A series of Ce-Fe-Zr-O(x)/MgO(x denotes the mass fraction of Ce-Fe-Zr-O,x=10%,15%,20%,25%,30%) complex oxide oxygen carriers for selective oxidation of methane to synthesis gas were prepared by the co-precipitation me...A series of Ce-Fe-Zr-O(x)/MgO(x denotes the mass fraction of Ce-Fe-Zr-O,x=10%,15%,20%,25%,30%) complex oxide oxygen carriers for selective oxidation of methane to synthesis gas were prepared by the co-precipitation method.The catalysts were characterized by means of X-ray diffraction and H2-TPR.The XRD measurements showed that MgFeO4 particles were formed and Fe2O3 particles well dispersed on the oxygen carriers.The reactions between methane diluted by argon(10% CH4) and oxygen carriers were investigated.Suitable content of CeO2/Fe2O3/ZrO2 mixed oxides could promote the reaction between methane and oxygen carriers.There are mainly two kinds of oxygen of carriers:surface lattice oxygen which had higher activity but lower selectivity,and bulk lattice oxygen which had lower activity but higher selectivity.Among all the catalysts,Ce-Fe-Zr-O(20%)/MgO exhibited the best catalytic performance.The conversion of the methane was above 56%,and the selectivity of the H2 and CO were both above 93%,the ratio of H2/CO was stable and approached to 2 for a long time.展开更多
Two-step steam reforming of methane (SRM) is a novel chemical looping process towards the production of pure hydrogen and syngas (synthesis gas), consisting of a syngas production step and a water-splitting step. Rene...Two-step steam reforming of methane (SRM) is a novel chemical looping process towards the production of pure hydrogen and syngas (synthesis gas), consisting of a syngas production step and a water-splitting step. Renewable energy can be used to drive this process for hydrogen production, especially solar energy. CeO2-Fe2O3 complex oxide oxygen carrier was prepared by the impregnation method and characterized by means of X-ray diffractometer (XRD), Raman spectroscopy (Raman) and hydrogen programmed reduction (H2-TPR). CH4 temperature programmed and isothermal reactions were adopted to test syngas production reactivity, and water splitting reaction was employed to investigate water-splitting activity. Moreover, two-step SRM performance was evaluated by a successive redox cycle. The results showed that CO-uncontaminated H2 and highly selective syngas (with H2/CO ratio close to 2) could be respectively obtained from two steps, and CeFeO3 formation was found in the first redox cycle and proved to be enhanced by the redox treatment. After 10 successive cycles, obvious CeFeO3 phase was detected, which may be responsible for favorable successive redox cycle performances.展开更多
基金Project supported by the Natural Science Foundation (50774038,51004060)National Natural Science Foundation of Major Research Projects (90610035)+2 种基金Natural Science Foundation of Yunnan Province (2008E030M,2010ZC108)Research Fund for the Doctoral Program of Higher Education of China (20095314120005)Foundation of Kunming University of Science and Technology (KKZ3200927010)
文摘A series of Ce-Fe-Zr-O(x)/MgO(x denotes the mass fraction of Ce-Fe-Zr-O,x=10%,15%,20%,25%,30%) complex oxide oxygen carriers for selective oxidation of methane to synthesis gas were prepared by the co-precipitation method.The catalysts were characterized by means of X-ray diffraction and H2-TPR.The XRD measurements showed that MgFeO4 particles were formed and Fe2O3 particles well dispersed on the oxygen carriers.The reactions between methane diluted by argon(10% CH4) and oxygen carriers were investigated.Suitable content of CeO2/Fe2O3/ZrO2 mixed oxides could promote the reaction between methane and oxygen carriers.There are mainly two kinds of oxygen of carriers:surface lattice oxygen which had higher activity but lower selectivity,and bulk lattice oxygen which had lower activity but higher selectivity.Among all the catalysts,Ce-Fe-Zr-O(20%)/MgO exhibited the best catalytic performance.The conversion of the methane was above 56%,and the selectivity of the H2 and CO were both above 93%,the ratio of H2/CO was stable and approached to 2 for a long time.
基金Project support by the National Natural Science Foundation of China (50574046, 50774038)the Natural Science Foundation of Yunnan Prov-ince (2008E030M)+1 种基金the Research Fund for the Doctoral Program of Higher Education of China (20095314120005)2010 Innovation Fund of Kunming University of Science and Technology
文摘Two-step steam reforming of methane (SRM) is a novel chemical looping process towards the production of pure hydrogen and syngas (synthesis gas), consisting of a syngas production step and a water-splitting step. Renewable energy can be used to drive this process for hydrogen production, especially solar energy. CeO2-Fe2O3 complex oxide oxygen carrier was prepared by the impregnation method and characterized by means of X-ray diffractometer (XRD), Raman spectroscopy (Raman) and hydrogen programmed reduction (H2-TPR). CH4 temperature programmed and isothermal reactions were adopted to test syngas production reactivity, and water splitting reaction was employed to investigate water-splitting activity. Moreover, two-step SRM performance was evaluated by a successive redox cycle. The results showed that CO-uncontaminated H2 and highly selective syngas (with H2/CO ratio close to 2) could be respectively obtained from two steps, and CeFeO3 formation was found in the first redox cycle and proved to be enhanced by the redox treatment. After 10 successive cycles, obvious CeFeO3 phase was detected, which may be responsible for favorable successive redox cycle performances.
