Synthesis of ethanol from paraformaldehyde, CO₂ and H₂

Ethanol is an important bulk chemical and alternative fuel that is currently synthesized by catalytic hydration of ethylene or fermentation of foods. CO₂ is a cheap and renewable carbon resource. Transformation of CO₂ into useful chemicals is an interesting topic in green chemistry. Production of ethanol using CO₂ and H₂ is a promising route, but the efficiency of the reaction is not satisfactory. In this paper, we propose a protocol to synthesize ethanol from paraformaldehyde, CO₂ and H₂. The reaction could be efficiently accelerated by a Ru-Co bimetallic catalyst using LiI as the promoter in 1,3-dimethyl-2-imidazolidinone (DMI) under mild conditions. The selectivity of ethanol in total products reached 50.9 C-mol%, which was obviously higher than that of the reported routes. Furthermore, the TOF of ethanol based on Ru metal was as high as 17.9 h^-1. To our knowledge, this is the first report on ethanol synthesis from paraformaldehyde, CO₂ and H₂. A detailed study indicated that the outstanding results of the reaction originated from the synergy of paraformaldehyde hydrogenation, reverse water gas shift reaction and methanol homologation.