Selective transformation of carbon dioxide into lower olefins with a bifunctional catalyst composed of ZnGa2O4 and SAPO-34

Article link: Chem. Commum. 2018, 54, 140-143.

The transformation of CO₂ into lower olefins is an attractive reaction for efficient utilization of CO₂ as a renewable feedstock for synthesis of key building-block chemicals. Despite tremendous efforts based on modified Fischer-Tropsch synthesis catalysts, the selectivity of lower olefins from CO₂ is typically lower than 60%. In this article, we report a bifunctional catalyst composed of ZnGa₂O₄ with spinel structure and molecular sieve SAPO-34, which successfully bridges the conversions of CO₂ to methanol and methanol to olefins. The selectivity of lower olefins reaches 86% with a CO₂ conversion of 13% at 370 ºC. We have demonstrated that the oxygen vacancy sites on ZnGa₂O₄ surfaces function for the activation and conversion of CO₂ into methanol/dimethyl ether, which are subsequently converted to lower olefins by SAPO-34. The coupling of CO₂-to-methanol with methanol-to-olefin not only drives the conversion of CO₂ but also suppresses the undesirable reversed water-gas-shift reaction. We have demonstrated that the reaction coupling is a promising methodology not only for selectivity control in converting syngas into hydrocarbon fuels, lower olefins and aromatics, but also for CO₂ conversion.

This work was mainly performed  by Liu Xiaoliang and Wang Mengheng. The Cover image was invited by the Editor because of the very positive comments from the reviewers and the high evaluation of the Editorial office. Zhou Cheng designed the graphical abstract and cover. This work was supported by Shell Global Solutions International B.V., the National Key Research and Development Program of the Ministry of Science and Technology (No. 2017YFB0602201), and the National Natural Science Foundation of China (No. 91545203, 21673188, 21503174, 21433008 and 21403177).

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