Ni catalysts supported on nanosheet and nanoplate γ-Al2O3 for carbon dioxide methanation

Nanosheet (S) and nanoplate (P) γ-Al2O3 were synthesized by simple hydrothermal methods and employed as supports for Ni catalysts in CO2 methanation. Both of the nanostructured Ni/Al2O3 catalysts displayed good activity. In comparison, the Ni/Al2O3-S catalyst showed higher CO2 conversion than the Ni/Al2O3-P counterpart at the reaction temperature ranging from 250 to 400 °C. The physical and chemical properties of the catalysts were systematically characterized by N2 sorption, X-ray diffraction (XRD), high resolution-transmission electron microscopy (HR-TEM), hydrogen temperature-programmed reduction (H2-TPR) and CO2 temperature-programmed desorption (CO2-TPD) techniques. Higher specific surface area and stronger metal-support interactions were confirmed on the Ni/Al2O3-S catalyst, which may lead to smaller particle size of Ni nanoparticles. Moreover, the Ni/Al2O3-S catalyst possessed more abundant weak and medium basic sites, which would benefit the activation of CO2. The smaller Ni size and more suitable basic sites may rationalize the superior activity of the Ni/Al2O3-S catalyst. Besides, the Ni/Al2O3-S catalyst exhibited excellent stability at 325 °C for 40 h.