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 °C and 800 °C. Characterizations using XRD, IR, N2 adsorption–desorption, H2-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 γ-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 γ-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 °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.
Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (113 K)Download as PowerPoint slideHighlights► The dispersion of BaTiO3 on γ-Al2O3 enlarges the specific surface area of BaTiO3. ► The strong electronic donor intensity of Ni/BaTiO3 catalyst results in heavy coking. ► The ideal electronic donor intensity of the synthesized catalyst was proved by XPS.
Journal: Applied Catalysis A: General - Volumes 413–414, 31 January 2012, Pages 163–169