stability of KO at Fischer-Tropsch conditions. The adsorption of CO on the Fe₅C₂(100)₀.₀₀ and Fe₅C₂(100)₀.₀₈₉ surfaces was done as a pre-cursor to investigating the effect of co-adsorbing K, O or KO with CO on the CO adsorption energy, CO stretching frequency and CO bond length. Subsurface carbon on the Fe₅C₂(100)₀.₀₀ surface caused a decrease in the CO8 adsorption energy of 0.38eV when compared to CO adsorption on a similar site with subsurface iron. On the Fe₅C₂(100)₀.₀₈₉ surface, the lack of subsurface carbon allowed for CO adsorption in the 1F adsorption configuration on top of a valley iron site. The strength of potassium adsorption on both surfaces was calculated to be similar to that of CO in its most stable state (~1.60eV). Potassium is highly mobile across the surface, with a maximum barrier for K diffusion of 0.02eV calculated on both surfaces. A Bader analysis revealed that potassium donates electrons to the surface (~0.72) and that the electron donation from the potassium to the surface is localised and affects only the iron atoms not the carbon atoms. The co-adsorption of O with K leads to a significant increase in the stability of O adsorption on both surfaces, with increases in the O adsorption energy of O of ~0.60eV on the Fe₅C₂(100)₀.₀₀ surface and ~0.40eV on the Fe₅C₂(100)₀.₀₈₉ surface. The O also stabilises the K with the maximum barrier for diffusion of K increasing to 0.07eV on the Fe₅C₂(100)₀.₀₀ surface and 0.15eV on the Fe₅C₂(100)₀.₀₈₉ surface. However, these maximum barriers for diffusion are still extremely low, indicating that potassium is still highly mobile on the surface. The charge density difference plot showed some polarisation of the O towards the K and vice versa, indicating interaction between the two species. No orbital overlap between the adsorbed O and adsorbed K was observed in the charge density difference plot. This together with the results from a local density of states (LDOS) plot indicates that the interaction between O and K on the surface is ionic in nature. The co-adsorption of CO with either K or KO on both the Fe₅C₂(100)₀.₀₀ and Fe₅C₂(100)₀.₀₈₉ surfaces resulted in a significant increase in the calculated CO adsorption energy coupled with an increase in the CO bond length and a decrease in the CO stretching frequency. The magnitude of the increases in calculated CO adsorption energy and CO bond length as well as the magnitude of the decrease in the CO stretching frequency was virtually the same irrespective of whether CO was co-adsorbed with K or KO. The combination of these results shows that K and KO both enhance CO adsorption to a similar degree on Hägg iron carbide surfaces while possibly making CO dissociation more facile. Co-adsorbing CO with O on the Fe₅C₂(100) 0;00 surface lead to a significant decrease in the CO adsorption energies, an increase in CO bond length and an increase in the CO stretching frequency in certain cases. This negative effect on CO adsorption is very localised and restricted to CO adsorption sites which are near to the adsorbed O and have subsurface carbon which prevents CO migration away from the O to a more stable site. On the Fe₅C₂(100)₀.₀₈₉ surface where no subsurface carbon is present, the CO migrates away from the O to a site unaffected by the presence of O.
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Yim, Chi Ming. „LEEM investigations of adsorption and diffusion of CO on the Pt(111) surface /“. View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202007%20YIM.
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Pupier, Olivier. „Equilibres de co-adsorption de mélanges gazeux : application au stockage du gaz naturel“. Perpignan, 2004. http://www.theses.fr/2004PERP0571.
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La connaissance et la compréhension des phénomènes de co-adsorption présents dans de nombreux procédés industriels ont guidé la réalisation de ce mémoire. Dans une première partie, et dans le cadre de la problématique des véhicules fonctionnant au gaz naturel (VGN) avec la technologie Gaz Naturel Adsorbé (GNA), l'importance de ces phénomènes de co-adsorption a pu être mise en évidence. Une série de 730 cycles de chargement - déchargement d'un réservoir de stockage avec du GN a été réalisée. Celle-ci a permis de quantifier une diminution globale de la capacité de stockage du réservoir de l'ordre de 50 %. De plus, par analyse chromatographique, l'influence spécifique de chacun des constituants du GN a été déterminée. Dans une deuxième partie, un banc de volumétrie dynamique, développé au laboratoire pour l'acquisition d'isothermes de co-adsorption de mélanges binaires, a été présenté. A partir de mesures réalisées sur un charbon actif commercial pour le binaire CH4 - CO2, ce montage a pu être validé à 273 et 298 K, et pour des pressions allant jusqu'à 1 MPa. Le modèle de co-adsorption IAST (Ideal Adsorbed Solution Theory), en utilisant les isothermes expérimentales des gaz purs, a été confronté aux résultats du binaire CH4 - CO2 : un écart inférieur à 5 % a été observé entre valeurs calculées et expérimentales. Le modèle MPD (Myers-Prausnitz-Dubinin), intégrant la modélisation des isothermes d'adsorption des gaz purs selon le formalisme de DA (Dubinin - Asthakov) dans le modèle IAST, a également été testé et permet d'obtenir une bonne adéquation entre valeurs calculées et expérimentales. Ce modèle MPD constitue un outil de travail particulièrement intéressant et fiableThe knowledge and the comprehension of the co-adsorption's phenomena present in many industrial processes, guided the realization of this memory. In a first part, and framework of NGV's topic with ANG technology, the importance of these phenomena of co-adsorption is highlighted. A series of 730 cycles of loading - unloading of a storage tank with NG was carried out. This one made it possible to quantify a total loss in the storage capacity of the tank of about 50 %. Moreover, by chromatographic analysis, the specific influence of each component of the GN was given. In a second part, a dynamic volumetry device, developed at the laboratory for the acquisition of co-adsorption isotherms of binary mixtures, was presented. From measurements carried out on a commercial activated carbon for the binary CH4 - CO2, this apparatus has been validated to 273 and 298 K, and for pressures going up to 1 MPa. The co-adsorption model IAST (Ideal Adsorbed Solution Theory), while using experimental isotherms of pure gases, was confronted with the results of the binary CH4 - CO2 : a lower deviation than 5 % was observed between computed values and experimental. The model MPD (Myers-Prausnitz-Dubinin), integrating the modeling of the isotherms of adsorption of pure gases according to the formalism of DA (Dubinin - Asthakov) in model IAST, was also tested and gives a good adequacy between computed values and experimental. This model MPD constitutes a particularly interesting and reliable working tool which could be easily integrated in simulation's models of industrial processes
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Da'na, Enshirah Azmi Mahmoud. „Amine-Modified SBA-15 (Prepared by Co-condensation) for Adsorption of Copper from Aqueous Solutions“. Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20636.
