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Relevant bibliographies by topics / Deactivation by carbon

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Academic literature on the topic 'Deactivation by carbon'

Author: Grafiati

Published: 4 June 2021

Last updated: 7 February 2022

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Journal articles on the topic "Deactivation by carbon"

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Garoma, T., and J. Kocher. "Investigation of surfactant-modified activated carbon for recycled water disinfection." Water Science and Technology 62, no. 8 (August 1, 2010): 1755–66. http://dx.doi.org/10.2166/wst.2010.458.

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This study investigated the effectiveness of surfactant-loaded granular activated carbon (GAC) to deactivate total coliform, E. coli, and enterococci found in tertiary effluent under various experimental conditions, i.e. varying surfactant dose, GAC dose, and contact time. The results indicate that GAC loaded with 100 mg/g of hexadecyltrimethylammonium bromide (CTAB) and didodecyldimethylammonium bromide (DDAB), achieved log reductions as high as 1.02 and 1.86 of total coliform, respectively. At varying GAC doses and contact times, 200 mg/g of DDAB dose achieved 99.9 to 100% reduction in total coliform at initial concentrations as high as 38,000 MPN/100 mL. Complete deactivation of E. coli and enterococci were observed for CTAB and DDAB at 200 mg/g dose for varying GAC doses and contact times used in this study. DDAB was more effective than CTAB at deactivating total coliform and E. coli, both Gram-negative bacteria, while both surfactants were shown to have similar disinfection capabilities against enterococci. Surfactant dose and GAC dose were shown to enhance bacteria deactivation; however, surfactant dose was found to be the most important parameter. For contact times evaluated in this research, bacterial deactivation remained the same or slightly decreased with contact time. In conclusion, surfactant-modified GAC can be used as an effective disinfection technique for recycled water.

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Vander Wal, Randy, and Mpila Makiesse Nkiawete. "Carbons as Catalysts in Thermo-Catalytic Hydrocarbon Decomposition: A Review." C — Journal of Carbon Research 6, no. 2 (April 14, 2020): 23. http://dx.doi.org/10.3390/c6020023.

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Thermo-catalytic decomposition is well-suited for the generation of hydrogen from natural gas. In a decarbonization process for fossil fuel—pre-combustion—solid carbon is produced, with potential commercial uses including energy storage. Metal catalysts have the disadvantages of coking and deactivation, whereas carbon materials as catalysts offer resistance to deactivation and poisoning. Many forms of carbon have been tested with varied characterization techniques providing insights into the catalyzed carbon deposition. The breadth of studies testing carbon materials motivated this review. Thermocatalytic decomposition (TCD) rates and active duration vary widely across carbons tested. Regeneration remains rarely investigated but does appear necessary in a cyclic TCD–partial oxidation sequence. Presently, studies making fundamental connections between active sites and deposit nanostructures are few.

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Liang, Wei, Hao Yan, Chen Chen, Dong Lin, Kexin Tan, Xiang Feng, Yibin Liu, Xiaobo Chen, Chaohe Yang, and Honghong Shan. "Revealing the Effect of Nickel Particle Size on Carbon Formation Type in the Methane Decomposition Reaction." Catalysts 10, no. 8 (August 6, 2020): 890. http://dx.doi.org/10.3390/catal10080890.

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Carbon species deposition is recognized as the primary cause of catalyst deactivation for hydrocarbon cracking and reforming reactions. Exploring the formation mechanism and influencing factors for carbon deposits is crucial for the design of rational catalysts. In this work, a series of NixMgyAl-800 catalysts with nickel particles of varying mean sizes between 13.2 and 25.4 nm were obtained by co-precipitation method. These catalysts showed different deactivation behaviors in the catalytic decomposition of methane (CDM) reaction and the deactivation rate of catalysts increased with the decrease in nickel particle size. Employing TG-MS and TEM characterizations, we found that carbon nanotubes which could keep catalyst activity were more prone to form on large nickel particles, while encapsulated carbon species that led to deactivation were inclined to deposit on small particles. Supported by DFT calculations, we proposed the insufficient supply of carbon atoms and rapid nucleation of carbon precursors caused by the lesser terrace/step ratio on smaller nickel particles, compared with large particles, inhibit the formation of carbon nanotube, leading to the formation of encapsulated carbon species. The findings in this work may provide guidance for the rational design of nickel-based catalysts for CDM and other methane conversion reactions.

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Hu, Ing-Feng, Dale H. Karweik, and Theodore Kuwana. "Activation and deactivation of glassy carbon electrodes." Journal of Electroanalytical Chemistry and Interfacial Electrochemistry 188, no. 1-2 (June 1985): 59–72. http://dx.doi.org/10.1016/s0022-0728(85)80050-4.

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Mukkavilli, Suryanarayana, Charles Wittmann, and Lawerence L. Tavlarides. "Carbon deactivation of Fischer-Tropsch ruthenium catalyst." Industrial & Engineering Chemistry Process Design and Development 25, no. 2 (April 1986): 487–94. http://dx.doi.org/10.1021/i200033a023.

