Direct conversion of syngas to ethanol over Rh/Mn-supported on modified SBA-15 molecular sieves: Effect of supports

SBA-15 molecular sieves with a tunable pore size (SBA-15-HCl, SBA-15-HPMo, SBA-15-HPW, and SBA-15-HSiW) were synthesized through adding heteropoly acids to a template and extending crystallization time. Loaded with RhCl3 and Mn(NO3)2, SBA-15-HPMo catalyzed well the direct conversion of syngas to ethanol. In the first 2 h the CO conversion over the Rh-Mn/SBA-15-HPMo catalyst was up to 100%. Average CO conversion over the SBA-15-HPMo-supported catalyst increased significantly from 4.2 to 21.9% and selectivity to ethanol from 9.3 to 12.8% compared with the amorphous silica-supported one. The enhanced redox property of the encapsulated Rh and Mn oxides within the mesoporous channels, and multi-dispersed centers formed by confined metal particles contributed to improved catalytic performances.