Enhanced stability of CO2-assisted shale gas aromatization through the introduction of Mg promoter on Mo/ZSM-5

CO2-assisted shale gas aromatization is an effective method for directly producing benzene, toluene, and xylene (BTX) and H2 as well as for suppressing coke formation compared to non-oxidative conversion. However, Mo/ZSM-5, the conventional catalyst for aromatization, should be improved to make it more resistant to coke formation and enhance the BTX yield further for practical applications of the proposed reaction system. This study proposes Mg-promoted Mo/ZSM-5, labeled as Mg/Mo/ZSM-5, to enhance the efficiency of CO2-assisted shale gas aromatization by controlling the acidic and basic properties of Mo/ZSM-5. The addition of Mg on Mo/ZSM-5 selectively removed its Brønsted acid sites and increased its base site density, resulting in the enhanced catalytic stability by suppressing hard coke formation and protecting the active phase of Mo. Thus, the modified catalyst showed a higher BTX production than conventional Mo/ZSM-5, with the complete conversion of CO2 over a longer period than with Mo/ZSM-5. These benefits were maximized at a CO2 concentration of 10 %; moreover, the Mg/Mo/ZSM-5 catalyst improved regeneration efficiency.