Highly coking resistant and stable Ni/Al2O3 catalysts prepared by W/O microemulsion for partial oxidation of methane

Three supported nickel catalysts were prepared by conventional impregnation (IMP), sol–gel and water-in-oil microemulsion (ME) methods, respectively. Their catalytic activities and coking resistant for partial oxidation of methane (POM) to syngas were studied in a fixed-bed reactor under atmospheric pressure. The crystalline structure and catalytic properties for three catalysts were investigated by using X-ray diffraction (XRD), transmission election microscopy (TEM) and temperature-programmed reduction (TPR). For partial oxidation of methane to syngas, although three catalysts had comparable activity, they showed a great difference in the way of coking resistant. The catalyst prepared by microemulsion method had excellent coking resistant with no obvious coke observed even after 5 h of reaction on stream, under thermodynamically severe conditions (O2/CH4=0.53) at 923 K. Due to nickel strong interaction with supported Al2O3 and high BET surface area, and small metallic Ni particles, the catalyst prepared by water-in-oil microemulsion has excellent coking resistant and stability.