文献类型：期刊文献

英文题名：Comparative studies of Zr-based MCM-41 and MCM-48 mesoporous molecular sieves:: Synthesis and physicochemical properties

作者：Chen, L.F.[1]; Zhou, X.L.[2]; Nore?a, L.E.[1]; Wang, J.A.[3]; Navarrete, J.[4]; Salas, P.[4]; Montoya, A.[4]; Del Angel, P.[4]; Llanos, M.E.[4]

机构：[1]Univ Autonoma Metropolitana Azcapotzalco, Dept Ciencias Basicas, Mexico City 02200, DF, Mexico;[2]E China Univ Sci & Technol, Petr Proc Res Ctr, Shanghai 200237, Peoples R China;[3]Inst Politecn Nacl, SEPI, ESIQIE, Lab Calalisis & Mat, Mexico City 07738, DF, Mexico;[4]Inst Mexicano Petr, Grp Mol Ingn, Mexico City 07730, DF, Mexico

年份：2006

卷号：253

期号：5

起止页码：2443

外文期刊名：APPLIED SURFACE SCIENCE

收录：;EI(收录号：20064910286423);WOS:【SCI-EXPANDED(收录号:WOS:000243244300015)】；

语种：英文

外文关键词：mesoporous solid; Zr-MCM-41; Zr-MCM-48; surface acidity; templated synthesis

摘要：Two surfactant-templated synthetic routes are developed for the preparation of new types of mesoporous molecular sieves, Zr-MCM-41 and Zr-MCM-48, using different Si sources but keeping the same zirconium precursor (zirconium-n-propoxide). When fumed silica was used as Si precursor, a Zr-MCM-48 material of cubic structure was formed with a surface area of 654.8 m(2)/g and an unimodal pore diameter distribution. It shows low stability: after calcination at 600 degrees C, the ordered structure was transformed into a relatively disordered worm-like mesostructure with many defects and silanol groups. The use of tetraethyl orthosilicate as Si source led to the formation of a Zr-MCM-41 mesoporous solid, which had good thermal stability and a highly ordered hexagonal arrangement, with a surface area 677.9 m(2)/g and an uniform pore diameter distribution. Fourier transform infrared (FT-IR) characterization and Si-29 NMR analysis confirm that zirconium ions indeed incorporated into the framework of the solid. The in situ FT-IR spectroscopy of pyridine adsorption reveals that both, Lewis and Bronsted acid sites, were formed on the surface of these mesoporous materials. The strength and number of the Bronsted acid sites of the Zr-MCM-48 solid were greater than those of the Zr-MCM-41, due to a lower degree of condensation reaction during the synthesis that led to more structural defects in the framework and more silanol groups stretching from the solid surface. (c) 2006 Elsevier B.V. All rights reserved.