Ethanol synthesis via CO2 hydrogenation is of great importance in view of its high-value utilization. Herein, combining with heterogeneous and homogenous catalysis, we have developed an efficient biphasic Lewis-acid-base pairs synergistic catalysis strategy from CO2 hydrogenation. Apart from conventional heterogeneous ethanol synthesis route, it was surprisingly found that LiI homogenous promoter significantly enhanced CO2 conversion, ethanol selectivity, and productivity. LiI promoted CO2 dissolution in pure water and accelerated reaction intermediates consumption, favoring CO2 conversion. In detail, it can weaken C-O bond of CH3OH intermediate through Li+-I- Lewis-acid-base catalysis. The formed CH3I* with lower bond energy for C-I was more facile to dissociate into CH3*, favoring its subsequent coupling with CO* to form ethanol. In combination of Rh1/CeTiOx catalyst, LiI promoter, and methanol as solvent, a record-breaking ethanol yield was achieved (223.1 mmol·g−1·h−1). The obtained ethanol yield was about 18.7 times of that reported the best result in literatures. Especially, the established catalyst system could also be applied for synthesis of higher-carbon-number alcohols by the CO2 hydrogenation with other alcohols solvent (CnH2n+1OH, n = 2,3…).

中文翻译：

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碘化锂通过双相路易斯-酸-碱对协同催化促进 CO2 加氢向乙醇


鉴于其高价值利用率，通过 CO2 加氢合成乙醇非常重要。在此，结合非均相和均相催化，我们开发了一种来自 CO2 加氢的高效双相 Lewis-acid-base 对协同催化策略。除了传统的异质乙醇合成路线外，令人惊讶的是，LiI 均相启动子显着提高了 CO2 转化率、乙醇选择性和生产率。LiI 促进了 CO2 在纯水中的溶解，加速了反应中间体的消耗，有利于 CO2 转化。具体来说，它可以通过 Li+-I-Lewis-Acid-base 催化削弱 CH3OH 中间体的 C-O 键。形成的 CH3I* 对 C-I 键能较低，更容易解离成 CH3*，有利于其随后与 CO* 偶联形成乙醇。将 Rh1/CeTiOx 催化剂、LiI 促进剂和甲醇作为溶剂组合，实现了创纪录的乙醇产率 （223.1 mmol·g-1·h-1）。获得的乙醇收率约为文献中报道的最佳结果的 18.7 倍。特别是，所建立的催化剂体系也可用于通过与其他醇类溶剂 （CnH2n+1OH， n = 2,3...） 进行 CO2 加氢合成高碳数醇。