Methanation of Syngas over Ni-Based Catalysts with Different Supports

CO methanation over the 20% nickel catalyst prepared by impregnation-precipitation method on different supports of commercial γ-Al₂O₃, TiO₂, SiO₂ and nano-γ-Al₂O₃* was investigated. The nano-γ-Al2O3* support was pulverized using a ball milling method. Catalyst characterization was done using the methods of BET, XRD, SEM, ICP-OES methods. Carbon monoxide methanation process was carried out at the temperature of 350°C in pressure of 3 bar of H₂:CO syngas with the molar ratio of 3:1 and with the GHSV of 3000 h^-1 in a fixed bed reactor. The initial temperature of methane formation increased according to the order of Ni/γ-Al₂O₃* < Ni/SiO₂ < Ni/γ-TiO₂ < Ni/γ-Al₂O₃. The Ni/γ-Al₂O₃*, which was prepared on the surface of nano milled γ-Al₂O₃ support, produced methane from the lowest temperature of 178°C to 350°C in CO methanation. The Ni/γ-Al₂O₃* catalyst gave the highest amount of methane (0.1224 mmol/g-cat) for 1 h methanation among other catalysts. XRD and SEM analysis proved that NiO particles in the Ni/γ-Al₂O₃* were finely distributed, and their sizes were smaller compared to those in the traditional one. The pulverization of γ-Al₂O₃ improved the dispersion of catalytic active nickel species inside porosity of the support leading to the improvement of its catalytic performance for CO methanation.