胶溶剂对MCM-22分子筛催化剂性能的影响

Effect of Peptizator on Performance of MCM-22 Zeolite Catalyst

以硝酸、盐酸、醋酸和甲酸为胶溶剂,采用挤条成型工艺制备了一系列MCM-22分子筛催化剂,并用颗粒强度仪和热重天平等手段对其物理性质进行表征,考察了胶溶剂对MCM-22分子筛催化剂强度和总酸量等性质的影响。结果表明,采用无机酸胶溶剂的催化剂具有较高强度和总酸量;随硝酸胶溶剂用量的增加,催化剂总酸量增加,强度呈现先增后减的变化趋势,最高强度对应的硝酸质量分数约为10%。以苯和丙烯烷基化为模型反应,分别采用气-液半连续和液-液连续两种操作方式对催化剂进行了反应性能评价,结果表明无机酸作胶溶剂的催化剂具有较高活性和异丙苯选择性;当硝酸质量分数小于20%时,MCM-22分子筛催化剂活性随硝酸用量的增加而增加;当硝酸质量分数为10%时,异丙苯选择性最大。

A series of MCM-22 zeolite catalyst samples were prepared with nitric acid, hydrochloric acid, acetic acid and formic acid as the peptizators. The zeolites were characterized by means of particle strength apparatus and TG-DTA apparatus to investigate the effect of peptizators on the physical properties of MCM-22 catalyst. The results show that the strength and total acid of zeolites with inorganic acid as peptizator are higher than the zeolites with organic acid. With the increasing nitric acid dosage, the mechanical strength of the zeolite catalyst increases at first and then decreases, with the maximal catalyst strength being obtained at a dosage of 10%. The total acid is enhanced by adding the appropriate amount of nitric acid. Taking the alkylation of benzene with propylene as a model reaction, the catalytic performances of the MCM-22 zeolite catalysts were evaluated by means of a semi-continuous gas-liquid reactor and a liquid liquid continuous reactor. The experimental results show that activity and selectivity of zeolite in inorganic acid is stronger than that in organic acid. When the nitric acid dosage is less than 20 %, the activity of MCM- 22 zeolite is increased with increasing of nitric acid dosage. The selectivity to cumene reaches a maximum value when nitric acid dosage is 10%.