CO/CO_(2)加氢制低碳醇改性费托合成催化剂研究进展

Advances in modified Fischer-Tropsch synthesis catalysts for CO/CO_(2) hydrogenation to higher alcohols

一氧化碳/二氧化碳(CO/CO_(2))加氢制低碳醇(C2+OH)是碳一化学的重要组成部分,是将煤、天然气、生物质、CO_(2)等非石油资源转化为液体燃料和高附加值化学品的重要途径。该过程具有工艺路线短、原子经济性高、操作可行性强等优点,是颇具前景的合成路线。改性的费托合成催化剂是该体系最具潜力的催化剂之一,但仍存在低碳醇时空收率不理想、反应网络复杂、产物分布难以调控及稳定性差等问题,高效稳定催化剂的开发极具挑战。本文首先从热力学上分析了CO/CO_(2)加氢反应制低碳醇适宜的工艺条件;其次,对改性费托合成催化剂上CO/CO_(2)加氢制低碳醇的反应路径进行了解析,并据此提出催化剂的设计思路。随后,介绍了铁基和钴基催化剂的研究现状,详细阐述了前体结构、助剂、金属-载体相互作用等因素对催化剂性能的影响机制,重点分析了高性能催化剂的构建策略。后续可借助于先进表征技术和理论计算进一步加深对反应机理的认识,并通过催化剂结构的精细调控,获取低碳醇时空收率和催化剂稳定性的提升策略。

Carbon monoxide/carbon dioxide(CO/CO_(2))hydrogenation to higher alcohols(C2+OH),as the important part in C1 chemistry,is one of the most essential approaches to convert the non-petroleum carbon resources such as coal,natural gas,biomass and CO_(2) into liquid fuels and value-added chemicals.The short route,high atom economy and operational feasibility endow this process great potential to convert CO/CO_(2) to C2+OH.The modified Fischer-Tropsch synthesis(FTS)catalysts are one of the most prospective candidates for CO/CO_(2) hydrogenation to C2+OH,but the application of these catalysts is still limited by the low space time yield,the wide product distribution and poor catalytic stability,as well as the complicated reaction pathways.Thus,the development of efficient and stable catalysts is crucial but still challenging.Herein,the optimal reaction conditions for CO/CO_(2) hydrogenation to C2+OH were obtained on the basis of thermodynamics,and the reaction pathways of CO/CO_(2) hydrogenation on the modified FTS catalysts were clarified.Subsequently,the progress of iron or cobalt-based catalysts in CO/CO_(2) hydrogenation to C2+OH were reviewed,including the impact of precursors,promoters,the metal-support interaction on the catalytic performance,and the construction strategies of highly selective and stable catalysts were emphasized.In the future,it is crucial to clarify the catalytic mechanism through advanced characterizations and theoretical calculations,as well as to improve the space time yield of C2+OH and to enhance the stability via regulating the surface structure precisely.