CO hydrogenation to higher alcohols over CuZnAl catalysts without promoters: Effect of pH value in catalyst preparation

CO hydrogenation to higher alcohols (C2+ OH) was examined in a slurry bed reactor. CuZnAl samples without promoters were prepared by a complete liquid-phase method at different pH value (pH = 7-10), with the aim of studying the influence of pH value on the catalytic performance in this catalytic reaction. The pH value had significantly influence on the Cu-0 crystallite size, the amount of reducible Cu+, surface Cu/Zn atomic ratios and the acidity, which led to the diverse activities toward C-2 (+) OH synthesis. Characterization results showed that relatively larger crystallite size of Cu-0 and a suitable amount of acid sites was beneficial to the formation of C-2 (+) OH. Activity results indicated that the sample prepared at pH = 8 exhibited the best catalytic performance compared with other samples. In addition, the catalytic performance of pH = 8 sample showed that increasing temperature favored to the formation of C-2 (+) OH.