Steam reforming of simulated biogas over plate Ni-Cr catalysts: Influence of pre-oxidation on catalytic activity

The activity and stability of NiCr plate catalysts were significantly enhanced by a pretreatment process involving pre-oxidation at ≥600°C with subsequent reduction at 700°C. Analytical techniques including SEM, TEM, and XPS-depth profiling studies revealed that the pretreatment induced surface reconstruction in the bulk NiCr material generating new Ni sites with improved activity. The catalytic activity was highly dependent upon the oxidation temperature. In addition to the creation of novel Ni sites, chromium oxide acted as a structural promoter to suppress sintering of the Ni active sites. Activation of the NiCr plate catalyst via pretreatment at 700°C resulted in improved stability for biogas reforming reactions over a period of 100h. Moreover, the stability of the reforming catalyst was sustained over 100h with a steam/CH₄ ratio of ≥1.5. The influences of temperature, inlet H₂O/CH₄ ratio, and CH₄/CO₂ ratios on the steam reforming of biogas were further studied.