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During the last few decades, concerns about water shortages and pollution have increased. Consequently, environmental legislations and regulations for wastewater discharge have been issued. The objective of this work was to contribute in developing an efficient dsorbent for removing heavy metal ions from wastewater. The thesis focused on evaluating amine-modified SBA-15 as copper and other heavy metal ions adsorbent, by determining a variety of adsorptive properties with the aim of gaining a deep understanding of its behavior and to outline its advantages and limitations.
The influence of synthesis conditions on the mesostructural stability of the resultant materials after different water treatments was
systematically investigated. N2 adsorption results indicated that the material prepared via co-condensation and aged at 100 ºC was not stable and lost its ordered mesoporous structure after contacting water even at room temperature. Aging at 130 ºC and addition of inorganic salts resulted in materials that maintained their mesporous structure under
different water treatments. The material synthesized in the presence of KCl was used as adsorbent for the rest of the thesis work. It was shown that the structural collapse observed in amine-modified SBA-15 prepared
by conventional method when contacted with aqueous solutions is associated with the drying process, and not the treatment itself. This structural collapse was avoided by replacing water with more volatile liquids such as acetone, before drying.
Amino-functionalized SBA-15 was tested for the removal of copper ions from aqueous solutions under different temperatures, pH, initial
concentrations and agitation speeds. The obtained results indicated that the amino-functionalized SBA-15 was very efficient and equilibrium was achieved in less than 30 min at room temperature. The adsorption capacity
increased dramatically with increasing temperature, initial copper concentration and pH. Under suitable conditions, the material exhibited high adsorption capacity even at very low copper concentration.
To further investigate the effect of dsorption parameters, a 24 factorial design experiments were used to screen the factors affecting the copper removal efficiency. All the parameters main effects were significant within a 95 % confidence level. Surface composite design was used to develop a reliable model representing the adsorption process. The statistical tests used proved the adequacy of the second order model. Optimization of the factors levels was carried out and the recommended optimum conditions are: copper concentration of 20 mg/L, adsorbent/solution ratio of 1.57 g/L, pH of 6.5, and T = 294 K with 95% copper removal.
The effect of regeneration conditions was investigated after three adsorption–desorption cycles, under different batchwise regeneration
conditions. Using a composite surface design methodology, the effect of the regeneration conditions on the performance of the adsorbent was investigated. It was found that all the studied parameters have a statistically significant influence on the working dsorption capacity.
With respect to structural properties and amine content, none of the factors was found to be significant. Regeneration using EDTA was found to be more efficient than acid treatment.
Amino-functionalized SBA-15 was studied as potential absorbent for Cd2 +, Co2 +, Cu2 +, Zn2 +, Pb2 +, Ni2 +, Al3+ and Cr3 +. The adsorption capacity and selectivity of the material were investigated in single and
multi-metal solutions. Using very dilute solutions, i.e., 10 ppm, more than 95% of cations were removed, except for Co2+ and Cr3 +, indicatingthe high sensitivity of the current adsorbent. The adsorption capacities
in multi-metal solutions were lower than in single-metal ones because of competition between metallic elements for the amine groups. The adsorbent was not affected in the presence of sodium, potassium, and calcium,
indicating that the ionic strength does not affect the adsorption properties. Application of this material to remove copper in tap water,
river water, and electroplating wastewater was shown to be successful. Dynamic experiments were carried out on the adsorption of copper ions in a laboratory packed-bed of amine-modified SBA-15. Breakthrough curves were
analyzed at different flowrates and after two adsorption-desorption cycles. Furthermore, a model based on mass balance was developed and tested for predicting the breakthrough curves under different experimental conditions used. The results suggested that the developed model was in
good agreement with the experimental data. Bed regeneration was performed by circulating 0.2 M EDTA solution through the column for 30 min.
Résumé
Durant les quelques dernières décennies, les préoccupations concernant les
pénuries d'eau et la pollution en général ont augmenté. Par conséquent,
des législations et des réglementations environnementales pour les rejets
d'eaux usées ont été introduites. L'objectif de ce travail était de
contribuer au développement d'un adsorbant efficace pour éliminer les ions
de métaux lourds des eaux usées. Cette thèse porte sur l'évaluation de
SBA-15 modifiée avec des amines comme adsorbant pour le cuivre et d'autres
ions de métaux lourds par la détermination d'une multitude de propriétés
d'adsorption dans le but d'acquérir une profonde compréhension de son
comportement et d’identifier ses avantages et ses limites.
