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00283 Catalytic reforming of methane with carbon dioxide over nickel catalysts. I. Catalyst characterization and activity
03
Gaseous
03
fuels
(sources,
propetties,
recovery, treatment) 97100281
GASEOUS FUELS Sources,
Properties,
Recovery,
Treatment
Adsorption equilibria and rate parameters 97100276 nitrogen and methane on Maxsorb activated carbon
Adsorption parameters for strongly adsorbed vapours on some commercial adsorbents
97/00282
hy-
1996, Gas Sep. htrif., 10, (I), 25-33. Alpay, E. et al., High-temperature measurements of the adsorption properties of strongly adsorbed hydrocarbon vapours on a wide range of commercially available adsorbents are presented. These adsorhents include various cationic forms of the type A, X and Y zeolites, activated alumina and carbon, and some clays. The studies are based upon pulse chromatography experiments using low concentrations of hyrdrocarbon vapours (toluene and methycyclohexane) in nitrogen carrier gas. The temperature range of investigation was chosen as 400-700 K. which is typical for the catalytic dehydrogenation of methylcyclohexane to toluene. Even at these temperatures, the relatively strong adsorption properties of the hydrocarbons necessitated the use of high carrier gas flow rates. As a consequence, significant deviation from isobaric operation existed. In this work, non-isobaric pulse chromatography theory was applied to the first moment data, and found to describe accurately the adsorption trends. Furthermore, the temperature dependence of the adsorption equilibria parameters could be determined. The data provide a useful reference in the design and assessment of processes in which the simultaneous operations of high-temperature chemical reaction and adsorptive separation take place, as in chromatographic and pressure swing based reactors.
97lOO278 methanation
Air tolerance reaction
of a Ru-RuO,/TiOz
catalyst
for CO*
Gupta, N. M. and Kamble, V. S. Indian J. Chem., Sect. A: Inorg., Bioirwrg., Phys.. Theor. Anal. Chem. 1996. 35A, (7), 557-559. In this study a partially oxidized ruthenium on titania catalyst is active for carbon dixoide methanation reaction in the presence of air and both carbon dixoide and oxygen are reduced simultaneously. Carbon dixoide methanation commenced only after the complete reduction of the oxygen present in the hydrogen-deficient reaching stream. The FTIR results suggest that the ruthenium sites, vital for carbon dixoide decomposition, undergo cyclic oxidation-regeneration during CO2 + HL or O2 + HZ reactions making this catalyst resistant to oxygen poisoning.
97100279 An apparatus from coal gasification
for cooling
solids
laden
hot gases
Eur. Pat Appl. EP 722,999 (Cl. ClOJ3/86), 24 Van Dongen, F. G. et al., Jul 1996, EP Appl. 95/200,145, 20 Jan. 1995. This paper considers the self-cleaning apparatus for cooling a solids laden hot gas comprises a vessel with a gas inlet and a gas outlet and a plurality of (convective) heat transfer surfaces, extending longitudinally and forming a plurality of gas passages. The overall cross-sectional inlet area of the passages between the heat transfer surfaces decreases in the direction of decreasing process temperature in such a manner that the gas velocity is kept constant.
Analysis of ZLC technique for diffusivity ments in bidisperse porous adsorbent pellets
97lOO200
measure-
Silva, J. A. C. and Rodrigues, A. E., Gas Purification and Separation, 1996, IO, (4), 207-224. The zero length column (ZLC) technique has been successfully used to measure diffusivities in zeolite crystals. However, in industrial applications pellets with bidisperse structure, containing macropores and micropores (crystals), are commonly used as zeolites. In this paper, a model of ZLC desorption curves for bidisperse porous materials is developed. Model equations are analytically solved for linear systems. A numerical solution of model equations using orthogonal collocation is also used. The various regions of control (macropore diffusion, micropore diffusion) are identified. Simulations allow the choice of operating conditions for the ZLC technique. Procedures for the analysis of ZLC experiments are repotted.
