Optimization of nano-sized Ni/MgAl2O4 catalyst synthesis by the surfactant-assisted deposition precipitation method for steam pre-reforming of natural gas

Abstract

In this work, steam pre-reforming of natural gas over magnesium aluminate-supported nickel catalysts (Ni/MgAl₂O₄) was studied. The catalysts were synthesized by a deposition precipitation (DP) method in the presence of surfactants. The performance of the obtained catalysts was tested at 400–550 °C, low steam to carbon molar ratio (S/C = 1.5) and atmospheric pressure. Taguchi L9 statistical design was applied to investigate the effect of the main synthesis parameters such as type of surfactant, aging time, pH of solution, and precipitation temperature on the nickel dispersion and the catalytic activity of the Ni/MgAl₂O₄ catalysts. The prepared catalysts were characterized by N₂ adsorption/desorption, H₂-TPR, BET, XRD, TPR, ICP, TPO, and TPD techniques. The results indicated that both the metal dispersion and the catalytic activity were strongly affected by precipitation deposition conditions. The type of surfactant has the highest effect on nickel dispersion and catalytic performance. The optimum synthesis conditions for the highest catalytic activity were sodium stearate as the anionic surfactant, aging time = 5 h, pH = 10, temperature = 30 °C. The optimized catalyst provided around 100% ethane and propane conversions at 500–550 °C under the reaction conditions.