L'influence des conditions de synthèse sur la stabilité des matériaux
mésoporeux obtenus après différents traitements a été étudié de façon
systématique. Les résultats d'adsorption de N2 ont indiqué que le matériel
préparé par co-condensation et vieilli à 100 °C n'était pas stable et a
perdu sa structure mésoporeuse ordonnée après avoir été en contact avec
l'eau même à température ambiante. Le vieillissement à 130 °C, avec ajout
de sels inorganiques, a abouti à des matériaux qui ont maintenu leur
structure mésoporeuse sous différents traitements en présence d'eau. Le
matériau synthétisé en présence de KCl a été utilisé comme adsorbant pour
le reste du travail de cette thèse. Il a été démontré que l'effondrement
de la structure observé dans la SBA-15 modifiée aux amines, préparée par
la méthode conventionnelle en contact avec des solutions aqueuses est
associé avec le processus de séchage, et non le traitement lui-même. Cet
effondrement de structure a été évité en remplaçant l'eau avec des
liquides plus volatils tels que l'acétone, avant le séchage.
La SBA-15 amino-fonctionnalisée a été testée pour l'élimination des ions
de cuivre des solutions aqueuses à différentes températures, pH,
concentrations initiales et vitesses d'agitation. Les résultats obtenus
ont indiqué que la SBA-15 amino-fonctionnalisée était très efficace et
l'équilibre a été atteint en moins de 30 min à température ambiante. La
capacité d'adsorption a considérablement augmenté avec la température, la
concentration initiale de cuivre et le pH. Sous des conditions
appropriées, le matériau a manifesté une grande capacité d'adsorption,
même à des concentrations très faibles en cuivre.
Afin d’étudier l'effet des paramètres d'adsorption, un plan factoriel de
24 expériences a été utilisé pour dépister les facteurs affectant
l'efficacité d'élimination du cuivre. Tous les effets principaux des
paramètres étaient importants à 95% de niveau de confiance. La
méthodologie de la surface composite a été utilisée pour développer un
modèle fiable qui représente le processus d'adsorption. Les tests
statistiques utilisés ont prouvé la pertinence du modèle de second ordre.
L’optimisation des niveaux des facteurs a été effectuée et les conditions
optimales recommandées sont: la concentration en cuivre de 20 mg/L, le
rapport adsorbant/solution de 1.57 g/L, pH de 6.5 et T = 294 K pour
l'élimination de 95% de cuivre.
L'effet des conditions de régénération a été étudié après trois cycles
d'adsorption-désorption, sous différentes conditions de régénération. En
utilisant la méthodologie de la surface composite, l'effet des conditions
de régénération sur la performance de l'adsorbant a été étudié. Il a été
constaté que tous les paramètres étudiés ont une influence statistiquement
significative sur la capacité de travail d'adsorption. En ce qui concerne
les propriétés structurelles et la teneur en amine, aucun des facteurs n’a
été jugé significatif. La régénération à l'aide d'EDTA a été jugée plus
efficace que le traitement acide.
La SBA-15 amino-fonctionnalisée a été étudiée comme absorbant potentiel de
Cd2+, Co2+, Cu2+, Zn2+, Pb2+, Ni2+, Al3+ and Cr3+. La capacité
d'adsorption et la sélectivité du matériau ont été étudiées dans des
solutions mono- et multi-métalliques. En utilisant des solutions très
diluées, soit 10 ppm, plus de 95% de cations ont été enlevés, sauf pour le
Co2+ et Cr3+, indiquant la forte sensibilité de l'adsorbant. Les capacités
d'adsorption dans les solutions multi-métalliques étaient inférieures à
celles des solutions mono-métalliques en raison de la concurrence entre
les éléments métalliques pour les groupes amine. L'adsorbant n'a pas été
affecté par la présence de sodium, de potassium et de calcium, ce qui
indique que la force ionique n'affecte pas les propriétés d'adsorption.
L’usage avec succès de ce matériau pour éliminer le cuivre dans l'eau de
robinet, l’eau de rivière et les eaux usées de galvanoplastie a été
démontré.
Des expériences dynamiques ont été réalisées sur l'adsorption des ions de
cuivre par la SBA-15 amine-modifiée sur une colonne à lit fixe de
laboratoire. Les courbes de perçage ont été analysées à des débits
différents et après deux cycles d'adsorption-désorption. De plus, un
modèle basé sur le bilan de matière a été développé et testé pour prédire
les courbes de perçage sous les différentes conditions expérimentales
utilisées. Les résultats suggèrent que le modèle développé est en bon
accord avec les données expérimentales. La régénération du lit a été
réalisée en faisant circuler une solution EDTA à 0.2 M à travers la
colonne pendant 30 min.
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Perryman, Adrian Colin. „An investigation of catalyst preparative methods and a study of high pressure CO adsorption“. Thesis, Brunel University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333030.
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Rahman, Imran Yusuf, Yarrow Nelson und Tryg Lundquist. „REMOVAL OF BORON FROM PRODUCED WATER BY CO-PRECIPITATION / ADSORPTION FOR REVERSE OSMOSIS CONCENTRATE“. DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/156.
