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

Nanosheet (S) and nanoplate (P) γ-Al 2 O 3 were synthesized by simple hydrothermal methods and employed as supports for Ni catalysts in CO 2 methanation . Both of the nanostructured Ni/Al 2 O 3 catalysts displayed good activity. In comparison, the Ni/Al 2 O 3 -S catalyst showed higher CO 2 conversion than the Ni/Al 2 O 3 -P counterpart at the reaction temperature ranging from 250 to 400 °C. The physical and chemical properties of the catalysts were systematically characterized by N 2 sorption , X-ray diffraction (XRD), high resolution-transmission electron microscopy (HR-TEM), hydrogen temperature-programmed reduction (H 2 -TPR) and CO 2 temperature-programmed desorption (CO 2 -TPD) techniques. Higher specific surface area and stronger metal-support interactions were confirmed on the Ni/Al 2 O 3 -S catalyst, which may lead to smaller particle size of Ni nanoparticles . Moreover, the Ni/Al 2 O 3 -S catalyst possessed more abundant weak and medium basic sites, which would benefit the activation of CO 2 . The smaller Ni size and more suitable basic sites may rationalize the superior activity of the Ni/Al 2 O 3 -S catalyst. Besides, the Ni/Al 2 O 3 -S catalyst exhibited excellent stability at 325 °C for 40 h.