Understanding the effects of sulfur on Mo2C and Pt/Mo2C catalysts: Methanol steam reforming

To enhance our understanding of the effects of sulfur on the properties of Mo2C and Pt/Mo2C catalysts, methanol steam reforming rates were measured in the absence and presence of 5 ppm H2S. Exposure to H2S quickly deactivated the Mo2C catalyst, although 60% of the initial rates were retained. Deactivation of the Pt/Mo2C catalyst was more gradual and the pseudo-steady state rates approached those for the Mo2C catalyst. Treatment in 15% CH4 in H2 at 590 °C for 4 h restored ∼100% and ∼15% of the initial rates for the Mo2C and Pt/Mo2C catalysts, respectively. X-ray photoelectron spectroscopy indicated domains of Mo2C, MoS2 and S-Mo on the Pt/Mo2C catalyst surface, but no sulfur was observed on the Mo2C catalyst surface. The results suggested that sulfur selectively poisoned some but not all of the active sites on Mo2C, and irreversibly poisoned the Pt sites producing inactive PtS.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (147 K)Download as PowerPoint slideHighlights► Mo2C and Pt/Mo2C catalysts highly active for methanol steam reforming. ► Mo2C was partially tolerant to sulfur exposure and fully regenerable. ► Methanol decomposition sites appeared to be sulfur tolerant but water gas shift sites intolerant.