Revealing the effect of synergistic interaction between ZnO and ZnCr2O4 on the syngas aromatization

Zn-Cr-based catalysts are widely used as oxide catalysts for syngas aromatization, and it is difficult to study the synergistic effect of ZnO and Zn-Cr spinel due to the complex system of non-stoichiometric Zn-Cr spinels. In order to reveal the synergistic effect, we physically mixed ZnO and ZnCr2O4 with definite structure to avoid ambiguous structure of non-stoichiometric Zn-Cr spinels. The results showed that the introduced ZnO affected the oxygen vacancies generation and promoted the activation of CO and H-2, leading to an increase of oxygenates compared to the sole ZnCr2O4. Due to the synergy of ZnO and ZnCr2O4, the xZZC catalysts could produce more adsorbed species than the ZnCr2O4 catalyst, while the ZnCr2O4/ZSM-5 catalyst was more difficult to convert formate species. The ZnO in xZZC/ZSM-5 decreased the formate adsorption strength, which favored the continued conversion of formate and further realized the enhanced pulling effect on CO conversion.