Effect Of Preparation Conditions on the Characteristics and Activity Of Cu/ZnO/CeO2/Al2O3 Catalysts for Oxidative Steam Reforming Of Methanol

Abstract

The effect of preparation conditions on the performance of Cu/ZnO/CeO2/Al2O3 catalysts has been investigated in the present study for the selective production of hydrogen via oxidative steam reforming of methanol. Cu/ZnO/CeO2/Al2O3 catalyst of composition Cu:Zn/Ce/Al:30/20/10/40 wt%, has been prepared by co-precipitation method with varying preparation conditions like precipitation pH, precipitation temperature, precipitate ageing time and calcination temperature. The catalysts and precursors were characterised for their surface areas, pore volumes, scanning electron microscopy (SEM), X-ray diffraction (XRD) patterns, temperature programmed oxidation (TPO), CO chemisorptions and thermo gravimetric-differential thermal analysis (TG-DTA). The catalyst precursor prepared by precipitation at pH 7.0 mainly consisted of layered double hydroxide (LDH) and was more active. The ageing time also played an important role in the structure of catalyst and its activity. The catalyst precursors calcined at a temperature greater than 400°C resulted in the loss of copper dispersion due to sintering of copper crystallites. Hence, there was decline in the catalytic activity for OSRM. The catalytic activity has been tested as a function of reaction temperature 200-300°C at contact-time 11 kgcat s mol–1, steam to methanol molar ratio 1.5, oxygen to methanol molar ratio 0.15 and pressure 1 atm. The favourable preparation conditions for Cu/ZnO/CeO2/Al2O3 catalyst can be suggested as: precipitation temperature 70°C, pH 7.0, precipitate ageing time 2 h and calcination temperature 400°C.