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ZnO catalyst: effects of Pd loading
03 Gaseous fuels (derived gaseous fuels) this development. In reality, the most important threats to gas security will be a decreasing ability to meet peak demand, and the possibility of UK field, pipeline and terminal failure. There is an increasingly urgent need for a framework within which to analyse: the impact of specific security events, the level of risk attached to such events, and the cost of measures which would provide insurance against them. In the absence of such a framework, statements which project high levels of import dependence and equate these with deteriorating levels of gas security are largely meaningless.
05/00605 Worldwide selection of early opportunities for CO2-enhanced oil recovery and CO2-enhanced coal bed methane production van Bergen, F. et al. Energy, 2004, 29, (9-10), 1611-1621. A study has been undertaken to assess the potential for low cost opportunities for CO2 capture and storage/sequestration worldwide. Such opportunities should provide options for early implementation of projects worldwide. They combine high purity (100%) CO2 gas streams with short transmission distance and potentially profitable CO2 enhanced fossil fuel recovery schemes such as CO2-enhaneed oil recovery (EOR) and CO2-enhanced coal bed methane production (ECBM), which simultaneously sequester CO2. The study has used a geographical information system to link high purity CO2 point sources to oil and gas reservoirs within 100 km of the point source. In doing this some 420 possible CO2-EOR opportunities and a further 79 possible CO2-ECBM opportunities were identified.
Derived gaseous fuels 05•00606 A new integrated approach of coal gasification: the concept and preliminary experimental results Wu, J. et al. Fuel Processing Technology, 2004, 86, (3), 261-266. The total carbon conversion of conventional fiuidized bed gasifier is relatively low (<90%) mainly because of carbon loss in fly-ash. In this paper, a new concept of integrated coal gasification-fluidized bed+entrained flow is introduced. Within this process, large partition of coal with higher reactivity is converted in an ash agglomerating fluidized bed reactor under moderate temperature (1000°C). The remaining small partition of coal (fly-ash) with lower reactivity is converted in a small integrated entrained flow gasifier under higher temperature (1200-1400°C). Low carbon content ash is withdrawn in dry mode by ash agglomerating, with no need to be melted. Preliminary experimental results show that the whole system can be operated steadily, total carbon conversion reaches > 95 %, efficient gas (CO + H2) concentration is 78-82%. Heat exchange between two reactors has been realized, the high temperature gas from entrained flow gasifier can be cooled, and in the mean time the temperature of fluidized bed nearly keeps constant. The high-temperature ash from entrained flow gasifier can be cooled by the char in dense phase of the fluidized bed and then withdrawn in agglomerating mode. All these results prove the concept correct and feasible.
05•00607 Continuous experiment regarding hydrogen production by coal/CaO reaction with steam (I) gas products Lin, S. et al. Fuel, 2004, 83, (7-8), 869-874. Coal/CaO powder mixtures were continuously supplied into a reactor to react with steam at high pressure and high temperature. At 923 K and 5.0 MPa, the gas produced from the reaction of Taiheiyo coal/CaO with steam consisted of mainly H2, with smaller amounts of CH4, C2H4, C2H6 and CO2. Increasing the pressure enhanced H2 production and CH 4 decomposition. Above 3 MPa, the gas from the reaction contained <3% CO and CO2. Under high pressure, CaO reacted with steam to form Ca(OH)2 which absorbed CO> The HffCH4 ratio in the product gases from three different rank coals (Datong coal (bituminous), Taiheiyo coal (sub-bituminous), Wyoming coal (lignite)), followed the order Datong > Taiheiyo > Wyoming. The Wyoming and Datong coals produced less H2 than the Taiheiyo coal.
