HEMT沸石负载12-钨硅酸对异丁烷与丁烯烷基化反应的催化性能

Catalytic Performances of HEMT-Supported 12-Tungstosilicic Acid for Alkylation of Isobutane with Butene

在压力为 2 0MPa的连续流动液相反应系统中 ,考察了HEMT负载 12 钨硅酸催化剂对异丁烷与丁烯烷基化反应的催化性能 ,并与HEMT沸石及 12 钨硅酸催化剂进行了比较 .采用差热分析、比表面积测定、红外光谱及程序升温脱附等方法对催化剂进行了表征 .发现HEMT负载 12 钨硅酸后 ,催化剂的稳定性及对烷基化反应的催化活性和选择性有了明显提高 ,其中高辛烷值的目的产物三甲基戊烷的选择性较HEMT提高了 17 6 % .

The catalytic performances of 12-tungstosilicic acid, HEMT zeolite, and HEMT-supported 12-tungstosilicic acid for the liquid phase alkylation of isobutane with butene have been studied. The reaction was operated in a continuous fixed-bed reactor at pressure of 2.0 MPa, temperature of 60 degreesC, and butene LHSV of 1.0 h(-1) The catalysts were characterized by DTA analysis, BET area measurement, and Py-FTIR-TPD technique. The HEMT-supported 12-tungstosilicic acid catalyst has higher activity and stability than the HEMT and 12-tungstosilicic acid catalysts, and it is more selective to trimethylpentanes (TMPs) and less selective to C-8 olefins than the latter two catalysts during the whole reaction time. Especially, the selectivity for TMPs over HEMT-supported 12-tungstosilicic acid is 17.6% higher than that over HEMT at the initial reaction stage (time on stream = 5 min). This indicates that the supported catalyst has great ability to transfer hydride ions, which is favorable for the reproduction of C-4(+) ions and the formation of TMPs. The relationship between the alkylation of isobutane with butene and the acidity of HEMT-support ed 12tungstosilicic acid was also discussed.