High catalytic performance of the Al-promoted Ni/Palygorskite catalysts for dry reforming of methane

The Al-promoted Ni-based catalysts were prepared by co-precipitation method using natural clay mineral-palygorskite (Pal) as the support. The physicochemical properties of the catalysts were studied by XRD, BET, H-2-TPR, TEM, XPS and Raman spectroscopy. The catalytic performances of the catalysts for CO2 reforming of methane (DRM) were investigated under different parameters including Al content, reaction temperatures, CH4 concentration and gas hourly space velocity (GHSV), and the long-term stability was also evaluated. The results showed that the addition of Al apparently favored the catalytic activity and stability of the catalysts for DRM reactions. The Ni/Pal catalyst with Al content of 8% (Ni-8/Al-8/Pal) exhibited the best activity for DRM at 700 degrees C in terms of the CH4 and CO2 conversions, which was related to the high dispersion and small crystal sizes of Ni particles. The variations of CH4 concentration and GHSV showed little effect on the catalytic activity of Ni-8/Al-8/Pal for CH4 conversion. Long-term stability (140 h) and H-2/CO molar ratio of roughly 0.98 can be achieved. The carbon deposition of the spent catalysts indicated that mainly graphite-type carbon deposition was formed on the surface of the catalysts when Al content was lower than 8%; however, most of the carbon deposition was removed over the Ni-8/Al-8/Pal and Ni-8/Al-15/Pal catalysts.