Investigation of the role of the Na2WO4/Mn/SiO2 catalyst composition in the oxidative coupling of methane by chemical looping experiments

A series of Na2WO4/Mn/SiO2 catalysts supported on mesoporous silica were prepared and tested for the oxidative coupling of methane in chemical looping experiments. The parameter variations were done for specific surface area, Mn-loading and support material. Chemical looping experiments reveal that highest catalytic activity is observed at 2 wt% Mn and 5 wt% Na2WO4 on mesoporous silica. Repetitive methane pulse experiments allowed us to determine the oxygen uptake of the Na2WO4/MniSiO(2) catalyst in chemical looping experiments. We found a correlation between oxygen storage capacity and manganese loading, which is in line with the reversible change of Mn(III) concentration observed in oxidation and reduction cycles of the material. Furthermore, we observed that ethylene formation is independent of the catalyst material in chemical looping conditions. No indication for the presence of W(V) was found. (C) 2018 Elsevier Inc. All rights reserved.