2017 Volume 60 Issue 6 Pages 311-321
Direct synthesis of methane from glycerol has been carried out over silica-modified nickel catalysts in the presence of water without the supply of hydrogen. The catalysts were synthesized by co-loading nickel species with silica on γ-Al2O3 by using a gel containing nickel and silica sources. In the conversion of glycerol over the Ni–SiO2/Al2O3 catalyst, glycerol was firstly decomposed to CO and H2; subsequently, methane was produced through the methanation of CO and CO2 with H2 generated during the reaction. Higher reaction temperatures and pressures resulted in the enhancement of the methane formation. In addition, the yield of methane was increased by increasing the water content in the glycerol aqueous solution. 20 wt%Ni-20 wt%SiO2/Al2O3 gave the maximum space-time yield (STY) of methane of 122 mol kg–1 h–1 with the feed of 50 wt% glycerol aqueous solution at 673 K under the pressure of 0.3 MPa. Co-loading of nickel species with silica on γ-Al2O3 was effective in suppressing the sintering of nickel particles. The coke deposition on the catalyst was significantly suppressed by modifying nickel particles with silica. The amount of deposited coke was decreased by increasing the amount of silica; the amount of coke deposited on Ni-30 wt%SiO2/Al2O3 was one-third of that on conventional Ni/γ-Al2O3.