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Afineevskii, Andreiy V., Dmitriy A. Prozorov, Mikhail V. Lukin, Tatiana Yu Osadchaya, and Yaroslav P. Sukhachev. "NICKEL CATALYTIC PROPERTIES IN REACTION OF LIQUID-PHASE HYDROGENATION OF CARBON-CARBON DOUBLE BOND." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 60, no. 6 (July 19, 2017): 95. http://dx.doi.org/10.6060/tcct.2017606.5409.

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The hydrogenating of carbon-carbon double bond in a molecule of sodium maleate over a partially deactivated catalysts based on nickel in a water solution at atmospheric pressure was investigated. Kinetic regularities of the investigated processes were obtained. It was found that sulfide additives lead to the decrease in an order of the reaction for both skeletal and supported nickel catalysts, however, the correlation of activity versus the amounts of sulfur introduced is complex and independent on the amount of active metal on the catalyst surface. We proposed the method for the synthesis of a supported nickel catalyst resistant to oxidation with atmospheric oxygen and an activity of the one is more than twice better then activity of Raney nickel. The stability of the nickel catalyst (Raney nickel and nickel supported on silica) in the presence of sulfide ions impurities in the reaction system was shown. It was found that the supported nickel catalyst has a much higher resistance to deactivation than the skeletal catalyst. The role of the support at the adsorption of sulfide from solution during deactivation of the investigated catalysts was demonstrated. It was suggested that the higher stability of the supported catalyst for deactivation is due to the sorption of the catalytic poison by silica gel. It is suggested the possibility of adjusting the selectivity of the catalyst deactivation character without changing the nature of the solvent. It was presented the possibility of purposeful variation in a wide range of adsorption properties of the active metal surface relative to the reactants, which makes possible to develop approaches to the synthesis of catalysts with given parameters of activity and selectivity relative to certain classes of organic compounds.Forcitation:Afineevskii A.V., Prozorov D.A., Osadchaya T.Yu., Sukhachev Ya.P., Lukin M.V. Nickel catalytic properties in reaction of liquid-phase hydrogenation of carbon-carbon double bond. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60.N 6. P. 95-101.

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Liao, Hsueh-Chun, Jui-Chang Lin, and Ruey-Dar Chang. "Deactivation of Phosphorus by Carbon in Recrystallized Silicon." ECS Journal of Solid State Science and Technology 8, no. 4 (2019): P262—P266. http://dx.doi.org/10.1149/2.0041904jss.

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Kuwana, Kazunori, Hajime Endo, Kozo Saito, Dali Qian, Rodney Andrews, and Eric A. Grulke. "Catalyst deactivation in CVD synthesis of carbon nanotubes." Carbon 43, no. 2 (2005): 253–60. http://dx.doi.org/10.1016/j.carbon.2004.09.008.

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MO, X., D. LOPEZ, K. SUWANNAKARN, Y. LIU, E. LOTERO, J. GOODWINJR, and C. LU. "Activation and deactivation characteristics of sulfonated carbon catalysts." Journal of Catalysis 254, no. 2 (March 10, 2008): 332–38. http://dx.doi.org/10.1016/j.jcat.2008.01.011.

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LUND, C. "Nickel catalyst deactivation in the steam-carbon reaction." Journal of Catalysis 95, no. 1 (September 1985): 71–83. http://dx.doi.org/10.1016/0021-9517(85)90009-0.

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Dissertations / Theses on the topic "Deactivation by carbon"

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Hu, Ing-Feng. "Activation and deactivation of glassy carbon electrodes /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu148726339902366.

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Carron, David. "FISCHER-TROPSCH SYNTHESIS IN SUPERCRITICAL PHASE CARBON DIOXIDE: DEACTIVATION STUDIES." OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/643.

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ABSTRACT This thesis presents the results of investigations regarding the effect of supercritical CO2 on the long term activity, life and deactivation rates of an Fe-Zn-K catalyst during Fischer Tropsch Synthesis from syngas (H2:CO =1:1) typically produced from coal gasification. Previous studies at SIUC on FTS in Supercritical CO2 (SC-CO2) have shown that CH4 selectivity was inhibited and with the presence of excess CO2, the WGS reaction was reversed. This increased the carbon economy as result of the reduction in parasitic loss of CO to CO2. In addition, it was observed that the conversion of CO, under these pressures and CO2 dilution, was significantly enhanced. Studies in a continuous flow system showed the use of SC-CO2 affected the distribution of hydrocarbons, mainly producing heavier hydrocarbons (diesel fuel). In this thesis, results from four long term experiments (21-28 day) varying the CO2:syngas ratio are reported. The experiments were conducted at 350 oC, 1200 psi with a feed rate of 200sccm in a fixed bed supercritical reactor with a volume of 150 cc. The results show that the conversion of syngas increased from 47% to 95% at the optimum ratio 5:1 (CO2:Syngas). The steady state reaction rate constant also increased 4.756 times the baseline run from 0.021215 min-1 to 0.100907 min-1, for pure syngas and a CO2:syngas ratio of 5:1 respectively. The deactivation rate did not improve with the use of supercritical CO2; however, the life span of the catalyst more than doubled that of the base line run with an increase in SC- CO2. Product tailoring can also be performed by simply changing the SC-CO2:Syngas ratio. Ratios less than 5:1 will yield a product distribution of predominately alcohols, ratios greater than 5:1 produce heavier hydrocarbons. Both of these product distributions can be beneficial, but for this research a ratio of 5:1 yielded the desired product distribution of light to heavy hydrocarbons generically known as gasoline and diesel fuel. Liquid selectivity was observed to increase with CO2 content in the feed upto a CO2:syngas ratio of 5:1, thereafter it declined slightly. CO2 is produced in the experiment of pure syngas with no Sc-CO2, however the introduction of Sc-CO2 resulted in the consumption of CO2 for the production of hydrocarbons. The methane selectivity was found to monotonically decrease with the increase in CO2 content in the feed. With oil prices increasing, the use of SC- CO2 as a reaction media for FTS is showing more promise in providing liquid fuels more effectively. The evidence of consumption of CO2 means that CO2 does not need to be removed from the syngas feed stream after the gasification and water gas shift unit processes. The increase in the observed life of the catalyst under supercritical conditions will ultimately reduce the operating cost as less material will be needed to produce the same amount of product allowing for FTS to become economically competitive.

