Porous amorphous silica materials featured with large surface area and ordered mesopores such as MCM-41 and SBA-15 are widely used as catalysts or the supports in heterogeneous catalysis. During the past decades, numerous routes for the synthesis of MCM-41 materials have been developed. Recently, we developed a one-step method for the synthesis of [Si]MCM-41 and [Al]MCM-41 materials with different silica/alumina ratios at room temperature. This type of [Si]MCM-41 contained the high amount of OH groups with weak acidity, which could initiate the Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam with the highest activity compared with other types of silica. [Si]MCM-41 materials doped with Al were able to enhance the acidity of SiOH groups and generate Brønsted acidity in [Al]MCM-41, which were found to be catalytically active sites for phenylglyoxal conversion in alcohols and contributed the much higher turnover frequency (99.3/h) than a dealuminated zeolite Y (1.7/h). The high density of weakly acidic OH groups could enhance the Ni dispersion on the internal surface of [Si]MCM-41 to promote the hydrogen production and minimize the coke formation during biomass gasification. The location of Ni particles within MCM-41 support had influenced the catalytic performance. One significant advantage of our one-pot synthesis was to rapidly alter the surface property of MCM-41 for better multi-functional catalysts. For example, the open and close of support acidity had been tuned for the higher performance of Ni/MCM-41 catalysts in CO<sub>2</sub> reforming of methane. After the well design of surface acidity of [Al]MCM-41, it was observed that the ionic effects to Pt surface were generated by the covered acid sites rather than free acid sites and the late only enhanced the hydrogenation conversion of aromatic ketones. In addition, the rich base sites on MCM-41 could stabilize the catalytically active metal single-sites for the low-temperature water-gas shift reactions.

Nanocatalysts based on amorphous porous silica for high-efficient reaction processes

253rd National Meeting (2017)

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