The effects of ceria and zirconium oxides additions to alumina-supported palladium catalysts on methane combustion behavior were investigated. The structure and TPR/TPO properties were studied by XRD, TPR, TPO techniq...The effects of ceria and zirconium oxides additions to alumina-supported palladium catalysts on methane combustion behavior were investigated. The structure and TPR/TPO properties were studied by XRD, TPR, TPO techniques. The results show that the addition of Ce-Zr oxides improves the thermal stability of alumina and PdO. The Pd/Ce0.2Zr0.8/Al2O3 exhibits the highest activity and thermal stability for methane combustion.展开更多
The transition metals （Cu, Co, and Fe） were applied to modify Ni/Ce0.2Zr0.1Al0.7Oδ catalyst. The effects of transition metals on the catalytic properties of Ni/Ce0.2Zr0.1Al0.7Oδ autothermal reforming of methane we...The transition metals （Cu, Co, and Fe） were applied to modify Ni/Ce0.2Zr0.1Al0.7Oδ catalyst. The effects of transition metals on the catalytic properties of Ni/Ce0.2Zr0.1Al0.7Oδ autothermal reforming of methane were investigated. The Ni-supported catalysts were characterized by XRD, TPR and XPS. Tests in autothermal reforming of methane to hydrogen showed that the addition of transition metals （Cu and Co） significantly increased the activity of catalyst under the conditions of lower reaction temperature, and Ni/Cu0.05Ce0.2Zr0.1Al0.65Oδ was found to have the highest conversion of CH4 among all catalysts in the operation temperatures ranging from 923 K to 1023 K. TPR, XRD and XPS measurements indicated that the cubic phases of CexZr1-xO2 solid solution were formed in the preparation process of catalysts. Strong interaction was found to exist between NiO and CexZr1-xO2 solid solution. The addition of Cu improved the dispersion of NiO, inhibited the formation of NiAl2O4, and thus significantly promoted the activity of the catalyst Ni/Cu0.05Ce0.2Zr0.1Al0.65Oδ展开更多
Using SnxTi1-xO2 as carriers, CuO/Sn0.9Zi0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide （CuO） were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O...Using SnxTi1-xO2 as carriers, CuO/Sn0.9Zi0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide （CuO） were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Zi0.3O2 were examined using a microreactor-gas chromatography （GC） NO＋CO reaction system and the methods of BET （Brun- auer-Emmett-Teller）, TG-DTA （themogravimetric and differential thermal analysis）, X-ray diffraction （XRD） and H2-temperature programmed reduction （TPR）. The results showed that NO conversions of Sn0.9Zi0.1O2 and Sn0.7Ti0.3O2 were 47.2% and 43.6% respectively, which increased to 95.3% and 90.9% at 6 wt% CuO loading. However, further increase in CuO loading caused a decrease in the catalytic activity. The nitrogen adsorption-desorption isotherm and pore-size distribution curve of Sn0.9Zi0.1O2 and Sn0.7Ti0.3O2 represented type IV of the BDDT （Brunauer, Deming, Deming and Teller） system and a typical mesoporous sample. There were two CuO diffraction peaks （2θ 35.5° and 38.7°）, and the diffraction peak areas increased with increasing CuO loading. TPR analysis also detected three peaks （α, β and γ） from the CuO-loaded catalysts, suggesting that the α peak was the reduction of the highly dispersed copper oxide, the β peak was the reduction of the isolated copper oxide, and the y peak was the reduction of crystal phase copper oxide. In addition, a fourth peak （5） of the catalysts meant that the SnxTi1-xO2 mixed oxides could be reductive.展开更多
The relationship between the activity and the precursor phase composition of the molten iron catalyst for ammonia synthesis has been studied with high pressure testing equipment and XRD. A humped curve between the act...The relationship between the activity and the precursor phase composition of the molten iron catalyst for ammonia synthesis has been studied with high pressure testing equipment and XRD. A humped curve between the activity and Fe2+/Fe3+ has been obtained. It is found that the unicity of the iron oxidate phase in precursor is an essential condition of the high activity of the iron catalyst and that the uniform distribution of the adominant phase and the promoters is the key to preparing a catalyst with better performance The humped curve is interpreted using the ratio f of the phase compositions in precursor. A new idea has been obtained that the activity change of the molten iron catalyst depends essentially on the molecule ratio of the different iron oxidates in precursor under the certain promoters, and it is found that the FeO based catalyst for ammonia synthesis with Wustite phase structure (Fe1-xO, 0.04≤x≤0.10) has the highest activity of all the molten iron catalysts for ammonia synthesis.展开更多
文摘The effects of ceria and zirconium oxides additions to alumina-supported palladium catalysts on methane combustion behavior were investigated. The structure and TPR/TPO properties were studied by XRD, TPR, TPO techniques. The results show that the addition of Ce-Zr oxides improves the thermal stability of alumina and PdO. The Pd/Ce0.2Zr0.8/Al2O3 exhibits the highest activity and thermal stability for methane combustion.