05100608 Development of novel sorbents for mercury control at elevated temperatures in coal-derived syngas." results of initial screening of candidate materials Portzer, J. W. et al. Fuel Processing Technology, 2004, 85, (6-7), 621630. For next-generation coal-fired power plants such as the integrated gasification combined cycle (IGCC), controlling mercury emissions from the flue gas (turbine exhaust) may not be the most cost-effective option. Rather, it may be more advantageous to remove mercury from the fuel gas (syngas) before its combustion in a gas turbine. This approach aims to maintain the thermodynamic advantages of the IGCC while achieving the desired mercury control. Supported by US Department of Energy's National Energy Technology Laboratory,
RTI is screening chemically reactive solid sorbents to remove mercury. The concept of using reactive solid sorbents is analogous to technology RTI has developed for elevated-temperature syngas desulfurization. The goal is a sorbent tailored to remove mercury at the conditions of the syngas produced in a gasifier fed with carbonaceous feedstocks such as coal and petroleum coke. For the sorbent screening programme, RTI has assembled a mercury vapour exposure apparatus and is evaluating selected sorbents for mercury removal at high temperatures (400-600°F) in the simulated syngas. The initial testing has identified several effective candidate sorbents, while confirming the expected failure of conventional sorbents under high-temperature conditions. Mercury uptake by each sorbent was measured by analysing the exposed material. The experimental protocol includes breakthrough testing and additional quality control runs without a sorbent present.
05100609 Dissociation of vibrationally excited methane on Ni catalyst: Part 1. Application to methane steam reforming Nozaki, T. et al. Catalysis Today, 2004, 89, (1-2), 57 65. This paper describes extensive experimental research on steam reforming of methane using barrier discharges with/without Ni/SiO2 catalyst. Nickel catalyst clearly showed chemical activity at 400°C in the presence of barrier discharge. Methane conversion largely exceeded over equilibrium conversion rate, whereas product selectivity tended to follow equilibrium composition at given temperature: energy cost and energy efficiency achieved 134 MJ/kg H2 and 69%, respectively. Electric property was unchanged in the presence of nickel catalyst, but at least 400°C must be maintained in order to derive synergistic effect between barrier discharge and Ni/SiO2 catalyst. Methane activation mechanism is also discussed based on numerical simulation on streamer propagation in pure methane. Vibrationally excited methane is most abundant (1016 cm -3 at 300 K, 101.3 kPa) and long-lived (~1 ~ts) radical species produced by electron impact, and those vibrational species seemed to improve dissociative chemisorption on nickel surface at low temperature, leading to remarkable process improvement.
05100610 Dissociation of vibraUonally excited methane on Ni catalyst: Part 2, Process diagnostics by emission spectroscopy Nozaki, O. et al. Catalysis Today, 2004, 89, (1~), 67-74. Barrier discharge enhanced catalyst bed (BEC) reactor was developed for methane steam reforming. Synergistic effect between barrier discharge and Ni/SiO2 catalyst was clearly observed when bed temperature exceeded 400°C, energy cost and energy efficiency achieved 134 MJ/kg H2 and 26%, respectively. This paper concentrates on two-temperature analysis of BEC reactor for better understanding of reaction mechanism. Catalyst bed temperature and plasma gas temperature were separately analysed by emission spectroscopy of rotational band of CH(A2~). Gas temperature distribution in packedbed reactor was also estimated by using empirical correlations, and compared to spectroscopic data. Even though plasma gas temperature reached 400-500°C, synergistic effect was not observed when catalyst bed temperature was below 400°C. On the other hand, thermal reforming reaction was dominated over barrier discharges if the bed temperature exceeded 700°C. As key radical species, reactivity of vibrationally excited methane is discussed based on vibrational temperature of CH(A2A). Vibrational temperature was significantly increased in the presence of nickel catalyst, showing increased reactivity of vibrationally excited species.
05100611 Effective reforming of methane with CO2 and 02 to low H2/CO ratio syngas over Ni/MgO-SiO2 using fluidized bed reactor Jing, Q. S. et al. Energy Conversion and Management, 2004, 45, (20), 3127-3137. Reforming of methane with CO2 and oxygen was used to produce low H2/CO ratio syngas over a Ni/MgO-SiO2 catalyst under certain reaction conditions. The effects of the reaction temperature, space velocity and feed gas composition were evaluated. The effect of catalyst fluidization on the conversion of methane was investigated over Ni/ MgO-SiO2 and Pt-Ni/MgO-SiO2 catalysts. Circulation of Ni/MgOSiO2 particles in the fluidized bed reactor gave much higher CH4 conversion than the case without circulation in the fixed bed reactor. This reactor effect was dependent on the catalyst properties. In addition, carbon deposition was inhibited in the fluidized bed reactor.
