Carbon dioxide reforming of methane to synthesis gas over Ni-MCM-41 catalysts

A series of nickel incorporated MCM-41 mesoporous molecular sieves (Ni-MCM-41) were prepared by direct hydrothermal synthesis. Nickel nitrate was used as the Ni precursor. The catalytic properties of the Ni-MCM-41 were studied for the reforming of methane with carbon dioxide. The catalysts were carefully characterized by X-ray diffraction (XRD), N₂ physisorption, H₂ temperature-programmed reduction (TPR), H₂ chemisorption, thermogravimetry, and Raman spectra. The results indicated that the presence of a suitable amount of nickel in Ni-MCM-41 was beneficial for maintaining high catalytic activity and long-term stability. The improved catalytic performance was suggested to closely associate with both the amount of active centers on the pore wall surface and the stabilized dispersion of these active sites by the silica matrix and/or the surrounding unreduced nickel ions. This anchoring effect facilitated the formation of the active Ni nano-clusters with high dispersion under reaction conditions. Hence the reforming reaction is favored and the carbon formation is suppressed. Two types of carbon species: active carbon and graphite were produced over the spent catalysts. The Ni-MCM-41 catalysts provided good catalytic activity, high stability and reasonable CO/H₂ ratios in the product. Thus, the Ni-MCM-41 catalyst prepared by the direct hydrothermal synthesis promised a novel and stable catalyst candidate for CO₂ reforming of CH₄.