Studies on stability and coking resistance of Ni/BaTiO3-Al2O3 catalysts for lower temperature dry reforming of methane (LTDRM)

Wt.%BaTiO3-Al2O3 (wt.%BaTiO3 = 0-100%) composite supports were synthesized through varying the BaTiO3 content by the sol-(xero)gel method. Ni/wt.%BaTiO3-Al2O3 nickel-based catalysts prepared by incipient wetness method were evaluated for dry reforming of methane carried out between 690 degrees C and 800 degrees C. Characterizations using XRD, IR, N-2 adsorption-desorption, H-2-TPR, SEM, and XPS were conducted to investigate the structure or properties of the wt.%BaTiO3-Al2O3 composite supports as well as the Ni/wt.%BaTiO3-Al2O3 catalysts. The results demonstrate that BaTiO3 particles are discontinuously dispersed on the surface of gamma-Al2O3 in the form of individual isolated particles for the wt.%BaTiO3-Al2O3 composite supports. Meanwhile, it is probably that the coexistence of BaAl2O4 spinel phase with the BaTiO3 phase on the surface of gamma-Al2O3 inhibits the Ni/wt.%BaTiO3-Al2O3 catalysts from the formation of NiAl2O4 spinel phase, improving the catalytic performance of the catalysts. The Ni/BaTiO3 catalyst showed poor stability and severe coke formation in the dry reforming of methane tested at 690 degrees C, which was thought to be mainly originated from the excessive strong electronic donor intensity of Ni/BaTiO3 catalyst as well as the resulted CO disproportionation reaction. Compared with the Ni/BaTiO3 catalyst, the Ni/wt.%BaTiO3-Al2O3 catalysts with the addition of BaTiO3 had a higher dispersion of active nickel and a weakened electronic donor intensity of the NiOx species. As a result, the synthesized Ni/32.4%BaTiO3-Al2O3 catalyst exhibited a high catalytic activity, excellent stability as well as coking resistance for lower temperature dry reforming of methane. (C) 2011 Elsevier B.V. All rights reserved.