硅改性对甲苯择形歧化催化剂性能的影响  

Effect of Silica Modification on Performance of Catalyst for Toluene Selective Disproportionation

作　　者：张荣[1] 祁晓岚[1] 孔德金[1] 

机构地区：[1]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：《化学反应工程与工艺》2011年第2期127-132,共6页Chemical Reaction Engineering and Technology

基　　金：国家重点基础研究发展计划(973计划2009CB623501)

摘　　要：以聚硅氧烷为改性剂,对HZSM-5分子筛甲苯择形歧化催化剂进行改性,采用X射线衍射(XRD)、N_2低温吸附和核磁共振(^(27)Al MAS NMR)等手段对改性前后的催化剂进行表征,并考察了硅改性对甲苯择形歧化催化剂性能的影响。结果表明:随着改性次数的增加,催化剂上二氧化硅的沉积量增加,催化剂的活性降低,对二甲苯(PX)选择性增加,产物中苯和对二甲苯物质的量之比先下降后上升;在改性过程中,随着二氧化硅沉积量的增加,催化剂的微孔体积基本不变,介孔体积下降,一次改性沉积的二氧化硅主要覆盖催化剂外表面和介孔孔道,二次改性主要起修饰微孔孔口作用;硅改性后,分子筛结构未发生明显变化,但非骨架铝含量增加:一次硅改性后,甲苯饱和吸附量下降约20%,间二甲苯饱和吸附量降低约84%。The HZSM-5 molecular sieve catalyst tor toluene selective chsproportlonatlon to p-xylene was modified using polysiloxane as modifier and was characterized by means of X-ray diffraction（XRD）, low-temperature nitrogen adsorption-desorption technique and nuclear magnetic resonance（27AI MAS NMR）. The effect of silica modification on the catalytic performance of the catalyst was investigated. The results showed that with the increase of deposited silica, the catalytic activity decreased while the selectivity ofp-xylene increased, the molar ratio of benzene to xylene decreased after the first modification while increased after the second deposition. After modification, the micropore volume hardly changed, while the mesopore volume reduced. The external surface and the micropores were covered by silica after first modification and the second deposition mainly resulted in the decrease of the micropore size. The structure of HZSM-5 molecular sieve was kept but the content of non-framework aluminum increased. The amount of saturated adsorption of toluene reduced by 20% after the first modification while 84% ofm-xylene.

关 键 词：改性 择形歧化 对二甲苯 甲苯 

分 类 号：TQ426.6[化学工程]