20
Fuel and Energy Abstracts
January 1997
for continuous
gas sampling
for
Gas h~$cation a@ Separation, 1996, IO, (3), 161Sheikh, M. A. et al., 168. Equilibrium and kinetic parameters for methane and nitrogen on a new. high specific area active carbon Maxsorb are reported. Volumetric and chromatographic methods are used to measure the pure component adsorption isotherm and the effective mass transfer coefficient for each gas. The adsorption isotherms at 300 K, measured up to a pressure of 550 kPa. are approximately linear for both methane and nitrogen on Maxsorb. The equilibrium separation factor is 3.0 in favour of methane. The mass transfer resistance is observed to be very low for each sorbate. The equilibrium and kinetic parameters are input in the mathematical model of hinary breakthrough experiments using an axial dispersion model. The theoretical and experimental hreakthrough curves are observed to be in excellent agreement.
97/00277 drocarbon
Apparatus
Yamakawa, T. and Hayashida, N., Jpn. Kokai Tokkyo Koho JP O&122.228 [96,122,228] (Cl. GOlN1122). 17 May 1996, Appl. 94,253,43X. 19 Ott 1994. (In Japanese) The continuous gas sampling apparatus is composed of a gas sampling probe for coal gas, a filter packed with balls and equipped with a backwashing nozzle, a scrubber by crmtact with steam or water, a moisture remover, and a coal-gas analyser. Clogging by, for example, (NHd)HCO1 is prevented.
Catalytic
hot gas cleaning
Simell. P., VTT Symp., 1996, 163, 123-129. This article describes how fuel gas, containing particulates derived from peat and biomass, can be purified from tars and NHI by using nickel monolith catalysts. Temperatures >9OO”C were required at 20 bar pressure to avoid deactivation by H>S and carbon. Dolomites and limestones were effective tar decomposing. catalysts only when calcined. Tar decomposition in gasification conditions can take place by steam or dry (CO?) reforming reactions, which follow apparent first-order kinetics with respect to hydrocarbons under gasification conditions.
97100283 Catalytic over nickel catalysts.
reforming of methane with carbon dioxide I. Catalyst characterization and activity
Bradford, M. C. J. and Vannice, M. A., Appl. Cata!.. A 1996, 142, (I). 7396. This first part of this study on reforming of methane with carbon dixode over nickel supported on MgO, TiOz, SiO2, and activated carbon looks at catalyst activity and carbon deposition resistivity. In each case this wac different. Although considerable formation of filamentous carbon was noted over NiiSiO:, there was negligible initial loss of catalytic activity, The catalytic activity of NiiC was very similar to that of NiiSiO?, but no filamentous carbon appeared to be formed. In contrast to Ni/SiO?, substantially less coking was observed over either the Ni/TiOl or the Ni/ MgO catalysts. Evidence of strong metal-support interactions (SMSI) for the Ni/TiOz catalyst indicated that large ensembles of nickel atoms, active for carbon deposition, were deactivated or removed by the presence of mobile TiO, species. Chemisorption, XRD, and TEM results indicated the formation of a partially reducible NiO-MgO solid solution, which appears to stabilize the reduced nickel surfaces and to provide resistance to carbon deposition.
Catalytic over nickel catalysts.
97100284
reforming of methane with carbon dioxide II. Reaction kinetics.
