Low-Temperature Reverse Water-Gas Shift Process and Transformation of Renewable Carbon Resources to Value-Added Chemicals

The use of CO2 instead of toxic CO in the production of important chemicals has attracted widespread interest, and the reverse water-gas shift reaction (RWGSR) is the key step for this kind of processes. Although the thermodynamic limitations are overcome by the reaction of CO with other compounds, the temperature of most reactions involving RWGSR is usually very high owing to the inertness of CO2. Herein, it was found that Ru-3(CO)(12) could catalyze the RWGSR in the ionic liquid HMimBF(4) without ligand or promoter, and CO could be produced at 80 degrees C, which was much lower than the temperatures reported to date. Detailed studies showed that the BF4- in the ionic liquid played a crucial role in the low-temperature RWGSR. Based on the low-temperature RWGSR, three important routes to transform CO2 into valuable chemicals were developed, including synthesis of xanthone from CO2 and diaryl ethers, synthesis of phenol and acetic acid from CO2 and anisole, and production of acetic acid from CO2 and lignin. The reactions could occur at temperature as low as 80 degrees C, and low-temperature RWGSR was essential for the reactions under mild conditions. The strategy opens the way to produce value-added chemicals by using CO2 and H-2 as feedstocks under low temperature.