Synthesis of ethanol via methanol homologation with CO2 and H2 using an industrially relevant Ru–Co catalyst

Abstract

Homogeneously catalyzed ethanol synthesis from CO₂ and H₂ usually uses expensive, unstable and complex catalyst precursors, hindering their industrial viability. In this work, a homogeneous catalytic system consisting of economic and stable catalyst precursors (RuCl₃·3H₂O and CoCl₂·6H₂O), cocatalyst (LiI) and N-ethyl-2-pyrrolidone (NEP) solvent was designed to accelerate ethanol production via methanol homologation with CO₂ and H₂. After activation of the catalyst precursors at 200 °C with CO, the target reaction could proceed efficiently under mild conditions (170 °C), with top level reaction selectivity (64.9%) and much higher space time yield (STY) of ethanol (3.9 g L⁻¹ h⁻¹) compared to previous reports with Ru/Co catalysts. The impact of activation conditions, reaction conditions, and the catalytic mechanism of the reaction were studied by a series of control experiments. This method of ethanol production has the advantages of a stable and easily available catalyst, excellent performance, and easy separation and recycling of the catalyst, showing great potential for industrialization.