摘要
采用浸渍法制备了系列磷镁改性ZSM-5催化剂,考察了磷镁改性对HZSM-5催化剂甲苯甲醇烷基化反应活性和选择性的影响。并对其进行了NH3-TPD,Py-IR,XRD等表征,研究了改性氧化物在ZSM-5分子筛表面的分布状态以及其对催化剂的酸性质的影响,结果表明磷元素改性有效降低了催化剂的酸强度,抑制了甲苯歧化反应;MgO质量含量低时,主要以无定形状态高度分散在分子筛外表面上,含量较高时形成结晶态MgO。MgO改性主要作用是覆盖了催化剂外表面酸性活性中心,堵塞了孔口,提高了反应产物的对位选择性。
A series of catalysts containing different amount of phosphorous and magnesium have been pre- pared by impregnating ZSM-5 with phosphorous and magnesium compound and have been used to study the activ- ity and Para-selectivity on toluene alkylation with methanol. NH3-TPD and Pyridine-IR have been used to mea- sure the acidity of the catalysts. The state of magnesium oxidation on the surface of ZSM-5 catalysts has been characterized by XRD. We find that phosphorous lowers the acid strength of catalysts, suppresses the dispropor- tionation of toluene; High para-selectivity has been obtained due to the external active sites being covered and the mouth of pore being blocked by magnesium oxidation.
出处
《化学工程师》
CAS
2012年第5期50-53,共4页
Chemical Engineer
关键词
ZSM-5
甲苯
烷基化
歧化
对位选择性
ZSM-5
toluene
alkylation
disproportionation
para-selectivity
