Direct aromatization of methane hydrate to chemicals on Mo-based ZSM-5 catalysts under extraordinary condition

Abstract

The direct aromatization of methane hydrate to naphthalene and hydrogen over Ga(Zn)-Mo/ZSM-5 catalysts is important in terms of effective utilization of natural gas under conditions of supersonic expansion. Reaction intermediates, products and reactants were analyzed using a sensitive time-of-flight mass spectrometry and gas chromatography, respectively. The structure and properties of the Mo-based catalyst were characterized by means of techniques such as TPR, NH3-TPD, BET, HRTEM and XRD. There is a clear change of product distribution and the increase of hydrogen production, plausibly due to a change in reaction pathways. The presence of a small mount of water in the methane feedstock can improve the stability of the Mo-based catalyst. The TPO and NH3-TPD studies of used catalyst reveal that the presence of water vapor can effectively suppress the formation of coke and regulate the acid-base properties of catalyst.