Coke suppression by holmium promoter in dry reforming of methane

The present research mainly focused on the development of highly coke resistant catalysts. In this context, Ni/ZrO₂ novel catalysts with holmium (Ho) promoter were prepared using the polyol method and investigated, for CH₄-CO₂ reforming, at atmospheric pressure in the temperature range of 500-700°C. For each catalyst, the Ni loading was fixed at 5 wt.%, while Ho loading was varied from 0.0-1.5 wt.%. Various techniques such as BET, H₂-TPR, CO₂-TPD, XRD, TGA and FESEM were used to characterize the prepared catalysts. The results demonstrated that the addition of Ho in Ni/ZrO₂ catalyst had a notable effect on carbon suppression. Moreover, CO₂-TPD results revealed that the incorporation of Ho in Ni/ZrO₂ catalyst fairly enhanced its Lewis basicity. These improvements in basicity favored the chemisorption and activation of CO₂ over the catalyst surface which in turn minimized coke deposition. Carbon deposition on the 1.5 wt.% Ho promoted catalyst (Ni-1.5Ho-Zr) was reduced about 92.7% compared to the un-promoted catalyst.