应用于流化床CO2-CH4重整反应的多级结构催化剂和磁场强化机制研究

Catalytic CH4–CO2 reforming has attracted much attention in recent years, as it reforms two greenhouse gases, CH4 and CO2, into syngas with lower H2/CO ratios, which is preferable to the use of Fischer–Tropsch plants. However, the carbon depositions on the catalyst surface and sintering of Ni crystalline inhibit the catalytic activity and thermal stability. Recent investigations have shown that operating the reforming process in a fluidized-bed reactor can improve the gas–solid contact efficiency, which can improve the catalytic performance of the catalysts and the resistance to the formation of carbon on the surface of the catalyst. However, it is difficult to fluidize the aerogel catalyst particles in the fluidized-bed reactor because of the strong cohesive forces among the particles. Magnetic field-assisted fluidized-beds enhanced the catalytic performance and the resistance to carbon deposition. Nevertheless, the technology of the magnetic field-assisted fluidized-beds for the application in industry is still not well developed. The core is the relationship between the fluidized particles structures and the diffusion and reaction in the fluidized bed. .We are aiming to develop a new approach for the CH4–CO2 reforming in fluidized bed reactor derived from magnetic field-assistant and catalyst structure designation. The key is to gain an insight in to the process intensification of fluidized bed reactor for the CH4–CO2 reforming. To elucidate the relationship between the particle structures of catalyst and the diffusion and reaction based on CH4–CO2 reforming in the fluidized bed. To reveal the intensification mechanism of magnetic field-assistant based on magnetic inert for improving the fluidization quality. These fundamental researches provide new insights for the scale up of fluidized reactor, and new technologies for efficient CH4–CO2 reforming.

二氧化碳的甲烷重整反应过程存在的严重积碳问题是制约该过程工业化的关键问题，寻求高温下抗积碳能力强的高活性催化剂及过程强化方法成为国内外研究CH4-CO2 重整反应的焦点。本申请提出了基于催化剂结构设计的磁场内构件强化CO2-CH4重整新思路，基本思路是从催化剂结构设计出发，构建具有高分散、高稳定性结构的和适合于流化床反应器的多级纳米结构催化剂；同时耦合耦合磁场、内构件流化床强化催化剂颗粒流动，提高反应物和产物在催化剂表面和孔道内部的传递和扩散速率。揭示流化床气固传质和过程强化与CH4-CO2重整催化剂结构和催化性能的内在关系。从磁链内构件角度，理解磁场对流化床中聚团和气泡的破碎的作用机制，阐明磁场强化流化床气固传质和反应的规律，发展系统的过程强化方法。为流化床CH4-CO2重整反应过程的工业化提供技术支持，对CO2的减排和转化利用具有重要意义和理论价值。

本项目针对二氧化碳的甲烷重整反应过程存在的严重积碳问题，提出了基于催化剂结构设计的磁场内构件强化CO2-CH4重整新思路。从催化剂颗粒与流化床反应器匹配角度出发，通过对催化剂结构设计、磁场对催化剂颗粒聚团的强化作用和活性金属氧化与积碳失活的关系等进行了大量探索性研究，发展了高分散纳米金属多级结构催化剂的制备方法，揭示了CO2-CH4重整过程磁场对Co/MgO催化剂颗粒的强化作用，探明了活性金属Co纳米颗粒的氧化对催化剂积碳失活的影响规律。主要结论如下：.(1) 构建了具有高分散、高稳定性结构的和适合于流化床反应器的多级纳米结构催化剂，并将Co/MgO催化剂应用于CO2-CH4重整反应，能够显著提高CO2和CH4的转化速率。.(2) 探明了磁场在磁控鼓泡流域内才可以改善Geldart-B 类颗粒的流化质量，在沟流鼓泡或分级鼓泡流域内不能改善颗粒的流化质量。.(3) CO2-CH4重整过程磁场对Co/MgO催化剂颗粒的强化作用的核心在于，磁场通过对磁性催化剂的作用，加速了磁性催化剂颗粒聚团的破碎-聚并频率，从而强化气固传质和反应。.(4) Co/MgO负载型催化剂的快速失活源于Co纳米颗粒氧化，Co纳米颗粒的氧化加速了Co纳米颗粒表面积碳，包覆了Co活性中心。.相关研究发表刊物论文5篇，其中SCI论文3篇，包括AIChE J.、Chem. Eng. Sci.等化学工程领域顶级刊物。研究达到了课题预期目标。同时还受邀参与编写《化学工程手册》（第三版）“流态化”篇和“颗粒及颗粒系统”篇。申请获得2017年国家留学基金委访问学者项目（1年）。