Mesoporous materials first generation synthesis

The introduction of microporous and mesoporous supports with well-dispersed Ti has allowed for some detailed kinetic studies into the PO and water generation mechanisms primarily as a result of the outstanding stability of catalysts prepared from these materials. Prior to the synthesis of stable catalysts, a number of reaction mechanisms were proposed based on observed trends in reactivity, DPT calculations [63,64,76,78], and analogs to liquid-phase epoxidation reactions over Ti-based catalysts [14,15,89] rather than kinetic analysis. The first proposed mechanisms were constructed for the Au/Ti02 and Au/Ti02/Si02 system. 

External templates were used to structure silicates and generate porous materials for the first time in the early 1990s by independent groups in Waseda University in Japan [7] and at Mobil in the United States [8]. These syntheses took place under hydrothermal conditions similar to those for the synthesis of zeolites basic media and in the presence of cationic surfactants such as cetyltrimethylam-monium bromide. After this pioneer work, numerous silicates have been synthesized using a wide variety of surfectants. They have allowed the preparation of many mesoporous silicates such as MCM-41 with a hexagonal pore structure, MCM-48 with a cubic structure, and MCM-50 with a lamellar structure. 

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