Mn-Na2WO4-Ce/TiO2 catalyst promoted with Mg and Sr in the oxidative coupling of methane

The activity and product selectivity of Na2WO4-MnO2-CeO2/TiO2 (MNTiCe) catalysts promoted by Sr and Mg in the oxidative coupling of methane (OCM) reaction was studied. The OCM reaction holds significance due to its potential for methane utilization, production of valuable chemicals, and environmental benefits. The Sr and Mg promoters are added simultaneously or after the impregnation of Ce to the catalyst. The catalyst activity results showed that the simultaneous addition of Sr and Mg promoters along with Ce provides more C-2 selectivity for the catalyst. These results show that the C-2 selectivity of the MNTiCe catalyst in the OCM reaction is improved by simultaneous Sr and Mg addition, in which the optimum loading of Sr is 0.75 wt% and the optimum loading of Mg is 0.25 wt%. According to the XPS results, the catalytic surface of catalyst loading with 0.75 wt% of Sr has a higher concentration of O-2(-) species and increases the ability of the catalyst in the OCM reaction. The surface areas of all catalysts are lower than 10 m(2)/g which is suitable for OCM reaction and increased by the addition of Sr and Mg. According to the TPR results the catalyst reduction in simultaneously Sr and Mg loading catalysts are higher than in unpromoted catalyst.