论文部分内容阅读
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。
The organic amine modified mesoporous molecular sieve catalysts APTMS-FSM-16, MAPTMS-FSM-16 and DMAPTMS-FSM-16 were prepared. Compared with the typical organic amine and FSM-16 mixed catalysts, Aldol condensation reaction of formaldehyde with acetone. The experimental results showed that the order of catalytic activity of primary amine, secondary amine and tertiary amine co-catalyzed with FSM-16 was piperidine + FSM-16> cyclohexylamine + FSM-16> triethylamine + FSM-16. In the modified mesoporous molecular sieve catalyst, MAPTMS-FSM-16 showed the highest activity. The order of the catalytic activity of the catalyst was MAPTMS-FSM-16> APTMS-FSM-16> DMAPTMS-FSM-16. The study also found that after the graft modified catalyst MAPTMS-FSM-16 was recycled, the active site aminosilane grafted onto hydroxyl groups of FSM-16 decreased gradually and the activity of the catalyst decreased. At the same time, due to the increase of hydroxyl groups on the surface of mesoporous molecular sieve and the hydrogen bonding with β-hydroxyketone product A, the selectivity of β-unsaturated ketone B is increased.