环烷烃催化裂解生成乙烯和丙烯反应探析  

Exploration and Analysis on Ethylene and Propylene Formation in Naphthene Catalytic Cracking

作　　者：于珊[1] 张久顺[1] 魏晓丽[1] 

机构地区：[1]中国石化石油化工科学研究院,北京100083

出　　处：《石油学报（石油加工）》2013年第3期475-481,共7页Acta Petrolei Sinica(Petroleum Processing Section)

基　　金：国家科技支撑计划项目(2012BAE05B01)资助

摘　　要：采用小型固定流化床装置研究了不同环烷烃催化裂解生成乙烯和丙烯的反应规律。结果表明,环烷烃的催化裂解反应中,无取代基的双环环烷烃比单环环烷烃更有利于生成乙烯和丙烯,但两者容易发生脱氢缩合反应;给电子诱导效应相对最强的正丙基环己烷比甲基环己烷和乙基环己烷更易生成正碳离子,利于生成乙烯和丙烯;对于含有2个取代基的环烷烃,取代基之间的距离越近,环烷烃环上的电子分布越不均匀,越容易生成正碳离子;具有较大环张力和较小动力学直径的甲基环戊烷比甲基环己烷更易催化裂解生成乙烯和丙烯。根据甲基环戊烷催化裂解的产物分析和分子模拟计算结果,推测H+优先进攻甲基环戊烷取代基的碳原子,进而发生电荷转移,形成C(1)五配位正碳离子。Ethylene and propylene formation in cyclic alkane catalytic cracking was studied in a small-scale fixed fluid catalytic cracking unit. The results indicated that bicyclic alkane without substituent was more favorable to generate ethylene and propylene than monocyclic alkane in catalytic cracking. However, bicyclic alkane and monocyclic alkane were more favorable to dehydrogenate, n-Propylcyclohexane was favorable to form carbocation than methylcyclohexane and ethylcyclohexane due to the relatively stronger electron-donating inductive effect, which was beneficial to generating ethylene and propylene. In the case of the double-substituent cyclic alkane, carbocation was easier to form, because the distribution of electron was non-uniform when two substituents got closer. Methylcyclopentane was more reactive in catalytic cracking to generate ethylene and propylene than methylcyclohexane due to its relatively higher ring strain and smaller kinetic diameter. Based on the product distribution in methylcyclopentane catalytic cracking and molecular simulation results, it was supposed that H＋ preferred to attack the carbon atom of methyl-substituent before charge transfer, forming C（1） pentacooridinated carbocation.

关 键 词：环烷烃 催化裂解 乙烯 丙烯 机理 

分 类 号：TQ203.2[化学工程—有机化工]