Transition-metal influence (Fe, Co, Ni, Cu) on the MoWS catalyst for biphenyl hydrogenation

Abstract The hydrogenation of aromatic hydrocarbon compounds derived of hydrocarbon fuels is crucial to avoid the current environment pollution, harmful to human health. Also, the hydrogenated products can be used as chemical intermediates, additives, and in other chemical processes. The search of efficient and cost-effective catalysts for the hydrogenation of aromatic hydrocarbon compounds is a current challenge in the industrial and scientific community. In this study, trimetallic unsupported MMoW (M = Fe, Co, Ni, and Cu) sulfide catalysts were synthetized and tested in the liquid-phase biphenyl (BP) hydrogenation at 300 °C and 5.5 MPa of H2 pressure. The catalysts were characterized by XRD, SEM-EDX, TEM-SAED and adsorption–desorption of N2. The presence of NiS, CoSx, MoFe2S4, Cu9S5 crystalline sulfide phases together with Mo(W)S2 crystalline sulfide phase, as well as the crystallite size and the surface area, influenced the catalytic performance. Ni-based catalysts were the most active in the BP hydrogenation. A BP conversion value of ~99% of biphenyl and selectivity of 52% towards cyclohexylbenzene (CHB) and 47% towards bicyclohexyl were reached using NiMoWS catalyst. The presence of NiS crystals, stacked curve-shape Mo(W)S2 crystalline phases and larger surface area values increased the catalytic activity using NiMoWS catalysts.