Relay catalysis in the direct conversion of carbon dioxide to high-value chemicals

Abstract

Hydrogenation of CO2 using renewable hydrogen to build block chemicals, such as lower olefins and aromatics, not only mitigates the CO2 emissions, but also realizes the utilization of CO2 as a carbon resource. However, it is difficult to activate the inert CO2 and precisely control the C-C coupling. As a result, the hydrogenation of CO2 mainly produces C1 product, and selective synthesis of hydrocarbon chemicals with C-C chains is challenging. In 2016, Chinese scientists first reported the relay catalysis, in which metal oxides and acidic zeolites were integrated together as bifunctional catalysts, for converting synthesis gas to lower olefins and aromatics. Inspired by this, a number of bifunctional catalysts have been recently reported for the hydrogenation of CO2 to lower olefins and aromatics, using the concept of replay catalysis. In this review, we summarize the recent advances in the transformation of CO2 to high-value chemicals and try to clarify how to connect two reactions with different characteristics. The key factors that affect the product distribution are also discussed.