Effects of composite oxide supports on catalytic performance of Ni-based catalysts for CO methanation

Abstract

Metal-oxide-modified NiO/Al 2 O 3 catalysts for methanation of CO were prepared using a modified grinding-mixing method and characterized using X-ray diffraction, transmission electron microscopy, N 2 adsorption-desorption isotherms, temperature-programmed reduction by H 2 , temperature-programmed desorption by H 2 , Raman spectroscopy, and X-ray photoelectron spectroscopy. The results show that the activity of an MgO-modified NiO/Al 2 O 3 catalyst is better than those of NiO/ZrO 2 -Al 2 O 3 and NiO/SiO 2 -Al 2 O 3 in the reaction temperature range 300–700 °C. The incorporation of a metal oxide into NiO/Al 2 O 3 was found to weaken Ni–Al interactions, leading to generation of large numbers of active Ni species, and this was confirmed to be responsible for the improvement in the performances of the catalysts in the methanation reaction. 采用改良的粉末混合法制备了系列经过其它金属氧化物改性的 NiO/Al 2 O 3 催化剂, 并运用 X 射线衍射、透射电子显微镜、N 2 低温物理吸附-脱附、程序升温还原、程序升温脱附、拉曼以及 X 射线光电子能谱对催化剂进行了表征. 结果显示, 在 300–700 o C 经 MgO 修饰的 NiO/Al 2 O 3 催化剂上 CO 甲烷化反应活性比 NiO/ZrO 2 -Al 2 O 3 和 NiO/SiO 2 -Al 2 O 3 的高. 另一金属氧化物的加入削弱了 NiO/Al 2 O 3 催化剂中 Ni-Al 间相互作用, 形成更多的活性 Ni 物种, 从而促进了反应的进行. NiO/MO x -Al 2 O 3 (M = Mg, Si, Zr) catalysts for CO methanation, prepared using a modified grinding-mixing method, have higher catalytic activities than that of a conventional NiO/Al 2 O 3 catalyst. This is attributed to the weakening of Ni-Al interactions after adding MOx.