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-Al 2 O 3 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(CH 3 COO) 2 ·4H 2 O] at 2. The effects of hydrazine [N 2 H 5 OH]/[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 CH 4 /O 2 = 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 CH 4 conversion, and H 2 selectivity, 90.60%. The optimum [N 2 H 5 OH]/[Ni] ratio was determined as 4.1, which means a good catalytic performance and 89.35% selectivity to H 2 for the partial oxidation of methane.

Sr Promoted Ni/W–Zr Catalysts for Highly Efficient CO2 Methanation: Unveiling the Role of Surface Basicity

“…EVA v4.2.1 software was used to evaluate the data. The obtained crystallite particle size was used to evaluate Ni metal dispersion using eq D .25em ( % ) = C d .25em ( n m ) where C is a constant equivalent to 97 for Ni and d is the crystallite diameter (nm) assuming spherical crystallites …”

“…where C is a constant equivalent to 97 for Ni and d is the crystallite diameter (nm) assuming spherical crystallites. 51 TEM images of reduced and used catalysts were recorded on a transmission electron microscope JEOL JEM-2100F, USA, operated at 120 kV. These images were used to evaluate the particle size distribution and calculate the average diameter size.…”