Ni-based catalyst derived from Ni/Al hydrotalcite-like compounds by the urea hydrolysis method for CO methanation

Abstract

The catalytic methanation of CO was investigated at atmospheric pressure over Ni-based catalysts derived from Ni/Al hydrotalcite-like compounds. The catalysts were prepared by the urea hydrolysis method and characterized by using XRD, TGA, N₂ adsorption–desorption, H₂-TPR, H₂-TPD and TEM. The H₂-TPD analysis revealed an increase in the Ni surface area, from 14.9 to 21.8 m² g⁻¹, as the Ni/Al molar ratio was increased from 0.5 to 2, and a nearly constant Ni surface area, of about 22.3 m² g⁻¹, at Ni/Al molar ratios > 2. A similar dependence on Ni/Al molar ratio was also found for CO conversion. The NA1 (Ni/Al molar ratio to 1) catalyst exhibited excellent stability at 600 °C for 1800 min on the stream. The NA1 catalyst prepared from Ni/Al hydrotalcite-like compounds exhibited higher catalytic stability due to higher Ni dispersion and stronger resistance to coke deposition than did the impregnated NA1-I catalyst.