Production of Hydrogen and Carbon Nanofiber via Methane Decomposition

Abstract

Ni/MgO and Ni/O-D(oxidized diamond) catalysts were prepared by wetness impregnation method.The effects of reaction temperature and space velocity of methane on the methane conversion were investigated in a fixed-bed.The surface area,structure and morphology were characterized with BET,XPS,SEM,EDS techniques.The results show that the conversion of methane was above 8% within 150 min(t=500 ℃) in the presence of 33Ni/O-D catalyst and higher than 25% within 120 min(t=650 ℃) in the presence of 41Ni/MgO catalyst.The initial conversion increases with the increasing temperature of the decomposition reaction,but their catalytic activities decrease rapidly if the temperature is too high.Decreasing the space velocity of methane is propitious to improving the methane conversion,but not favorable for the hydrogen yield.The appearance of carbon resulted from the methane decomposition lies on the support type and the condition of catalytic reaction.It showed fiber shape on the surface of Ni/O-D at the relatively lower temperature such as 500 ℃ and 550 ℃,but grain shape stacked on and overlaid on the surface of the metal nickel at 650 ℃.The carbon fiber can form on the Ni/MgO surface at 650 ℃ and the diameter of the carbon fiber increases with the decreasing space velocity.