Abstract:
The reforming of methane with CO₂ produces synthesis gas with high CO/H₂ ratio, which is suitable to produce higher hydrocarbons and oxygenated compounds by Fischer-Tropsch synthesis. In this study, the sol-gel technique, which has several advantages over conventional technique, was applied to prepare 5% Ni/Al₂O₃ catalyst and alumina support. The performance of 5% sol-gel catalyst on CH₄ reforming with CO₂ was compared to that of 5% impregnation catalysts supported on commercial alumina and on sol-gel alumina. It was found that all three catalysts deactivated with time on stream, because of carbon deposition on the catalysts resulting in total loss of catalytic activity. In addition, the reverse water gas shift reaction, the side reaction, uses H₂ to produce CO. Therefore, Co selectivity is higher than H₂ selectivity. Temperature programmed oxidation (TPO) on thermogravimetric analyzer (TGA) was used to determine the amount of carbon on the three prepared catalysts used for 20 hours. It was found that the carbon deposition on the catalyst can be oxidized at high temperatures in the range of 670-700 ℃ and % carbon on Ni/sol-gel Al₂O₃ is 147.61%, whereas that on sol-gel Ni/Al₂O₃ is 25.15% and on Ni/commercial Al₂O₃ is 17.89%.
