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Yasuo Ohtsuka - One of the best experts on this subject based on the ideXlab platform.
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catalytic performance of Limonite ores in the decomposition of model compounds of biomass derived tar
Energy & Fuels, 2017Co-Authors: Naoto Tsubouchi, Yuuki Mochizuki, Enkhsaruul Byambajav, Satoko Takahashi, Yuu Hanaoka, Yasuo OhtsukaAbstract:Catalytic decomposition of toluene (C6H5CH3) or benzene (C6H6) with inexpensive Limonite ores, composed mainly of goethite (α-FeOOH), was examined using a vertical, cylindrical flow fixed-bed quartz reactor to develop a novel method of removing biomass-derived tar components. The unsupported Limonite catalyst was active for the decomposition of 480 ppm of C6H5CH3 and 1700 ppm of C6H6 in 15 vol % H2O/45 vol % H2/He, leading to C6H5CH3 and C6H6 conversions at 500 °C of nearly 100 and 97%, respectively. When the C6H5CH3 decomposition temperature was increased from 500 to 800 °C, the overall reaction path changed from demethylation to hydrocracking and then to steam reforming. A honeycomb-supported Limonite catalyst also was effective and achieved nearly complete C6H5CH3 conversion at 600 °C. In addition, the honeycomb-supported catalyst promoted C6H6 conversion of nearly 100% without carbon deposits at 700 °C in 15 vol % H2O/20 vol % H2/26 vol % CO/20 vol % CO2/5 vol % CH4 that was designed to simulate raw f...
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high catalytic performance of magnesium cations added Limonite in the decomposition of ammonia in a simulated syngas rich fuel gas
Journal of Molecular Catalysis A-chemical, 2015Co-Authors: Naoto Tsubouchi, Hiroyuki Hashimoto, Yasuo OhtsukaAbstract:Abstract Catalytic decomposition of 2000 ppm NH 3 with an Australian Limonite ore, which is composed mostly of goethite (α-FeOOH), has been studied from a viewpoint of hot gas cleanup with a vertical, cylindrical quartz reactor at 750–850 °C under a high space velocity of 45,000 h −1 . It has already been reported that the Limonite achieves the almost complete decomposition of NH 3 in inert He at 500 °C and shows very stable performance in the reaction at 750 °C in the coexistence of 50–500 ppm H 2 S or at 850 °C in the presence of fuel gas components produced in an air-blown coal gasification process. In the coexistence of a high concentration of syngas (50% CO/25% H 2 ) produced with an O 2 -blown coal gasifier, the Limonite is deactivated almost completely because of the remarkable occurrence of carbon deposition from the CO. On the other hand, the addition of small amounts of CO 2 and H 2 O, which are always included in actual coal-derived fuel gas, to the syngas improves the activity of the Limonite, and conversions of NH 3 –N 2 at 750 and 850 °C become about 65% and almost 100% without carbon deposition, respectively. When several Limonite-based catalysts with alkali metal and alkaline earth metal cations are prepared by the impregnation method and then used in the NH 3 decomposition at 750 °C in 50% CO/25% H 2 /5% CO 2 /3% H 2 O, fine particles of MgO derived from Mg cations can work more effectively as the promoter, and the 3 mass% Mg-added Limonite maintains the high and stable NH 3 conversion of almost 100% for 25 h. In this case, no significant carbon deposition takes place. It is probable that MgO with strong basicity suppresses the carbon formation from CO, and that the Limonite-based composite catalyst thus shows the superior performance in the decomposition of NH 3 in syngas-rich fuel gas that simulates product gas in O 2 -blown coal gasification.
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catalytic performance of Limonite in the decomposition of ammonia in the coexistence of typical fuel gas components produced in an air blown coal gasification process
Energy & Fuels, 2007Co-Authors: Naoto Tsubouchi, Hiroyuki Hashimoto, Yasuo OhtsukaAbstract:Catalytic decomposition of 2000 ppm NH 3 in different atmospheres with an Australian α-FeOOH-rich Limonite ore at 750-950 °C under a high space velocity of 45000 h-1 has been studied with a cylindrical quartz reactor to develop a novel hot gas cleanup method of removing NH 3 from fuel gas produced in an air-blown coal gasification process for an integrated gasification combined cycle (IGCC) technology. The Limonite shows very high catalytic activity for the decomposition of NH 3 diluted with inert gas at 750 °C, regardless of whether the catalyst material is subjected to H 2 reduction before the reaction or not. Conversion of NH 3 to N 2 over the reduced Limonite reaches ≥99% at 750-950 °C, and the catalyst maintains the high performance for about 40 h at 750 °C. When the decomposition reaction is carried out in the presence of fuel gas components, the coexistence of syngas (20% CO/10% H 2 ) causes not only the serious deactivation of the Limonite catalyst but also the appreciable formation of deposited carbon and CO 2 . On the other hand, the addition of 10% CO 2 or 3% H 2 O to the syngas improves the catalytic performance and concurrently suppresses the carbon deposition almost completely, and the NH 3 conversion in the 3% H 2 O-containing syngas reaches about 90% and almost 100% at 750 and 850 °C, respectively. Influential factors controlling the catalytic activity of the Limonite ore in the coexistence of fuel gas components are discussed on the basis of the results of the powder X-ray diffraction measurements, thermodynamic calculations, and some model experiments.