05/00612 Hydrogen production by oxidative methanol reforming on Pd/ZnO catalyst: effects of Pd loading Liu, S. et al. Catalysis Today, 2003, 87, (1-4), 247-253. Catalytic performances of Pd/ZnO in oxidative methanol reforming reaction were studied as a function of Pd loading. It was confirmed that the formation of Pd-Zn alloy is essential to the selective production of hydrogen. High active Pd/ZnO, comparable to commercial Cu-Zn catalyst, was obtained with higher Pd loading. Selectivity of the
Fuel and Energy Abstracts
March 2005 91
04 By-products related to fuels reaction was greatly increased by increasing Pd loading on ZnO. At higher Pd loadings (>5%), co-precipitation was superior to impregnation for the catalyst preparation. The catalytic performances were also discussed based on results from X-ray diffraction (XRD) characterization.
05•00613 Metal effect and flow rate effect in the hydrogen production from methane Spiess, F.-J. et al. Catalysis Today, 2004, 89, (1-2), 3 5 4 5 . The metal effect of the inner electrode used for the decomposition of methane and the resulting evolution of hydrogen by discharge plasmas was investigated. Several different electrodes were used in this study including noble metals such as palladium and other metals such as iron and copper. The noble metals showed the highest activity in methane decomposition and hydrogen production. Nickel and gold showed considerable deactivation, whereas the activity of iron decreased less. Coated electrodes with copper and tin oxide nanoparticles exhibited high activity in these reactions. The effect of the flow rate and the cleaning of the electrode were examined as further objectives of this study. The decomposition of methane and the evolution of hydrogen decreased with increasing flow rate in a negative exponential manner due to the lower residence time. The cleaning of the electrode has a profound effect on the conversions and allows one to observe the catalytic effect of the metal electrodes, which are otherwise covered by coke produced in the reaction. A mechanism was developed using data obtained from mass spectrometry and combined gas chromatography and mass spectrometry.
05/00614 Plasma catalytic conversion of methane into syngas: the combined effect of discharge activation and catalysis Heintze, M. and Pietruszka, B. Catalysis Today, 2004, 89, (1-2), 21-25. This study investigates the combined operation of a dielectric barrier discharge and an c~-alumina supported Ni catalyst in the partial oxidation of methane. In order to separate the effects of plasma activation from catalytic processes, the study includes both purely catalytic and plasma-activated operation of the reactor. Whereas the catalyst alone is only active above 300°C, plasma induced partial oxidation of methane is observed in the entire temperature range investigated (100-400°C). By comparing the reaction over the Ni catalyst in different oxidation states with the catalyst support only, conclusions are drawn regarding surface and gas phase processes.
05•00615 Some temperature effects on stability and carbon formation in low temperature ac plasma conversion of methane Le, H. et al. Catalysis Today, 2004, 89, (1-2), 15-20. Methane conversion using a low temperature plasma generated by an ac corona discharge has recently been extensively studied. Different products can be produced: C2, C3, H2, CO, COs and coke. The understanding of the role of temperature has been limited. This paper discusses the use of an IR thermal imaging and measurement system to study the effects of temperature on the stability and carbon formation in low temperature ac plasma conversion of methane. Three types of coke are observed during the methane conversion process using plasma generated by an ac corona discharge under various conditions. The first type of coke is dark brown and powder coke. The second type of coke is dark greenish and forms a soft coating. The third type is coke filaments, which strongly affects the discharge stability by quickly connecting the two electrodes. In the partial oxidation or steam reforming of methane, the temperature is generally less than 300°C under normal experimental conditions. Increasing the feed temperature in the steam reforming of methane increases the reactor temperature, causing the formation of coke filaments when the water concentration is not high enough. Therefore, feeding liquid water at room temperature into the reactor helps improve the stability.
05/00616 Syngas production from methane reforming with CO2/H20 and 02 over NiO-MgO solid solution catalyst in fluidized bed reactors Tomishige, K. Catalysis Today, 2004, 89, (4), 405418. Catalyst performance of NiO-MgO solid solution catalysts for methane reforming with CO2 and HzO in the presence of oxygen using fluidized and fixed bed reactors under atmospheric and pressurized conditions was investigated. Especially, methane and COs conversion in the fluidized bed reactor in methane reforming with COs and Oz was higher than those in the fixed bed reactor over Ni0.15Mg0.ssO catalyst under 1.0 MPa. In contrast, conversion levels in the fluidized and fixed bed reactor were almost the same over MgO-supported Ni and Pt catalysts. It is suggested that the promoting effect of catalyst fluidization on the activity is related to the catalyst reducibility. On a catalyst with suitable reducibility, the oxidized and deactivated catalyst can be reduced with the produced syngas and the reforming activity regenerates in the fluidized bed reactor during the catalyst fluidization. In addition, the catalyst fluidization inhibited the carbon deposition.
