Dry reforming of methane (DRM) is a useful way to mitigate the emission of greenhouse gases by converting them into syngas. However, the DRM process requires a significant amount of energy, and the catalyst used is prone to deactivation. Oxidative dry reforming of methane (ODRM) is an integrated approach that combines the partial oxidation of methane (POM) and DRM, requires less energy, and provides stable conversions. Since calcination temperature is an important factor for the preparation of a low-cost Ni3Co-Al2O3 catalyst, the catalyst was calcined at 500oC (Ni3Co-500) and 850°C (Ni3Co-850). The DRM and ODRM reactions were performed at 600 and 750°C to examine the catalyst stability, relative conversions, and syngas ratios. The feed composition of CH4:CO2:O2:N2=1:1:x:1-x was maintained, where x=0 and 0.225 for DRM and ODRM, respectively. The Ni3Co-500 outperforms Ni3Co-850 with higher CH4 conversions of 48% (for DRM) and 59% (for ODRM) at 600°C due to highly dispersed Ni-Co alloy sites. Syngas ratio was also increased from 0.62 to 0.92 with minimal carbon deposition during ODRM. Partially oxidized Ni0 and Co0 phases were observed in the spent catalysts after ODRM. Moreover, an increase in reaction temperature to 750°C made the catalyst surface Ni-rich due to Co0 migration to bulk phase. A shift of alloy peak to higher 2θ value by XRD and decrease in Co0/Ni0 value by XPS was consistent with the Co0 migration as shown in Figure.

Effect of calcination temperature on the Ni-Co alloy catalyst for oxidative dry reforming of methane

ACS Spring 2022

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