Enhancement of aldehyde-water shift reaction over CuZnAl catalyst by Mn promoter

A series of Mn promoted CuZnAl catalysts were prepared by coprecipitation method. Doping of manganese in CuZnAl strongly enhanced the AWS activity and propionic acid selectivity. The interaction between Cu and Mn ions results in suppressed the hydrogenation of propanal to propyl alcohol and enhanced the selectivity of propionic acid. According to our results, the most favorable Mn/Cu molar ratio is 1:1. Higher temperature is also beneficial to the selectivity of propionic acid on CuZnAl-based catalysts. [Display omitted] •Doping of manganese in CuZnAl strongly raised AWS activity.•Mn-doping enhanced the selectivity of propionic acid.•A redox mechanism may be involved in heterogeneous AWS reaction.•High temperature is favor of propionic acid selectivity.