92
Fuel and Energy Abstracts March 2005
05100617 Synthesis gas production via dielectric barrier discharge over Ni/~,,-AI203 catalyst Song, H. K. et al. Catalysis Today, 2004, 89, (1 2), 27-33. A study of methane conversion from CO2 reforming of methane using dielectric barrier discharge over Ni/7-A1203 catalyst was performed. The main products of reactions were CO, H2, C2H6, C3H8, and C4Hl0. The effects of input power, total flow rate, and CH4/CO2 ratio on conversion and product selectivity were investigated. Carbon dioxide and methane conversions were enhanced with increasing the input power and decreasing the total flow rate. Ni/'7-AIzO3 catalyst had a great effect on the CO selectivity and CO2 conversion. When Ni/3,A1203 catalyst was applied to DBD, the CO selectivity increased from 49.17 to 60.9% and CO2 conversion increased by about 3%. Even though Ni/'~-AI203 catalyst was helpful to improve the COs conversion and CO selectivity, the fundamental mechanism of reaction and characterization of catalysts are still unknown and, therefore, further investigations are necessary.
05/00618 Tri-reforming of CH4 using synthesis gas to dimethyl ether
CO 2
for production of
Lee, S.-H. et al. Catalysis Today, 2003, 87, (1-4), 133-137. In general, there are three processes for production of synthesis gas; steam reforming, CO2 reforming and partial oxidation of methane or natural gas. The study refers to tri-reforming of methane to synthesize syugas with desirable H2/CO ratios by simultaneous oxy-COz-steam reforming of methane. It also reports the results obtained on trireforming of methane over the Ni/ZrO2 based catalyst in order to restrain the carbon deposition and to evaluate the catalytic performance. Results of tri-reforming of CH4 by three catalysts (Ni/Ce-ZrO2, Ni/ZrO2 and Haldor Topsoe R67-7H) are showed that the coke on the reactor wall and the surface of catalyst were reduced dramatically. It was found that the weak acidic site, basic site and redox ability of C e ZrO2 play an important role in tri-reforming of methane conversion. Carbon deposition depends not only on the nature of support, but also on the oxidant as like steam or oxygen. Therefore, the process optimization by reactant ratios is important to manufacture the synthesis gas from natural gas and carbon dioxide.
04
BY-PRODUCTS RELATED TO FUELS
05/00619 Processing and properties of a glass-ceramic from coal fly ash from a thermal power plant through an economic process Kim, J. M. and Kim, H. S. Journal of the European Ceramic Society, 2004, 24, (9), 2825-2833. Coal fly ash from a thermal power plant with the addition of selected oxides was used for the preparation of a glass-ceramic with high mechanical properties through an economic process. The starting materials were fly ash, shell (ark shell) as a source of CaO and TiO2 as a nucleating agent to reduce the melting temperature and to promote internal crystallization. A nuclei formed with Fe and Ti ions from the ash components and added materials, respectively, which had a synergetic effect to induce nuclei in the glass for devitrification. Under a single stage heat treatment, a new crystalline phase formed in the microstructure of glass-ceramics having a crystal size of 2.09×0.36×0.096 ~tm3 with a high aspect ratio, 12. The resulting mechanical properties (hardness, strength, fracture toughness, elastic constant and wear rate) of the glass-ceramic indicated good possibilities for use in structural materials.
05/00620 The characterisation of tar from the pyrolysis of animal bones Purevsuren, B. et al. Fuel, 2004, 83, (7-8), 799-805. This report outlines results of an investigation of the composition of bone pyrolysis tar produced in Mongolia. The liquid product (tar) yield was low" approximately 4.9%. The elemental composition of the tar was C: 73.3%, H:10.1%, N: 11.3%, O: 5.3%. Size-exclusion chromatograms signalled the presence of generally smaller mass material than coal tars and pitches, with a range from about 2000 U downwards. GC-MS showed the tar to be mainly composed of aliphatic material with nitrogen functionalities attached as nitriles, pyridines, pyrroles and amides. Pyridines and phenols turned up as only minor components. Probe-mass spectra also showed no significant aromatic features in this bone tar. Traditional bone tar contains pyridines and quinolines in larger quantities than found here and was used for medicinal purposes. It was presumably prepared by higher temperature pyrolysis than the present tar. The disposal of this tar is likely to present environmental problems. In the absence of more profitable uses, destruction of the oil by combustion with excess air may provide a reasonable alternative.
