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00619 Processing and properties of a glass-ceramic from coal fly ash from a thermal power plant through an economic process
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•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.