Activities of Ni-based nano catalysts for CO2–CH4 reforming prepared by polyol process

Nano nickel catalysts supported over nano sized oxide powders (CeO2, ZrO2 and Al2O3) were prepared by the polyol method in ethylene glycol (EG) medium with polyvinylpyrrolidone (PVP) as a nucleation-protective agent. The activities of the prepared catalysts were evaluated for CO2 reforming of methane in the temperature range 500–800°C. For comparison purpose, another series of Ni based catalysts was prepared by conventional impregnation method. Numerous techniques, such as N2 adsorption–desorption isotherm, temperature-programmed reduction (H2-TPR), temperature-programmed desorption (CO2-TPD), X-ray diffraction (XRD), thermogravimetric analysis (TGA), high resolution transmission electron microscopy (HRTEM), and pulse chemisorption were applied for characterization of fresh and spent catalysts. The results of catalyst testing and characterization revealed that the catalysts synthesized by polyol method have superior catalytic performance (activity and stability) than those prepared by impregnation method. The better performance of polyol catalysts could be attributed to stronger metal to support interaction and presence of evenly distributed nano nickel particles in these catalysts; since strong metal to support interaction resists sintering and small nickel crystallite size hinders coking.