Studies on Au/Cu-Zn-Al catalyst for methanol synthesis from CO2

Abstract

Methanol synthesis from CO2 via gas phase hydrogenation was carried out on Au/Cu-Zn-Al catalysts. The base Cu-Zn-Al with different Cu contents was synthesized by rapid precipitation method and subsequently gold (0.5-3 wt.%) was deposited on the base Cu-Zn-Al by deposition-precipitation method. Solid catalysts investigated in this study were characterized by BET surface area, XRD, HR-TEM, XPS and CO2, CO and H2-TPD techniques. Formation of methanol in this study was influenced by the copper content in base Cu-Zn-Al and also on gold loading. Among the catalysts studied 1Au/C4ZA (1 wt.% Au deposited on Cu:Zn:Al = 4:1:1 mole ratio) exhibited maximum methanol yield of 16.6% mass. Among the catalysts studied the decreasing order of CO2 conversion is as follows: 1Au/C4ZA > 0.5Au/C4ZA > C4ZA > 3Au/C4ZA at GHSV 7000 h-1. The greater methanol yield on 1Au/C4ZA attributed to: (i) H2 spillover in Au-Cu-Zn-Al, (ii) higher adsorption capacities to H2 and CO at Cu-Au interface and (iii) Cu/Au ratio on the surface ∼5. To the best of our knowledge, this is the first report for gold influence on Cu-Zn-Al system in CO2 hydrogenation process.