Vanadium doped Ni/Al2O3: Efficient and coke resistant catalysts for methane dry reforming

The effects of vanadium promotion on γ-alumina supported nickel catalysts were investigated for Methane Dry reforming (MDR). Three samples were compared: bare Ni/Al2O3 as reference, Ni-V/Al2O3, and Ni-V-Ca/Al2O3 to evaluate whether the introduction of these additional doping agents can further improve the activity and the stability of the catalyst. The catalysts were synthetized via incipient wetness impregnation and tested in MDR at 650 °C, first with a reagents ratio CH4:CO2:He= 1:1:18 and then CH4:CO2:He= 1:1:8. Fresh and spent catalysts were studied by different techniques, such as N2 physisorption, TPR, XRD, DRUV–VIS, SEM-EDX, O2 chemisorption and TPO. In diluted gases conditions, the introduction of vanadium is crucial to hinder catalyst deactivation by coke deposition. In particular, the formation of nanotubes was reduced, with an increase in hydrogen yield. When coupled with calcium, selectivity toward hydrogen/syngas production was improved. Under concentrated gases was highlighted how vanadium is fundamental for a higher activity, with an increase of 30% and 15% in CH4 and CO2 conversions, if compared with the non-doped catalyst.