Catalytic properties of Ag promoted ZnO/Al2O3 catalysts for hydrogen production by steam reforming of ethanol

Ag promoted ZnO/Al2O3 catalysts were prepared by using the incipient wetness impregnation method. The catalytic properties of steam reforming reaction for hydrogen production on the prepared catalysts were evaluated with H2O:C2H5OH molar ratios of 3:1 at 450 °C and atmospheric pressure. Ag promoted ZnO/Al2O3 catalysts show higher SRE catalytic activity than ZnO/Al2O3 catalysts. H2 and CH3CHO are the major products on Ag promoted catalysts, and C2H4 is also produced probably due to acid sites on Al2O3. SRE mechanism on Ag promoted ZnO/Al2O3 catalysts, which contains C–C scission, is different from that on ZnO/Al2O3 catalysts. A method based on thermogravimetry (TG), differential scanning calorimetry (DSC) and mass spectrometry (MS) was used to analysis the coking behavior on catalyst surface. The surfaces of Ag promoted ZnO/Al2O3 catalysts show two different types of coking, and suffer higher coke deposition during the steam reforming reaction.