- Email: [email protected]
00350 Methane reforming with carbon dioxide to syngas. l. Performance of cobalt-alumina catalyst calcined at high temperature
03
Gaseous fuels (derived gaseous fuels)
key factor for SO2 removal efficiency of CFB-FGD process. (4) The absorbent can be enhanced in the CFB reactor. (5) The CFB reactor is a better one for the dry/ semi-dry FGD technology.
Initial carbon-carbon bond formation during s nthesis. gas conversion to higher alcohols on K-Curxg&eO. catalysts Xu, M. and Iglesia, E. Coral. Len., 1998, 51, (l/Z), 47-52.
occurred when oxygen was introduced downstream from the sample and was mixed with the biomass pyrolysis vapours. To monitor the products formed at the various experimental conditions a molecular beam mass spectrometer system was used.
99lW344
Using ‘3CO/Hz/‘ZCHsOH mixtures, isotopic tracer studies of alcohol synthesis pathways have shown that ethanol is formed predominantly by direct reactions of 13C0 on Cuc.sMg&eO, promoted with potassium at short residence times, without significant involvement of the 12CHs0H present in the feed. The observed decrease in “C content in ethanol with increasing residence time is caused by reverse aldol reactions of higher alcohols, which contain lower “C contents because of the significant involvement of “CHsOH in their formation, and by reactions of Me formate with “CH30Hderived species. There is a consistency between the effects of residence time on the ‘“C distribution within reaction products and on the rates of formation of ethanol, Me formate, and Me acetate, with the intermediate role of Me formate and Me acetate in ethanol formation.
Internal consistent of coal gasification reactivities determined In bent K-scale reactors: effect of pyrolysis conditions on char reactivities under high-pressure CO2
66166345
Megaritis, A. et al. Fuel, 1998, 77, (13), 1411-1420. Using a wire-mesh, a fluidized-bed and a ‘hot-rod’ (fixed-bed) reactor, relationships between char preparation conditions and CO2 gasification conversions have been examined. Conversions from the direct gasification of untreated coal have been compared with those from the gasification of chars prepared: (i) in-situ under helium in each reactor, before switching over to COz; and (ii) from gasification in all three reactors of a char sample, pre-prepared in the fixed bed reactor. Conversions from direct gasification were slightly higher than experiments where samples were first pyrolysed in situ and gasified under CO2 in the same reactor. In some cases, conversions were within experimental error. Under these conditions and within several percentage points, the pyrolysis and gasification steps may be considered as additive. Lower overall conversions observed in the hot-rod reactor have been attributed to the combined effect of: (i) formation of a low reactivity charowing to tar-solids contact leading to secondary char deposition; and (ii) poor contact between char and the reactive gas. In the wire-mesh and the fluidized-bed reactors, direct COz-gasification conversions were considerably larger than those determined using the common sample of char, pre-prepared in the hot-rod (fixed-bed) reactor. This sharp drop in overall conversion shows that care must be taken in interpreting reactivity data from ‘two-reactor, two-step’ procedures where char preparation conditions are not identical to those of the gasification step. A broadly linear relationship has been observed between conversions from a pilot plant reactor and direct C02-gasification in the bench-scale high-pressure wire-mesh reactor. Despite differences between operating parameters in the two reactors, the results suggest that data from the wire-mesh reactor may be successfully used to compare relative coal reactivities under pilotplant gasification conditions.
Kinetics of CO hydrogenation over Ni-Mo/Ai203 catalysts with and without potassium promotion
99106346
Aksoylu, A. E. and Onsan, Z. I. Ind. Eng. Chemical Res., 1998, 37, (6), 2397-2403. In the 498-548 K range the effect of potassium promotion on the CO hydrogenation activity and C2-C4 hydrocarbons selectivity of 15 wt% Nickel and 10 wt% Molybdenum on AlzO3, catalyst was investigated using unpromoted and l-3 wt% potassium-promoted samples. CO2 methanation tests at 523 K were used as a probe to confirm activity trends. Intrinsic kinetic data were obtained in the initial rate region on both unpromoted and 1 wt% potassium-promoted Ni-Mo catalysts. Potassium promotion of the bimetallic Ni-Mo catalyst decreases both the activity and the specific activity of the Ni sites while increasing the Cz-C3 olefin-to-paraffin ratio. The most plausible kinetic model among those tested for both Ni-Mo and Ni-MO-K catalysts was given by the surface carbide mechanism with dissociative adsorption of hydrogen as the rate-limiting step.
