Deactivation studies over NiO/gamma-Al2O3 catalysts for partial oxidation of methane to syngas

Two types of NiO/gamma -Al2O3 catalysts prepared by the impregnation and th e sol-gel method were used for the partial oxidation of methane to syngas a t 850 degreesC (GHSV similar to 1.8 x 10(5) l kg(-1) h(-1)). The effects of the carbon deposition, the loss and sintering of nickel and the phase tran sformation of gamma -Al2O3 support on the catalytic performance during 80 h POM reaction were investigated with a series of characterization such as X RD, BET, AAS, TG, and XPS. The results indicated that the carbon deposition and the loss and sintering of nickel could not cause the serious decrease of catalytic performance over NiO/gamma -Al2O3 catalyst during the short-ti me reaction. However, the slow process of the support gamma -Al2O3 phase tr ansforming into alpha -Al2O3 could slowly decrease the performance of NiO/g amma -Al2O3 catalysts. Aimed at the reasons of the deactivation, an improve d catalyst was obtained by the complexing agent assisted sol-gel method. (C ) 2000 Elsevier Science B.V. All rights reserved.