Single step methane conversion to value-added products is an attempt to economically exploit the unlocked vast resources of low cost stranded natural gas reservoir, but this valorization step is impeded by rapid deactivation by coking of zeolite-based bi-functional catalyst. In the present study, efforts have been made by studying the effect of in-situ transformation of molybdenum oxide grafted on MFI to its carbide phase to retard the coke formation rate. It is found out that increment in the carbon chain length of the carburizing agent results in the particle size reduction with an average particle diameter less than 5nm. Carburization of Mo/MFI with a mixture of H2 and C1 molar ratio (3:1) at moderate temperature, 450°C (CAT 1) for 4 hours results in hexagonal close packing carbide whereas induction of carbon using modeled natural gas stabilizes the carbide giving rise to metastable FCC carbide (CAT2) as verified by XRD. The accretion in performance and stability of bi-functional catalyst is credited to the formation of metastable Mo carbide face-centered cubic (FCC) structure. Choice of higher hydrocarbon and formulation procedure results in the steady-state methane conversion of 9% at 700°C in a fixed-bed reactor coupled with gas chromatography and benzene formation rate with a maximum of 2750 nmol/gcat.s and three time less coke formation rate (5000 nmol/gcat.s ) as compared to conventional carburization procedure.

Study of parameters affecting carburization extent of active metallic species for the non-oxidative valorization of natural gas

256th National Meeting (2018)

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