Laboratory 99/00347 asification oxidatlon of biomass pyro8ysis vapors
studies
via
partial
Dayton, D. C. and Evans, R. J. Making Bus. Biomass Energy, Environ., Chemical, Fibers Mater., Proc. Biomass Conf. Am., 3rd. 1997, (1). 673-682. Edited by Overend, R. P. and Chornet, E. In a quartz-tube flow reactor biomass gasification was simulated at the bench scale by the partial oxidation of biomass pyrolysis vapours in various atmospheres. At two temperatures, 700” and 1000” small samples of switchgrass were pyrolysed and subsequent gas phase reactions were studied at 850”. The O2 concentration in the reactor was varied between 1% and 10% and in certain experiments steam was added to the atmosphere. The lowest 02 concentration corresponded to enough 02, in addition to the oxygen in the biomass, to provide 30% of the stoichiometric limit to oxidize a 50.0-mg switchgrass sample. The point at which the oxygen was introduced into the reactor was also varied. Partial oxidation of char and volatiles occurred when oxygen was introduced at the rear of the reactor so oxygen flowed over the sample. Partial oxidation of the volatiles
34
Fuel and Energy Abstracts January 1999
Long-chain hydrocarbons from syngas on nanosized cobalt catalyst. Promotion effect of ruthemum
99166346
Zhang, Y. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1997, 14, (28), 510. Using the sol-gel method, SiOz aerogel ultrafine powder and ZrOz-SiOz ultrafine complex oxide were prepared. Co/Zr02-SiOz and Co-Ru/Zr02SiOz catalysts were prepared by incipient wetness technique and physical mixing method. The effects of ruthenium addition on the texture, structure, reduction, Hz desorption and Fischer-Tropsch reaction of nano-sized cobalt-based catalysts were investigated. The results indicate that addition of ruthenium makes the reduction of Co2+ difficult to take place. The selectivity to CH4 decreases and selectivity to Cg+ increases. The distribution of hydrocarbon products has two peaks at Cs and Ci4, deviating from the Schulz-Flory distribution.
Mathematical modeling of the gasification of cellulose-containing biomass with the aid of a zone model
99166349
Jung, K. ef al. DGMK Tagungsber., 1998, 9802, 335-342. (In German) In a solid-bed reactor using pure 02 as a gasification medium the gasification of biomass was studied theoretically on the example of wood as raw material. For the modelling the reactor was devided into a drying and pyrolysis zone, an oxidation zone, and a reduction zone. The chemical equilibrium of the components in the reactor were shown and the enthalpies of formation and decomposition of the components were calculated. Based on the carbon, oxygen, hydrogen, nitrogen, and sulfur content of the raw material and the knowledge of the chemical equilibrium in the plant under specified pressure and temperature, the resulting gas composition was calculated. For dry and moisture containing gas the calculated data for the gas composition showed relatively good agreement with experimental data.
Methane reforming with carbon dioxide to syngas. I. Performance of cobalt-alumina catalyst calcined at high temperature
99l60360
Wang, P. er al. Cuihua Xuebao, 1998, 19, (3), 196-200. (In Chinese) In COz-reforming of CH4 to syngas the catalytic performance of Co/Alz03 catalyst calcined at high temperature has been studied by using a fixed-bed flow apparatus. Content of carbon deposited on catalyst is measured by gas chromatography. About 9% Co/Al203 catalyst calcined at 1073-1473 Knot only exhibits high catalytic activity, but also shows optimal resistance to carbon deposition. The results of TPR, XRD and catalytic tests indicate that it is Co and CoA120., that play a very important role in the reaction, and that there are many different catalytic features between Co/A1203 or Ni/AlzO, calcined at low temperature and Co/Alz03 calcined at low temperature.
