THE EFFECT OF Al2O3, CeO2, AND ZrO2 ON THE PERFORMANCE OF Cu/ZnO CATALYST IN METHANOL SYNTHESIS FROM BIOMASS PYROLYSIS SYNGAS

Abstract

The effect of Al<sub>2</sub>O<sub>3</sub>, CeO<sub>2</sub>, and ZrO<sub>2</sub> 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 (S<sub>N</sub>) 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<sup>-1</sup>, and 24 h time on stream using simulated biomass pyrolysis syngas with a composition of 25% H<sub>2</sub>, 25% CO, 20% CH<sub>4</sub>, 20% CO<sub>2</sub>,10% N<sub>2</sub> (S<sub>N</sub> = 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 N<sub>2</sub> adsorption/desorption, Powder X-ray Diffraction (XRD), and Temperature Programmed Reduction of hydrogen (H<sub>2</sub>-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.