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Otor, Hope O. "Catalyst Development and Control of Catalyst Deactivation for Carbon Dioxide Conversion." University of Toledo / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1596134702392137.

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Barrientos, Javier. "Deaktivering av metanisering katalysatorer." Thesis, KTH, Skolan för kemivetenskap (CHE), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-156183.

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A titania-supported nickel catalyst was prepared and tested in methanation in order to evaluate its catalytic properties (activity, selectivity and specially, activity loss), and compare it with an alumina-supported nickel catalyst. The titania-supported catalyst did not only show higher stability than alumina, but also presented a different cause of deactivation, carbon formation. In addition, a kinetic model was obtained for the titania-supported catalyst, and a study of the effect of different operating conditions (temperature, composition and partial pressures of synthesis gas and water) on the deactivation rate and carbon formation of this catalyst was performed.

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Patterson, Veronica A. "The effects of carbon deposition on catalyst deactivation in high temperature Fischer-Tropsch catalysts." Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3086.

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In this work, carbonaceous deposits on spent HTFT catalysts were investigated. This research was required in order to better understand the observed loss in productivity observed in the industrial reactors, with the aim of improving the economy of the HTFT process. A host of complementary techniques were employed to systematically determine the composition of a typical catalyst recovered from a reactor. Spent HTFT catalysts are comprised of magnetite and a mixture of iron carbides as well as adsorbed hydrocarbon products (soft carbon) and hard carbon. Reaction initiates at the particle surface and along the promoter-rich grain boundaries toward the core of the grains. A partially reacted particle would therefore have a core-shell structure, with magnetite representing the unreacted region of the catalyst. The reacted region consists of a porous carbonaceous matrix with soft carbon and carbide crystallites nestled in this matrix. The hard carbonaceous species is a mixture of polymeric carbon and polycyclic aromatic hydrocarbons. The particle structure is linked to the sample preparation method and an alternative method yielding catalyst particle with uniformly distributed promoter elements could be beneficial. Investigating carbonaceous species is a complex process, and development of a fresh methodology would aid in the quest for insight into the nature of carbonaceous species in various systems. A new approach which entails a combination of the traditional techniques combined with MALDI-TOF MS enabled a deeper investigation. Additional aspects such as the molecular weight distributions along with known information about crystallinity and morphology of the catalyst provide a comprehensive study of carbonaceous material. Polymeric carbon and very large polycyclic aromatic hydrocarbons constitute hard carbon and can be observed with minimal sample preparation procedures. The evolution of the HTFT catalysts was investigated as a function of time-on-stream. This enabled us to study the effects of increasing amounts of hard carbon on the activity and the chemical and physical properties of the catalysts. The catalyst activity was found to decrease with increasing hard carbon content, although the effect of carbon deposition cannot be distinguished from phase transformation (oxidation) which occurs simultaneously. A method to quantify the amount of hard carbon, which progressively builds up on the catalyst, was demonstrated. This required a great deal of method development, which provides a platform for future investigations of these catalysts. Importantly, it allows predictions of the amounts of carbon that will be deposited after a certain reaction time. This allows more efficient regulation of catalyst replacement. The production of fine carbon-rich particles in the industrial reactor poses a major problem in the process. Carbon deposition leads to an increase in particle diameter with time on-stream. Permissible levels of hard carbon were identified, beyond which the mechanical strength of the catalyst particles deteriorate. This leads to break-up of the particles and therefore fines formation. The surface area and pore volume generally increase with progressive deposition of hard carbon, while the bulk density of the catalyst material exhibits a linear decrease with carbon build-up. A mechanism is proposed for hard carbon formation which apparently occurs through the dissociative adsorption of CO to form a carbon monolayer. This is followed by polymerisation of the carbon atoms. Meta-stable interstitial carbides are formed at the iron-carbon interface. Owing to a carbon concentration gradient between the top of the surface and the bottom of the metal or carbide particle, carbon diffusion across the crystal (carbide decomposition) and grows as a PAH molecule lifting the iron carbide away from the particle. As this corrosion process is intrinsic to iron-based catalysts, a catalyst that contains sulphur is proposed for future development.