99100351 especially generator
Method and apparatus for optimum gasification, of wood chips, and especially in a cocurrent
Jakobsen, H. H. Dan. DK 172,277 (Cl. ClOJ3/00), 16 Feb 1998, Appl. 94/ 1,248, 28 Ott 1994; 11 pp. (In Danish) The method comprises a gasifier whose pyrolysis zone is provided with a temperature sensor covering several temperature ranges (A, B, and C) and capable of continuously adjusting the pyrolysis and combustion temperature downward or upward and thereby controlling the exact limits of the pyrolysis zone. The exact temperatures A, B, and C in the pyrolysis zone and combustion zone can be adjusted downward or upward in a number of ways; cooling by injecting water, by changing the flow of primary air, or by changing the simultaneous flow of secondary air. The apparatus comprises a suction pump to draw of the gas and keep the pyrolysis zone and combustion zone at a partial vacuum whereby the primary and secondary air are forced in the direction of flow and into the upper pyrolysis and combustion zone. 99lW3S2 Modeling of gasification behavior in freeboard of fluidized bed gasifier
Tang, Z. et al. Proc. Annu. Inf. Pittsburgh Coal Conf., 1997, 14, (2). 53-59. For investigating the gasification behaviour in freeboard of a fluidized bed gasifier a mathematical model has been developed. In this model, MonteCarlo method was used to describe the particle movement in freeboard. Comparing the simulation results with experiment data, it can be seen that the freeboard has little effect on gasification reaction in fluidized bed gasifier at the condition that there is no fine recycling. In this article some advice was given to improve the freeboard reaction ability.
Mono and bifunctional pathways reforming over Pt and Rh based catalysts
99l66353
of
CO&H4
Bitter, J. H. et al. J. Catal., 1998, 176, (1) 93-101. Applied Pt/Zr02 and Rh supported on y-Al203 and ZrOz are active and stable catalysts for CO/CH4 reforming, despite the high thermodynamic driving force to form coke under the reaction conditions. Steady state, transient kinetic measurements and physico-chemical characterization techniques have shown that the catalyst activity is determined by the available Pt-ZrOz perimeter. Methane is decomposed on the metal to CH,
Gaseous fuels (derived gaseous fuels)
key factor for SO2 removal efficiency of CFB-FGD process. (4) The absorbent can be enhanced in the CFB reactor. (5) The CFB reactor is a better one for the dry/ semi-dry FGD technology.
Initial carbon-carbon bond formation during s nthesis. gas conversion to higher alcohols on K-Curxg&eO. catalysts Xu, M. and Iglesia, E. Coral. Len., 1998, 51, (l/Z), 47-52.
occurred when oxygen was introduced downstream from the sample and was mixed with the biomass pyrolysis vapours. To monitor the products formed at the various experimental conditions a molecular beam mass spectrometer system was used.
99lW344
Using ‘3CO/Hz/‘ZCHsOH mixtures, isotopic tracer studies of alcohol synthesis pathways have shown that ethanol is formed predominantly by direct reactions of 13C0 on Cuc.sMg&eO, promoted with potassium at short residence times, without significant involvement of the 12CHs0H present in the feed. The observed decrease in “C content in ethanol with increasing residence time is caused by reverse aldol reactions of higher alcohols, which contain lower “C contents because of the significant involvement of “CHsOH in their formation, and by reactions of Me formate with “CH30Hderived species. There is a consistency between the effects of residence time on the ‘“C distribution within reaction products and on the rates of formation of ethanol, Me formate, and Me acetate, with the intermediate role of Me formate and Me acetate in ethanol formation.