05/00605 Worldwide selection of early opportunities for CO2-enhanced oil recovery and CO2-enhanced coal bed methane production van Bergen, F. et al. Energy, 2004, 29, (9-10), 1611-1621. A study has been undertaken to assess the potential for low cost opportunities for CO2 capture and storage/sequestration worldwide. Such opportunities should provide options for early implementation of projects worldwide. They combine high purity (100%) CO2 gas streams with short transmission distance and potentially profitable CO2 enhanced fossil fuel recovery schemes such as CO2-enhaneed oil recovery (EOR) and CO2-enhanced coal bed methane production (ECBM), which simultaneously sequester CO2. The study has used a geographical information system to link high purity CO2 point sources to oil and gas reservoirs within 100 km of the point source. In doing this some 420 possible CO2-EOR opportunities and a further 79 possible CO2-ECBM opportunities were identified.
Derived gaseous fuels 05•00606 A new integrated approach of coal gasification: the concept and preliminary experimental results Wu, J. et al. Fuel Processing Technology, 2004, 86, (3), 261-266. The total carbon conversion of conventional fiuidized bed gasifier is relatively low (<90%) mainly because of carbon loss in fly-ash. In this paper, a new concept of integrated coal gasification-fluidized bed+entrained flow is introduced. Within this process, large partition of coal with higher reactivity is converted in an ash agglomerating fluidized bed reactor under moderate temperature (1000°C). The remaining small partition of coal (fly-ash) with lower reactivity is converted in a small integrated entrained flow gasifier under higher temperature (1200-1400°C). Low carbon content ash is withdrawn in dry mode by ash agglomerating, with no need to be melted. Preliminary experimental results show that the whole system can be operated steadily, total carbon conversion reaches > 95 %, efficient gas (CO + H2) concentration is 78-82%. Heat exchange between two reactors has been realized, the high temperature gas from entrained flow gasifier can be cooled, and in the mean time the temperature of fluidized bed nearly keeps constant. The high-temperature ash from entrained flow gasifier can be cooled by the char in dense phase of the fluidized bed and then withdrawn in agglomerating mode. All these results prove the concept correct and feasible.
05•00607 Continuous experiment regarding hydrogen production by coal/CaO reaction with steam (I) gas products Lin, S. et al. Fuel, 2004, 83, (7-8), 869-874. Coal/CaO powder mixtures were continuously supplied into a reactor to react with steam at high pressure and high temperature. At 923 K and 5.0 MPa, the gas produced from the reaction of Taiheiyo coal/CaO with steam consisted of mainly H2, with smaller amounts of CH4, C2H4, C2H6 and CO2. Increasing the pressure enhanced H2 production and CH 4 decomposition. Above 3 MPa, the gas from the reaction contained <3% CO and CO2. Under high pressure, CaO reacted with steam to form Ca(OH)2 which absorbed CO> The HffCH4 ratio in the product gases from three different rank coals (Datong coal (bituminous), Taiheiyo coal (sub-bituminous), Wyoming coal (lignite)), followed the order Datong > Taiheiyo > Wyoming. The Wyoming and Datong coals produced less H2 than the Taiheiyo coal.
05100608 Development of novel sorbents for mercury control at elevated temperatures in coal-derived syngas." results of initial screening of candidate materials Portzer, J. W. et al. Fuel Processing Technology, 2004, 85, (6-7), 621630. For next-generation coal-fired power plants such as the integrated gasification combined cycle (IGCC), controlling mercury emissions from the flue gas (turbine exhaust) may not be the most cost-effective option. Rather, it may be more advantageous to remove mercury from the fuel gas (syngas) before its combustion in a gas turbine. This approach aims to maintain the thermodynamic advantages of the IGCC while achieving the desired mercury control. Supported by US Department of Energy's National Energy Technology Laboratory,
RTI is screening chemically reactive solid sorbents to remove mercury. The concept of using reactive solid sorbents is analogous to technology RTI has developed for elevated-temperature syngas desulfurization. The goal is a sorbent tailored to remove mercury at the conditions of the syngas produced in a gasifier fed with carbonaceous feedstocks such as coal and petroleum coke. For the sorbent screening programme, RTI has assembled a mercury vapour exposure apparatus and is evaluating selected sorbents for mercury removal at high temperatures (400-600°F) in the simulated syngas. The initial testing has identified several effective candidate sorbents, while confirming the expected failure of conventional sorbents under high-temperature conditions. Mercury uptake by each sorbent was measured by analysing the exposed material. The experimental protocol includes breakthrough testing and additional quality control runs without a sorbent present.
