Platinum nanoparticles, ‘intimately’ incorporated in aluminum modified amorphous mesoporous silica, produce highly efficient bifunctional catalyst for n-hexadecane isomerization. Superior catalytic performance of the modified silica catalyst, as compared to zeolite catalyst, is primarily due to sufficiently mild acidic sites generated by post-synthetic doping of the silica surface with aluminum species. Systematic investigation of the catalytically relevant factors shows that platinum nanoparticles with the smallest particle size and mesoporous silica with the highest concentration of Brønsted acid sites produce the most effective hydroisomerization catalyst. The smallest nanoparticles are more likely to generate more ‘intimate’ bifunctional sites because of higher and more uniform inclusion of the particles in the mesoporous silica. Regardless of the pore size and structure of the aluminum modified silica supports, hydroisomerization turnover frequency linearly increases as a function of surface Brønsted acid density, demonstrating the unusual catalytic property of the aluminum modified silica. Furthermore, amorphous silica catalysts isomerize n-hexadecane with nearly 100% selectivity, while crystalline microporous silica and zeolite catalysts produce considerable amount of cracked products. All in all, our work presents an efficient hydroisomerization catalyst with distinct properties and the ways to optimize its catalytic activity.

Hydroisomerization of n-hexadecane: Remarkable selectivity of platinum nanoparticles supported on amorphous mesoporous silica post-synthetically modified with aluminum

253rd National Meeting (2017)

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