Internal consistent of coal gasification reactivities determined In bent K-scale reactors: effect of pyrolysis conditions on char reactivities under high-pressure CO2
66166345
Megaritis, A. et al. Fuel, 1998, 77, (13), 1411-1420. Using a wire-mesh, a fluidized-bed and a ‘hot-rod’ (fixed-bed) reactor, relationships between char preparation conditions and CO2 gasification conversions have been examined. Conversions from the direct gasification of untreated coal have been compared with those from the gasification of chars prepared: (i) in-situ under helium in each reactor, before switching over to COz; and (ii) from gasification in all three reactors of a char sample, pre-prepared in the fixed bed reactor. Conversions from direct gasification were slightly higher than experiments where samples were first pyrolysed in situ and gasified under CO2 in the same reactor. In some cases, conversions were within experimental error. Under these conditions and within several percentage points, the pyrolysis and gasification steps may be considered as additive. Lower overall conversions observed in the hot-rod reactor have been attributed to the combined effect of: (i) formation of a low reactivity charowing to tar-solids contact leading to secondary char deposition; and (ii) poor contact between char and the reactive gas. In the wire-mesh and the fluidized-bed reactors, direct COz-gasification conversions were considerably larger than those determined using the common sample of char, pre-prepared in the hot-rod (fixed-bed) reactor. This sharp drop in overall conversion shows that care must be taken in interpreting reactivity data from ‘two-reactor, two-step’ procedures where char preparation conditions are not identical to those of the gasification step. A broadly linear relationship has been observed between conversions from a pilot plant reactor and direct C02-gasification in the bench-scale high-pressure wire-mesh reactor. Despite differences between operating parameters in the two reactors, the results suggest that data from the wire-mesh reactor may be successfully used to compare relative coal reactivities under pilotplant gasification conditions.
Kinetics of CO hydrogenation over Ni-Mo/Ai203 catalysts with and without potassium promotion
99106346
Aksoylu, A. E. and Onsan, Z. I. Ind. Eng. Chemical Res., 1998, 37, (6), 2397-2403. In the 498-548 K range the effect of potassium promotion on the CO hydrogenation activity and C2-C4 hydrocarbons selectivity of 15 wt% Nickel and 10 wt% Molybdenum on AlzO3, catalyst was investigated using unpromoted and l-3 wt% potassium-promoted samples. CO2 methanation tests at 523 K were used as a probe to confirm activity trends. Intrinsic kinetic data were obtained in the initial rate region on both unpromoted and 1 wt% potassium-promoted Ni-Mo catalysts. Potassium promotion of the bimetallic Ni-Mo catalyst decreases both the activity and the specific activity of the Ni sites while increasing the Cz-C3 olefin-to-paraffin ratio. The most plausible kinetic model among those tested for both Ni-Mo and Ni-MO-K catalysts was given by the surface carbide mechanism with dissociative adsorption of hydrogen as the rate-limiting step.
Laboratory 99/00347 asification oxidatlon of biomass pyro8ysis vapors
studies
via
partial
Dayton, D. C. and Evans, R. J. Making Bus. Biomass Energy, Environ., Chemical, Fibers Mater., Proc. Biomass Conf. Am., 3rd. 1997, (1). 673-682. Edited by Overend, R. P. and Chornet, E. In a quartz-tube flow reactor biomass gasification was simulated at the bench scale by the partial oxidation of biomass pyrolysis vapours in various atmospheres. At two temperatures, 700” and 1000” small samples of switchgrass were pyrolysed and subsequent gas phase reactions were studied at 850”. The O2 concentration in the reactor was varied between 1% and 10% and in certain experiments steam was added to the atmosphere. The lowest 02 concentration corresponded to enough 02, in addition to the oxygen in the biomass, to provide 30% of the stoichiometric limit to oxidize a 50.0-mg switchgrass sample. The point at which the oxygen was introduced into the reactor was also varied. Partial oxidation of char and volatiles occurred when oxygen was introduced at the rear of the reactor so oxygen flowed over the sample. Partial oxidation of the volatiles
34
Fuel and Energy Abstracts January 1999
Long-chain hydrocarbons from syngas on nanosized cobalt catalyst. Promotion effect of ruthemum
99166346
Zhang, Y. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1997, 14, (28), 510. Using the sol-gel method, SiOz aerogel ultrafine powder and ZrOz-SiOz ultrafine complex oxide were prepared. Co/Zr02-SiOz and Co-Ru/Zr02SiOz catalysts were prepared by incipient wetness technique and physical mixing method. The effects of ruthenium addition on the texture, structure, reduction, Hz desorption and Fischer-Tropsch reaction of nano-sized cobalt-based catalysts were investigated. The results indicate that addition of ruthenium makes the reduction of Co2+ difficult to take place. The selectivity to CH4 decreases and selectivity to Cg+ increases. The distribution of hydrocarbon products has two peaks at Cs and Ci4, deviating from the Schulz-Flory distribution.
