Synthesis of Ni/Al2O3 catalysts via alkaline polyol method and hydrazine reduction method for the partial oxidation of methane

Abstract

Nickel catalysts supported on γ-Al2O3were synthesized in the presence of polyvinylpyrrolidone (PVP) using both alkaline polyol method and hydrazine reduction method while fixing the weight ratio of [(PVP)]/[Ni(CH3COO)2 4H2O] at 2. The effects of hydrazine [N2H5OH]/[Ni] and [NaOH]/[Ni] molar ratios on the structural properties of the catalysts were characterized by transmission electron microscopy (HRTEM) and by X-ray diffraction (XRD). The average of monodispersed Ni nanoparticles ranged between 8.0 and 13.0 nm. The catalytic tests were performed for the partial oxidation of methane in the temperature range of 600-800°C under a flow rate of 157,500 L kg-1 hr-1 with CH4O2= 2. At the molar ratio of [NaOH]/[Ni] = 2, the resultant nickel nanoparticles on alumina was established completely without impurities; thus, it demonstrated the highest catalytic activity, 88% for CH4 conversion, and H2 selectivity, 90.60%. The optimum [N2H5OH]/[Ni] ratio was determined as 4.1, which means a good catalytic performance and 89.35% selectivity to H2 for the partial oxidation of methane.