Oxidative Coupling of Methane over Different Supported Mn/Na2WO4 Catalysts

Different supported Na-W-Mn/S catalysts (S= SiO2, different SiO2/MgO ratio) were preparedusing the impregnation and characterized by XRD, BET, AAS and SEM methods. The catalystsperformance was evaluated for the oxidative coupling of methane (OCM) reaction; alsoinfluence of different supports was evaluated on the selectivity and yield. Methane conversionstudies were performed at different temperatures in a constant GHSV of 6×103 h-1, CH4:O2 ratioof 4:1, over the Mn /Na2WO4/SiO2 (Powder) (Impo1), Mn /Na2WO4/ SiO2 (Spray-dried) (Impo2)and Mn /Na2WO4/SiO2 (mesh-30-35) (Impo3), Mn/Na2WO4/1SiO2/1MgO (Impo4), and Mn/Na2WO4/1SiO2/3MgO (Impo5) catalysts. The XRD patterns of the catalysts revealed thepresence of crystoballites, Mn2O3 and Na2WO4 phases respectively; the OCM activates of whichwere not the same. The Impo 2 catalyst, prepared by the impregnation of the active elementson spray-dried support, showed promising result for the OCM reaction at 825 C (C2-selectivity 75.7 % by 37% methane conversion). The yield of different catalysts increaseddramatically by increasing the temperature from 750°C to 800°C.