Hao Shumin, Wang Yongrui, Xing Enhui, Mu Xuhong
State Key Laboratory of Petroleum Molecular & Process Engineering, SINOPEC Research Institute of Petroleum Processing Co., Ltd., 18 Xueyuan Road, Beijing 100083, China.
Materials (Basel). 2025 May 13;18(10):2252. doi: 10.3390/ma18102252.
A study systematically investigating the structural modifications and catalytic performance of IM-5 zeolite treated with hexafluorosilicic acid in pseudocumene alkylation with methanol was carried out. Characterization techniques revealed significant alterations in crystal structure, morphology, textural properties, coordination environment, and acidity induced by the modifications. Catalytic evaluations demonstrated altered pseudocumene conversion, durene selectivity, and products distribution for optimized samples, with IM-5-0.01 (treated with 0.01 M modifier) showing superior activity stability. The improved performance was attributed to two key factors: a stable framework with high-density medium-strength Brønsted acid sites facilitating complete alkylation and expanded mesoporous volume promoting efficient product diffusion to mitigate deactivation. Conversely, reduced durene selectivity in modified samples stem from intensified isomerization reactions driven by increased external surface area, resulting in higher C product fractions. In contrast, the parent IM-5 zeolite exhibited rapid deactivation, with durene selectivity peaking at 40 h before declining. Mechanistic insights revealed dynamic processes including dealumination, defect formation, silicon repair, and aluminum redistribution during treatment, providing a theoretical foundation for rational catalyst design in alkylation reactions.
开展了一项系统研究，考察用六氟硅酸处理的IM-5沸石在均三甲苯与甲醇烷基化反应中的结构修饰和催化性能。表征技术揭示了修饰引起的晶体结构、形态、织构性质、配位环境和酸度的显著变化。催化评价表明，优化后的样品的均三甲苯转化率、杜烯选择性和产物分布发生了改变，其中IM-5-0.01（用0.01 M改性剂处理）表现出优异的活性稳定性。性能的提高归因于两个关键因素：具有高密度中强度布朗斯台德酸位的稳定骨架促进了完全烷基化，以及扩大的介孔体积促进了产物的有效扩散以减轻失活。相反，改性样品中杜烯选择性的降低源于外比表面积增加导致的异构化反应加剧，从而使C产物馏分更高。相比之下，母体IM-5沸石表现出快速失活，杜烯选择性在40 h时达到峰值，然后下降。机理分析揭示了处理过程中脱铝、缺陷形成、硅修复和铝重新分布等动态过程，为烷基化反应中合理的催化剂设计提供了理论基础。