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Barrientos, Javier. "Deactivation of cobalt and nickel catalysts in Fischer-Tropsch synthesis and methanation." Doctoral thesis, KTH, Kemisk teknologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-190593.

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A potential route for converting different carbon sources (coal, natural gas and biomass) into synthetic fuels is the transformation of these raw materials into synthesis gas (CO and H2), followed by a catalytic step which converts this gas into the desired fuels. The present thesis has focused on two catalytic steps: Fischer-Tropsch synthesis (FTS) and methanation. The Fischer-Tropsch synthesis serves to convert synthesis gas into liquid hydrocarbon-based fuels. Methanation serves instead to produce synthetic natural gas (SNG). Cobalt catalysts have been used in FTS while nickel catalysts have been used in methanation. The catalyst lifetime is a parameter of critical importance both in FTS and methanation. The aim of this thesis was to investigate the deactivation causes of the cobalt and nickel catalysts in their respective reactions. The resistance to carbonyl-induced sintering of nickel catalysts supported on different carriers (γ-Al2O3, SiO2, TiO2 and α-Al2O3) was studied. TiO2-supported nickel catalysts exhibited lower sintering rates than the other catalysts. The effect of the catalyst pellet size was also evaluated on γ-Al2O3-supported nickel catalysts. The use of large catalyst pellets gave considerably lower sintering rates. The resistance to carbon formation on the above-mentioned supported nickel catalysts was also evaluated. Once again, TiO2-supported nickel catalysts exhibited the lowest carbon formation rates. Finally, the effect of operating conditions on carbon formation and deactivation was studied using Ni/TiO2 catalysts. The use of higher H2/CO ratios and higher pressures reduced the carbon formation rate. Increasing the temperature from 280 °C to 340 °C favored carbon deposition. The addition of steam also reduced the carbon formation rate but accelerated catalyst deactivation. The decline in activity of cobalt catalysts with increasing sulfur concentration was also assessed by ex situ poisoning of a cobalt catalyst. A deactivation model was proposed to predict the decline in activity as function of the sulfur coverage and the sulfur-to-cobalt active site ratio. The results also indicate that sulfur decreases the selectivity to long-chain hydrocarbons and olefins.

QC 20160817

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Chien, Chang-Yin. "Methane and Solid Carbon Based Solid Oxide Fuel Cells." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1299670407.

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Keyvanloo, Kamyar. "Preparation of Active, Stable Supported Iron Catalysts and Deactivation by Carbon of Cobalt Catalysts for Fischer-Tropsch Synthesis." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5705.

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The first half of this dissertation reports the development of supported Fe FT catalysts including the effects of various, carefully chosen preparation methods on the performance of alumina-supported iron/copper/potassium (FeCuK/Al2O3); it was determined that non-aqueous slurry impregnation and co-impregnation yielded catalysts with activities as high as any reported in the literature. Furthermore, the effects of support properties including pore size, hydroxyl group concentration, and support stabilizer were investigated for FeCuK/Al2O3 catalysts containing 20 or 40% Fe. For the first time, we report the performance of a supported Fe FT catalyst that is not only more active and stable than any supported Fe catalyst previously reported, but also has activity equivalent to that of the most active, unsupported catalysts. More importantly, the catalyst is extremely stable as evidenced by the fact that after 700 h on stream, its activity and productivity are still increasing. These catalyst properties result from the use of a novel γ-alumina support material doped with silica and pretreated at 1100°C. This unique support has a high pore volume, large pore diameter, and unusually high thermal stability. The ability to pretreat this support at 1100°C enables preparation of a material having a low number of acid sites and weak metal oxide-support interactions, all desirable properties for an FT catalyst. The second half of this dissertation investigates the effects of operating conditions including the partial pressures of CO and H2 and temperature on the deactivation by carbon of 25 wt% Co/ 0.25 wt% Pt/Al2O3 catalyst. It also reports the kinetics of the main FT reaction on this catalyst. As temperature increases, the H2 and CO orders for the main reaction (in the absence of deactivation) become more positive and more negative, respectively. A new mechanism was proposed to account for the inhibition effect of CO at high reaction temperatures, which includes H-assisted dissociation of CO to C* and OH*. Further, twelve samples of the CoPt/Al2O3 catalyst were tested over a period of 800 hours and XCO < 24%, each at a different set of CO and H2 partial pressures and temperature (220-250°C). At reaction temperature of 230°C, increasing PCO or PH2 increases the deactivation rate; possibly due to formation of polymeric carbons. The H2 and CO partial pressure orders for the deactivation rate at 230°C were found to be 1.12 and 1.43, respectively using a generalized-power-law-expression (GPLE) with limiting activity of 0.7 and 1st order deactivation. For a H2/CO of 2 (PH2 = 10 bar and PCO = 5 bar) the deactivation rate increases as process temperature increases from 220 to 250°C with an activation energy of 81 kJ/mol. However, at higher CO partial pressure (PCO = 10 bar) the deactivation rate for the Co catalyst of this study decreases with increasing temperature; this can possibly be attributed to the formation of more active cobalt sites at higher temperatures due to surface reconstruction.