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Sulfur tolerance of an inexpensive Limonite catalyst for high temperature decomposition of ammonia
Powder Technology, 2007Co-Authors: Naoto Tsubouchi, Hiroyuki Hashimoto, Yasuo OhtsukaAbstract:Abstract Catalytic performance of Limonite in the decomposition of 2000 ppm NH 3 in the presence of a small concentration of H 2 S has been studied with a cylindrical quartz reactor at a high space velocity of 45000 h − 1 to examine the sulfur tolerance of the Limonite catalyst. It is not poisoned apparently by 50–500 ppm H 2 S at 750 °C, but the remarkable sulfur poisoning is observed at 2000 ppm H 2 S. In the coexistence of 100 ppm H 2 S, conversion of NH 3 to N 2 decreases gradually with time after 10 h at 650 °C, whereas the Limonite maintains the high conversion of almost 100% for 50 h at 750 °C. The SEM-EDX measurements after reaction show that the surface composition at 750 °C is richer in metallic Fe, which may be produced by the reaction of NH 3 and/or H 2 with FeS formed. Commercially-available FeS promotes the decomposition of NH 3 diluted with inert gas at 750 °C, and the FeS is partly transformed into H 2 S and α-Fe in this process. Possible mechanisms for the decomposition of NH 3 in the presence of H 2 S with the Limonite are discussed on the basis of the results of some model experiments.
Naoto Tsubouchi - One of the best experts on this subject based on the ideXlab platform.
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catalytic performance of Limonite ores in the decomposition of model compounds of biomass derived tar
Energy & Fuels, 2017Co-Authors: Naoto Tsubouchi, Yuuki Mochizuki, Enkhsaruul Byambajav, Satoko Takahashi, Yuu Hanaoka, Yasuo OhtsukaAbstract:Catalytic decomposition of toluene (C6H5CH3) or benzene (C6H6) with inexpensive Limonite ores, composed mainly of goethite (α-FeOOH), was examined using a vertical, cylindrical flow fixed-bed quartz reactor to develop a novel method of removing biomass-derived tar components. The unsupported Limonite catalyst was active for the decomposition of 480 ppm of C6H5CH3 and 1700 ppm of C6H6 in 15 vol % H2O/45 vol % H2/He, leading to C6H5CH3 and C6H6 conversions at 500 °C of nearly 100 and 97%, respectively. When the C6H5CH3 decomposition temperature was increased from 500 to 800 °C, the overall reaction path changed from demethylation to hydrocracking and then to steam reforming. A honeycomb-supported Limonite catalyst also was effective and achieved nearly complete C6H5CH3 conversion at 600 °C. In addition, the honeycomb-supported catalyst promoted C6H6 conversion of nearly 100% without carbon deposits at 700 °C in 15 vol % H2O/20 vol % H2/26 vol % CO/20 vol % CO2/5 vol % CH4 that was designed to simulate raw f...
