Boosting propane dehydrogenation performance by engineering of cobalt positions in MFI zeolite

The distribution and location of active metal in zeolite determine the performance in catalytic processes, and catalysts encapsulated with small-sized and highly dispersed metal sites have received tremendous progress in propane dehydrogenation (PDH), while the identification of the migration of metal sites in silicalite-1 (S-1) and its structural characteristics have been rarely investigated. In this work, we engineered the location of cobalt in the S-1 by developing dissolution and recrystallization method, and migration behavior of cobalt during recrystallization stage is systematically investigated. It is found that active Co 2+ species are mainly located at the intersection of straight and sinusoidal β channels, and the abundance of Co 2+ located at β channel increase Lewis acid site of the catalyst, which regulates the catalyst more active in the PDH process. This work enriches a deep understanding of the β-located Co 2+ sites, and provides a novel idea for the synthesis of high-performance PDH catalysts.