Zhang Z, Han Y, Xiao F S, Qiu S, Zhu L, Wang R, Yu Y, Zhang Z, Zou B, Wang Y, Sun H, Zhao D, Wei Y
Department of Chemistry, Jilin University, Changchun 130023, China.
J Am Chem Soc. 2001 May 30;123(21):5014-21. doi: 10.1021/ja004138t.
Highly ordered hexagonal mesoporous aluminosilicates (MAS-5) with uniform pore sizes have been successfully synthesized from assembly of preformed aluminosilcate precursors with cetyltrimethylammonium bromide (CTAB) surfactant. The aluminosilicate precursors were obtained by heating, at 100--140 degrees C for 2--10 h, aluminasilica gels at the Al(2)O(3)/SiO(2)/TEAOH/H(2)O molar ratios of 1.0/7.0--350/10.0--33.0/500--2000. Mesoporous MAS-5 shows extraordinary stability both in boiling water (over 300 h) and in steam (800 degrees C for 2 h). Temperature-programmed desorption of ammonia shows that the acidic strength of MAS-5 is much higher than that of MCM-41 and is comparable to that of microporous Beta zeolite. In catalytic cracking of 1,3,5-triisopropylbenzene and alkylation of isobutane with butene, MAS-5 exhibits greater catalytic activity and selectivity, as compared with MCM-41 and HZSM-5. The MAS-5 samples were characterized with infrared, UV--Raman, and NMR spectroscopy and numerous other techniques. The results suggest that MAS-5 consists of both mesopores and micropores and that the pore walls of MAS-5 contain primary and secondary structural building units, similar to those of microporous zeolites. Such unique structural features might be responsible for the observed strong acidity and high thermal stability of the mesoporous aluminosilicates with well-ordered hexagonal symmetry.
通过将预制的铝硅酸盐前驱体与十六烷基三甲基溴化铵（CTAB）表面活性剂组装，成功合成了具有均匀孔径的高度有序的六方介孔铝硅酸盐（MAS-5）。铝硅酸盐前驱体是通过在100-140℃下加热2-10小时，由摩尔比为1.0/7.0-350/10.0-33.0/500-2000的铝硅凝胶获得的。介孔MAS-5在沸水中（超过300小时）和蒸汽中（800℃下2小时）都表现出非凡的稳定性。氨程序升温脱附表明，MAS-5的酸性强度远高于MCM-41，与微孔β沸石相当。在1,3,5-三异丙基苯的催化裂化和异丁烷与丁烯的烷基化反应中，与MCM-41和HZSM-5相比，MAS-5表现出更高的催化活性和选择性。通过红外、紫外-拉曼和核磁共振光谱以及许多其他技术对MAS-5样品进行了表征。结果表明，MAS-5由介孔和微孔组成，并且MAS-5的孔壁包含初级和次级结构单元，类似于微孔沸石。这种独特的结构特征可能是观察到的具有良好有序六方对称性的介孔铝硅酸盐具有强酸性和高热稳定性的原因。
