钛硅分子筛(TS-1)是一种新型的环境友好催化剂,它的成功应用被认为是八十年代沸石催化领域的里程碑。由于TS-1分子筛中四价钛取代四价硅进入分子筛骨架,没有多余的电荷需要平衡,因此通常认为TS-1分子筛晶体中没有
很强的酸性。尽管TS-1分子筛被认为是氧化的催化剂,然而,越来越多的研究表明,TS-1分子筛催化氧化的本质可以仅仅被认为是分子筛作为固体Lewis酸催化剂提高了氧化剂的亲电性,从而促进了反应的进行。因此,对TS-1分子筛的酸性研究不容忽视。本论文采用高分辨固体核磁共振技术,研究了TS-1分子筛的酸性、催化活性中心以及酸性对苯乙烯氧化反应产物分布的影响,并且结合顺磁共振技术与理论模拟计算等方法对TS-1分子筛催化苯乙烯氧化反应的机理进行了研究。主要结果如下:
1.测定了TS-1分子筛的~1H MAS NMR谱和吸附三甲基膦碱性探针分子后的~(31)P MAS NMR谱,发现在TS-1分子筛中既存在Brφnsted酸中心,也具有Lewis酸中心。这些Brφnsted酸中心来自分子筛本身的缺陷位,如TiOH和部分SiOH,Lew...
【英文摘要】
The successful synthesis of titanium rnolecuiar sieve TS-1 which is an environment benign catalyst has been considered to be a milestone in zeolite catalysis in 80th. Since TS-1 zeolite contains a very small percentage of Ti substituting Si and there is no charge on the framework, it is usually recognized that there should be no strong acidity in TS-1 zeolite. While TS-1 was initially described as a redox catalyst, it is now being increasingly recognized simply as a Lewis acid solid, in which the tetracoord...