HZSM-5沸石中Lewis酸与Brnsted酸协同作用下的甲基环己烷开环反应(英文)  

Synergism between the Lewis and Br nsted acid sites on HZSM-5 zeolites in the conversion of methylcyclohexane

作　　者：宋晨海 王蒙[1] 赵理[1] 薛念华[1] 彭路明[1] 郭学锋[1] 丁维平[1] 杨为民[2] 谢在库[2] 

机构地区：[1]南京大学化学化工学院介观化学教育部重点实验室,江苏南京210093 [2]中国石油化工股份有限公司上海石油化工研究院,上海201208

出　　处：《催化学报》2013年第11期2153-2159,共7页

基　　金：supported by the National Natural Science Foundation of China (21273107, 21103087);the Fundamental Research Funds for the Central Universities (1107020524);the Specialized Research Fund for the Doctoral Program of Higher Education (20100091120035)~~

摘　　要：由于水蒸气处理HZSM-5生成的骨架外铝在分子筛中体现Lewis酸性,分子筛中骨架外铝物种的可移动性导致Lewis酸与分子筛本身的Br nsted酸在空间上具有临近性.当甲基环己烷分子在HZSM-5的笼中转化时,Lewis酸与Br nsted酸的协同作用加快了甲基环己烷分子的转化速率,且骨架外铝物种浓度越高,这种协同效应越明显.而产物的选择性只与催化剂的孔道结构有关,与水蒸气处理所导致的酸性质的变化无关.Catalytic conversion of methylcyclohexane was studied on four specially designed HZSM-5 zeolites. A careful steam treatment was used to produce pair-sites composed of a Lewis acid site,due to extra-framework Al species from the dealumination by steaming,and a Br nsted acid site,due to bridging hydroxyl in the steamed HZSM-5.The spatial proximity of these component acid sites of the pair-site was verified by 1H double quantum magic spinning NMR. Product selectivities of methylcyclohexane conversion showed the same trend for all the samples,which indicated that the pores of the zeolites were not changed by the steam treatment.The Lewis acid site that was created, however,gave a synergistic effect with the Br nsted acid site in the pair-site,which gave higher conversions and cracking rates of methylcyclohexane.The rate of methylcyclohexane conversion increased with increased concentration of extra-framework Al,which gave more pair-sites.

关 键 词：甲基环己烷 HZSM-5 水蒸气处理 协同效应 LEWIS酸 BR nsted酸 

分 类 号：O643.32[理学—物理化学]