Bradford, M. C. J. and Vannice. M. A., Appl. Catal., A 1996, 142, (I), 97122. The second part of this study of the reforming of methane with carbon dixode over nickel supported on SiOz, TiO,, MgO, and activated carbon. shows that specific activities on a turnover frequency basis decreased in the order: Ni/TiOz > NilC > NiiSiOz > NiiMgO. A two-fold increase in activation energy for this reaction was noted over Ni/TiOz after several hours time on stream. The reverse water-gas shift reaction was close to thermodynamics equilibrium over all catalysts. Partial pressure dependencies were obtained with the NiiC and NiiSiOz catalysts at 723 K for comparative purposes only, but a more thorough kinetic analysis was made with the NiiMgO and NiiTiOz catalysts, which were shown previously to strongly inhibit carbon deposition. Partial pressure dependencies were obtained at 673, 698, and 723 K for Ni/TiO: and at 773. 798, and X23 K for NiiMgO. In-situ DRIFTS studies clearly showed the presence of both linear and bridged methane adsorption on Ni/SiOz under reaction conditions; however, adsorbed methane could not be identified on Ni/TiOZ. A reaction model for methane-carbon dixode reforming, based on methane activation to form CH, and CH,O decomposition as the slow kinetic steps, successfully correlated the rate data.
Chemical structure from coal using benzene-ethanol
97100285
of the
substances
extracted
Sugimoto, Y. et al., S&tan Kagaku Kalgi Happyo Ronhunsh[c, 1093, 30. 126-I 28. (In Japanese) In this study coals and related materials were extracted by 2:1 benzeneethanol at 2Oo”C, and the extractable and non-extractable materials were hydrogenated at 350°C over Ni-Mo/Alz03. An investigation followed in to the polycyclic aromatic compounds and long-chain n-alkanes in the extracts and hydrogenated products.
97100286
Development
of catalytic
gas cleaning
in biomass
gasification Simell, P. ef al., VTTSymp., 1996, 164 (Power Production from Biomass 11 with Special Emphasis on Gasification and Pyrolysis R&DD). 133-140. Contaminating dust from gasification gas can be efficiently purified of tars and ammonia with a nickel monolith catalyst. Temperatures above 900°C and a residence time of about 1 s (2500 l/h) were needed at 5 bar pressure to achieve complete tar decomposition and 80% ammonia conversion. Catalyst deactivation was not absorbed during test runs of 100 h. At lower pressures, dolomites and limestones can also be applied for tar removal at about 900°C.
Gaseous
03
fuels
(sources,
propetties,
recovery, treatment) 97100281
GASEOUS FUELS Sources,
Properties,
Recovery,
Treatment
Adsorption equilibria and rate parameters 97100276 nitrogen and methane on Maxsorb activated carbon
Adsorption parameters for strongly adsorbed vapours on some commercial adsorbents
97/00282
hy-
1996, Gas Sep. htrif., 10, (I), 25-33. Alpay, E. et al., High-temperature measurements of the adsorption properties of strongly adsorbed hydrocarbon vapours on a wide range of commercially available adsorbents are presented. These adsorhents include various cationic forms of the type A, X and Y zeolites, activated alumina and carbon, and some clays. The studies are based upon pulse chromatography experiments using low concentrations of hyrdrocarbon vapours (toluene and methycyclohexane) in nitrogen carrier gas. The temperature range of investigation was chosen as 400-700 K. which is typical for the catalytic dehydrogenation of methylcyclohexane to toluene. Even at these temperatures, the relatively strong adsorption properties of the hydrocarbons necessitated the use of high carrier gas flow rates. As a consequence, significant deviation from isobaric operation existed. In this work, non-isobaric pulse chromatography theory was applied to the first moment data, and found to describe accurately the adsorption trends. Furthermore, the temperature dependence of the adsorption equilibria parameters could be determined. The data provide a useful reference in the design and assessment of processes in which the simultaneous operations of high-temperature chemical reaction and adsorptive separation take place, as in chromatographic and pressure swing based reactors.