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Lakhapatri, Satish L. "Analysis of Deactivation Mechanism on a Multi-Component Sulfur-Tolerant Steam Reforming Catalyst." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1279327420.

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Ferrandon, Magali. "Mixed metal oxide - noble metal catalysts for total oxidation of volatile organic compounds and carbon monoxide." Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3156.

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Book chapters on the topic "Deactivation by carbon"

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Rostrup-Nielsen, Jens R., and Jens Sehested. "Whisker Carbon Revisited." In Catalyst Deactivation 2001, Proceedings of the 9th International Symposium, 1–12. Elsevier, 2001. http://dx.doi.org/10.1016/s0167-2991(01)80174-9.

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Lødeng, R., M. Barrè-Chassonnery, M. Fathi, O. A. Rokstad, and A. Holmen. "Carbon formation from decomposition of CH4 on supported Ni catalysts." In Catalyst Deactivation, Proceedings of the 7th International Symposium, 561–66. Elsevier, 1997. http://dx.doi.org/10.1016/s0167-2991(97)80200-5.

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Batina, N., L. M. Ioffe, and Y. G. Borodko. "AFM study of carbon formation on a manganese oxide catalyst." In Catalyst Deactivation, Proceedings of the 7th International Symposium, 655–63. Elsevier, 1997. http://dx.doi.org/10.1016/s0167-2991(97)80211-x.

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Hoost, T. Eddy, and James G. Goodwin. "Potassium Effects on the Deactivation by Carbon of Ruthenium Catalysts." In Studies in Surface Science and Catalysis, 691–98. Elsevier, 1991. http://dx.doi.org/10.1016/s0167-2991(08)62701-9.

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Reymond, J. P., and B. Pommier. "Deactivation of iron catalysts in the hydrogenation of carbon monoxide." In Catalyst deactivation 1999, Proceedings of the 8th International Symposium, 299–306. Elsevier, 1999. http://dx.doi.org/10.1016/s0167-2991(99)80479-0.

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Baker, R. T. K., M. S. Kim, A. Chambers, C. Park, and N. M. Rodriguez. "The relationship between metal particle morphology and the structural characteristics of carbon deposits." In Catalyst Deactivation, Proceedings of the 7th International Symposium, 99–109. Elsevier, 1997. http://dx.doi.org/10.1016/s0167-2991(97)80144-9.

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Vleeming, J. H., F. A. de Bruijn, B. F. M. Kuster, and G. B. Marin. "Deactivation of carbon-supported platinum catalysts during oxidations in aqueous media." In Catalyst Deactivation 1994, Proceedings of the 6th International Symposium, 467–74. Elsevier, 1994. http://dx.doi.org/10.1016/s0167-2991(08)62774-3.

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Owens, W. T., M. S. Kim, N. M. Rodriguez, and R. T. K. Baker. "Influence of Sulfur on the Interaction of Iron with Carbon Monoxide." In Catalyst Deactivation 1994, Proceedings of the 6th International Symposium, 191–98. Elsevier, 1994. http://dx.doi.org/10.1016/s0167-2991(08)62740-8.

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Quincoces, C. E., A. Diaz, M. Montes, E. N. Ponzi, and M. G. Gonzalez. "CO2 Reforming of Methane. Effect of Ni-SiO2 Interactions on Carbon Deposition." In Catalyst Deactivation 2001, Proceedings of the 9th International Symposium, 85–92. Elsevier, 2001. http://dx.doi.org/10.1016/s0167-2991(01)80184-1.

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Chen, De, Rune Lødeng, Kjersti Omdahl, Arne Anundskås, Ola Olsvik, and Anders Holmen. "A Model for Reforming on Ni Catalyst with Carbon Formation and Deactivation." In Catalyst Deactivation 2001, Proceedings of the 9th International Symposium, 93–100. Elsevier, 2001. http://dx.doi.org/10.1016/s0167-2991(01)80185-3.

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Conference papers on the topic "Deactivation by carbon"

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Hojnik Podrepšek, Gordana, Željko Knez, and Maja Leitgeb. "Enzyme Deactivation Using High Pressure Carbon Dioxide Technology." In International Conference on Technologies & Business Models for Circular Economy. University of Maribor, University Press, 2020. http://dx.doi.org/10.18690/978-961-286-353-1.16.

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Crevier, P. P., P. Eng, A. M. Adab, H. M. BaAqeel, I. A. Hummam, and A. S. Misfer. "Saudi Aramco Eliminates Claus Catalyst Deactivation Caused by Aromatics Using Activated Carbon." In IPTC 2007: International Petroleum Technology Conference. European Association of Geoscientists & Engineers, 2007. http://dx.doi.org/10.3997/2214-4609-pdb.147.iptc11432.

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Seto, Kelvin S. H., and Brian M. Ikeda. "Model Passivated Carbon Electrodes for Fluorine Generation in MSRs and the Nuclear Fuel Cycle." In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-16642.

