Promotional effect of La 2O 3 and CeO 2 on Ni/γ-Al 2O 3 catalysts for CO 2 reforming of CH 4

Abstract

The CO 2 reforming reaction of CH 4 was conducted by using a Ni-based catalyst prepared by the co-impregnation method. The properties of the catalysts and the carbon deposition performance on the catalyst surface were surveyed by XRD, TPR, TG-DTA, and SEM. The results showed that the activity of the Ni/γ-Al 2O 3 catalyst with Ni loading of 10% was higher than that of those with other Ni loadings. However, the Ni/γ-Al 2O 3 catalyst was not stable in the continuous reaction due to a large amount of carbon deposition on the catalyst surface. Although the activity of Ni/γ-Al 2O 3 with the La 2O 3 and CeO 2 as promoters was not obviously increased, the carbon deposition on Ni/γ-Al 2O 3 with La 2O 3 and CeO 2 as promoters was greatly suppressed in the CO 2 reforming reaction of CH 4. The amount of carbon deposition on the 10%Ni/3%CeO 2–3%La 2O 3–γ-Al 2O 3 catalyst was reduced 76.2% compared with the 10%Ni/γ-Al 2O 3 catalyst, due to alkaline function and dispersion enhancement of La 2O 3–CeO 2, as well as the electronic interactions between CeO 2 and Ni. The results of SEM showed that the moss-like carbon on the 10%Ni/γ-Al 2O 3 catalyst was not easily gasified with CO 2 and Ni particles, which would result in the catalyst deactivation. On the other hand, the filamentous carbon on the 10%Ni/3%CeO 2–3%La 2O 3–γ-Al 2O 3 catalysts could be eliminated readily by gasifying with CO 2. Because of the suppression in the sintering of Ni particles and the dominant formation of the reactive filamentous carbon on the Ni-based catalyst that included La 2O 3 and CeO 2 promoters, 10%Ni/3%CeO 2–3%La 2O 3–γ-Al 2O 3 catalyst showed stable activity in the continuous CO 2 reforming reaction of CH 4 at 1073 K and atmospheric pressure.