Influence of particle size and metal-support interaction on the catalytic performance of Ni-Al2O3 catalysts for the dry and oxidative-dry reforming of methane

Abstract

Dry reforming of methane (DRM) is a promising route for converting CH4 and CO2 to syngas. A Ni-Al2O3 catalyst was calcined at 500 and 850 °C to form NiAl-500 and NiAl-850. The oxidized nickel phase in both calcined catalysts are reduced to metallic nickel at conditions based on the temperature programmed reduction profile and found to be catalytically active for the DRM reaction with and without 7.5% v/v oxygen co-feed. Carbon deposition is most evident for DRM at 600 °C. Furthermore, after DRM the spent NiAl-500 shows detachment of nickel particles, whereas detachment was not readily seen in the spent NiAl-850 catalyst. By co-feeding oxygen, almost “carbon-free” operations were achieved even at 600 °C for both catalysts. The NiAl-500 catalyst possesses smaller particles due to lower reduction temperatures used. This catalyst shows higher CH4 and CO2 conversions, H2 and CO yields, and lower carbon formation for both reactions. At the same reduction temperature, the nickel particles in NiAl-500 were larger than those in NiAl-850 and the conversions and yields were smaller. Changes in the crystallite size and fraction of near-surface nickel were also detected in the catalysts after DRM and ODRM reactions.