Stability of supported and promoted-molybdenum carbide catalysts in dry-methane reforming

The stability of molybdenum carbide (Mo2C) in dry-methane reforming (DMR) was studied over Al2O3, ZrO2 and MgO supports and in the presence of Ce, K and Zr promoters at 900 °C, 1 bar, a GHSV of 3800 h−1 and a stoichiometric feed. All catalysts deactivated via moving front oxidation under these conditions. The γ-alumina appeared to be superior compared to other supports due to its high surface area and high thermal stability, and Mo2C/γ-Al2O3 had a much higher activity than a bulk Mo2C catalyst. Over this support, a high Mo loading was found to be crucial for maintaining the stability of the catalyst due to the higher concentration of more reducible Mo oxides and the higher CH4 conversion over the carbide. The impregnation order was found to be an important factor for Ce, and the 3 wt.% Ce-Mo2C/Al2O3 was found to be the most stable catalyst due to the redox properties of the Ce promoter. On the other hand, the addition of CO in the feed, while preventing oxidation of all catalysts, resulted in slow deactivation due to coking over the Ce-promoted catalyst.