Partial oxidation of methane to syngas on bulk NiAl2O4 catalyst. Comparison with alumina supported nickel, platinum and rhodium catalysts

In this work the catalytic performance of NiAl2O4 catalyst in the partial oxidation of methane (CH4(1)/O2(0.5)/N2(8.5) and 4800 mL CH4 g−1 h−1) was investigated. This bulk catalyst resulted more active (70% conversion at 625 °C) than alumina supported nickel catalysts prepared by conventional impregnation (11%Ni/Al2O3-30% conversion at 625 °C and 14%Ni/Al2O3-65% conversion at 625 °C) and a commercial platinum catalyst (1%Pt/Al2O3-30% conversion at 625 °C). Further, the behaviour of NiAl2O4 was comparable to that of a commercial rhodium catalyst (1%Rh/Al2O3-75% conversion at 625 °C). Fresh and spent catalysts were characterised by N2-physisorption, H2-TPR, UV-vis-DRS, WDXRF, XRD, TGA-MS, TEM and Raman spectroscopy. After catalyst reduction CH4 conversion over bulk NiAl2O4 was associated with the formation of large amounts of metallic nickel crystallites with a relatively small size. Although significant coking was noticed, conversion and selectivity to H2/CO were not significantly affected after prolonged time on stream.

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► Bulk NiAl2O4 resulted highly active for POM to syngas.
► Its catalytic activity was comparable to that exhibited by a commercial Rh catalyst.
► Reduction of NiAl2O4 favoured the formation of small Ni0 crystallites.
► This catalyst resulted markedly stable during extended time on stream.