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Elemental fluorine, F2, is used in the nuclear fuel cycle for the isotopic separation of uranium-235 and 238, as well as for the purification of LiF-BeF2 in molten salt reactors. F2 is generated on an industrial scale by an electrochemical process using carbon electrodes in a KF-2HF molten salt. Carbon electrodes are used for industrial F2 generation due to its chemical stability, high conductivity, and relatively low cost. One of the main issues faced when using carbon electrodes in this chemical system is passivation through the formation of C-F compounds on the surface of the electrode. This results in a loss of anode wettability to the electrolyte and diminished charge transfer rate. The voltage needed for the fluorine evolution reaction increases which negatively impacts the safety of the system, increases the operating costs, and leads to faster degradation of the electrode. The degradation of electrical properties during passivation is progressive, eventually leading to electrode deactivation. The process of deactivation begins with a passivating C-F layer at potentials above the equilibrium potential (2.92 V). The layer is both non-wetting to the KF-2HF media and insulating. Deactivation begins with inhibited F2 bubble detachment, formation of a persistent gas layer, and finally deactivation as the electrode surface is completely covered by a thick, insulating C-F layer causing charge transfer to cease. Only a small current is able to flow, even at high potentials (up to 9 V), indicating F2 generation is completely inhibited. The purpose of this study is to manufacture and test model carbon electrodes and, to examine the non-wetting properties of a partially fluorinated surface. The electrodes will be prepared by mixing PTFE-particles with Vulcan carbon powder and then pressing to form pellets. These electrodes should have a reproducible surface for electrochemical performance studies that will lead to a better understanding of the surface chemistry. The research will develop novel electrodes with a goal to minimize the voltage required for F2 production. This will enhance the efficiency in the overall process and lower the manufacturing costs for F2. Carbon electrodes with different PTFE-content (20 w.% and 35 w.%) were synthesized. Electrochemical fluorination was then carried out at different potentials in the F2 generation region (4 to 8 V) in molten KF·2HF electrolyte at ∼90 °C. The electrochemical behaviour of the carbon-PTFE electrodes was examined and compared for both fluorine passivated and non-passivated graphite, amorphous carbon, and vitreous carbon electrodes. The growth of the electrical double-layer capacitance between the carbon electrodes and the KF·2HF molten salt was studied. The effects of composition of fluorinated and non-fluorinated carbon on electrode performance are presented.

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Chang, Ruey-Dar, Hsueh-Chun Liao, Jui-Chang Lin, and Jung-Ruey Tsai. "Impact of Carbon on the Deactivation Behaviors of Boron and Phosphorus in Preamorphized Silicon." In 2018 22nd International Conference on Ion Implantation Technology (IIT). IEEE, 2018. http://dx.doi.org/10.1109/iit.2018.8807894.

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Bond, Gary, A. Halman, H. Eccles, R. Mao, S. Pollington, P. Hinde, V. Demidyuk, and A. Gkelios. "A COMPARATIVE STUDY OF MICROWAVE AND BARRIER DISCHARGE PLASMA FOR THE REGENERATION OF SPENT ZEOLITE CATALYSTS." In Ampere 2019. Valencia: Universitat Politècnica de València, 2019. http://dx.doi.org/10.4995/ampere2019.2019.9936.

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Due to their acid characteristics and pore structure, which can induce high product selectivity; zeolite catalysts are used extensively in industry to catalyse reactions involving hydrocarbons. However, these catalysts can suffer from deactivation due to cracking reactions that result in the deposition of carbon leading to poisoning of the acid sites and blocking of the pores [1]. Depending upon the reaction and the particular catalyst involved this deactivation may take place over several months or even years but in some cases occurs in minutes. Therefore, zeolite catalysts are frequently reactivated / regenerated. This generally involves a thermal treatment involving air which results in oxidation of the carbon [2]. However, the oxidation of carbon is highly exothermic, and if not carefully controlled, results in the generation of exceedingly high localized temperatures which can destroy the zeolite structure and result in subsequent loss of catalyst activity. More conservative thermal treatments can result in incomplete regeneration and again a catalyst displaying inferior activity. This paper explores the use of non-thermal plasma which had been either generated using microwaves or via a barrier discharge to regenerate spent zeolite catalysts. The catalyst, H-mordenite, was tested for the disproportionation of toluene (Figure 1) using conventional heating. The spent catalyst was then regenerated using a plasma or conventional thermal treatment before having its activity re-evaluated for the toluene disproportionation reaction as previous. Fig. 1. Reaction Scheme for Toluene Disproportionation. Interestingly, not only is plasma regeneration highly effective but also catalysts can be regenerated in greatly reduced times. There is an additional advantage in that plasma regeneration can impart physical properties that result in a zeolite that is resistant to further deactivation. However, the results are highly dependent upon the experimental conditions involved for plasma regeneration. References Wu J, Leu L., Appl. Catal., 1983; 7:283-294. M. Guisnet and P. Magnoux, Deactivation of Zeolites by Coking. Prevention of Deactivation and Regeneration. In: Zeolite Microporous Solids: Synthesis, Structure, and Reactivity. E.G. Derouane, F Lemos, C. Naccache, F. Ramôa Ribeiro, Eds. Pages 437-456. Springer 1992.