97lOO278 methanation
Air tolerance reaction
of a Ru-RuO,/TiOz
catalyst
for CO*
Gupta, N. M. and Kamble, V. S. Indian J. Chem., Sect. A: Inorg., Bioirwrg., Phys.. Theor. Anal. Chem. 1996. 35A, (7), 557-559. In this study a partially oxidized ruthenium on titania catalyst is active for carbon dixoide methanation reaction in the presence of air and both carbon dixoide and oxygen are reduced simultaneously. Carbon dixoide methanation commenced only after the complete reduction of the oxygen present in the hydrogen-deficient reaching stream. The FTIR results suggest that the ruthenium sites, vital for carbon dixoide decomposition, undergo cyclic oxidation-regeneration during CO2 + HL or O2 + HZ reactions making this catalyst resistant to oxygen poisoning.
97100279 An apparatus from coal gasification
for cooling
solids
laden
hot gases
Eur. Pat Appl. EP 722,999 (Cl. ClOJ3/86), 24 Van Dongen, F. G. et al., Jul 1996, EP Appl. 95/200,145, 20 Jan. 1995. This paper considers the self-cleaning apparatus for cooling a solids laden hot gas comprises a vessel with a gas inlet and a gas outlet and a plurality of (convective) heat transfer surfaces, extending longitudinally and forming a plurality of gas passages. The overall cross-sectional inlet area of the passages between the heat transfer surfaces decreases in the direction of decreasing process temperature in such a manner that the gas velocity is kept constant.
Analysis of ZLC technique for diffusivity ments in bidisperse porous adsorbent pellets
97lOO200
measure-
Silva, J. A. C. and Rodrigues, A. E., Gas Purification and Separation, 1996, IO, (4), 207-224. The zero length column (ZLC) technique has been successfully used to measure diffusivities in zeolite crystals. However, in industrial applications pellets with bidisperse structure, containing macropores and micropores (crystals), are commonly used as zeolites. In this paper, a model of ZLC desorption curves for bidisperse porous materials is developed. Model equations are analytically solved for linear systems. A numerical solution of model equations using orthogonal collocation is also used. The various regions of control (macropore diffusion, micropore diffusion) are identified. Simulations allow the choice of operating conditions for the ZLC technique. Procedures for the analysis of ZLC experiments are repotted.
20
Fuel and Energy Abstracts
January 1997
for continuous
gas sampling
for
Gas h~$cation a@ Separation, 1996, IO, (3), 161Sheikh, M. A. et al., 168. Equilibrium and kinetic parameters for methane and nitrogen on a new. high specific area active carbon Maxsorb are reported. Volumetric and chromatographic methods are used to measure the pure component adsorption isotherm and the effective mass transfer coefficient for each gas. The adsorption isotherms at 300 K, measured up to a pressure of 550 kPa. are approximately linear for both methane and nitrogen on Maxsorb. The equilibrium separation factor is 3.0 in favour of methane. The mass transfer resistance is observed to be very low for each sorbate. The equilibrium and kinetic parameters are input in the mathematical model of hinary breakthrough experiments using an axial dispersion model. The theoretical and experimental hreakthrough curves are observed to be in excellent agreement.
97/00277 drocarbon
Apparatus
Yamakawa, T. and Hayashida, N., Jpn. Kokai Tokkyo Koho JP O&122.228 [96,122,228] (Cl. GOlN1122). 17 May 1996, Appl. 94,253,43X. 19 Ott 1994. (In Japanese) The continuous gas sampling apparatus is composed of a gas sampling probe for coal gas, a filter packed with balls and equipped with a backwashing nozzle, a scrubber by crmtact with steam or water, a moisture remover, and a coal-gas analyser. Clogging by, for example, (NHd)HCO1 is prevented.
Catalytic
hot gas cleaning
Simell. P., VTT Symp., 1996, 163, 123-129. This article describes how fuel gas, containing particulates derived from peat and biomass, can be purified from tars and NHI by using nickel monolith catalysts. Temperatures >9OO”C were required at 20 bar pressure to avoid deactivation by H>S and carbon. Dolomites and limestones were effective tar decomposing. catalysts only when calcined. Tar decomposition in gasification conditions can take place by steam or dry (CO?) reforming reactions, which follow apparent first-order kinetics with respect to hydrocarbons under gasification conditions.