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high catalytic performance of magnesium cations added Limonite in the decomposition of ammonia in a simulated syngas rich fuel gas
Journal of Molecular Catalysis A-chemical, 2015Co-Authors: Naoto Tsubouchi, Hiroyuki Hashimoto, Yasuo OhtsukaAbstract:Abstract Catalytic decomposition of 2000 ppm NH 3 with an Australian Limonite ore, which is composed mostly of goethite (α-FeOOH), has been studied from a viewpoint of hot gas cleanup with a vertical, cylindrical quartz reactor at 750–850 °C under a high space velocity of 45,000 h −1 . It has already been reported that the Limonite achieves the almost complete decomposition of NH 3 in inert He at 500 °C and shows very stable performance in the reaction at 750 °C in the coexistence of 50–500 ppm H 2 S or at 850 °C in the presence of fuel gas components produced in an air-blown coal gasification process. In the coexistence of a high concentration of syngas (50% CO/25% H 2 ) produced with an O 2 -blown coal gasifier, the Limonite is deactivated almost completely because of the remarkable occurrence of carbon deposition from the CO. On the other hand, the addition of small amounts of CO 2 and H 2 O, which are always included in actual coal-derived fuel gas, to the syngas improves the activity of the Limonite, and conversions of NH 3 –N 2 at 750 and 850 °C become about 65% and almost 100% without carbon deposition, respectively. When several Limonite-based catalysts with alkali metal and alkaline earth metal cations are prepared by the impregnation method and then used in the NH 3 decomposition at 750 °C in 50% CO/25% H 2 /5% CO 2 /3% H 2 O, fine particles of MgO derived from Mg cations can work more effectively as the promoter, and the 3 mass% Mg-added Limonite maintains the high and stable NH 3 conversion of almost 100% for 25 h. In this case, no significant carbon deposition takes place. It is probable that MgO with strong basicity suppresses the carbon formation from CO, and that the Limonite-based composite catalyst thus shows the superior performance in the decomposition of NH 3 in syngas-rich fuel gas that simulates product gas in O 2 -blown coal gasification.
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Catalytic decomposition of pyridine gas with fine particles of metallic iron formed from Limonite
Applied Catalysis A: General, 2015Co-Authors: Naoto Tsubouchi, Ayumu Ogawa, Yuuki MochizukiAbstract:Abstract Catalytic decomposition of 100 ppmv pyridine (C 5 H 5 N) with an Australian Limonite ore, composed mainly of goethite (α-FeOOH), has been examined for hot gas cleanup with a fixed-bed quartz reactor at 300–500 °C under a large space velocity of 51,000 h −1 . When α-FeOOH in the Limonite is reduced with pure H 2 at 500 °C, the transformation into nanoscale particles of metallic iron (α-Fe) occurs, and the catalyst achieves almost complete C 5 H 5 N decomposition in inert He at 500 °C and provides an N 2 yield greater than 80% for at least 10 h. The Limonite also exhibits a high catalytic activity at 500 °C, even without H 2 reduction. Based on the results of N 1s X-ray photoelectron spectroscopy and temperature-programmed desorption measurements, it is probable that the Limonite-catalyzed formation of N 2 from pyridine proceeds through cycle mechanisms involving α-Fe and iron nitride species.
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catalytic performance of Limonite in the decomposition of ammonia in the coexistence of typical fuel gas components produced in an air blown coal gasification process
Energy & Fuels, 2007Co-Authors: Naoto Tsubouchi, Hiroyuki Hashimoto, Yasuo OhtsukaAbstract:Catalytic decomposition of 2000 ppm NH 3 in different atmospheres with an Australian α-FeOOH-rich Limonite ore at 750-950 °C under a high space velocity of 45000 h-1 has been studied with a cylindrical quartz reactor to develop a novel hot gas cleanup method of removing NH 3 from fuel gas produced in an air-blown coal gasification process for an integrated gasification combined cycle (IGCC) technology. The Limonite shows very high catalytic activity for the decomposition of NH 3 diluted with inert gas at 750 °C, regardless of whether the catalyst material is subjected to H 2 reduction before the reaction or not. Conversion of NH 3 to N 2 over the reduced Limonite reaches ≥99% at 750-950 °C, and the catalyst maintains the high performance for about 40 h at 750 °C. When the decomposition reaction is carried out in the presence of fuel gas components, the coexistence of syngas (20% CO/10% H 2 ) causes not only the serious deactivation of the Limonite catalyst but also the appreciable formation of deposited carbon and CO 2 . On the other hand, the addition of 10% CO 2 or 3% H 2 O to the syngas improves the catalytic performance and concurrently suppresses the carbon deposition almost completely, and the NH 3 conversion in the 3% H 2 O-containing syngas reaches about 90% and almost 100% at 750 and 850 °C, respectively. Influential factors controlling the catalytic activity of the Limonite ore in the coexistence of fuel gas components are discussed on the basis of the results of the powder X-ray diffraction measurements, thermodynamic calculations, and some model experiments.