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Berry, David A., Dushyant Shekhawat, Todd H. Gardner, Maria Salazar, Daniel J. Haynes, and James J. Spivey. "Support Effects for Pt and Rh-Based Catalysts for Partial Oxidation of n-Tetradecane." In ASME 2006 4th International Conference on Fuel Cell Science, Engineering and Technology. ASMEDC, 2006. http://dx.doi.org/10.1115/fuelcell2006-97265.

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Catalytic partial oxidation (CPOX) of liquid fuels is an attractive option for producing a hydrogen-rich gas stream for fuel cell applications. However, the high sulfur content along with aromatic compounds present in liquid fuels may deactivate reforming catalysts. Deactivation of these catalysts by carbon deposition and sulfur poisoning is a key technical challenge. The relationship between catalyst supports and deactivation have been studied here for three catalysts (Rh/Ce0.5Zr0.5O2, Pt/Ce0.5Zr0.5O2, and Pt/Al2O3) in a fixed bed catalytic reactor using a mixture of n-tetradecane, 1-methylnaphthalene, and dibenzothiophene to simulate logistic fuels. Carbon production during CPOX reforming was directly related to olefin formation. Olefins, which are known coke precursors, were observed on the Pt catalysts during CPOX of n-tetradecane with no sulfur (particularly from Pt/Al2O3), but not on Rh/Ce0.5Zr0.5O2. For the Rh/Ce0.5Zr0.5O2, yields of H2 and CO dropped to a stationary level after the introduction of sulfur-containing feed (1000 ppm sulfur) or aromatic-containing feed (5 wt%), however, the catalyst activity was restored after removing the sulfur or aromatics from the feed. For the Pt catalysts, H2 and CO yields dropped continuously over time in the presence of sulfur or aromatics in feed. The superior performance of Rh/Ce0.5Zr0.5O2 can be attributed to the higher oxygen-ion conductivity of the Ce0.5Zr0.5O2 support as well as the activity of the Rh sites.

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Ran, Jing-yu, and Liu-jie Zhao. "Thermodynamic Analysis of Temperature and Pressure on Carbon Deposition for Methane Reforming at Low Temperature in Micro-Combustor." In ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels collocated with 3rd Joint US-European Fluids Engineering Summer Meeting. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30152.

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Aimed at problems caused by carbon deposition in the micro-combustor, such as catalyst deactivation and channel block, based on the technology of methane-wet air autothermal reforming and the effects of hydrogen and methane conversion, the influences of temperature and pressure on carbon deposition below 973K are discussed with thermodynamic analysis method in this paper. Results show that for a definite feed gas composition, carbon deposition adds with increasing temperature firstly, and then decreases. Reaction pressure is suitable to maintain at 1atm. Moreover, the increasing methane mass flow, decreasing air and steam mass flow can lead to expansion of carbon deposition temperature region exists, also lead to the amount of carbon deposition increase and the temperature peak of carbon deposition shift to higher temperature segment. Under the research conditions that methane mass flow is 6.6g/h, reaction pressure is 1atm, air-methane ratio and steam-methane ratio are respectively 2 and 1 in the micro-combustor, the temperature range of carbon deposition production is at 680∼850K. The largest carbon deposition is occurred and its mass fraction is 0.66% when the reaction temperature is at 785K, also the methane conversion rate and the mass fraction of hydrogen are approximately 53.43% and 2.37% respectively.

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Kumar, Anand, and Anchu Ashok. "Catalytic Decomposition of Ethanol over Bimetallic Nico Catalysts for Carbon Nanotube Synthesis." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0039.

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In this work we investigate the use of NiCo bimetal/oxide as catalyst for hydrogen production from ethanol, with a focus on the deactivation pattern and the nature of the observed carbon deposition. It is well known that sintering and coke deposition during decomposition reaction significantly reduces the activity of the catalysts at higher temperature, by blocking the active sites of the catalysts. During ethanol decomposition reaction, the cleavage of C-C bond produces adsorbed *CH4 and *CO species that further decompose to form carbonaceous compounds. FTIR in-situ analysis was conducted between 50 to 400°C for all the catalysts to understand the reaction mechanism and product selectivity. Cobalt was found to be selective for aldehyde and acetate, whereas bimetallic Ni-Co was selective for the formation of CO at 400°C along with aldehyde. Complete conversion of ethanol was observed at 350°C and 420°C for NiCo and Cobalt respectively indicating an improvement in the rate of conversion when Ni was added to cobalt. The crystallinity, morphology and particle analysis of the used catalyst after reaction were studied using XRD, SEM and TEM respectively. The XRD shows the complete phase change of porous NiCoO2 to NiCo alloy and SEM indicates the presence of fibrous structure on the surface with 91.7 % of carbon while keeping 1:1 ratio of Ni and Co after the reaction. The detailed analysis of carbon structure using HRTEM-STEM shows the simultaneous growth of carbon nano fibers (CNFs) and multiwalled carbon nanotubes (MWCNTs) that were favored on larger and smaller crystallites respectively. Analysis of carbon formation on individual Co catalyst and bimetallic NiCo catalyst shows a clear difference in the initiation pattern of carbon deposition. Metallic Co nanoparticles were found to be more mobile where Co disperses along the catalysts surface, whereas NiCo nanoparticles were relatively less mobile, and maintained their structure.

