介孔分子筛MCM-48的氮化与表面胺化及其碱催化反应性能

Nitridation and surface amino-functionalization of mesoporous molecular sieve MCM-48 as solid base material and its basic catalytic performance

以介孔分子筛MCM-48为前驱体,通过表面胺化和高温NH3氮化方法制备出两种碱性分子筛.采用X射线衍射(XRD)、N2-吸附脱附、透射电镜(TEM)、红外光谱(FT-IR)、热重分析(TG)和哈密特指示剂法对上述分子筛的结构及表面酸碱性进行了详细表征,并通过苯甲醛与丙二腈的Knoevenagel缩合反应对其碱催化活性及稳定性进行了考察和对比.结果表明,表面胺化和高温氮化的方法均可制备出碱性介孔分子筛,且均在Knoevenagel碱性探针反应中表现出较好的碱催化活性,但与后者相比,前者制备的碱性分子筛具有更强的表面碱性和更好的反应稳定性.

Mesoporous molecular sieve MCM-48 were modified with （3-Aminopropyl）triethoxysilane and nitridized in ammonia at 950 ℃, respectively, to obtain two different types of mesoporous solid base catalysts. The structure and surface property of as-prepared samples were characterized by XRD, N2 adsorption-desorption, TEM, FT-IR, TG and Hammett indicator methods. The Knoevenagel condensation reaction between benzaldehyde and malononitrile was employed to explore the basic catalytic property and re-usability of as-prepared samples. The results showed that basic mesoporous molecular sieves can be prepared by both surface amino-functionalization and nitridation, and both samples present good basic catalytic properties in the Knoevenagel condensation. Compared to nitridized sample, the sample prepared by amino-functionalization exhibited stronger surface basicity and better catalyst recyclability as well.