Thermal effects during the oxidative coupling of methane over Mn/Na2WO4/SiO2 and Mn/Na2WO4/MgO catalysts Original Research Article

The exothermic reactions that occur during the oxidative coupling of methane over Mn/Na2WO4/SiO2 and Mn/Na2WO4/MgO catalysts result in relatively narrow hot spots that may produce temperature increases as large as 150°C. Under integral conditions, the temperature of the hot spots is related to the CH4/O2 ratio and the activity of the catalyst. Although the Mn/Na2WO4/SiO2 catalyst was stable for up to 97 h on stream, the Mn/Na2WO4/MgO catalyst gradually deactivated. This deactivation was manifested by motion of the hot spot toward the exit of the catalyst bed. The loss of activity is attributed mainly to the decrease in Mn concentration at the surface of the catalyst.