ZrO₂ On Cu/ZrO₂ Catalysts Modified And Affect The Performance Of Steam Reforming Of Methanol

The steam reforming of methanol is widely used in fuel cells and other fields, hence has been attracting more and more attentions, In the present work, the Cu/ZrO2 catalyst was used in the steam reforming of methanol reaction to produce hydrogen, at relatively low temperatures and pressures, in which the conversion of methanol was close to 100%, and carbon monoxide content lower than 1.5%. The effects of preparation methods, promoters such as ZrO2 or Ce4+ ions on the catalytic performance as well as stability of Cu/ZrO2 were investigated in details. The main results obtained are shown as follows:1. The xCu/yZrO2 catalysts were prepared by two kinds of different methods, furthermore, the effects of preparation methods and the loadings of ZrO2 on the catalytic activities were investigated, the results show that, at the same reaction condition (Reaction temperature:483K?503K?523K, Reaction pressure:0.1Mpa), Cu/ZrO2 prepared by the fractionated precipitation method displayed the highest catalytic activity and stability with the lower content of CO and no production of CH4.2. The adsorption and reaction mechanisms over xCu/yZrO2 catalyst show that the Cu+ species and the surface oxygen vacancy over Cu/ZrO2 had a great influence on further decomposition for adsorbed methanol. At the same time, the spillover effect been copper and zirconia not only stabilizes Cu+ species, but also promotes the dehydrogenation of adsorbed methanol, hence accelerates activation and decomposition of adsorbed methanol.3. The effect of Ce4+ ion doping on the structure, catalytic performance and stability of CU/ZrO2 shows that the catalytic activity was enhanced because of the increased specific surface area with the introduction of Ce4+ions. Furthermore, CeO2 loadings had a significant influence on the activity of catalysts. When the mass fraction of CeO2 is 5%, the activity of catalysts was highest.The changed structure induced from ZrO2 permeating into CeO2 crystal cell can improve the oxygen storage capacity of CeO2, the dispersion of CuO, and augment the interface between copper and zirconia, and then promotes the catalytic activity. The results of reaction stability show that the methanol conversion was maintained at the level of more than 95% with uninterrupted operation for 24 h.