A highly efficient ruthenium catalytic system for the direct synthesis of butanol from propylene and CO2: a low-temperature reverse water–gas shift route

Abstract

A catalytic system containing (Ru(CO)₃Cl₂)₂, LiCl, an ionic liquid and an organic base was reported, which could effectively promote the following processes: low-temperature reverse water–gas shift (RWGS) (at 100 °C), hydroformylation and hydrogenation of butyraldehyde to butanol, enabling the direct synthesis of butanol from propylene and CO₂. The possible catalytic mechanism and the role of each additive were proposed based on the detection of reactive intermediates, control experiments and theoretical calculations. The critical step in this transformation is achieving RWGS at low temperatures without using external reductants or dehydrating agents. Up to 99% conversion of propylene with 97% selectivity for butanol (n : i = 1.4) was achieved, which represents the highest yield to date. Meanwhile, the catalytic system could maintain a certain degree of stability during the recovery process. The results reported here may create a chance for the industrial application of the direct synthesis of butanol from propylene and CO₂.