Oligomerization of methane via microwave heating using Raney nickel catalyst

Raney nickel has been used for the catalytic activation of methane using microwave radiation as a heating source. The effects of irradiation time, power level, and pretreatment of the catalyst have been studied. Compared to previous studies, higher catalytic activity was observed for Raney nickel than for regular nickel powder. The maximum conversion obtained was 24% at 400 W and 10 min of irradiation time. For regular nickel powder that conversion can be achieved only after 700 W of power and more than 20 min of reaction. BET surface area, scanning electron microscopy, X-ray photoelectron spectroscopy, and temperature-programmed desorption and reduction analysis were performed to characterize the catalyst before and after reaction. Oligomers such as ethylene, benzene, and ethane have been prepared selectively under different conditions. Ethylene, with a selectivity of 70%, was the major product at 530 W and 5 min of irradiation time. Deactivation of Raney nickel by fouling and sintering was observed after 500 W and/or 15 min of reaction.