基于MOFs材料制备限域型纳米双金属催化剂用于CO/CO2加氢制含氧化学品的研究

Methanol, ethanol and C2+ alcohol are important oxygenate chemicals, which can be produced by the hydrogenation of CO/CO2. However, due to the harsh reaction conditions, traditional catalysts always show easily deactivation accompanying metal sintering, coke deposition and phase change. As a result, the processes of CO2/CO hydrogenation into methanol and high alcohols are still in the fundamental research phases, and breakthroughs are highly demanded to develop new catalysts with high performance and stability. Thus, it is urgent to rationally prepare catalysts to get a required structure and performance. The present research project chooses CO2 hydrogenation into methanol and CO hydrogenation into high alcohols as the target reactions, focusing on the crucial challenges of rational design and preparation, selectivity control and structure stability through thermal pyrolysis of MOFs-based bimetallic materials into bimetallic catalysts confined by carbon materials. On the basis of these, the project aims at designing and preparing new catalysts with high activity and stability, and understanding the relationship between the catalyst structure and its performance. On one hand, bimetallic catalyst has special electronic effect and synergistic effect differing from their monometallic counterparts. Thus, it is available to control the activity and stability by carefully control of bimetallic composition and structure. On the other hand, the forming carbon may cover the bimetallic nanoparticles and inhibit the growth of active sites, resulting in the improvement of stability. Moreover, unique active metallic carbides may be formed through proper treatment, which may play an important role in the catalytic performance.

甲醇、乙醇和C2+低碳醇是重要的有机含氧化学品，可以通过CO2/CO加氢而制得。由于反应要求较高的温度和压力，传统催化剂存在易烧结、积碳以及活性位相变等现象，进而导致催化剂易失活。目前CO2加氢制甲醇和合成气转化制低碳醇仍处于基础研究阶段，主要瓶颈在于高效高稳定性催化剂的开发。本项目以CO2加氢制甲醇和CO加氢制低碳醇为目标反应，围绕催化剂结构的精准设计与制备、稳定性控制和选择性调控等关键科学问题，拟从MOFs基双金属材料前驱体出发，通过高温热解制备碳材料限域双金属纳米催化剂，探索具有高活性高稳定性的加氢催化剂并进行构效研究。一方面，双金属具有电子、协同作用性质，通过精准调控制备双金属纳米催化剂，实现对活性以及稳定性进行调控；另一方面，所形成的碳结构对双金属有限域作用，从结构上抑制金属活性中心的热聚集，提高催化剂的稳定性；同时，通过适当处理，可望形成有利于目标反应的特殊活性金属碳化物物种。

CO/CO2加氢制含氧化合物具有良好的原子利用率，反应产物价值高用途广，备受研究者和工业界的共同关注，其最核心问题在于发展出涉C-O活化与重组和C-C键构建的高性能催化剂。根据项目原定计划，本项目根据原定研究计划，在项目执行期间（2016年1月–2018年12月），开展了包括新型碳材料负载/限域型、稀土氧化物负载/修饰型和原位析出表面限域型以及双活性位Co-Co2C等催化剂的制备和对CO/CO2加氢制备含氧化物的构和效关联研究，取得以下主要进展。.(1) 研究了MOFs衍生N杂碳材料限域/负载型Cu基催化剂的制备和选择性加氢/氧化，以及N杂-碳纳米管负载型Cu-Fe双金属催化剂和CNT掺杂/促进型NiMoK催化剂用于CO加氢制含氧化合物的性能和结构关联，提出了N物种结构效应的初步认识，即N杂碳载体中N含量适中（2–6%）且具有较高吡咯N浓度时，所制备催化剂具有较高反应性能。.(2) 研究了稀土氧化物负载/修饰型和原位析出表面限域型Cu基和NiMo基催化剂用于CO/CO2加氢制含氧化合物的制备和构效关联，提出和实验验证了Cu-LaOx界面有利于CO2加氢制甲醇的观点。.(3) 研究了Mn促进型双活性位Co-Co2C催化剂的制备方法和在合成气制低碳醇合成方面的应用，Mn的存在将阻碍Co0物种但促进CoC2物种的生成，进而有利于合成气加氢制低碳醇的产率。.(4) 在相关研究领域发表了SCI收录研究论文21篇，申请中国发明专利2项，培养博士生毕业获学位1名，在读3名；硕士生毕业获学位3名，在读3名。