Enhancing syngas-to-aromatics performance of ZnO&H-ZSM-5 composite catalyst via Mn modulation

Abstract

Application of cheap and environmentally friendly ZnO to oxide–zeolite composite catalysts for the syngas-to-aromatics (STA) reaction is still challenging. Here, we report 80.1% aromatics in products excluding CO2, with 14.8% CO conversion over a mixed composite catalyst containing H-ZSM-5 and nanosized porous ZnO modulated by Mn. As little as 0.6–3.0 wt% of Mn can lead to a dramatic decrease in the particle size of ZnO and an obvious increase in oxygen vacancies. Mn species themselves do not act as the primary catalytic sites. The ability to convert syngas is positively correlated with oxygen vacancy concentration, whereas the ability to hydrogenate olefins is negatively correlated with it. The porous aggregated nanoparticles of ZnO modulated by Mn are resistant to sintering during syngas conversion. This provides a new strategy for STA catalyst design.