Strategies for Improving Active Chemistry, Mitigation of Coke Formation and Sustaining Selectivity to Benzene in the Catalytic Aromatization of Methane

The heterogeneous catalytic conversion of methane, CH₄, to a mixture of benzene and hydrogen, by the non-oxidative methane aromatization reaction (6 CH₄(g) --> C₆H₆(g) + 9H₂(g)) constitutes a direct, one step process that upgrades methane to added-value products. Since this process does not require reagents, it can be performed at the gas source at lower cost. Our group is carrying out a fundamental and systematic study of this catalytic reaction with the goal to answer some fundamental questions, which can mitigate the technological challenges of this process.

Zeolite-supported molybdenum oxide catalysts have so far been the most widely studied catalysts for the methane aromatization reaction. Rapid catalyst deactivation and low conversions are disadvantages that impede commercialization of the methane aromatization process. It is agreed that Mo carbide species, originated by exposure of the Mo oxide species to the reactant methane, are responsible for methane activation, however, the nature and amount of carbide phases formed in the induction period of the reaction are not controlled.

We have explored pretreatment conditions that are necessary to purposefully prepare zeolite-supported metal carbide phases with the best catalytic properties and relate the reaction and deactivation pathways to the structure of specific carbide phases.