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Co-precipitation and absorption methods were investigated for removal of boron from produced water, which is groundwater brought to the surface during oil and natural gas extraction. Boron can be toxic to many crops and often needs to be controlled to low levels in irrigation water. The present research focused on synthetic reverse osmosis (RO) concentrate modeled on concentrate expected from a future treatment facility at the Arroyo Grande Oil Field on the central coast of California. The produced water at this site is brackish with a boron concentration of 8 mg/L and an expected temperature of 80°C. The future overall produced water treatment process will include lime softening, micro-filtration, cooling, ion exchange, and finally RO. Projected boron concentrations in the RO concentrate are 20 to 25 mg/L. Concentrate temperature will be near ambient. This RO concentrate will be injected back into the formation. To prevent an accumulation of boron in the formation, it is desired to reduce boron concentrations in this concentrate and partition the boron into a solid sludge that could be transported out of the area. The primary method explored for boron removal during this study was adsorption and co-precipitation by magnesium chloride. Some magnesium oxide tests were also conducted. Jar testing was used to determine the degree of boron removal as a function of initial concentration, pH, temperature, and reaction time. Synthetic RO concentrate was used to control background water quality factors that could potentially influence boron removal. The standard synthetic RO concentrate contained 8 g NaCl/L, 150 mg Si/L and 30 mg B/L. After synthetic RO concentrate was prepared, amendments (e.g. sulfate, sodium chloride) were added and the pH adjusted to the desired value. Each solution was then carried through a mixing and settling protocol (5 min at 200 RPM, 10 min at 20 RPM, followed by 30 min settling and filtration). Boron concentrations from the jar tests were determined using the Carmine colorimetric method.
Boron removal with magnesium chloride was greatest at a pH of 11.0. At this pH 87% of boron was removed using 5.0 g/L MgCl2◦6H2O at 20°C. Mixing time did not greatly affect boron removal for mixing periods of 5 to 1321 minutes. This result indicates equilibrium was achieved during the 45-min experimental protocol.
Maximum boron removal was observed in the temperature range of 29°C to 41°C. At 68°C boron removal decreased five-fold compared to the reduction observed at 29°C to 41°C. For treatment of the cool concentrate, this relatively low optimal temperature range gives magnesium chloride an advantage over magnesium oxide, which is effective only at high temperatures. Neither sodium chloride nor sodium sulfate affected boron removal by magnesium chloride for the chloride and sulfate concentrations expected in the produced water at this site. In contrast, silica did inhibit boron removal, with removal decreasing from 30% to 5% when silica concentration was increased from 0 to 100 mmols/L. This result was unexpected because other researchers have reported silica is necessary for effective removal of boron by magnesium chloride.
To investigate the reasons for the differing boron removal results for magnesium chloride and magnesium oxide, solids produced by the two reagents were compared using X-ray diffraction spectroscopy (XRD). Solids from magnesium chloride contained 30% amorphous material versus 10% for magnesium oxide. The crystalline components from the magnesium oxide treatment were for the most part magnesium oxide, whereas magnesium chloride crystalline solids were a combination of brucite (Mg(OH)2) and magnesium chloride hydroxide. The greater boron adsorption observed with magnesium chloride could thus either be attributed to the greater surface area of the amorphous precipitate and/or the higher boron affinity of brucite and magnesium chloride hydroxide.
Adsorption isotherms were plotted for boron removal by magnesium compounds formed during precipitation. Boron adsorption followed a linear isotherm (r2= 0.92) for boron concentrations up to 37.8 mg B/L. While the data also fit Langmuir and Freundlich models the data fell in the linear range of those models. The linearity of the adsorption curves indicates that adsorption sites for boron were not saturated at these concentrations. The linearity means that higher boron concentrations in the RO concentrate will lead to greater mass removal, up to concentrations of at least 37.8 mg/L boron.
Using magnesium chloride, boron removal by co-precipitation was more effective than by adsorption to pre-formed precipitate. Removal approximately doubled for a given dose of magnesium chloride. The effectiveness of co-precipitation presumably occurs due to entrapment of boron as the precipitate forms.
This study has shown the potential of magnesium chloride as an agent for boron removal by determining those conditions most effective for boron co-precipitation and adsorption. Magnesium chloride has been shown to be more effective than magnesium oxide. Magnesium chloride also out-performed treatment with slaked quicklime, which was tested previously by others. Two important limitations of boron removal with magnesium chloride are the high chemical requirements (5 g/L MgCl2) and sludge production (1 g/g MgCl2 used). These are greatly mitigated by treatment of RO concentrate rather than the full produced water flow. In addition, reagent use and sludge production might be decreased by recycling sludge from the up-front lime softening process. Compared to magnesium oxide, magnesium chloride removes greater quantities of boron per mole of magnesium added (20 mg B/g MgCl2). The magnesium chloride isotherm demonstrated that treatment of RO concentrate required less reagent and produced less sludge per mass of boron removed than treatment of the more dilute feed water.
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Delachaux, Florine. „Étude de la faisabilité d'un procédé d’adsorption gaz-solide pour le traitement des NOx et CO en présence d'eau : application aux émissions de moteurs diesel en espaces confinés“. Electronic Thesis or Diss., Université de Lorraine, 2018. http://www.theses.fr/2018LORR0273.
