湿混法制备甲醇氧化重整制氢CuZnAlZr催化剂

Oxidative steam reforming of methanol is an attractive technology for on-board production of hydrogen for fuel cell vehicles. In this work copper-zinc-aluminum- zirconium oxide catalysts (CuZnAlZr) were prepared by two different techniques, i.e. a simple wet-mixed method and the traditional co-precipitation method. The oxidative steam reforming of methanol reaction was performed over these catalysts in the range of temperature 225 ℃ to 275 ℃ at atmospheric pressure, using H2O/CH3OH molar ratio=3 and O2/CH3OH molar ratio=0.2. It was found that the wet-mixed catalyst shows almost the same activity as the co-precipitated catalyst at temperatures of 250 ℃～275 ℃, and lower activity at temperatures of 225 ℃~250 ℃. In addition, wet-mixed catalyst exhibits higher selectivity to CO2 than the co-precipitated catalyst. The physicochemical properties of the catalysts were investigated by X-ray diffraction (XRD), temperature-programmed reduction (TPR), thermal gravimetry and differential scanning calorimetry (TG-DSC), and surface area measurement (BET), the copper surface area was determined by N2O chemisorption. The results of the characterization reveales that in the wet-mixed catalyst, which had higher BET area than the co-precipitated catalyst, Cu species tends to move to the catalyst surface and the surface spinel specie, i.e., CuAl2O4 can be formed. Therefore the dispersion of copper and the surface area of Cu0 per gram of copper in the wet-mixed catalyst are higher than those of co-precipitated catalyst. The wet-mixed catalyst exhibits stable activity over 100h of on-stream operation at 275 ℃, the methanol conversion maintains over 90%, H2 concentration in the product gas is over 60% and the selectivity to CO2 approaches 99%.