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

Nickel catalysts supported on γ-Al₂O₃ were 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 CH₄/O₂= 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.