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Depuis 2012, les gaz d’échappement diesel sont considérés comme cancérigènes, ce qui représente un risque pour les travailleurs quotidiennement exposés à ces fumées. Cette étude s’intéresse plus particulièrement aux oxydes d’azotes (NOx) et au monoxyde de carbone (CO) présents dans l’échappement diesel. Actuellement, des solutions catalytiques permettent de réduire la concentration de sortie de ces composés mais elles ne sont pas viables pour les véhicules non routiers fonctionnant de façon discontinue et pour solutionner la problématique du « cold start ». La thèse s’est alors orientée vers l’adsorption sur des zéolithes. Dans un premier temps, sept zéolithes ont été choisies et l’étude de l’adsorption des corps purs en dynamique a montré qu’elles étaient peu efficaces dans la capture de NO et de CO mais qu’elles avaient de bonnes capacités d’adsorption vis à vis de NO2. L’étude plus poussée sur trois d’entre elles, Na Y, NH4 Y et H Y, a montré qu’en présence d’O2 et/ou de vapeur d’eau dans le flux gazeux, des réactions chimiques se produisent, conduisant notamment à la formation de NO2 et/ou de NO qui doivent alors être également adsorbé. Le rôle de la température d’adsorption a également été étudié sur la zéolithe Na Y. Son influence est importante à la fois sur la capacité d’adsorption et sur les cinétiques des réactions chimiques. Les capacités de rétention maximales des NOx sur la zéolithe Na Y sont obtenues à 30°C en présence d’O2 dans le flux gazeux et en absence totale d’eau. Afin d’améliorer la capture de NO et CO, il est possible d’estimer les capacités d’adsorption d’autres zéolithes en utilisant la modélisation moléculaire par Density Functional Theory (DFT) afin de calculer les chaleurs isostériques d’adsorptionSince 2012, diesel exhaust gases are considered to be carcinogenic, which is a risk to workers who are exposed to these fumes on a daily basis. This study focuses on nitrogen oxides (NOx) and carbon monoxide (CO) present in the diesel exhaust. Currently, catalytic solutions can reduce the outlet concentration of these compounds, but they are not viable for non road vehicles operating intermittently and to solve the problem of “cold start”. The thesis was then focuses on adsorption on zeolites. As a first step, seven zeolites were selected and the study of the adsorption of pure components in dynamics showed that they were ineffective in the uptake of NO and CO but they had good adsorption capacities for NO2. The further study on three of them, Na Y, NH4 Y and H Y, showed that in the presence of O2 and/or water vapor in the gaseous stream, chemical reactions occur, leading in particular to the formation of NO2 and/or NO which must then also be adsorbed. The role of adsorption temperature has also been studied on zeolite Na Y. Its influence is important on the adsorption capacity and on the kinetics of the chemical reactions. The maximum retention capacities of NOx on zeolite Na Y are obtained in presence of O2 in the gaseous mixture and in absence of water. In order to improve the uptake of NO and CO, it is possible to estimate the adsorption capacities of other zeolites by using molecular modeling by Density Functional Theory (DFT) to calculate the isosteric heats of adsorption
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Ghasemian, Langeroudi Elahe. „Quantitative aspects of CO₂-grafted amine interactions in gas-liquid-solid solubility equilibrium : applications to CO₂ capture“. Master's thesis, Université Laval, 2010. http://hdl.handle.net/20.500.11794/21467.
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Les effets liés à la présence d'eau liquide sur la capacité d'adsorption de CO₂ par une silice mésoporeuse de type SBA-15 fonctionnalisée au moyen des amines suivantes: aminopropyltrimethoxysilane (APS) et N-(2-aminoéthyl) -3 - (aminopropyl) trimethoxysilane (AEAPS) ont été examinés pour évaluer le potentiel de ce mode de contact dans des laveurs gaz-liquide-solide. Les résultats ont été comparés à la capacité d'adsorption de CO₂ des amines greffées dans des conditions humides et sèches ainsi qu'à la capacité d'absorption de CO₂ dans les systèmes gaz-liquide avec des solutions aqueuses d'aminés ayant des structures semblables à celles des amines greffées. Dans ces conditions, une estimation de l'adsorption physique de CO₂ a été obtenue par l'étude de la SB A-15 non-modifiée. En outre, afin d'évaluer l'efficacité et la stabilité à long terme de l'association amine/SBA-15, les amines greffées ont été soumises à huit cycles successifs d'immersion dans les milieux aqueux d'une durée de 24 h chacune. Les échantillons récupérés ont été caractérisés au moyen de la diffraction aux rayons, des isothermes de sorption d'azote et d'analyse élémentaire CHN. Jusqu'à 40% de la quantité d'aminés greffées a subi une lixiviation durant les quelques premiers cycles de régénération; par la suite, la teneur en azote de l'AEAPS est demeurée relativement stable, contrairement à l'APS qui a connu une moindre stabilité. Fait intéressant, les structures des deux matériaux greffés, APS et AEAPS, sont demeurées intactes après plusieurs expositions à l'eau. L'efficacité de capture de CO₂ la plus élevée a été obtenue dans le cas des amines aqueuses (voie homogène). Cependant, la capture de CO₂ à l'aide d'aminés greffées dans le cas du système triphasique (gaz-liquide-solide) a donné lieu, pour des conditions opératoires comparables, à des valeurs intermédiaires entre les voies sèche et humide du mode de contact gaz-solide.
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Bernardo, Maria Manuel Serrano. „Study of the valorisation of the solid by-products obtained in the co-pyrolysis of different wastes“. Doctoral thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10979.
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Guner, Ozge. „Acidity Characterization And Adsorption Characteristics Of Cobalt And Lead Doped Sba-15 Mesoporous Materials“. Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608954/index.pdf.
