Bifunctional Catalysts for One-Step Conversion of Syngas into Aromatics with Excellent Selectivity and Stability

Syngas (CO/H2) is a key platform for chemical utilization of non-petroleum carbon resources. Among syngas transformation routes, the direct synthesis of aromatics, which are among the most important bulk chemicals, is less successful because of the limited selectivity and poor catalyst stability. We report a successful design of bifunctional catalysts composed of Zn-doped ZrO2 nanoparticles dispersed on zeolite H-ZSM-5 for one-step conversion of syngas to aromatics with high selectivity and stability. Aromatics with 80% selectivity at CO conversion of 20% were achieved, and there was no catalyst deactivation in 1,000 hr. Methanol and dimethyl ether were formed as major intermediates on Zn-doped ZrO2, which were subsequently converted into aromatics on H-ZSM-5 via olefins. We discovered a self-promotion mechanism of CO in the selective formation of aromatics. As well as being a reactant, CO facilitates the removal of hydrogen species formed on H-ZSM-5 in the dehydrogenative aromatization of olefins.