Investigation of Al precursor for ethanol synthesis from syngas on Cu-based multifunctional catalyst

The use of cheap Cu-based catalyst to directly synthesize ethanol and higher alcohols from syngas has been favored by researchers. However, the role of Al-based components and carbon chain growth are still unclear. Herein, a series of Cu-based multifunctional catalysts prepared by various Al precursors using complete liquid phase method are investigated for ethanol and higher alcohols synthesis. It is found that the catalysts using aluminium isopropoxide and Al2O3 as the Al precursor exhibit comparable activity with about 20% of CO conversion, 27% of ROH selectivity and >50% of C2+OH selectivity. Results show that different Al precursors can simultaneously adjust the ratios of Cu+/(Cu++Cu0) and the amount of weak acid on catalyst surface, thus leading to various concentration of CHn*/CHxO* on catalyst surface. In-situ DRIFT experiment indicates that a strong intensity of bridge-adsorbed of CO occurs over slurry ternary CuZnAl catalysts, which facilitates the cleavage of C???O bond and consequently favors the formation of CHn* key intermediates. Moreover, we have found that the carbon chain growth can be proceeded by the C-C coupling of CHn* and CHxO*, or via CO* insert into CHn* to form CHnCHxO*/CHnCO* which is further hydrogenated to form ethanol and higher alcohols.

Automated summary

The use of cheap Cu-based catalyst for ethanol and higher alcohols synthesis from syngas has gained popularity among researchers. However, the role of Al-based components and carbon chain growth is still unclear. In this study, Cu-based catalysts prepared using various Al precursors were investigated for their activity in ethanol and higher alcohols synthesis. The results showed that catalysts prepared with aluminium isopropoxide and Al2O3 as the Al precursor exhibited comparable activity, with significant CO conversion and selectivity towards target products. The study also revealed that different Al precursors could modify the catalyst surface and influence the concentration of key intermediates involved in carbon chain growth.