97100283 Catalytic over nickel catalysts.
reforming of methane with carbon dioxide I. Catalyst characterization and activity
Bradford, M. C. J. and Vannice, M. A., Appl. Cata!.. A 1996, 142, (I). 7396. This first part of this study on reforming of methane with carbon dixode over nickel supported on MgO, TiOz, SiO2, and activated carbon looks at catalyst activity and carbon deposition resistivity. In each case this wac different. Although considerable formation of filamentous carbon was noted over NiiSiO:, there was negligible initial loss of catalytic activity, The catalytic activity of NiiC was very similar to that of NiiSiO?, but no filamentous carbon appeared to be formed. In contrast to Ni/SiO?, substantially less coking was observed over either the Ni/TiOl or the Ni/ MgO catalysts. Evidence of strong metal-support interactions (SMSI) for the Ni/TiOz catalyst indicated that large ensembles of nickel atoms, active for carbon deposition, were deactivated or removed by the presence of mobile TiO, species. Chemisorption, XRD, and TEM results indicated the formation of a partially reducible NiO-MgO solid solution, which appears to stabilize the reduced nickel surfaces and to provide resistance to carbon deposition.
Catalytic over nickel catalysts.
97100284
reforming of methane with carbon dioxide II. Reaction kinetics.
Bradford, M. C. J. and Vannice. M. A., Appl. Catal., A 1996, 142, (I), 97122. The second part of this study of the reforming of methane with carbon dixode over nickel supported on SiOz, TiO,, MgO, and activated carbon. shows that specific activities on a turnover frequency basis decreased in the order: Ni/TiOz > NilC > NiiSiOz > NiiMgO. A two-fold increase in activation energy for this reaction was noted over Ni/TiOz after several hours time on stream. The reverse water-gas shift reaction was close to thermodynamics equilibrium over all catalysts. Partial pressure dependencies were obtained with the NiiC and NiiSiOz catalysts at 723 K for comparative purposes only, but a more thorough kinetic analysis was made with the NiiMgO and NiiTiOz catalysts, which were shown previously to strongly inhibit carbon deposition. Partial pressure dependencies were obtained at 673, 698, and 723 K for Ni/TiO: and at 773. 798, and X23 K for NiiMgO. In-situ DRIFTS studies clearly showed the presence of both linear and bridged methane adsorption on Ni/SiOz under reaction conditions; however, adsorbed methane could not be identified on Ni/TiOZ. A reaction model for methane-carbon dixode reforming, based on methane activation to form CH, and CH,O decomposition as the slow kinetic steps, successfully correlated the rate data.
Chemical structure from coal using benzene-ethanol
97100285
of the
substances
extracted
Sugimoto, Y. et al., S&tan Kagaku Kalgi Happyo Ronhunsh[c, 1093, 30. 126-I 28. (In Japanese) In this study coals and related materials were extracted by 2:1 benzeneethanol at 2Oo”C, and the extractable and non-extractable materials were hydrogenated at 350°C over Ni-Mo/Alz03. An investigation followed in to the polycyclic aromatic compounds and long-chain n-alkanes in the extracts and hydrogenated products.
97100286
Development
of catalytic
gas cleaning
in biomass
gasification Simell, P. ef al., VTTSymp., 1996, 164 (Power Production from Biomass 11 with Special Emphasis on Gasification and Pyrolysis R&DD). 133-140. Contaminating dust from gasification gas can be efficiently purified of tars and ammonia with a nickel monolith catalyst. Temperatures above 900°C and a residence time of about 1 s (2500 l/h) were needed at 5 bar pressure to achieve complete tar decomposition and 80% ammonia conversion. Catalyst deactivation was not absorbed during test runs of 100 h. At lower pressures, dolomites and limestones can also be applied for tar removal at about 900°C.