Highly ordered cubic mesoporous aluminosilicates were synthesized using PEO 106 PPO 70 PEO 106 triblock copolymer and aluminosilicate sols containing Si-O-Al bonds, which are obtained by dissolving Na-A type zeolite in HCl, under mild acidic conditions (pH 1.9-3.2).The discovery of ordered mesoporous silicas (MSs) has led to a considerable interest in the development of various ordered mesoporous materials. 1 The high surface area and large pore sizes of ordered mesoporous aluminosilicates (MASs) have considerable potential for use as catalysts for conversion of highmolecular-weight petroleum fractions, which have high diffusion resistance through the micropores of conventional zeolites. Many research efforts have focused on developing MASs with a high content of Al tetrahedrally coordinated in the framework and with high hydrothermal stability. Recently, some methods for the preparation of MASs with short-range zeolitic building units have been reported. These methods are based on the use of protozeolitic nanoclusters, zeolite seeds prepared by a bottom-up approach from zeolite synthesis solutions. 2 The zeolite seeds are presumed to consist of zeolite primary and secondary structural building subunits, which provide Si-O-Al bonds originating in zeolite building units.Li et al. and Yang et al. have reported the synthesis of MASs using an aluminosilicate ester (sec-BuO) 2 AlOSi(OEt) 3 . 3 Aluminosilicate ester contains two alkoxide functionalities, one on the Si side and the other on the Al side, which may allow construction of a continuous Si-O-Al linkage. Inagaki et al. have prepared MCM-41 type MASs containing fragments of the structure of ZSM-5 zeolite using a filtrate of ZSM-5 dissolved by alkaline treatment. 4 On the other hand, our group has used zeolite LTA crystals dissolved in a HCl solution as both Al and Si precursors. 5 This method proceeds in two steps: (1) zeolite LTA crystals are dissolved in a HCl solution to produce a homogeneous solution containing Al and Si sources, and (2) a PEO 106 -PPO 70 PEO 106 triblock copolymer (Pluronic F127) coassembles with the inorganic species in the presence of an organic base tetramethylammonium hydroxide (TMAOH), followed by hydrothermal treatment. We note that the first step mentioned above is very important as it provides a Si-O-Al bond originating from a zeolite building unit.In this study, we have developed two-step synthesis of wellordered MASs under relatively mild acidic conditions. In the first step, zeolite nanoblocks are prepared by a top-down approach using zeolite crystals by dissolution of LTA in HCl solution at carefully controlled concentration. In the second step, we combine the above solution and aqueous Pluronic F127 solution in the absence of TMAOH to carry out the self-assembly process. We also describe the influence of pH on the mesostructure of products.In a typical preparation, 6 0.5 g of Pluronic F127 was dissolved in 130 g of deionized water with stirring at room temperature for 15 min. In parallel with the above procedure, 1 g of zeoli...
Aluminosilicate sols containing Si-O-Al bonds were obtained by dissolving zeolite LTA crystals in HCl solution. The solutions were used as single-source molecular precursors of silicon and aluminum. Highly ordered cage-like mesoporous aluminosilicates with Si/Al ratios ranging from 13 to 35 were synthesized using PEO 106 P-PO 70 PEO 106 triblock copolymer aqueous solution and LTA dissolved in HCl solution under mild acidic conditions.
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