An Easy Route to Synthesize Novel Mesostructured Silicas Al/SBA-16 and Its Catalytic Application
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An Easy Route to Synthesize Novel Mesostructured Silicas Al/SBA-16 and Its Catalytic Application Jing Ma • Liangsheng Qiang • Jinfu Wang Dongyan Tang • Xiangbo Tang
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Received: 9 July 2010 / Accepted: 29 October 2010 / Published online: 16 November 2010 Ó Springer Science+Business Media, LLC 2010
Abstract Al-containing SBA-16 (with different Si/Al molar ratios) was prepared by an easy post-grafting method using F127 as structure-directing agent and aluminum isopropoxide as Al source. The structure of the solid catalyst was fully characterized by X-ray diffraction (XRD) analysis, N2 adsorption, scanning electron micrographs (SEM), transmission electron micrographs (TEM) and 27Al MAS NMR. The results indicated that the materials possess three-dimension caged-like mesostructure and Al was successfully incorporated into the SBA-16 framework. The acid properties have been estimated by FT-IR of pyridine adsorption (Py-IR). Among various Si/Al ratios, Al/SBA16 with Si/Al ratio 20 performed good catalytic activity for the tert-butylation of phenol. Compared to hexagonal mesoporous Al/SBA-15, Al/SBA-16 showed higher catalytic properties due to its cage-like mesostructure, which could make the active acid sites more accessible to the reactant. Keywords Al/SBA-16 Three-dimensional Acid sites Tert-butylation Al/SBA-15
1 Introduction Mesoporous zeolites and M41S materials replaced the liquid acids and/or superacids in the application of catalysis field in past decades [1–6]. The M41S materials with a well ordered array of mesopores were applied as acid catalysts,
J. Ma L. Qiang (&) J. Wang D. Tang X. Tang Department of Chemistry, Harbin Institute of Technology, Harbin 150001, China e-mail: [email protected]
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but their relatively low hydrothermal stability and weak acidity would limit their practical application. To address this problem, mesoporous materials with periodically ordered pores have been developed. The mesoporous SBA materials synthesized by using a tri-block copolymer as structure-directing agent under strongly acidic conditions has attracted great attention in the field of catalysis [7–10]. Such materials exhibit high surface area, tunable pore diameters and good thermal stability which are significantly better than those of MCM-41 [11]. For new type of application, the materials with three-dimensional mesostructured porous have been developed. In particular, SBA-16 with three-dimensional channels is expected to be more favorable for immobilization of large molecules than the hexagonal structures with one dimensional channel [12–15]. In the past few years, large-pore mesoporous silica with cubic Im3m structure denoted as SBA-16-type was synthesized using F127 as a structure-directing agent under various synthesis conditions [16, 17]. Its unique threedimensional mesostructural channel is believed to provide a highly opened porous host for guest species. However, SBA-16 has not been studied extensively because of the difficult synthesis, such as strongly acidic conditions, the reagents c
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