Acid–base properties of the active sites responsible for C2+ and CO2 formation over MO–Sm2O3 (M=Zn, Mg, Ca and Sr) mixed oxides in OCM reaction

SnO2Based Catalysts with Low‐Temperature Performance for Oxidative Coupling of Methane: Insight into the Promotional Effects of Alkali‐Metal Oxides

“…As discussed above, the presence of surface alkaline sites are important for an effective OCM catalyst , . Therefore, the influence of surface basic sites, by the addition of different amounts of lithium oxide, has been probed by means of the CO 2 ‐TPD method.…”

“…Reducible metal oxides can store and release oxygen cyclically between multiple valence states . The surface lattice oxygen (O 2– ) has been proposed as the active site for OCM, whereas for both groups of catalysts, electrophilic surface‐oxygen species (O – , O 2 – , and O 2 2– ) are believed to be crucial for the reaction and could decide the selective formation of the coupling products , . To date, Mn/Na 2 WO 4 /SiO 2 and Li/MgO have been reported as the most promising catalysts for OCM reactions , , , .…”

Effects of Polyvinylpyrrolidone on the Preparation of Supported La2O3 Catalysts by a Modified Impregnation Method for the Oxidative Coupling of Methane

“…Papa et al 7. 9 studied mixed oxides MO–Sm 2 O 3 (M=Be, Zn, Mg, Ca, and Sr) for OCM and indicated that the surface basic sites were responsible for the formation of C2+ and the acidic sites were responsible for methane combustion. These results are in good agreement with our results above.…”

Synthesis of Na2WO4-Mn Supported YSZ as a Potential Anode Catalyst for Oxidative Coupling of Methane in SOFC Reactor

“…Catalytic Performance of Catalysts Table 3 summarizes the catalytic performances of different catalysts after 90 min of reaction at steady state under GHSV of 15000 ml g -1 h -1 , 800°C and a molar ratio of CH4/O2 of 4:1 [6,20]. For Na-W-Mn/SiO2 catalyst, 12.0% CO selectivity, 12.9% CO2 selectivity and 69.0% C2 selectivity at 28.5% CH4 conversion are obtained, which are in agreement with several reports [21][22][23][24].…”

“…However, decreases in C2 selectivity and C2 hydrocarbons yield are observed in the temperature range of 800-900°C because of kinetic limitations. The upper limit of OCM yield under the conventional fixed bed is considered to be dominated by the enthalpies of hydrogen severance from methane and oxygen dissociative adsorption [20]. The optimum temperature for three catalysts appears to be at 800°C, where C2 hydrocarbon yields are 19.7% and 16.3% for Na-W-Mn/SiO2 and Na-W-Mn/YSZ, respectively in which these results are not significantly different while higher C2 selectivity (61%) is observed over Na-W-Mn/YSZ.…”