Studies on stability and coking resistance of Ni/BaTiO 3–Al 2O 3 catalysts for lower temperature dry reforming of methane (LTDRM)

Abstract

Wt.%BaTiO 3–Al 2O 3 (wt.%BaTiO 3 = 0–100%) composite supports were synthesized through varying the BaTiO 3 content by the “sol–(xero)gel” method. Ni/wt.%BaTiO 3–Al 2O 3 nickel-based catalysts prepared by incipient wetness method were evaluated for dry reforming of methane carried out between 690 °C and 800 °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.%BaTiO 3–Al 2O 3 composite supports as well as the Ni/wt.%BaTiO 3–Al 2O 3 catalysts. The results demonstrate that BaTiO 3 particles are discontinuously dispersed on the surface of γ-Al 2O 3 in the form of individual isolated particles for the wt.%BaTiO 3–Al 2O 3 composite supports. Meanwhile, it is probably that the coexistence of BaAl 2O 4 spinel phase with the BaTiO 3 phase on the surface of γ-Al 2O 3 inhibits the Ni/wt.%BaTiO 3–Al 2O 3 catalysts from the formation of NiAl 2O 4 spinel phase, improving the catalytic performance of the catalysts. The Ni/BaTiO 3 catalyst showed poor stability and severe coke formation in the dry reforming of methane tested at 690 °C, which was thought to be mainly originated from the excessive strong electronic donor intensity of Ni/BaTiO 3 catalyst as well as the resulted CO disproportionation reaction. Compared with the Ni/BaTiO 3 catalyst, the Ni/wt.%BaTiO 3–Al 2O 3 catalysts with the addition of BaTiO 3 had a higher dispersion of active nickel and a weakened electronic donor intensity of the NiO x species. As a result, the synthesized Ni/32.4%BaTiO 3–Al 2O 3 catalyst exhibited a high catalytic activity, excellent stability as well as coking resistance for lower temperature dry reforming of methane.