To understand the role of alkaline sites played for CO₂ methanation and develop better catalysts, the promoted Ni/M_0.1Ce_0.9O_x catalysts, in which the CeO₂ are modified by different alkaline earth metal oxides with a M/Ce (M = Mg, Ca, Sr, Ba) molar ratio of 1/9, have been prepared. With the sol − gel method, different alkaline earth metal oxides present varied distribution states in the modified CeO₂ support. MgO and CaO are predominantly dissolved into the CeO₂ support lattice to form a pure solid solution structure, while SrO and BaO are dispersed as the carbonates on the CeO₂ support surface. The modification of all the alkaline earth metal oxides on CeO₂ can improve the intrinsic activity of the obtained supported Ni catalysts, whose activity follows the order of Ni/Ca_0.1Ce_0.9O_x > Ni/Sr_0.1Ce_0.9O_x > Ni/Mg_0.1Ce_0.9O_x > Ni/Ba_0.1Ce_0.9O_x > Ni/CeO₂. H₂-TPR, H₂ adsorption–desorption and XPS results have revealed that the modification of alkaline earth metal oxides can improve Ni dispersion, induce more surface oxygen vacancies and increase both the amount and the strength of the moderate alkaline sites, which are the major factors determining the activity of the Ni/M_0.1Ce_0.9O_x catalysts for CO₂ methanation. Ni/Ca_0.1Ce_0.9O_x, possessing the best Ni dispersion and the largest amount of the moderate alkaline sites, displays the highest activity among all the catalysts.

为了了解碱性位点对CO ₂甲烷化的作用并开发出更好的催化剂，推广了Ni / M _0.1 Ce _0.9 O _x催化剂，其中CeO ₂被不同的碱土金属氧化物以M / Ce改性（M =已经制备了Mg，Ca，Sr，Ba的摩尔比为1/9。通过溶胶-凝胶法，不同的碱土金属氧化物在改性的CeO ₂载体中呈现出不同的分布状态。MgO和CaO主要溶解在CeO ₂支撑晶格中以形成纯的固溶体结构，而SrO和BaO作为碳酸盐分散在CeO _2上支撑面。在CeO ₂上对所有碱土金属氧化物进行改性可以提高所获得的负载型Ni催化剂的固有活性，其活性遵循Ni / Ca _0.1 Ce _0.9 O _x > Ni / Sr _0.1 Ce _0.9 O _x > Ni / Mg _0.1 Ce _0.9 O _x＞ Ni / Ba _0.1 Ce _0.9 O _x＞ Ni / CeO ₂。H ₂ -TPR，H ₂吸附-解吸和XPS结果表明，碱土金属氧化物的改性可以改善镍的分散，诱导更多的表面氧空位，并增加中度碱性位的数量和强度，这是决定镍活性的主要因素。用于CO ₂甲烷化的Ni / M _0.1 Ce _0.9 O _x催化剂。Ni / Ca _0.1 Ce _0.9 O _x，具有最佳的Ni分散性和最大量的中等碱位，在所有催化剂中显示出最高的活性。