Light-enabled coupling of tandem ethane dehydrogenation and CO2 hydrogenation

The integration of electromagnetic energy into a thermal reaction is beneficial in catalytic performance and product distribution. To date, such a photothermal strategy has mainly been applied to relatively low-temperature reactions, such as CO2 hydrogenation, and its application to high-temperature reactions has yet to be explored. Herein, electromagnetic energy is successfully introduced into a tandem ethane dehydrogenation and CO2 hydrogenation system over a Zn-based catalyst. According to the experiments and theoretical simulations, light enables a new reverse water-gas shift reaction, which consumes the produced H2 and thus right shifts the ethane dehydrogenation reaction and enhances the catalytic performance. The resulting ethylene rate could achieve 11.5 mmol g−1 h−1 with a selectivity of 96%, and the estimated external quantum efficiency is up to 18.85% under weak light intensity (2 sun). In the meantime, the ethylene rate could be improved by about 600-fold with higher light intensities. [Display omitted] •The isolated Zn species were prepared from the thermal treatment of decorated ZnO•The light enhancement of the ethylene rate is up to a 600-fold with high light intensity•The estimated quantum efficiency could reach 18.84% with 2 sun light intensity•The tandem catalytic system is responsible for the photoenhancement Dehydrogenating ethane into ethylene by consuming CO2 is an attractive strategy for synthesizing value-added products with decreased CO2 emissions. However, constructing a tandem catalytic system of ethane dehydrogenation and CO2 hydrogenation to consume the produced hydrogen and right shift the ethane dehydrogenation is challenging. Meanwhile, it has been shown that integrating light into a CO2 hydrogenation system could significantly improve the catalytic performance. Thus, shedding light on ethane dehydrogenation with CO2 could potentially enable a new strategy for constructing a tandem system that could improve ethane conversion and convert CO2 into valuable fuels. We have discovered that the isolated Zn-decorated SAPO-34 could take advantage of all aforementioned factors to enable the tandem ethane dehydrogenation and RWGS with a high quantum efficiency of 18.85%. This work has shown an excellent high-temperature photo-assisted isolated Zn-based zeolite catalyst on which light could promote surface hydrogen transfer and consume the hydrogen from ethane dehydrogenation (C2H6 → C2H4 + H2) with reverse water-gas shift (CO2 + H2 →