关键词: 催化剂载体, 浸渍法, 粉末压片, 甲烷化, 一氧化碳, 二氧化碳

Abstract:

Two kinds of nickel-based catalysts supported on ZrO₂-Al₂O₃ composite were prepared by impregnation and powder pressing. The obtained catalysts were further characterized by N₂ isothermal physisorption, X-ray powder diffraction (XRD), H₂ temperature-programmed reduction (H₂-TPR), scanning electron microscope （SEM） and transmission electron microscope （TEM） techniques. The influences of zirconia addition and different preparation methods on the performance of the catalysts in CO methanation, CO₂ methanation and CO/CO₂ co-methanation were investigated. The results indicated that the addition of zirconia in the Al₂O₃ support could improve the dispersion of Ni species, leading to enhanced catalytic performance in CO methanation. Besides, the composite support made from powder pressing method could effectively improve the reducibility and decrease the reduction temperature of catalysts in contrast to that made from the impregnation method. However, the former method would decrease the specific surface area, pore volume and pore diameter of the catalysts. In the CO₂ methanation, catalysts prepared by the same method had little effect on CO₂ conversion, which was mainly limited by the physical properties of the catalysts such as specific surface area that originated from the difference in preparation method. In the CO/CO₂ co-methanation experiments, the methanation of CO is prior to that of CO₂ since in adsorption CO is more easily to occupy the on active sites than CO₂ , which causes the CO₂ content increased first and then decreased.

Key words: catalyst support, impregnation, powder pressing, methanation, carbon monoxide, carbon dioxide