摘要
制备了有机胺改性介孔分子筛催化剂APTMS-FSM-16、MAPTMS-FSM-16和DMAPTMS-FSM-16,通过与典型的有机胺及FSM-16混合催化剂比较,考察了它们催化对硝基苯甲醛与丙酮的Aldol缩合反应的活性。实验结果表明,伯胺、仲胺、叔胺分别与FSM-16共催化时,催化活性顺序为哌啶+FSM-16>环己胺+FSM-16>三乙胺+FSM-16。改性介孔分子筛催化剂中,MAPTMS-FSM-16表现出最高活性,在该反应中各种催化剂活性顺序为MAPTMS-FSM-16>APTMS-FSM-16>DMAPTMS-FSM-16。研究还发现,接枝改性催化剂MAPTMS-FSM-16经循环使用后,FSM-16表面羟基接枝的活性点氨基硅烷逐渐脱落减少,催化剂活性降低。同时,由于介孔分子筛表面羟基的增多以及与β-羟基酮产物A之间的氢键作用,使得脱水产物β-不饱和酮B的选择性增加。
Mesoporous molecular sieve catalysts APTMS-FSM-16,MAPTMS-FSM-16 and DMAPTMS-FSM-16 modified by organic amine were prepared. Comparing with a typical catalyst of organic amine mixed FSM-16,the catalytic activities for Aldol condensation reaction of nitrobenzene formaldehyde and acetone were investigated. The results show that the primary amine,secondary amine and tertiary amine,respectively mixed with FSM-16,the catalytic activity order was following as piperidine ＋ FSM-16〉 hexylamine ＋ FSM-16 〉triethylanmine ＋ FSM-16. Among modified mesoporous molecular sieve catalysts,MAPTMS-FSM-16 showed the highest activity,and the catalytic activity order was following as MAPTMS-FSM-16 〉APTMS-FSM-16 〉DMAPTMS-FSM-16.The active site of catalyst MAPTMS-FSM-16 grafted with organic amine was reduced gradually after recycling,and catalytic activity was declined. Furthermore,due to increasing surface hydroxyl of mesoporous molecular sieve increased and interacted with β-hydroxylketone product A by hydrogen bonding,the selectivity of dehydration product β-unsaturated ketone B was increased.
出处
《化学试剂》
CAS
北大核心
2016年第7期621-624,共4页
Chemical Reagents
