Direct confinement of Ru nanoparticles inside nanochannels of large pore mesoporous aluminosilicate for Fischer-Tropsch synthesis

Abstract

Metal/ordered mesoporous aluminosilicates (OMAS) have received great attention as bifunctional Fischer-Tropsch (FT) catalysts that directly convert syngas into liquid fuels. However, both synthesis of OMAS with large pores and efficient pore confinement of metal nanoparticles still remain challenging. Here, we report a simple method to synthesize Ru nanoparticles confined in the nanochannels of OMAS (Ru@OMAS). This method eliminates laborious multi-processes that are typically required for pore confinement of metal nanoparticles. We prepare three types of Ru@OMAS with different Si/Al molar ratios (denoted as Si/Al-x, x = 10, 30, and 50) having the same large pore size (similar to 30 nm) and Ru NP loading (3 wt%). Changing the Si/Al ratio strongly affects the number/strength of acid sites and the metal-support interaction, thereby mediating the catalytic activity and product selectivity. With increasing Al content (decreasing Si/Al ratio), support's acidity and metal-support interactions increase, whereas the reducibility of Ru decreases significantly. As a consequence, among the Si/Al-x catalysts, the Si/Al-50 shows the highest selectivity (63.6%) for liquid fuels (C-5-C-20) and excellent FT activity (CO conversion of 47.8%) due to its mild acidity and relatively good reducibility.