Oxidative bromination of methane by barium oxide or tungsten oxide on silica catalysts: effect of catalysts preparation

Abstract

Oxidative bromination of methane (OBM) has been proposed for methane activation. In this work, methane was brominated by HB1VH2O solution with oxygen as an oxidizing agent to produce methyl bromide. Barium oxide or tungsten oxide on silica were chosen as the catalysts to improve the activity and selectivity of the reaction. The catalysts were prepared by 2 techniques, incipient wetness impregnation and sol-gel method. The effects of catalyst preparations on oxidative bromination of methane were investigated. The reaction was carried out in a fixedbed continuous-flow reactor at atmospheric pressure. The catalysts were characterized by BET and XRD techniques. The results showed that, under the same condition (20 ml/min of CH4, 5 ml/min of O2, 5 ml/min of N2, 6.5 ml/h of 48 wt% HBr/H2O and temperature at 660 ํC), the sol-gel catalysts exhibited higher methane conversion and methyl bromide selectivity than impregnated catalysts. The reason might be that metal oxides on sol-gel catalysts are smaller than those in impregnated catalysts.