Mo2C/Graphene Nanocomposite As a Hydrodeoxygenation Catalyst for the Production of Diesel Range Hydrocarbons

Abstract

Carbon-supported Mo2C nanoparticles were synthesized and used as catalysts for the deoxygenation of oleic acid and soybean oil to produce diesel-range hydrocarbons. Various carbon materials, such as reduced graphene oxide (RGO), glassy spherical carbon (SC), activated carbon (AC), and mesoporous carbon (MC), were used as supports to determine the effects of RGO in the deoxygenation reactions. The effects of the flow rate, Mo content of the catalyst, and the structure of the carbon support on the conversion and product selectivity were investigated. The morphology analysis revealed that Mo2C nanoparticles were well-dispersed onto the RGO (Mo2C/RGO). Under moderate reaction condition (T = 350 degrees C, P = 5.0 MPa, H-2/oil ratio = 4.5, LHSV = 2 h(-1)), oleic acid was efficiently deoxygenated using the Mo2C/RGO catalyst, which produced hydrocarbons with >= 85% yield and >= 90% hydrocarbon selectivity. This value was much higher than those obtained using the Mo2C/SC, Mo2C/AC, and Mo2C/MC catalysts (yields = 18.550.3%) under identical conditions. The higher catalytic activity of the RGO-supported catalyst originated from its large pore size, which facilitated transport of the reactants, and uniform deposition of the Mo2C nanoparticles on the RGO surface. Even over a short contact time (LHSV = 8 h(-1)) and using natural triglyceride as a reactant, the Mo2C/RGO catalyst exhibited >= 40% yield of hydrocarbons, whereas a commercial CoMoSx/Al2O3 catalyst produced <= 10% yield under identical conditions. The Mo2C/RGO catalyst was highly selective toward CO bond scission in the hydroxyl group, which produced water and hydrocarbons without truncating the carbon skeleton of the starting material. Mo2C/RGO exhibited a prolonged catalyst lifetime for the deoxygenation of soybean oil (13% decrease in conversion after 6 h), compared with the commercial CoMoS/Al2O3 catalyst (42% decrease).