基金This work was supported by Guangdong Natural Science Foundation of China (030514)Science and Technology Programs of Guangdong Province of China (2004B33401006)
文摘The transition metals （Cu, Co, and Fe） were applied to modify Ni/Ce0.2Zr0.1Al0.7Oδ catalyst. The effects of transition metals on the catalytic properties of Ni/Ce0.2Zr0.1Al0.7Oδ autothermal reforming of methane were investigated. The Ni-supported catalysts were characterized by XRD, TPR and XPS. Tests in autothermal reforming of methane to hydrogen showed that the addition of transition metals （Cu and Co） significantly increased the activity of catalyst under the conditions of lower reaction temperature, and Ni/Cu0.05Ce0.2Zr0.1Al0.65Oδ was found to have the highest conversion of CH4 among all catalysts in the operation temperatures ranging from 923 K to 1023 K. TPR, XRD and XPS measurements indicated that the cubic phases of CexZr1-xO2 solid solution were formed in the preparation process of catalysts. Strong interaction was found to exist between NiO and CexZr1-xO2 solid solution. The addition of Cu improved the dispersion of NiO, inhibited the formation of NiAl2O4, and thus significantly promoted the activity of the catalyst Ni/Cu0.05Ce0.2Zr0.1Al0.65Oδ
基金Project (No. Y504131) supported by the Natural Science Foundation of Zhejiang Province, China
文摘Using SnxTi1-xO2 as carriers, CuO/Sn0.9Zi0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide （CuO） were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Zi0.3O2 were examined using a microreactor-gas chromatography （GC） NO＋CO reaction system and the methods of BET （Brun- auer-Emmett-Teller）, TG-DTA （themogravimetric and differential thermal analysis）, X-ray diffraction （XRD） and H2-temperature programmed reduction （TPR）. The results showed that NO conversions of Sn0.9Zi0.1O2 and Sn0.7Ti0.3O2 were 47.2% and 43.6% respectively, which increased to 95.3% and 90.9% at 6 wt% CuO loading. However, further increase in CuO loading caused a decrease in the catalytic activity. The nitrogen adsorption-desorption isotherm and pore-size distribution curve of Sn0.9Zi0.1O2 and Sn0.7Ti0.3O2 represented type IV of the BDDT （Brunauer, Deming, Deming and Teller） system and a typical mesoporous sample. There were two CuO diffraction peaks （2θ 35.5° and 38.7°）, and the diffraction peak areas increased with increasing CuO loading. TPR analysis also detected three peaks （α, β and γ） from the CuO-loaded catalysts, suggesting that the α peak was the reduction of the highly dispersed copper oxide, the β peak was the reduction of the isolated copper oxide, and the y peak was the reduction of crystal phase copper oxide. In addition, a fourth peak （5） of the catalysts meant that the SnxTi1-xO2 mixed oxides could be reductive.
基金Project supported by the Provincial Natural Science Foundation of Zhejiang.
文摘The relationship between the activity and the precursor phase composition of the molten iron catalyst for ammonia synthesis has been studied with high pressure testing equipment and XRD. A humped curve between the activity and Fe2+/Fe3+ has been obtained. It is found that the unicity of the iron oxidate phase in precursor is an essential condition of the high activity of the iron catalyst and that the uniform distribution of the adominant phase and the promoters is the key to preparing a catalyst with better performance The humped curve is interpreted using the ratio f of the phase compositions in precursor. A new idea has been obtained that the activity change of the molten iron catalyst depends essentially on the molecule ratio of the different iron oxidates in precursor under the certain promoters, and it is found that the FeO based catalyst for ammonia synthesis with Wustite phase structure (Fe1-xO, 0.04≤x≤0.10) has the highest activity of all the molten iron catalysts for ammonia synthesis.
