Accelerated syngas-to-heavy fuels production in heterogeneous catalysis via a proximity effect between a promoter and an active site
Chuan Qin, Ke Wu, Yanfei Xu, Shupeng Guo, Rui Li, Haifeng Fan, Di Xu, Mingyue Ding
Abstract
The proximity between a promoter and an active site can be crucial in influencing heterogeneous catalysis, but it is unclear if there is an optimal scale for proximity. Herein, we investigate the intimacy effect between a promoter (Mn) and a metal catalyst (Co) in the syngas-to-heavy hydrocarbons reaction. Building on the base structure of a yolk-shell catalyst, three catalysts with different intimacies—atom doping, contacted nanoparticles, and separated nanoparticles—are adjusted by changing the relative position of Mn. The contacted nanoparticles are the optimal system (Co-Mn@SiO2), facilitating rapid electron transfer to active sites and promoting the formation of heavy hydrocarbons (C5+). In contrast, the atomic doping strategy reduces the Co reduction degree and leads to strong CO adsorption that hampers the reaction. The Co-Mn@SiO2 with optimized Mn content shows excellent C5+ selectivity (95.5%) with limited methane selectivity (2.2%). The C5+ productivity reaches rates of 1.8 gC5+ gcat−1 h−1, which is in line with the best reported catalytic systems.