Catalytic properties of Rh, Ni, Pd and Ce supported on Al-pillared montmorillonites in dry reforming of methane

A natural Maghnia clay was pillared by Al-13 and impregnated by 3-10 wt.% Me (Me = Rh, Ni, Pd, Ce) to be used as catalysts in the reforming of methane with carbon dioxide to synthesis gas. The structural and textural properties of materials calcined at 450 degrees C were determined by several techniques (XRD, FT-IR, Al-27 magic angle spinning (MAS) NMR, X-ray photoelectron spectroscopy (XPS), BET, thermogravi metric analysis (TCA)-DSC, H-2-temperature programmed reduction (TPR) and NH3-TPR). Although impurities are present in the Al-pillared layered clay (PILC) support, most properties are close to those of pure Al-pillared Na-montmorillonite. Impregnation and calcination leads to the plugging of most micropores by clusters or microparticles of oxides. The NMR resonances of Al-VI and Al-IV specie are not modified after impregnation, and Al-VI/Al-IV ratio only varies on loading when compared to Al-PILC. Catalytic experiments show that the most active catalyst is 3% Rh/Al-PILC on which 88 mol.% of methane is converted at 650 degrees C with a minimum amount of carbon deposit. The conversions decrease along the 3% Rh approximate to 10% Ni > 3% Pd > 3% Ni > 3% Ce series. The H-2/CO ratio amounts to 1.1 with Rh and to 0.85 with Pd which are metallic at the temperature of reaction, but it has a lower value with Ni and Ce due to the RWGS reaction known to proceed in the presence of oxides. (C) 2008 Elsevier B.V. All rights reserved.