Al2O3-CeO2 supports containing 1-10 wt%Ce were prepared mechanochemically by milling aluminum and/or cerium nitrates with NH4HCO3.Heteropolymolybdate,（NH4）4NiMo6O（24）,was used as the precursor of the Ni and Mo to ...Al2O3-CeO2 supports containing 1-10 wt%Ce were prepared mechanochemically by milling aluminum and/or cerium nitrates with NH4HCO3.Heteropolymolybdate,（NH4）4NiMo6O（24）,was used as the precursor of the Ni and Mo to prepare NiMo6/Al2O3-CeO2 components in catalysts by impregnation method.The physicochemical properties of the catalysts were determined using chemical analysis,X-ray diffraction,temperature-programmed H2 reduction,temperature-programmed NH3 desorption,X-ray photoelectron spectroscopy（XPS）,and the Brunauer-Emmett-Teller method.The catalyst acidity decreased with increasing Ce concentration in the support.XPS showed that the NiS/MoS ratio decreased two-fold for the Ce-modified alumina support.NiMo6/Al2O3,which had the highest acidity,showed the highest activity in hydrodesulfurization of 1-benzothiophene（normalized per weight of catalyst）.The concentration of surface MoOxSy species（which is equal to the concentration of Mo^（5＋）） gradually decreased to zero for catalysts with Ce concentrations 10 wt%.However,the activities of all the catalysts prepared mechanochemically from Al2O3 and Al2O3-CeO2supports significantly exceeded that of a reference NiMo6/Al2O3 catalyst prepared by impregnation method using the same precursor and with the same composition.展开更多
In reverse water gas shift （RWGS） reaction COa is converted to CO which in turn can be used to pro- duce beneficial chemicals such as methanol. In the present study, Mo/AlaO3, Fe/AlaO3 and Fe-Mo/Al2O3 catalysts were...In reverse water gas shift （RWGS） reaction COa is converted to CO which in turn can be used to pro- duce beneficial chemicals such as methanol. In the present study, Mo/AlaO3, Fe/AlaO3 and Fe-Mo/Al2O3 catalysts were synthesised using impregnation method. The structures of catalysts were studied using X-ray diffraction （XRD）, Brunauer-Emmett-Teller （BET） method, inductively coupled plasma atomic emission spectrometer （ICP-AES）, temperature programmed reduction （H2-TPR）, CO chemisorption, energy dispersive X-ray （EDX） and scanning electron microscopy （SEM） techniques. Kinetic properties of all catalysts were investigated in a batch re- actor for RWGS reaction. The results indicated that Mo existence in structure of Fe-Mo/AlzO3 catalyst enhances its activity as compared to Fe/AlaO3. This enhancement is probably due to better Fe dispersion and smaller particle size of Fe species. Stability test of Fe-Mo/AlzO3 catalyst was carried out in a fixed bed reactor and a high CO yield for 60 h of time on stream was demonstrated. Fez（MoO4）3 phase was found in the structures of fresh and used catalysts. TPR results also indicate that Fez（MoO4）3 phase has low reducibility, therefore the Fe2（MoO4）3 phase significantly inhibits the reduction of the remaining Fe oxides in the catalyst, resulted in high stability of Fe-Mo/Al2O3 catalyst. Overall, this study introduces Fe-Mo/Al2O3 as a novel catalyst with high CO yield, almost no by-products and fairly stable for RWGS reaction.展开更多
基金Czech Science Foundation(Project P106/11/0902) for financial support
文摘Al2O3-CeO2 supports containing 1-10 wt%Ce were prepared mechanochemically by milling aluminum and/or cerium nitrates with NH4HCO3.Heteropolymolybdate,（NH4）4NiMo6O（24）,was used as the precursor of the Ni and Mo to prepare NiMo6/Al2O3-CeO2 components in catalysts by impregnation method.The physicochemical properties of the catalysts were determined using chemical analysis,X-ray diffraction,temperature-programmed H2 reduction,temperature-programmed NH3 desorption,X-ray photoelectron spectroscopy（XPS）,and the Brunauer-Emmett-Teller method.The catalyst acidity decreased with increasing Ce concentration in the support.XPS showed that the NiS/MoS ratio decreased two-fold for the Ce-modified alumina support.NiMo6/Al2O3,which had the highest acidity,showed the highest activity in hydrodesulfurization of 1-benzothiophene（normalized per weight of catalyst）.The concentration of surface MoOxSy species（which is equal to the concentration of Mo^（5＋）） gradually decreased to zero for catalysts with Ce concentrations 10 wt%.However,the activities of all the catalysts prepared mechanochemically from Al2O3 and Al2O3-CeO2supports significantly exceeded that of a reference NiMo6/Al2O3 catalyst prepared by impregnation method using the same precursor and with the same composition.
基金Supported by the Iranian Nano Technology Initiative Council and Petroleum University of Technology
文摘In reverse water gas shift （RWGS） reaction COa is converted to CO which in turn can be used to pro- duce beneficial chemicals such as methanol. In the present study, Mo/AlaO3, Fe/AlaO3 and Fe-Mo/Al2O3 catalysts were synthesised using impregnation method. The structures of catalysts were studied using X-ray diffraction （XRD）, Brunauer-Emmett-Teller （BET） method, inductively coupled plasma atomic emission spectrometer （ICP-AES）, temperature programmed reduction （H2-TPR）, CO chemisorption, energy dispersive X-ray （EDX） and scanning electron microscopy （SEM） techniques. Kinetic properties of all catalysts were investigated in a batch re- actor for RWGS reaction. The results indicated that Mo existence in structure of Fe-Mo/AlzO3 catalyst enhances its activity as compared to Fe/AlaO3. This enhancement is probably due to better Fe dispersion and smaller particle size of Fe species. Stability test of Fe-Mo/AlzO3 catalyst was carried out in a fixed bed reactor and a high CO yield for 60 h of time on stream was demonstrated. Fez（MoO4）3 phase was found in the structures of fresh and used catalysts. TPR results also indicate that Fez（MoO4）3 phase has low reducibility, therefore the Fe2（MoO4）3 phase significantly inhibits the reduction of the remaining Fe oxides in the catalyst, resulted in high stability of Fe-Mo/Al2O3 catalyst. Overall, this study introduces Fe-Mo/Al2O3 as a novel catalyst with high CO yield, almost no by-products and fairly stable for RWGS reaction.
