Non-oxidative conversion of methane into olefins using bimetallic Ni-Mo/HZSM-5 catalysts

Abstract

The direct route under non-oxidative conditions enables the intermediate syngas step to be suspended from processes that convert methane into olefins as well as prevents the carbon dioxide formation. The performance of bimetallic Ni-Mo supported on HZSM-5 (Si/Al = 25) has been studied for non-oxidative conversion of methane into olefins. The catalysts were prepared by polyol mediate process with the different loading of nickel (0.5 - 3 wt%) and molybdenum (3 wt%). They were tested for the reaction using a continuous down flow fixed-bed reactor under non-oxidative conditions at atmospheric pressure, GHSV of 1,500 ml/g/h. At the given condition, the effects of nickel loading, reaction temperature, and methane feed concentration were studied. From the result, the increasing of Ni content from 0.5 to 3 wt% increased the ethylene selectivity and aromatics selectivity decreased especially benzene and toluene. However, the 3%Ni/HZSM-5 provided the 100 % selectivity of ethylene. It can be suggest Ni would play an important role in enhancing the ethylene formation and obstructed the aromatization of ethylene. However, coke formation would prevail resulting in the deactivation of catalysts at a longer TOS. Furthermore, the effect of reaction temperature and methane feed concentration play the important roles for this reaction by improve favorable thermodynamics of reaction and enhance the methane conversion and ethylene selectivity.