Mesoporous MFI zeolite nanosponge supporting cobalt nanoparticles as a Fischer-Tropsch catalyst with high yield of branched hydrocarbons in the gasoline range

Abstract

A zeolite nanosponge was obtained by a seed-assisted hydrothermal synthesis route using C22H45− N+(CH3)2−C6H12−N+(CH3)2−C6H13 as the structure-direct-ing agent. The zeolite was composed of disordered network of 2.5-nm-thick MFI zeolite nanolayers having a narrow distribution of mesopore diameters centered at 4 nm. The highly mesoporous texture (mesopore volume = 0.5 cm3 g−1) was suitable for supporting cobalt nanoparticles with a narrow distribution of particle diameters centered at 4 nm. The Co/MFI zeolite exhibited high stability of the Co nanoparticles against particle growth, and there was accordingly high catalytic conversion of carbon monoxide to hydrocarbons and long catalytic lifetime in the Fischer−Tropsch synthesis. Furthermore, the Co/MFI catalyst exhibited high selectivity for branched hydrocarbons in the gasoline range (C5−C11), compared to conventional alumina-based catalysts. This high selectivity could be attributed to hydroisomerization in the extremely thin zeolite frameworks that provided short diffusion path lengths for branched hydrocarbons.