四氟氯代甲烷改性的HZSM-5分子筛的酸性和催化性能  

THE ACIDITY AND CATALYTIC ACTIVITY OF ZEOLITE HZSM-5 MODIFIED WITH TETRAFLUROCHLORO-METHANES

作　　者：邱平[1] 臧雅茹[1] 陶克毅[1] 高峰[1] 李赫咺[1] 

机构地区：[1]南开大学化学系

出　　处：《石油学报（石油加工）》1994年第1期49-55,共7页Acta Petrolei Sinica(Petroleum Processing Section)

基　　金：国家自然科学基金

摘　　要：本文研究CF_(4-n)Cl_1改性HZSM-5分子筛催化剂的总酸量、酸强度及种类分布和催化性能的变化。结果表明,经CF_(4-n)Cl_n改性后HZSM-5总酸量减少、酸性减弱;改性剂消除酸中心的能力为CF_3Cl>CF_2Cl_2>CFCl_3,CCl_4。F消除酸中心的能力大于Cl。HZSM-5中引入少量的F可增加B酸中心比例,而含F较高的催化剂B酸比例减少;Cl能使B酸比例减少。因此,通过CF_(4-n)Cl_n对HZSM-5改性可以调变其酸性。弱酸中心有利于乙苯-乙醇烷基化,较强的酸中心则有利于乙苯脱烷基,深度改性的HZSM-5可明显改善对乙苯-乙醇烷基化的稳定性。It was found by using ammonia adsorption and TPD determination as well as infrared spectraof pyridine adsorbed that both the acidity and acid sites on the zeolite HZSM-5 modi-fied with CF_(4-n)Cl_n were reduced, and the ratio of Lewis acid sites to Bronsted acid sites was also changed. The order of magnitude of these modifiers to make the zeolite losing acid sites is : CF_3Cl>CF_2Cl_2>CFCl_3 and CCl_4. There was more Bronsted sites on the modified catalysts containing small amount of F than that on the original HZSM-5, but it decreased sharply following the increase of F content. The stability for ethylbenzene alkylation with ethanol was improved and the activity for the dealky lation of ethylbenzene was suppressed' on the catalysts highly modified by CF_3Cl or CF_2Cl_2. These results suggest that weak acid sites may favor the alkylation of ethylbenzene with ethanol while strong acid sites favor the dealkylation of ethylhenzene.

关 键 词：改性 分子筛 酸度 催化 

分 类 号：TQ424.25[化学工程]