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In this study, the surface acidity of Co and/or Pb doped SBA15 mesoporous catalysts were investigated by both diffuse reflectance fourier transform (DRIFT) infrared spectroscopy and transmission mode fourier transform infrared spectroscopy. Pyridine was used to identify the Brønsted and Lewis acid sites of the surface, at room temperature. From the DRIFT spectrum typical stretching vibrations of isolated terminal silanol (Si-OH) groups were observed for all the catalysts. These silanol group bands dissappeared after pyridine adsorption, indicating that these silanol groups are acidic and serve as chemical adsorption sites for pyridine. Pyridine adsorption on these catalysts revealed that while monometallic additions did not influence the overall acidity of SBA15, in the bimetallic system, characteristic bands due to pyridine adsorption on Co2+ ions were observed.
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Daoudi, Abdelali. „Systèmes Métal-CO comme modèles de chimisorption : interaction de configuration et orbitales naturelles“. Paris 11, 1988. http://www.theses.fr/1988PA112050.
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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.
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Pepin, Christian. „Étude spectroscopique des dépositions de couches minces de Fe(CO)[indice]5 et de CpCo(CO)[indice]2 sur des substrats organiques : stabilité thermique et processus induits par des électrons lents“. Sherbrooke : Université de Sherbrooke, 2001.
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Lau, Ji-Ren. „Studies of the adsorption of C₂H₄, CO and PH₃ on the (OOO1) surface of zirconium“. Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/27587.
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The work in this thesis includes crystallographic investigations with low-energy electron diffraction (LEED) for two surface structures designated Zr(0001)-(1x1)-C (one of lower C coverage and the other of higher C coverage), as well as investigations of the adsorption of CO and PH₃ on the (0001) surface of zirconium by using Auger electron spectroscopy (AES) and LEED.
For the lower-coverage Zr(0001)-(1x1)-C surface, the intensity-versus-energy (I(E)) curves for a set of diffracted beams were measured with a video LEED analyzer, and then compared with the results of multiple scattering calculations made for various structural models. Levels of correspondence between experimental and calculated I(E) curves were assessed with the reliability index proposed by Pendry, and surface geometries determined by the conditions for the best correspondence between experiment and calculation. The LEED intensity analysis suggests that under the lower C coverage, the C atoms in Zr(0001)-(1x1)-C appear to just occupy octahedral holes between the first and second layers of hep zirconium; this is similar to the situation reported by Wong et al for the N adsorption structure formed on Zr(0001). The LEED-determined Zr-C bond distance is 2.30 Å, which is in reasonable agreement with the value determined by X-ray crystallography for bulk ZrC (2.34 Å). Only a very preliminary analysis could be attempted for the higher-C-coverage Zr(0001)-(1x1)-C structure; there the C atoms may occupy all tetrahedral holes between the first and second layers of hep zirconium.
Some I(E) curves were measured for CO adsorption on the Zr(0001) surface; a (2x2) LEED pattern formed with the initial CO exposure while a (1x1) pattern occurs with greater exposures. A comparison was made with CO adsorption on the Ti(0001) surface, and with oxygen adsorption on Zr(0001). The PH₃ adsorption on Zr(0001) can give a (3x3) LEED pattern which is unstable and only measurable in a short energy range. Unlike H₂S adsorption on Zr(0001) surface, ordering to form the (3x3)-PH₃ surface is inhibited by the loss of phosphorus during heating. An attempt was made to find the optimal recipe to get a sharp (3x3)-PH₃ pattern; it appears that the R[sub p] value (a ratio of Auger peak heights to indicate coverage) should be between 1.3 to 1.6, and that the ordering temperature should be higher than 560°C.Science, Faculty of
Chemistry, Department of
Graduate
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Peksa, Mikulás̆, Sareeya Bureekaew, Rochus Schmid, Jan Lang und Frank Stallmach. „On the nature of adsorption sites for CO 2 in MOF Zn 2 (bdc) 2 dabco“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-183198.
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Peksa, Mikulás̆, Sareeya Bureekaew, Rochus Schmid, Jan Lang und Frank Stallmach. „On the nature of adsorption sites for CO 2 in MOF Zn 2 (bdc) 2 dabco“. Diffusion fundamentals 20 (2013) 55, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A13631.
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Chihara, Kazuyuki, Shingo Ito, Hideo Nagashima, Masayuki Hikita und Ryosuke Suzuki. „Adsorption of organics on MSC5A in supercritical CO 2: chromatographic measurements & stop & go simulation“. Diffusion fundamentals 16 (2011) 83, S. 1-6, 2011. https://ul.qucosa.de/id/qucosa%3A13828.
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Chromatographic measurements were made for the adsorption of benzene, toluene and m-xylene on molecular sieving carbon (MSC) in a supercritical fluid CO2 mixed with organics. A supercritical chromatograph packed with MSC was used to detect pulse responses of the organics. Adsorption equilibria and adsorption dynamic parameters for organics were obtained by moment analysis of the response peaks. Dependences of adsorption equilibrium constants, K*, and micropore diffusivity, D, on the amount adsorbed were examined. The dependencies of adsorption equilibrium constants, K*, and micropore diffusivities, D, for benzene, toluene and m-xylene, on the molarity of benzene over a range of temperature and pressure were obtained. Experimental results were simulated using the “Stop & Go” method as well as by molecular simulation.