05100609 Dissociation of vibrationally excited methane on Ni catalyst: Part 1. Application to methane steam reforming Nozaki, T. et al. Catalysis Today, 2004, 89, (1-2), 57 65. This paper describes extensive experimental research on steam reforming of methane using barrier discharges with/without Ni/SiO2 catalyst. Nickel catalyst clearly showed chemical activity at 400°C in the presence of barrier discharge. Methane conversion largely exceeded over equilibrium conversion rate, whereas product selectivity tended to follow equilibrium composition at given temperature: energy cost and energy efficiency achieved 134 MJ/kg H2 and 69%, respectively. Electric property was unchanged in the presence of nickel catalyst, but at least 400°C must be maintained in order to derive synergistic effect between barrier discharge and Ni/SiO2 catalyst. Methane activation mechanism is also discussed based on numerical simulation on streamer propagation in pure methane. Vibrationally excited methane is most abundant (1016 cm -3 at 300 K, 101.3 kPa) and long-lived (~1 ~ts) radical species produced by electron impact, and those vibrational species seemed to improve dissociative chemisorption on nickel surface at low temperature, leading to remarkable process improvement.
05100610 Dissociation of vibraUonally excited methane on Ni catalyst: Part 2, Process diagnostics by emission spectroscopy Nozaki, O. et al. Catalysis Today, 2004, 89, (1~), 67-74. Barrier discharge enhanced catalyst bed (BEC) reactor was developed for methane steam reforming. Synergistic effect between barrier discharge and Ni/SiO2 catalyst was clearly observed when bed temperature exceeded 400°C, energy cost and energy efficiency achieved 134 MJ/kg H2 and 26%, respectively. This paper concentrates on two-temperature analysis of BEC reactor for better understanding of reaction mechanism. Catalyst bed temperature and plasma gas temperature were separately analysed by emission spectroscopy of rotational band of CH(A2~). Gas temperature distribution in packedbed reactor was also estimated by using empirical correlations, and compared to spectroscopic data. Even though plasma gas temperature reached 400-500°C, synergistic effect was not observed when catalyst bed temperature was below 400°C. On the other hand, thermal reforming reaction was dominated over barrier discharges if the bed temperature exceeded 700°C. As key radical species, reactivity of vibrationally excited methane is discussed based on vibrational temperature of CH(A2A). Vibrational temperature was significantly increased in the presence of nickel catalyst, showing increased reactivity of vibrationally excited species.
05100611 Effective reforming of methane with CO2 and 02 to low H2/CO ratio syngas over Ni/MgO-SiO2 using fluidized bed reactor Jing, Q. S. et al. Energy Conversion and Management, 2004, 45, (20), 3127-3137. Reforming of methane with CO2 and oxygen was used to produce low H2/CO ratio syngas over a Ni/MgO-SiO2 catalyst under certain reaction conditions. The effects of the reaction temperature, space velocity and feed gas composition were evaluated. The effect of catalyst fluidization on the conversion of methane was investigated over Ni/ MgO-SiO2 and Pt-Ni/MgO-SiO2 catalysts. Circulation of Ni/MgOSiO2 particles in the fluidized bed reactor gave much higher CH4 conversion than the case without circulation in the fixed bed reactor. This reactor effect was dependent on the catalyst properties. In addition, carbon deposition was inhibited in the fluidized bed reactor.
05/00612 Hydrogen production by oxidative methanol reforming on Pd/ZnO catalyst: effects of Pd loading Liu, S. et al. Catalysis Today, 2003, 87, (1-4), 247-253. Catalytic performances of Pd/ZnO in oxidative methanol reforming reaction were studied as a function of Pd loading. It was confirmed that the formation of Pd-Zn alloy is essential to the selective production of hydrogen. High active Pd/ZnO, comparable to commercial Cu-Zn catalyst, was obtained with higher Pd loading. Selectivity of the
Fuel and Energy Abstracts
March 2005 91
04 By-products related to fuels reaction was greatly increased by increasing Pd loading on ZnO. At higher Pd loadings (>5%), co-precipitation was superior to impregnation for the catalyst preparation. The catalytic performances were also discussed based on results from X-ray diffraction (XRD) characterization.