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Sulfur tolerance of an inexpensive Limonite catalyst for high temperature decomposition of ammonia
Powder Technology, 2007Co-Authors: Naoto Tsubouchi, Hiroyuki Hashimoto, Yasuo OhtsukaAbstract:Abstract Catalytic performance of Limonite in the decomposition of 2000 ppm NH 3 in the presence of a small concentration of H 2 S has been studied with a cylindrical quartz reactor at a high space velocity of 45000 h − 1 to examine the sulfur tolerance of the Limonite catalyst. It is not poisoned apparently by 50–500 ppm H 2 S at 750 °C, but the remarkable sulfur poisoning is observed at 2000 ppm H 2 S. In the coexistence of 100 ppm H 2 S, conversion of NH 3 to N 2 decreases gradually with time after 10 h at 650 °C, whereas the Limonite maintains the high conversion of almost 100% for 50 h at 750 °C. The SEM-EDX measurements after reaction show that the surface composition at 750 °C is richer in metallic Fe, which may be produced by the reaction of NH 3 and/or H 2 with FeS formed. Commercially-available FeS promotes the decomposition of NH 3 diluted with inert gas at 750 °C, and the FeS is partly transformed into H 2 S and α-Fe in this process. Possible mechanisms for the decomposition of NH 3 in the presence of H 2 S with the Limonite are discussed on the basis of the results of some model experiments.
Shin Ichi Ohira - One of the best experts on this subject based on the ideXlab platform.
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Sulfurized Limonite as material for fast decomposition of organic compounds by heterogeneous Fenton reaction.
Journal of Hazardous Materials, 2014Co-Authors: Kei Toda, Yutaka Tsuda, Masahiro Ban, Edwin P. Koveke, Toshinori Tanaka, Michio Koinuma, Shin Ichi OhiraAbstract:Abstract Rapid decomposition of wastewater contaminants using sulfurized Limonite (S-Limonite) was investigated. Limonite is used for desulfurization of biogases, and S-Limonite is obtained from desulfurization plants as solid waste. In this work, the profitable use of S-Limonite in water treatment was examined. The divalent Fe in S-Limonite was expected to produce OH radicals, as Fe 2+ ions and Limonite thermally treated with H 2 do. Methylene blue was used for batch-wise monitoring of the decomposition performance. The decomposition rate was fast and the methylene blue solution color disappeared in only 10 s when a small amount of H 2 O 2 was added (1 mM in the sample solution) in the presence of S-Limonite. The OH radicals were formed by a heterogeneous reaction on the S-Limonite surface and Fenton reaction with dissolved Fe 2+ . The decomposition of pentachlorophenol was also examined; it was successfully decomposed in batch-wise tests. The surfaces of Limonite before sulfurization, S-Limonite, and S-Limonite after use for water treatment were performed using scanning electron microscopy and X-ray photoelectron spectroscopy. The results show that S-Limonite reverted to Limonite after being used for water treatment.
Hiroyuki Hashimoto - One of the best experts on this subject based on the ideXlab platform.
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high catalytic performance of magnesium cations added Limonite in the decomposition of ammonia in a simulated syngas rich fuel gas
Journal of Molecular Catalysis A-chemical, 2015Co-Authors: Naoto Tsubouchi, Hiroyuki Hashimoto, Yasuo OhtsukaAbstract:Abstract Catalytic decomposition of 2000 ppm NH 3 with an Australian Limonite ore, which is composed mostly of goethite (α-FeOOH), has been studied from a viewpoint of hot gas cleanup with a vertical, cylindrical quartz reactor at 750–850 °C under a high space velocity of 45,000 h −1 . It has already been reported that the Limonite achieves the almost complete decomposition of NH 3 in inert He at 500 °C and shows very stable performance in the reaction at 750 °C in the coexistence of 50–500 ppm H 2 S or at 850 °C in the presence of fuel gas components produced in an air-blown coal gasification process. In the coexistence of a high concentration of syngas (50% CO/25% H 2 ) produced with an O 2 -blown coal gasifier, the Limonite is deactivated almost completely because of the remarkable occurrence of carbon deposition from the CO. On the other hand, the addition of small amounts of CO 2 and H 2 O, which are always included in actual coal-derived fuel gas, to the syngas improves the activity of the Limonite, and conversions of NH 3 –N 2 at 750 and 850 °C become about 65% and almost 100% without carbon deposition, respectively. When several Limonite-based catalysts with alkali metal and alkaline earth metal cations are prepared by the impregnation method and then used in the NH 3 decomposition at 750 °C in 50% CO/25% H 2 /5% CO 2 /3% H 2 O, fine particles of MgO derived from Mg cations can work more effectively as the promoter, and the 3 mass% Mg-added Limonite maintains the high and stable NH 3 conversion of almost 100% for 25 h. In this case, no significant carbon deposition takes place. It is probable that MgO with strong basicity suppresses the carbon formation from CO, and that the Limonite-based composite catalyst thus shows the superior performance in the decomposition of NH 3 in syngas-rich fuel gas that simulates product gas in O 2 -blown coal gasification.
