Direct conversion of syngas to isoparaffins over hierarchical beta zeolite supported cobalt catalyst for Fischer-Tropsch synthesis

Abstract

A hierarchical micro-meso-macroporous Beta zeolite (HB) was developed by a steam-assisted crystallization method and was employed for cobalt Fischer-Tropsch synthesis. Meso-macroporous silica (HS), alumina modified meso-macroporous silica (HAS) and conventional Beta zeolite (CB) were used for comparison. Structural characterization indicated that the as-synthesized HB exhibited nanosized Beta zeolite crystallites and a hierarchical micro-meso-macroporous structure. The HB supported catalyst showed very high isoparaffins selectivity because of the isomerization reaction at the strong acidic sites of the Beta zeolite, while due to its good macroporous structure, which is in favor of reducing the internal diffusion limitations, the methane selectivity was kept as low as HAS supported catalysts. In this paper, we use large particle catalysts for evaluation, which are very close to industrial condition. And the conclusions obtained may be very important for the design of new Fischer-Tropsch catalysts.