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Chance, Ronald R., Harry W. Deckman, T. E. Clark, C. J. Yoon, J. A. McHenry, D. C. Calabro und S. Jakubowicz. „CO 2 transport in amorphous silica membranes: adsorption, diffusion, and mitigation of the effects of water“. Diffusion fundamentals 3 (2005) 14, S. 1, 2005. https://ul.qucosa.de/id/qucosa%3A14302.
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Languille, Marie-Angélique. „Étude in situ de surfaces monocristallines Au et Pd-Au : adsorption du CO et de O2“. Lyon 1, 2008. http://www.theses.fr/2008LYO10034.
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La catalyse par l’or connaît un fort renouveau depuis une quinzaine d’années. Ce travail s’inscrit dans une démarche de compréhension de l’adsorption, à l’échelle atomique, des réactifs de la réaction d’oxydation du monoxyde de carbone sur des surfaces monocristallines d’or et d’alliage palladium-or. De plus, il vise à caractériser les surfaces sous pression de gaz. Pour cela, des techniques d’analyse /in situ /(STM, XPS, PM-IRRAS et SXRD), de développement récent, sont mises en œuvre de l’ultravide jusqu’à 500 Torr. Le CO s’adsorbe sur les surfaces Au(110), Au(111) et Pd-Au(110) sur des sites linéaires -et pontés dans le cas du bimétallique. Cette adsorption induit de fortes modifications de l’état (morphologie, structure, propriétés électroniques) de surface. Les reconstructions des surfaces sont décrites en fonction de p(CO). Si les surfaces monocristallines d’or conservent leurs structure et morphologie d’équilibre sous p(O_2 ), la surface d’alliage voit croître l’oxyde PdO suite à une ségrégation de palladiumInterest for catalysis by gold has grown since about fifteen years. This work fits within an approach to gain understanding, at atomic scale, of the adsorption of the gases participating in the oxidation of carbon monoxide on single-crystal surfaces of gold and palladium-gold alloy. Furthermore, the aim is to characterise surfaces under gas pressure. In order to do so, recently developed /in situ/ analysis techniques (STM, XPS, PM-IRRAS and SXRD) are operated from UHV conditions up to 500Torr. CO adsorbs on Au(110), Au(111) and Pd-Au(110) surfaces on top sites – and also on bridge sites in the case of the bi-metallic surface. This adsorption induces strong modification of the surface characteristics (morphology, structure, electronic properties). Surface reconstructions are described as a function of p(CO). While the structure and the morphology of single-crystal gold surfaces remain unchanged under p(O_2 ), Pd segregation and subsequent surface PdO formation is observed for the alloy surface
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Haddou, Elyakhloufi Mounir. „Liason CO-palladium sur catalyseurs modèles : une étude par analyse de surface (SSIMS et TDP)“. Aix-Marseille 3, 1993. http://www.theses.fr/1993AIX30035.
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Ce travail avait deux objectifs: 1) l'elaboration et la caracterisation sous ultravide de catalyseurs modeles au palladium; 2) l'etude de la liaison co-metal en fonction des caracteristiques du catalyseur et des conditions de chimisorption (taille, morphologie des particules, nature des supports, temperature. . . ). Pour atteindre ces buts nous avons utilise principalement la methode de spectrometrie de masse d'ions secondaires en regime statique (ssims) associee a la thermodesorption programmee (tdp). Une methode complementaire pour la caracterisation des catalyseurs a ete employee: la microscopie electronique par transmission (tem). Les catalyseurs sont elabores in situ par condensation de vapeurs metalliques sur differents supports monocristallins (-al#2o#3, -al#2o#3, mgo et tio#2), caracterises par ssims. Nous avons montre que la ssims est aussi tres fructueuse pour caracteriser la croissance et la morphologie des depots metalliques. Les resultats mettent en evidence la complementarite entre la microscopie electronique et cette methode qui a l'avantage de permettre d'acceder in situ a la morphologie du depot (2d, 3d), a la cohesion en surface des particules (rugosite) et a l'interaction metal-support. Le principal objectif de notre travail concernait l'etude de la chimisorption de co: la determination de la cinetique d'adsorption, la nature de la liaison de co avec les particules metalliques (adsorption dissociative ou moleculaire) et sa symetrie (lineaire ou en pont), l'interaction entre adsorbat-adsorbat (co-co). Nous avons montre que co s'adsorbe soit lineairement soit en pont suivant le taux de couverture. L'influence de la taille des particules et de la nature de support a ete mise en evidence. La dissociation de co qui apparait pour les plus faibles tailles de particule, a ete caracterisee sur les differents supports, donc c'est un effet de taille general. Nous avons mis en evidence de plus un effet tres interessant: la reconstruction reversible de la surface des particules lors de l'adsorption de co
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Beckerle, John David. „Dynamics of molecular adsorption : I--collision induced dissociative chemisorption and desorption of CH4ON Ni(111), II--adsorption of CO and O2ON Ni(111) at 8 K“. Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14605.
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Gao, Teng Gao. „Controllable Methylation of Polyethyleneimine by Cu Coordination for NOX, SO2, and CO2 Capture“. University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1522428169157346.
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Duarte, Mendes Catita Leonor. „Contribution of NMR and Raman imaging for modeling and rationalization of the impregnation process of metallic precursors in porous media“. Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1262/document.
