CeO2、CaO助剂对甲烷部分氧化制合成气Ni/MgOAl2O3催化剂结构和性能的影响

The effects of CeO2 and/or CaO as promoters on the physicochemical properties and the catalytic performance over Ni/MgOAl2O3 catalyst for partial oxidation of methane to syngas were studied by means of BET, XRD, H2TPR, TEM and reaction activity evaluation. Compared with the catalyst without promoters, the catalyst promoted by CeO2 or CaO alone exhibited better reducibility of nickel species, and the one promoted by CaO showed better catalytic activity. When both of CeO2 and CaO were added to modify the Ni/MgOAl2O3 catalyst, an obvious synergetic effect between CeO2 and CaO were detected. It was deduced that the formation of CaOCeO2 solid solution could result in a better dispersion of active nickel species and promote the conversion of Ce4+ to Ce3+ species, thus reduced the size of nickel crystallites efficiently. Better oxygen adsorption ability, more oxygenvacant sites and more migration of oxygen anions could benefit oxygen exchange between NiO and CeO2. The above effects were contributed to higher CH4 conversion, CO selectivity and H2 selectivity over the catalyst promoted with CeO2 and CaO in the partial oxidation of methane.