Synthesis of ethanol from syngas over CuZnAl catalysts with different Cu/Zn/Al molar ratios in polyethylene glycol 600 medium

Abstract

CuZnAl catalysts with different molar ratios were prepared by a completely liquid-phase technology. Polyethylene glycol 600 (PEG600) was acted as the heat treatment and reaction medium. The activity evaluation of the catalyst with different molar ratios for CO hydrogenation was investigated in a slurry reactor, and the catalysts were characterized by XRD, XPS, H2-TPR, NH3-TPD-MS and BET. It was found that PEG600 adopted as heat treatment and reaction medium obviously improved ethanol selectivity over CuZnAl catalysts without any promoters. Moreover, the Cat-0.8 catalyst contained the lowest Al content showed the highest CO conversion and ethanol selectivity, reaching 33.49 and 35.49%. The characterization results showed that the Cat-0.8 could facilitate the synergistic action of Cu0 and Cu+, increase the weak acid sites and boost the average pore diameter, which favoring the improvement of ethanol selectivity. Moreover, the results showed that the stability of CuZnAl catalyst gradually improved with the increase of Al content. Further studies will provide a new way for ethanol synthesis from syngas with high selectivity and good stability.