CO2加氢制取异构烷烃催化剂结构调控与性能研究

Utilizing CO2 as the carbon source to manufacture value-added hydrocarbons would be a sustainable way of reducing CO2 emissions, replacing fossil fuels and facilitating the storage of renewable energy, if H2 used for converting CO2 was supplied by water electrolysis with renewable electricity. Unfortunately, the activation of CO2 and its hydrogenation to long-chain hydrocarbons are challenging tasks because CO2 is a thermodynamically stable and chemically inert molecule. Environmentally benign and high-octane isoparaffins are ideal gasoline components. However, there is little research on the catalyst for CO2 hydrogenation to isoparaffins, and the developed catalysts have the characteristics of low selectivity to isoparaffins and poor stability. Herein, the program focuses on the study on the structural modulation and catalytic performance of catalyst for CO2 hydrogenation to isoparaffins. The effects of zeolite pore structure and acidty on the product selectivity and coke formation will be investigated during CO2 hydrogenation over Na–Fe3O4/Zeolite multifunctional catalysts. The project will further study the nature and formation mechanism of the coke, explore the reason of zeolite deactivation and the method of zeolite regeneration, and then modulate the distribution of zeolite acid sites by in-situ synthesis and post-modification. Thus, the yield to isoparaffins will be increased obviously during the process of CO2 hydrogenation. The study of this project will provide theoretical guidance for the development and modification of the catalyst for CO2 hydrogenation to higher hydrocarbons, and offer a new route for the efficient utilization of CO2.

以CO2作为碳源，与可再生能源发电分解水产生的氢气催化转化为高附加值的烃类化合物，不仅可实现CO2减排，还可解决对化石燃料的过度依赖以及可再生能源的存储问题。由于CO2具有高度热力学稳定性和化学惰性，CO2活化及其加氢转化合成长链烃极具挑战性。环境友好、辛烷值高的异构烷烃是理想的汽油组分。目前关于CO2加氢制取异构烷烃催化剂研究较少，现有催化剂存在异构烷烃选择性低、稳定性差的特点。本项目拟开展CO2催化加氢直接合成异构烷烃催化剂结构调控与性能研究，研究分子筛的孔道结构和酸性对产物分布和积碳形成的影响，探索积碳物种的本质及形成机制，探讨分子筛失活原因及分子筛再生方法，通过原位合成和后改性法调控分子筛的酸性分布，显著提升CO2加氢过程中异构烷烃的收率，为CO2加氢制取高碳烃催化剂的研发和改进提供理论指导，为CO2的高效资源化利用提供新路线。

二氧化碳催化加氢转化为高附加值的烃类化合物，不仅可实现CO2减排，还可解决对化石燃料的过度依赖以及可再生能源的存储问题。由于CO2具有高度热力学稳定性和化学惰性，CO2活化及其加氢转化合成高碳烃极具挑战性。本项目主要围绕NaFe/Zeolite串联催化体系的构建及其在CO2加氢反应中的构效关系开展了研究。项目研究了分子筛孔道结构和酸性对复合催化剂上CO2加氢产物分布和积碳形成的影响，通过设计具有独特孔道结构和合适Brønsted酸位浓度的复合催化剂，成功将CO2和H2一步、高收率地合成了异构烷烃；通过精准调控复合催化剂中分子筛Brønsted酸位性质，实现了CO2加氢反应中轻质芳烃在芳烃产物中占比达75%，对二甲苯（PX）在二甲苯中占比达72%，达到同类文献报道最高值。项目还通过调变NaFe基催化剂制备中前驱体的种类和比例实现铁氧化物结构组成的转变，继而研究其在CO2加氢反应中的结构性能关系，为该催化剂成功实现吨级批量化制备和工业中试应用奠定了基础。本项目的成功实施将为CO2加氢制取高碳烃催化剂的研发和改进提供理论指导，为CO2的高效资源化利用提供新路线。

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