Structural elucidation of ethylene in H-ZSM-5 zeolites

The adsorption structure of substrates is crucial to the reaction pathways over heterogeneous catalysts. Recently, we conducted a comprehensive analysis of ethylene adsorption in Brønsted acidic H-ZSM-5 zeolites with a combination of neutron powder diffraction (NPD) and inelastic neutron scattering (INS). We found that depending on Brønsted acid sites (BASs) distribution, ethylene forms clusters with different configurations that determine the final catalytic products. However, due to the limited beamtime, in our previous neutron experiments, the loading amount of ethylene in H-ZSM-5 zeolites was not consistent. In this study, we would like to perform additional NPD experiments to determine the precise structure of ethylene clusters in H-ZSM-5 at various loadings. In this way, the relationship between BAS distribution, ethylene structure and related catalytic performance will be revealed.

底物的吸附结构对多相催化剂上的反应路径至关重要。近期，我们结合中子粉末衍射（neutron powder diffraction，NPD）与非弹性中子散射（inelastic neutron scattering，INS）技术，对布伦斯特酸性H-ZSM-5分子筛中的乙烯吸附行为开展了全面分析。研究发现，依据布伦斯特酸位点（Brønsted acid sites，BASs）的分布差异，乙烯会形成不同构型的团簇，进而决定最终的催化产物。但受限于有限的束流时间，此前的中子实验中，H-ZSM-5分子筛内的乙烯负载量并不统一。本研究拟开展补充性中子粉末衍射实验，以测定不同负载量下H-ZSM-5分子筛内乙烯团簇的精确结构，借此阐明布伦斯特酸位点分布、乙烯构型与相关催化性能之间的内在关联。