物理化学学报2020，Vol.36Issue(9)：18-24,7.DOI:10.3866/PKU.WHXB201912001
理性设计核-壳Rh@沸石催化材料用于二烯烃选择加氢反应
Rational Design of a Core-Shell Rh@Zeolite Catalyst for Selective Diene Hydrogenation
摘要
Abstract
Selective hydrogenation of dienes and alkynes to monoenes is an important topic of research in the fields of pharmacology and organic synthesis.Catalyst design plays a key role in this process,where a general principle involves controlling the steric diene adsorption by modifying the surface of the metal nanoparticles.For example,upon introducing Bi species into Rh nanoparticles,the resulting RhBi/SiO2 showed 90％ selectivity to 2-hexene,with 95％ conversion of 1,4-hexadiene under ambient conditions,because of the suppressed adsorption of the internal C =C bond.However,the catalyst activity decreased remarkably;that is,the activity of the unmodified Rh/SiO2 was about 27 times higher than that of RhBi/SiO2.Controlled steric adsorption of the diene molecules could also be achieved by the constructing porous channels around the metal nanoparticles.For example,metal-organic framework (ZIF-8) or mesoporous silica (MCM-41) encapsulated noble metals showed high selectivity for the hydrogenation of terminal C=C bonds.However,these catalysts had poor durability under the thermal/hydrothermal reaction/regeneration conditions.In contrast,zeolites have superior durability under harsh reaction conditions,but they are rarely used in semi-hydrogenation reactions.We recently found that metal nanoparticles fixed within zeolite crystals (e.g.,ZSM-5 and Beta) efficiently catalyze the selective hydrogenation of molecules bearing multiple reducible groups.Thus inspired,we developed a catalyst by fixing Rh nanoparticles within zeolite crystals via an inter-zeolite transformation method.The Rh@CHA catalyst was synthesized by introducing Rh species into the parent Y zeolite (Rh@Y) and transformation of the Y zeolite to chabazite (CHA zeolite) under hydrothermal conditions.X-ray diffraction patterns,N2 sorption isotherms,scanning/transmission electron microscopy images,and model reactions (hydrogenation of probe molecules) confirmed the successful fixation of the Rh nanoparticles inside the CHA zeolite crystals.As expected,the Rh@CHA catalyst was highly selective for the hydrogenation of dienes.For example,Rh@CHA showed a 2-hexene selectivity of 86.7％,with 91.2％ conversion of 1,4-hexadiene.In contrast,the generally supported Rh nanoparticle catalyst (Rh/CHA) showed a low 2-hexene selectivity of 37.2％ under identical reaction conditions.Considering that Rh@CHA and Rh/CHA comprise the same CHA zeolite crystals and have similar Rh nanoparticle sizes,the remarkably high selectivity of Rh@CHA is assigned to the steric adsorption of dienes on the Rh surface controlled by the micropores of the CHA zeolite.This work demonstrates that a zeolite-fixed metal core-shell structure is a powerful tool for developing efficient catalysts to be used in diene hydrogenation.关键词
多相催化/二烯烃加氢/铑纳米颗粒/CHA沸石/核-壳结构/转晶合成沸石Key words
Heterogeneous catalysis/Diene hydrogenation/Rh nanoparticle/CHA zeolite/Core-shell structure/Inter-zeolite transformation分类
化学化工引用本文复制引用
张建,王亮,伍芷毅,王成涛,苏泽瑞,肖丰收..理性设计核-壳Rh@沸石催化材料用于二烯烃选择加氢反应[J].物理化学学报,2020,36(9):18-24,7.基金项目
The project was supported by the National Key Research and Development Program of China (2018YFB0604801),the National Natural Science Foundation of China (21822203,91645105,91634201),the Natural Science Foundation of Zhejiang Province,China (LR18B030002),the Beijing Advanced Innovation Center for Soft Matter Science,Engineering of the Beijing University of Chemical Technology,China (21530009067),and the Fundamental Research Funds for the Central Universities,China (2019XZZX004-02).国家重点研发计划(2018YFB0604801),国家自然科学基金(21822203,91645105,91634201),浙江省自然科学基金(LR18B030002),北京化工大学高精尖研究中心科研启动费(21530009067)及中央高校基本科研基金(2019XZZX004-02)资助项目 （2018YFB0604801）