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Michelbacher, John A., Carl E. Baily, Daniel K. Baird, S. Paul Henslee, Collin J. Knight, and Kenneth E. Rosenberg. "Shutdown and Closure of the Experimental Breeder Reactor–II." In 10th International Conference on Nuclear Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/icone10-22462.

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The Department of Energy mandated the termination of the Integral Fast Reactor (IFR) Program, effective October 1, 1994. To comply with this decision, Argonne National Laboratory-West (ANL-W) prepared a plan providing detailed requirements to maintain the Experimental Breeder Reactor-II (EBR-II) in a radiologically and industrially safe condition, including removal of all irradiated fuel assemblies from the reactor plant, and removal and stabilization of the primary and secondary sodium, a liquid metal used to transfer heat within the reactor plant. The EBR-II is a pool-type reactor. The primary system contained approximately 325 m3 (86,000 gallons) of sodium and the secondary system contained 50 m3 (13,000 gallons). In order to properly dispose of the sodium in compliance with the Resource Conservation and Recovery Act (RCRA), a facility was built to react the sodium to a solid sodium hydroxide monolith for burial as a low level waste in a land disposal facility. Deactivation of a liquid metal fast breeder reactor (LMFBR) presents unique concerns. Residual amounts of sodium remaining in circuits and components must be passivated, inerted, or removed to preclude future concerns with sodium-air reactions that could generate potentially explosive mixtures of hydrogen and leave corrosive compounds. The passivation process being implemented utilizes a moist carbon dioxide gas that generates a passive layer of sodium carbonate/sodium bicarbonate over any quantities of residual sodium. Tests being conducted will determine the maximum depths of sodium that can be reacted using this method, defining the amount that must be dealt with later to achieve RCRA clean closure. Deactivation of the EBR-II complex is on schedule for a March, 2002, completion. Each system associated with EBR-II has an associated layup plan defining the system end state, as well as instructions for achieving the layup condition. A goal of system-by-system layup is to minimize surveillance and maintenance requirements during the interim period between deactivation and decommissioning. The plans also establish document archival of not only all the closure documents, but also the key plant documents (P&IDs, design bases, characterization data, etc.) in a convenient location to assure the appropriate knowledge base is available for decommissioning, which could occur decades in the future.

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Hassan, Bilal, Tariq Shamim, and Ahmed F. Ghoniem. "A Parametric Study of Multi-Stage Chemical Looping Combustion for CO2 Capture Power Plant." In ASME 2012 Heat Transfer Summer Conference collocated with the ASME 2012 Fluids Engineering Division Summer Meeting and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ht2012-58597.

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A thermodynamic model and parametric analysis of a natural gas fired power plant with carbon dioxide (CO2) capture using multi-stage chemical looping combustion (CLC) are presented. CLC is an innovative concept and an attractive option to capture CO2 with a significantly lower energy penalty than other carbon-capture technologies. The principal idea behind CLC is to split the combustion process into two separate steps (redox reactions) carried out in two separate reactors: an oxidation reaction and a reduction reaction, by introducing suitable metal oxide which acts as an oxygen-carrier that circulates between the two reactors. In this study, an Aspen Plus model was developed by employing the conservation of mass and energy for all the components of the CLC system. In the analysis, equilibrium based thermodynamic reactions with no oxygen-carrier deactivation were considered. The model was employed to investigate the effect of various key operating parameters such as air, fuel and oxygen carrier (OC) mass flow rates, operating pressure, and waste heat recovery on the performance of a natural gas fired power plant with multi-stage CLC. Results of these parameters on the plant efficiency are presented. The analysis shows efficiency gain of more than 6% over that of conventional power plant with CO2 capture technologies when CLC is integrated with the power plant.

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Reports on the topic "Deactivation by carbon"

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Baker, R. T. K. Carbon deposition and deactivation of metallic catalysts. Final report. Office of Scientific and Technical Information (OSTI), September 1997. http://dx.doi.org/10.2172/531125.

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Bartholomew, C. Deactivation by carbon of iron catalysts for indirect liquefaction. Office of Scientific and Technical Information (OSTI), October 1989. http://dx.doi.org/10.2172/5590023.

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Bartholomew, C. H. Deactivation by carbon of iron catalysts for indirect liquefaction. Office of Scientific and Technical Information (OSTI), January 1991. http://dx.doi.org/10.2172/6154234.

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Bartholomew, C. H. Deactivation by carbon of iron catalysts for indirect liquefaction. Office of Scientific and Technical Information (OSTI), October 1990. http://dx.doi.org/10.2172/6568801.

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Bartholomew, C. Deactivation by carbon of iron catalysts for indirect liquefaction. Office of Scientific and Technical Information (OSTI), February 1991. http://dx.doi.org/10.2172/5719686.

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Bartholomew, C. H. Deactivation by carbon of iron catalysts for indirect liquefaction. Office of Scientific and Technical Information (OSTI), October 1990. http://dx.doi.org/10.2172/6540326.

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