Catalytic methanation reaction over alumina supported cobalt oxide doped noble metal oxides for the purification of simulated natural gas

A series of alumina supported cobalt oxide based catalysts doped with noble metals such as ruthenium and platinum were prepared by wet impregnation method. The variables studied were difference ratio and calcination temperatures. Pt/Co(10:90)/Al₂O₃ catalyst calcined at 700℃ was found to be the best catalyst which able to convert 70.10% of CO₂ into methane with 47% of CH₄ formation at maximum temperature studied of 400℃. X-ray diffraction analysis showed that this catalyst possessed the active site Co₃O₄ in face-centered cubic and PtO₂ in the orthorhombic phase with Al₂O₃ existed in the cubic phase. According to the FESEM micrographs, both fresh and spent Pt/Co(10:90)/Al₂O₃ catalysts displayed small particle size with undefined shape. Nitrogen Adsorption analysis showed that 5.50% reduction of the total surface area for the spent Pt/Co(10:90)/Al₂O₃ catalyst. Meanwhile, Energy Dispersive X-ray analysis (EDX) indicated that Co and Pt were reduced by 0.74% and 0.14% respectively on the spent Pt/Co(10:90)/Al₂O₃catalyst. Characterization using FT-IR and TGA-DTA analysis revealed the existence of residual nitrate and hydroxyl compounds on the Pt/Co(10:90)/Al₂O₃ catalyst.