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Cette thèse s’inscrit dans le domaine de la catalyse hétérogène pour des applications en raffinage et en pétrochimie. Plus particulièrement, nous avons choisi d’étudier le cas des catalyseurs d’hydrotraitement largement utilisés dans les procédés de conversion du pétrole en carburant. Ces catalyseurs sont constitués d’une phase métallique sulfurée supporté sur un support poreux inorganique.Dans ce travail, nous nous sommes particulièrement intéressés à la compréhension et la modélisation de la première étape de préparation d’un catalyseur d’hydrotraitement : l’étape d’imprégnation. Une méthodologie innovante basée sur la technique d’imagerie RMN qui permet d’observer operando le transport des précurseurs métalliques dans le support et sur la technique d’Imagerie Raman a été développée. Les résolutions spatiales et temporelles obtenues ont permis de valider cette méthodologie pour caractériser l’étape d’imprégnation en termes de phénomènes physiques (capillarité et diffusion) et chimiques (interaction de surface) et pour identifier les descripteurs clés de cette étape.En conclusion, ces travaux permettront un meilleur contrôle de l'étape d'imprégnation et donc du profil de distribution de la phase active, ce qui aura une forte répercussion sur la performance catalytiqueThe objective of this work is to characterize the impregnation step in terms of physical phenomena (capillarity and diffusion) and chemical phenomena (surface interaction) in order to identify the key descriptors of this step in order to improve the preparation hydrotreating catalysts. This involves monitor spatial and temporally the transport of the species in the impregnation solution within the porosity, more particularly in the case of Ni(Co)MoP/?-Al2O3 catalysts preparation.An original MRI approach has been developed to follow in-situ the impregnation step from a solution of mixed nature with more than one metal precursor in the presence of an additive. MRI provides access to the spatial distribution of all species within the catalyst with a spatial resolution of 39 × 39 µm. Raman imaging allows an identification of the chemical nature of the species in solution with a spatial resolution of 16.2 × 16.2 µm.First, the phenomena involved in the impregnation of model solutions composed of Ni (or Co), were studied by modifying the parameters of the solution. These experiments were then used as the basis for the development of a mathematical model to rationalize the impregnation step. In a second part, this study was extended to the preparation of hydrotreatment catalysts. Several phenomena have been evaluated here, notably the impact of the presence of phosphorus on the transport of Mo species, possible competition of adsorption between P, Co and Mo and the effect of the presence of citric acid.This study allows a better control of the impregnation step and thus of the distribution profile of the active phase, which has an impact on the catalytic performance
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Pykavy, Mikhail. „Ab-initio-Cluster-Rechnungen und Monte-Carlo-Simulationen zur Adsorption von CO auf der Cr203(0001)-Oberfläche“. [S.l. : s.n.], 1999. http://deposit.ddb.de/cgi-bin/dokserv?idn=959773851.
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Wörlén, Cecilia. „Co-precipitation/Adsorption of Boron for Treatment of Produced Water at the Arroyo Grande Oil Field, California“. Thesis, KTH, Industriell ekologi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-32895.
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The goal of this Master’s thesis project is to develop a method for boron precipitation inproduced waters from the Arroyo Grande oil field outside San Luis Obispo in centralCalifornia. The current oil recovery is a closed system that pumps up to 1,500 barrelsoil/day. A new system is proposed to increase oil production three times andsimultaneously dewater half of the water in the oil formation during the time span of tenyears, which amounts to 55,000 barrels/day. The water will be treated and used forirrigation or discharged into a stream. The water contains high levels of boron (7-8mg/L), which will be removed with chemical precipitation/adsorption. The full treatmentsystem will include, besides precipitation, lime softening, walnut shell filter, strong-acidcation exchange, microfiltration, and reverse osmosis. All experiments were conducted at site-similar conditions, i.e. at water temperatures of70 ºC. Titrations were conducted with NaOH-solution and slaked lime (Ca(OH)2) toestablish the amount needed to increase the pH to levels needed in the precipitationexperiments. Softening to remove divalent ions (Ca2+ and Mg2+) and silica will be needed to protectcoming steps in the treatment, with the possible removal of some boron. The amount oflime, added as slaked lime, needed was determined experimentally to 500 mg/L. Limesoftening calculations were in good agreement with experimental results. Up to 20 %boron was removed by adding large amounts of lime, up to 2700 mg/L. The experiments were conducted varying the amount of magnesia (0-30 g/L), pH (9.7-11), and reaction temperature (50-90 °C), showing that 90 % boron can be removed whenadding 30 g/L magnesia, on the other hand, little or no boron was removed for additionslower than 5 g/L MgO. Increase in temperature and lowering pH was advantageous to theboron removal. The silica removal was strongly promoted by an increase in temperature.Magnesia was added to synthetic water, at low and high temperatures (50 and 80 °C), atlow and high pH, with sodium hydroxide and lime, confirming previous results.Magnesium chloride was added to the produced water, and compared to samples ofmagnesia with the same molar concentrations; magnesium chloride was more efficient atlow concentrations and less efficient at high concentrations, removing 31 % when adding5 g/L, and 11 % when adding 25 g/L. When studying the adsorption onto alumina, the amount was varied between 0 and 35 g/Land the pH was varied between 7 and 10.4. The boron removal increased, with theincreasing alumina, removing 38 % when adding 35 mg/L. Changing the pH did notimprove or worsen the removal.These results are important for determining a suitable boron removal process in thewastewater treatment plant at the Arroyo Grande oil field, though more studies must beconducted to reach optimum and realistic results.Division Industrial Ecologywww.kth.se/itm/indecowww.ima.kth.se