New progress achieved in the catalytic hydrogenation of carbon dioxide to produce isomer alkanes

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New progress made in the catalytic hydrogenation of CO2 to produce isoparaffins, Science Today, 2018-10-14 12:55:15 http://p1.pstatp.com/large/pgc-image/R6QNNe99djsnSg. Recently, the research teams led by Sun Jian and Ge Qingjie from the Institute of Carbon Resources, Small Molecules and Hydrogen Energy at the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, have made new advances in the field of catalytic hydrogenation of CO2 to produce isoparaffins; the relevant findings were published in ACS Catalysis, a journal issued by the American Chemical Society. Using CO2 as a carbon source and catalytically converting it into high-value hydrocarbon compounds together with H2 produced by the electrolysis of renewable energy sources can not only help reduce CO2 emissions but also address the over-reliance on fossil fuels as well as the storage issues associated with renewable energy, holding significant strategic importance. Precise control of C-O bond activation and C-C bond coupling are highly challenging issues in the hydrogenation conversion of CO2, and they are key to achieving efficient conversion and utilization of CO2. In recent years, by designing catalysts with multiple active sites, this team has achieved the direct conversion of CO2 via hydrogenation to produce gasoline-range hydrocarbons, linear α-olefins, and low-carbon olefins. In this work, the researchers combined Na-Fe3O4 and HMCM-22 molecular sieves to form a multifunctional catalyst, enabling efficient synergistic catalysis of three sequential reactions: reverse water-gas shift, C-C coupling, and isomerization. As a result, isoalkanes were successfully synthesized from CO2 and H2 in a single step with high yield. When the one-way conversion of CO2 is maintained at around 26%, the CO selectivity is only 17%; the selectivity for C4+ hydrocarbons among the hydrocarbons produced is 82%, with isoparaffins accounting for as much as 74% of them. The space-time yield can reach 105 mg iso per gcat-1h-1. Studies have shown that the unique pore structure and Brønsted acid properties of the MCM-22 molecular sieve promote the isomerization of olefin intermediates while suppressing aromatization reactions. In addition, this study also explores the formation process of heteroalkanes, the reasons for molecular sieve deactivation, the nature of carbon deposition, and molecular sieve regeneration methods. This work provides new insights into the design and application of catalysts for the hydrogenation of CO2 to produce high-carbon hydrocarbons. (Source: Science Network, Liu Wansheng, Wei Jian, Yao Ruwei)