Methanation of Syngas over Ni-Based Catalysts with Different Supports

摘要

CO methanation over the 20% nickel catalyst prepared by impregnation-precipitation method on different supports of commercial γ -Al_(2)O_(3), TiO_(2), SiO_(2) and nano- γ -Al_(2)O_(3)* 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 in pressure of 3 bar of H_(2):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 -Al_(2)O_(3)* < Ni/SiO_(2) < Ni/ γ -TiO_(2) < Ni/ γ -Al_(2)O_(3). The Ni/ γ -Al_(2)O_(3)*, which was prepared on the surface of nano milled γ -Al_(2)O_(3) support, produced methane from the lowest temperature of 178 to 350 in CO methanation. The Ni/ γ -Al_(2)O_(3)* 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 -Al_(2)O_(3)* were finely distributed, and their sizes were smaller compared to those in the traditional one. The pulverization of γ -Al_(2)O_(3) improved the dispersion of catalytic active nickel species inside porosity of the support leading to the improvement of its catalytic performance for CO methanation.