The effect of Al₂O₃, CeO₂, and ZrO₂ on the performance of Cu/ZnO catalyst in methanol synthesis from biomass pyrolysis syngas

The effect of Al2 O3 , CeO2 , and ZrO2 as promoters on the catalytic activity of a Cu/ZnO catalyst for methanol synthesis from biomass pyrolysis syngas was investigated. The catalysts were prepared using a coprecipitation method, with the wt.% ratio of Cu:Zn:M = 68:28:4 (M = Al, Ce, and Zr). The activity of the catalysts was tested to determine the most appropriate promoter for the Cu/ZnO catalyst to accommodate methanol production from low stoichiometric number (SN ) syngas. The experiment was performed in a continuous flow fixed bed reactor at 513 K, 4 MPa, gas hourly space velocity (GHSV) of 2000 h–1, and 24 h time on stream using simulated biomass pyrolysis syngas with a composition of 25% H2 , 25% CO, 20% CH4 , 20% CO2 , 10% N2 (SN = 0.111). The effluent gas was analyzed every 6 h using gas chromatography to determine the conversion of gases and production of hydrocarbons. The catalysts were characterized by N2 adsorption/desorption, Powder X-ray Diffraction (XRD), and Temperature Programmed Reduction of hydrogen (H2-TPR) techniques. It was found that the promoter in Cu/ZnO-based catalysts plays a crucial role in the methanol selectivity and catalysts stability, yet does not significantly affect feed conversion. Nevertheless, the findings will significantly contribute to developing a robust catalyst that can be used for a direct route for methanol production from biomass pyrolysis syngas.