Y分子筛的氢转移反应性能及其调控机制

Hydrogen Transfer Reaction Performance and Regulation Mechanism of Y Zeolites

利用原位红外光谱技术考察了HY分子筛和镧离子改性Y(LaHY)分子筛的氢转移反应性能;结合分子筛晶体结构、织构性质和酸性质等表征数据,探讨了稀土改性以及水热处理对Y分子筛氢转移反应性能的调控机制。结果表明,Y分子筛的Brønsted(B)酸密度和强酸强度减弱,同时落位于超笼中的稀土物种形成弱Lewis(L)酸位,超笼中B酸和L酸位点的协同作用促进了氢转移反应的发生;经过水热处理,HY-LH和LaHY-LH分子筛的总酸量显著减少,同时超笼中与稀土物种有关的L酸中心完全消失,显著降低了HY分子筛氢转移反应性能。研究成果可为深入理解催化裂化反应过程中氢转移反应的规律,以及调控烯烃产物选择性和抑制结焦失活等提供理论指导。

The hydrogen transfer properties of HY zeolite and lanthanum ion modified Y(LaHY)zeolite were investigated using in situ FTIR technology.Combined with characterization data of zeolite crystal structure,texture properties,and acidity,the regulatory mechanism of rare earth modification and hydrothermal treatment on the hydrogen transfer reaction performance of Y zeolite was explored.The results show that the Brønsted(B)acid density and strong acid strength of Y zeolite decreased,while rare earth species located in the supercage formed weak Lewis(L)acid sites.The synergistic effect of B acid and L acid sites in the supercage promoted the occurrence of hydrogen transfer reaction.After hydrothermal treatment,the total acidity of HY-LH and LaHY-LH zeolites significantly decreased,and the L acid centers related to rare earth species in the supercages completely disappeared,which significantly reduced the hydrogen transfer reaction performance of HY zeolites.The research results can provide important theoretical guidance for a deeper understanding of the laws of hydrogen transfer reactions in catalytic cracking reactions,as well as achieving the goals of regulating olefin product selectivity and inhibiting coking deactivation.