Hydrogen or synthesis gas production via the partial oxidation of methane over supported nickel-cobalt catalysts

Activity, selectivity, and coking-resistance of a series of Ni_x Co_y (where x, y are the respective metal loadings of 0, 1, 2 or 3 wt.%; x + y = 3) bimetallic catalysts supported on CaAl₂ O₄ / Al₂ O₃ have been studied for hydrogen/synthesis gas production via the catalytic partial oxidation (CPO) of methane. Catalysts were characterized by temperature programmed reduction (TPR), transmission electron microscopy (TEM) and X-ray fluorescence multi-element analysis (XRF). Their activity for the partial oxidation of methane to hydrogen and carbon monoxide (at 1 bar, gas hourly space velocity (GHSV) of 144, 000 cm³ g^{- 1} h^{- 1} and CH₄/O₂ molar ratio of 2) was investigated, and coke deposited on the spent catalysts was studied by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and thermogravimetric analysis (TGA). The activity was found to decrease in the order of Ni₂ Co > Ni₃ > NiCo₂ ≫ Co₃, while CO and H₂ selectivities were found to be in the order ofNi₂ Co > Ni₃ ≈ NiCo₂ > Co₃ . Ni₂Co is also shown to be more resistant to coking as compared to Ni₃, which is a current catalyst of choice. Results show that not only does Ni₂Co have the highest activity and selectivity among all the catalysts tested, it is also relatively resistant to coking. This finding would be helpful for catalyst design to achieve high coking resistivity catalysts for hydrogen production from CPO of methane.