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Synthesis and Catalytic Performances of Mesoporous Zeolites Templated by Polyvinyl Butyral Gel as the Mesopore Directing Agent

2008; American Chemical Society; Volume: 112; Issue: 44 Linguagem: Inglês

10.1021/jp805766m

1932-7455

Haibo Zhu, Zhicheng Liu, Dejin Kong, Yangdong Wang, Zaiku Xie,

Polyoxometalates: Synthesis and Applications

The mesoporous zeolites with BEA and MEL topology were synthesized by using polyvinyl butyral gel as the mesopore directing agent. The PVB/silica composite was readily prepared by sol−gel technique and then used as precursor for the synthesis of mesoporous zeolites. Upon the direct hydrothermal crystallization of PVB/silica composite, the silica was transformed into zeolite, whereas the PVB gel was incorporated in the zeolite crystals. Calcination of the obtained PVB/zeolite composite yielded the opening of micropores and mesopores in zeolites, respectively. The characterization techniques confirmed that the obtained porous materials consisted of well-defined microporosity and irregular mesoporosity. The mesoporous zeolites exhibited higher conversion and enhanced resistance toward deactivation in the cracking of 1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene, as compared with conventional zeolites. The improved catalytic activity can be attributed to the more efficient diffusion of reactants and products in the crystals with the help of mesopores.