Impact of extreme downsizing of *BEA-type zeolite crystals on n-hexadecane hydroisomerization

Abstract

A series of *BEA-type zeolites with crystal sizes ranging from few nanometers to micrometers were synthesized. These materials were then transformed into bifunctional catalysts by platinum loading and tested in n-hexadecane isomerization. The behavior of Pt/H-*BEA catalysts depends on several parameters such as the balance between the platinum and acid functions, the metal particle size and the zeolite crystal size. In order to design an “ideal” bifunctional catalyst, the metal and acid sites must be well balanced to avoid the cracking of isomer products at low conversion, the metal must be well dispersed in order to inhibit the hydrogenolysis side reactions, and the crystal size must be as small as possible to maximize the isomer yield. But, the extreme decrease of the zeolite crystal thickness to few zeolite unit cells lowers the turnover frequency of acid sites and favors the metal sintering.