05•00613 Metal effect and flow rate effect in the hydrogen production from methane Spiess, F.-J. et al. Catalysis Today, 2004, 89, (1-2), 3 5 4 5 . The metal effect of the inner electrode used for the decomposition of methane and the resulting evolution of hydrogen by discharge plasmas was investigated. Several different electrodes were used in this study including noble metals such as palladium and other metals such as iron and copper. The noble metals showed the highest activity in methane decomposition and hydrogen production. Nickel and gold showed considerable deactivation, whereas the activity of iron decreased less. Coated electrodes with copper and tin oxide nanoparticles exhibited high activity in these reactions. The effect of the flow rate and the cleaning of the electrode were examined as further objectives of this study. The decomposition of methane and the evolution of hydrogen decreased with increasing flow rate in a negative exponential manner due to the lower residence time. The cleaning of the electrode has a profound effect on the conversions and allows one to observe the catalytic effect of the metal electrodes, which are otherwise covered by coke produced in the reaction. A mechanism was developed using data obtained from mass spectrometry and combined gas chromatography and mass spectrometry.
05/00614 Plasma catalytic conversion of methane into syngas: the combined effect of discharge activation and catalysis Heintze, M. and Pietruszka, B. Catalysis Today, 2004, 89, (1-2), 21-25. This study investigates the combined operation of a dielectric barrier discharge and an c~-alumina supported Ni catalyst in the partial oxidation of methane. In order to separate the effects of plasma activation from catalytic processes, the study includes both purely catalytic and plasma-activated operation of the reactor. Whereas the catalyst alone is only active above 300°C, plasma induced partial oxidation of methane is observed in the entire temperature range investigated (100-400°C). By comparing the reaction over the Ni catalyst in different oxidation states with the catalyst support only, conclusions are drawn regarding surface and gas phase processes.
05•00615 Some temperature effects on stability and carbon formation in low temperature ac plasma conversion of methane Le, H. et al. Catalysis Today, 2004, 89, (1-2), 15-20. Methane conversion using a low temperature plasma generated by an ac corona discharge has recently been extensively studied. Different products can be produced: C2, C3, H2, CO, COs and coke. The understanding of the role of temperature has been limited. This paper discusses the use of an IR thermal imaging and measurement system to study the effects of temperature on the stability and carbon formation in low temperature ac plasma conversion of methane. Three types of coke are observed during the methane conversion process using plasma generated by an ac corona discharge under various conditions. The first type of coke is dark brown and powder coke. The second type of coke is dark greenish and forms a soft coating. The third type is coke filaments, which strongly affects the discharge stability by quickly connecting the two electrodes. In the partial oxidation or steam reforming of methane, the temperature is generally less than 300°C under normal experimental conditions. Increasing the feed temperature in the steam reforming of methane increases the reactor temperature, causing the formation of coke filaments when the water concentration is not high enough. Therefore, feeding liquid water at room temperature into the reactor helps improve the stability.
05/00616 Syngas production from methane reforming with CO2/H20 and 02 over NiO-MgO solid solution catalyst in fluidized bed reactors Tomishige, K. Catalysis Today, 2004, 89, (4), 405418. Catalyst performance of NiO-MgO solid solution catalysts for methane reforming with CO2 and HzO in the presence of oxygen using fluidized and fixed bed reactors under atmospheric and pressurized conditions was investigated. Especially, methane and COs conversion in the fluidized bed reactor in methane reforming with COs and Oz was higher than those in the fixed bed reactor over Ni0.15Mg0.ssO catalyst under 1.0 MPa. In contrast, conversion levels in the fluidized and fixed bed reactor were almost the same over MgO-supported Ni and Pt catalysts. It is suggested that the promoting effect of catalyst fluidization on the activity is related to the catalyst reducibility. On a catalyst with suitable reducibility, the oxidized and deactivated catalyst can be reduced with the produced syngas and the reforming activity regenerates in the fluidized bed reactor during the catalyst fluidization. In addition, the catalyst fluidization inhibited the carbon deposition.
