Catalytic Hydrogenation of Cyclic Carbonates: A Practical Approach from CO2 and Epoxides to Methanol and Diols

摘要

As an economical, safe and renewable carbon resource, CO2 turns out to be an attractive Q building block for making organic chemicals, materials, and carbohydrates. From the viewpoint of synthetic chemistry,' the utilization of CO2 as a feedstock for the production of industrial products may be an option for the recycling of carbon. On the other hand, the transformation of chemically stable CO2 represents a grand challenge in exploring new concepts and opportunities for the academic and industrial development of catalytic processes. The catalytic hydrogenation of CO2 to produce liquid fuels such as formic acid (HCO2H) or methanol is a promising solution to emerging global energy problems. Methanol, in particular, is not only one of the most versatile and popular chemical commodities in the world, with an estimated global demand of around 48 million metric tons in 2010, but is also considered as the key to weaning the world off oil in the future. Although the production of methanol has already been industrialized by the hydrogenation of CO with a copper/zinc-based heterogeneous catalyst at high temperatures (250-300 °C) and high pressures (50-100 atm), the development of a practical catalytic system for the hydrogenation of CO2 into methanol still remains a challenge, as high activation energy barriers have to be overcome for the cleavage of the C=0 bonds of CO2, albeit with favorable thermodynamics.'81 Heterogeneous catalysis for the hydrogenation of CO2 into CH3OH has been extensively investigated, and Cu/Zn-based multi-component catalyst was found to be highly selective with a long life, but under relatively harsh reaction conditions (250 °C, 50 atm). Therefore, the production of methanol from CO2 by direct hydrogenation under mild conditions is still a great challenge for both academia and industry.