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catalytic performance of Limonite in the decomposition of ammonia in the coexistence of typical fuel gas components produced in an air blown coal gasification process
Energy & Fuels, 2007Co-Authors: Naoto Tsubouchi, Hiroyuki Hashimoto, Yasuo OhtsukaAbstract:Catalytic decomposition of 2000 ppm NH 3 in different atmospheres with an Australian α-FeOOH-rich Limonite ore at 750-950 °C under a high space velocity of 45000 h-1 has been studied with a cylindrical quartz reactor to develop a novel hot gas cleanup method of removing NH 3 from fuel gas produced in an air-blown coal gasification process for an integrated gasification combined cycle (IGCC) technology. The Limonite shows very high catalytic activity for the decomposition of NH 3 diluted with inert gas at 750 °C, regardless of whether the catalyst material is subjected to H 2 reduction before the reaction or not. Conversion of NH 3 to N 2 over the reduced Limonite reaches ≥99% at 750-950 °C, and the catalyst maintains the high performance for about 40 h at 750 °C. When the decomposition reaction is carried out in the presence of fuel gas components, the coexistence of syngas (20% CO/10% H 2 ) causes not only the serious deactivation of the Limonite catalyst but also the appreciable formation of deposited carbon and CO 2 . On the other hand, the addition of 10% CO 2 or 3% H 2 O to the syngas improves the catalytic performance and concurrently suppresses the carbon deposition almost completely, and the NH 3 conversion in the 3% H 2 O-containing syngas reaches about 90% and almost 100% at 750 and 850 °C, respectively. Influential factors controlling the catalytic activity of the Limonite ore in the coexistence of fuel gas components are discussed on the basis of the results of the powder X-ray diffraction measurements, thermodynamic calculations, and some model experiments.
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Sulfur tolerance of an inexpensive Limonite catalyst for high temperature decomposition of ammonia
Powder Technology, 2007Co-Authors: Naoto Tsubouchi, Hiroyuki Hashimoto, Yasuo OhtsukaAbstract:Abstract Catalytic performance of Limonite in the decomposition of 2000 ppm NH 3 in the presence of a small concentration of H 2 S has been studied with a cylindrical quartz reactor at a high space velocity of 45000 h − 1 to examine the sulfur tolerance of the Limonite catalyst. It is not poisoned apparently by 50–500 ppm H 2 S at 750 °C, but the remarkable sulfur poisoning is observed at 2000 ppm H 2 S. In the coexistence of 100 ppm H 2 S, conversion of NH 3 to N 2 decreases gradually with time after 10 h at 650 °C, whereas the Limonite maintains the high conversion of almost 100% for 50 h at 750 °C. The SEM-EDX measurements after reaction show that the surface composition at 750 °C is richer in metallic Fe, which may be produced by the reaction of NH 3 and/or H 2 with FeS formed. Commercially-available FeS promotes the decomposition of NH 3 diluted with inert gas at 750 °C, and the FeS is partly transformed into H 2 S and α-Fe in this process. Possible mechanisms for the decomposition of NH 3 in the presence of H 2 S with the Limonite are discussed on the basis of the results of some model experiments.
Kei Toda - One of the best experts on this subject based on the ideXlab platform.
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Sulfurized Limonite as material for fast decomposition of organic compounds by heterogeneous Fenton reaction.
Journal of Hazardous Materials, 2014Co-Authors: Kei Toda, Yutaka Tsuda, Masahiro Ban, Edwin P. Koveke, Toshinori Tanaka, Michio Koinuma, Shin Ichi OhiraAbstract:Abstract Rapid decomposition of wastewater contaminants using sulfurized Limonite (S-Limonite) was investigated. Limonite is used for desulfurization of biogases, and S-Limonite is obtained from desulfurization plants as solid waste. In this work, the profitable use of S-Limonite in water treatment was examined. The divalent Fe in S-Limonite was expected to produce OH radicals, as Fe 2+ ions and Limonite thermally treated with H 2 do. Methylene blue was used for batch-wise monitoring of the decomposition performance. The decomposition rate was fast and the methylene blue solution color disappeared in only 10 s when a small amount of H 2 O 2 was added (1 mM in the sample solution) in the presence of S-Limonite. The OH radicals were formed by a heterogeneous reaction on the S-Limonite surface and Fenton reaction with dissolved Fe 2+ . The decomposition of pentachlorophenol was also examined; it was successfully decomposed in batch-wise tests. The surfaces of Limonite before sulfurization, S-Limonite, and S-Limonite after use for water treatment were performed using scanning electron microscopy and X-ray photoelectron spectroscopy. The results show that S-Limonite reverted to Limonite after being used for water treatment.