Mathematical modeling of the gasification of cellulose-containing biomass with the aid of a zone model
99166349
Jung, K. ef al. DGMK Tagungsber., 1998, 9802, 335-342. (In German) In a solid-bed reactor using pure 02 as a gasification medium the gasification of biomass was studied theoretically on the example of wood as raw material. For the modelling the reactor was devided into a drying and pyrolysis zone, an oxidation zone, and a reduction zone. The chemical equilibrium of the components in the reactor were shown and the enthalpies of formation and decomposition of the components were calculated. Based on the carbon, oxygen, hydrogen, nitrogen, and sulfur content of the raw material and the knowledge of the chemical equilibrium in the plant under specified pressure and temperature, the resulting gas composition was calculated. For dry and moisture containing gas the calculated data for the gas composition showed relatively good agreement with experimental data.
Methane reforming with carbon dioxide to syngas. I. Performance of cobalt-alumina catalyst calcined at high temperature
99l60360
Wang, P. er al. Cuihua Xuebao, 1998, 19, (3), 196-200. (In Chinese) In COz-reforming of CH4 to syngas the catalytic performance of Co/Alz03 catalyst calcined at high temperature has been studied by using a fixed-bed flow apparatus. Content of carbon deposited on catalyst is measured by gas chromatography. About 9% Co/Al203 catalyst calcined at 1073-1473 Knot only exhibits high catalytic activity, but also shows optimal resistance to carbon deposition. The results of TPR, XRD and catalytic tests indicate that it is Co and CoA120., that play a very important role in the reaction, and that there are many different catalytic features between Co/A1203 or Ni/AlzO, calcined at low temperature and Co/Alz03 calcined at low temperature.
99100351 especially generator
Method and apparatus for optimum gasification, of wood chips, and especially in a cocurrent
Jakobsen, H. H. Dan. DK 172,277 (Cl. ClOJ3/00), 16 Feb 1998, Appl. 94/ 1,248, 28 Ott 1994; 11 pp. (In Danish) The method comprises a gasifier whose pyrolysis zone is provided with a temperature sensor covering several temperature ranges (A, B, and C) and capable of continuously adjusting the pyrolysis and combustion temperature downward or upward and thereby controlling the exact limits of the pyrolysis zone. The exact temperatures A, B, and C in the pyrolysis zone and combustion zone can be adjusted downward or upward in a number of ways; cooling by injecting water, by changing the flow of primary air, or by changing the simultaneous flow of secondary air. The apparatus comprises a suction pump to draw of the gas and keep the pyrolysis zone and combustion zone at a partial vacuum whereby the primary and secondary air are forced in the direction of flow and into the upper pyrolysis and combustion zone. 99lW3S2 Modeling of gasification behavior in freeboard of fluidized bed gasifier
Tang, Z. et al. Proc. Annu. Inf. Pittsburgh Coal Conf., 1997, 14, (2). 53-59. For investigating the gasification behaviour in freeboard of a fluidized bed gasifier a mathematical model has been developed. In this model, MonteCarlo method was used to describe the particle movement in freeboard. Comparing the simulation results with experiment data, it can be seen that the freeboard has little effect on gasification reaction in fluidized bed gasifier at the condition that there is no fine recycling. In this article some advice was given to improve the freeboard reaction ability.
Mono and bifunctional pathways reforming over Pt and Rh based catalysts
99l66353
of
CO&H4
Bitter, J. H. et al. J. Catal., 1998, 176, (1) 93-101. Applied Pt/Zr02 and Rh supported on y-Al203 and ZrOz are active and stable catalysts for CO/CH4 reforming, despite the high thermodynamic driving force to form coke under the reaction conditions. Steady state, transient kinetic measurements and physico-chemical characterization techniques have shown that the catalyst activity is determined by the available Pt-ZrOz perimeter. Methane is decomposed on the metal to CH,