含氮杂原子B—Beta分子筛的制备及其对Knoevenagel缩合反应的催化性能

Preparation of nitrogen-incorporated B-Beta zeolites and their catalytic performance for Knoevenagel condensation

水热合成杂原子B-Beta分子筛,低温氮化二次处理制备N掺杂的新型碱催化剂,利用Knoevenagel缩合反应进行碱性催化性能评价,考察氮化温度、反应时间、不同氮化前驱体及催化剂稳定性对反应的影响。结果表明,采用低温500℃氮化处理的杂原子B-Beta分子筛催化剂具有优异的催化活性,苯甲醛转化率及产物选择性均接近100%。XRD、N_2吸附及FT-IR红外分析结果表明,反应活性好归因于低温氮化保留了较好的结晶度、高的比表面积及引入了对反应有利的碱性—NH_2和—NH—基团。

The novel basic catalysts were prepared by ammonia treatment of crystalline borosilicates zeolite at relatively low temperature by a secondary synthesis technique. The catalytic properties of the catalysts for Knoevenagel condensation of benzaldehyde with malononitrile were evaluated. The effects of nitridation temperature, reaction time, different zeolites and catalyst stability were investigated. The results showed that the sample nitridated at 500 ℃ exhibited the best catalytic activities and the conversion of benzaldehyde and the selectivity to the product over the catalyst were almost 100%. By means of XRD, nitrogen adsorption and FT-IR analysis techniques,the high activity of the catalyst was attributed to high crystallinity, high surface area and -NH2 and -NH- basic groups formed during the nitridation.