92
Fuel and Energy Abstracts March 2005
05100617 Synthesis gas production via dielectric barrier discharge over Ni/~,,-AI203 catalyst Song, H. K. et al. Catalysis Today, 2004, 89, (1 2), 27-33. A study of methane conversion from CO2 reforming of methane using dielectric barrier discharge over Ni/7-A1203 catalyst was performed. The main products of reactions were CO, H2, C2H6, C3H8, and C4Hl0. The effects of input power, total flow rate, and CH4/CO2 ratio on conversion and product selectivity were investigated. Carbon dioxide and methane conversions were enhanced with increasing the input power and decreasing the total flow rate. Ni/'7-AIzO3 catalyst had a great effect on the CO selectivity and CO2 conversion. When Ni/3,A1203 catalyst was applied to DBD, the CO selectivity increased from 49.17 to 60.9% and CO2 conversion increased by about 3%. Even though Ni/'~-AI203 catalyst was helpful to improve the COs conversion and CO selectivity, the fundamental mechanism of reaction and characterization of catalysts are still unknown and, therefore, further investigations are necessary.
05/00618 Tri-reforming of CH4 using synthesis gas to dimethyl ether
CO 2
for production of
Lee, S.-H. et al. Catalysis Today, 2003, 87, (1-4), 133-137. In general, there are three processes for production of synthesis gas; steam reforming, CO2 reforming and partial oxidation of methane or natural gas. The study refers to tri-reforming of methane to synthesize syugas with desirable H2/CO ratios by simultaneous oxy-COz-steam reforming of methane. It also reports the results obtained on trireforming of methane over the Ni/ZrO2 based catalyst in order to restrain the carbon deposition and to evaluate the catalytic performance. Results of tri-reforming of CH4 by three catalysts (Ni/Ce-ZrO2, Ni/ZrO2 and Haldor Topsoe R67-7H) are showed that the coke on the reactor wall and the surface of catalyst were reduced dramatically. It was found that the weak acidic site, basic site and redox ability of C e ZrO2 play an important role in tri-reforming of methane conversion. Carbon deposition depends not only on the nature of support, but also on the oxidant as like steam or oxygen. Therefore, the process optimization by reactant ratios is important to manufacture the synthesis gas from natural gas and carbon dioxide.
04
BY-PRODUCTS RELATED TO FUELS
05/00619 Processing and properties of a glass-ceramic from coal fly ash from a thermal power plant through an economic process Kim, J. M. and Kim, H. S. Journal of the European Ceramic Society, 2004, 24, (9), 2825-2833. Coal fly ash from a thermal power plant with the addition of selected oxides was used for the preparation of a glass-ceramic with high mechanical properties through an economic process. The starting materials were fly ash, shell (ark shell) as a source of CaO and TiO2 as a nucleating agent to reduce the melting temperature and to promote internal crystallization. A nuclei formed with Fe and Ti ions from the ash components and added materials, respectively, which had a synergetic effect to induce nuclei in the glass for devitrification. Under a single stage heat treatment, a new crystalline phase formed in the microstructure of glass-ceramics having a crystal size of 2.09×0.36×0.096 ~tm3 with a high aspect ratio, 12. The resulting mechanical properties (hardness, strength, fracture toughness, elastic constant and wear rate) of the glass-ceramic indicated good possibilities for use in structural materials.
05/00620 The characterisation of tar from the pyrolysis of animal bones Purevsuren, B. et al. Fuel, 2004, 83, (7-8), 799-805. This report outlines results of an investigation of the composition of bone pyrolysis tar produced in Mongolia. The liquid product (tar) yield was low" approximately 4.9%. The elemental composition of the tar was C: 73.3%, H:10.1%, N: 11.3%, O: 5.3%. Size-exclusion chromatograms signalled the presence of generally smaller mass material than coal tars and pitches, with a range from about 2000 U downwards. GC-MS showed the tar to be mainly composed of aliphatic material with nitrogen functionalities attached as nitriles, pyridines, pyrroles and amides. Pyridines and phenols turned up as only minor components. Probe-mass spectra also showed no significant aromatic features in this bone tar. Traditional bone tar contains pyridines and quinolines in larger quantities than found here and was used for medicinal purposes. It was presumably prepared by higher temperature pyrolysis than the present tar. The disposal of this tar is likely to present environmental problems. In the absence of more profitable uses, destruction of the oil by combustion with excess air may provide a reasonable alternative.