Cai Dongren, Cai Yanmei, Tan Kok Bing, Zhan Guowu
Integrated Nanocatalysts Institute (INCI), College of Chemical Engineering, Huaqiao University, 668 Jimei Avenue, Xiamen 361021, China.
Materials (Basel). 2023 Mar 31;16(7):2803. doi: 10.3390/ma16072803.
Methanol synthesis from the hydrogenation of carbon dioxide (CO) with green H has been proven as a promising method for CO utilization. Among the various catalysts, indium oxide (InO)-based catalysts received tremendous research interest due to the excellent methanol selectivity with appreciable CO conversion. Herein, the recent experimental and theoretical studies on InO-based catalysts for thermochemical CO hydrogenation to methanol were systematically reviewed. It can be found that a variety of steps, such as the synthesis method and pretreatment conditions, were taken to promote the formation of oxygen vacancies on the InO surface, which can inhibit side reactions to ensure the highly selective conversion of CO into methanol. The catalytic mechanism involving the formate pathway or carboxyl pathway over InO was comprehensively explored by kinetic studies, in situ and ex situ characterizations, and density functional theory calculations, mostly demonstrating that the formate pathway was extremely significant for methanol production. Additionally, based on the cognition of the InO active site and the reaction path of CO hydrogenation over InO, strategies were adopted to improve the catalytic performance, including (i) metal doping to enhance the adsorption and dissociation of hydrogen, improve the ability of hydrogen spillover, and form a special metal-InO interface, and (ii) hybrid with other metal oxides to improve the dispersion of InO, enhance CO adsorption capacity, and stabilize the key intermediates. Lastly, some suggestions in future research were proposed to enhance the catalytic activity of InO-based catalysts for methanol production. The present review is helpful for researchers to have an explicit version of the research status of InO-based catalysts for CO hydrogenation to methanol and the design direction of next-generation catalysts.
通过二氧化碳（CO₂）与绿色氢气加氢合成甲醇已被证明是一种很有前景的CO₂利用方法。在各种催化剂中，氧化铟（In₂O₃）基催化剂由于具有出色的甲醇选择性和可观的CO₂转化率而受到了广泛的研究关注。在此，对用于热化学CO₂加氢制甲醇的In₂O₃基催化剂的近期实验和理论研究进行了系统综述。可以发现，人们采取了多种步骤，如合成方法和预处理条件，来促进In₂O₃表面氧空位的形成，这可以抑制副反应，以确保CO₂高度选择性地转化为甲醇。通过动力学研究、原位和非原位表征以及密度泛函理论计算，全面探索了In₂O₃上涉及甲酸盐途径或羧基途径的催化机理，结果大多表明甲酸盐途径对甲醇生成极为重要。此外，基于对In₂O₃活性位点以及In₂O₃上CO₂加氢反应路径的认识，人们采取了一些策略来提高催化性能，包括：（i）金属掺杂以增强氢气的吸附和解离，提高氢溢流能力，并形成特殊的金属-In₂O₃界面；（ii）与其他金属氧化物混合以改善In₂O₃的分散性，增强CO₂吸附能力，并稳定关键中间体。最后，针对未来研究提出了一些建议，以提高In₂O₃基催化剂用于甲醇生产的催化活性。本综述有助于研究人员明确了解用于CO₂加氢制甲醇的In₂O₃基催化剂的研究现状以及下一代催化剂的设计方向。
