Upgrading the performance of syngas to ethanol via Mn modified Rh-based catalyst

Abstract

Significant strides have been undertaken to catalyze the production of ethanol from syngas, yet the challenge remains in developing catalysts that simultaneously exhibit high activity and selectivity. In this study, we designed a high-performance Rh-Mn catalyst. The CO conversion of finally screened 1Rh1Mn/TiO₂ catalyst is 51.8 %, and the total alcohol selectivity and ethanol yield are 72.1 % and 24.1 % respectively. This is the highest ethanol yield reported to date for Rh-based catalysts. Additionally, this catalyst also kept good stability. The outstanding performance is attributed to the fact that Mn facilitates the formation of Rh⁺ active sites, the process of CO insertion, and the generation of CH₃CHO and CH₃CO species—critical intermediates in ethanol production. In contrast, the unpromoted 1Rh/TiO₂ catalyst showed poor ethanol selectivity and mainly produced the Rh⁰ species, whereas the 1Rh1Mn/TiO₂ catalyst with the addition of Mn showed an increase in total alcohol and ethanol selectivity of 26.5 % and 31.3 %, respectively, as well as a reduction in CO₂ of 50.4 %. In addition, we elucidated the CO₂ generation and conversion pathways in the syngas to ethanol process, which is important for the effective utilization of carbon resources.