A study of Pt–Pd/γ-Al2O3 catalysts for methane oxidation resistant to deactivation by sulfur poisoning

The catalytic oxidation of methane was studied over calcined and reduced Pt–Pd/γ-Al2O3 catalysts, in the presence and the absence of SO2 in the CH4–O2 reaction feed. The effect of sulfation (SO2 + O2 for 4 h at 500 °C) was also studied on the catalyst resistance to deactivation by sulfur poisoning. Sulfating the calcined Pt–Pd/γ-Al2O3 catalysts resulted in a strong deactivation for the CH4–O2 reaction. However, the catalytic activity of the reduced-sulfated Pt–Pd/γ-Al2O3 catalyst for CH4–O2 reaction remained rather unaffected in the presence and in the absence of SO2 in the reaction feed. XPS analysis revealed, over reduced-sulfated Pt–Pd/γ-Al2O3 catalysts, the presence of Pt(0) metallic surface species on which SO2 interactions may be faster related to Pd surface species. The presence of Pt(0) may be necessary to prevent the interactions between SO2 and Pd surface species. Long time catalytic tests showed that the activity of a reduced Pt–Pd/γ-Al2O3 catalysts for CH4–O2 reactions remained rather unaffected despite the presence of SO2 in the reaction feed.

Graphical abstractThe catalytic oxidation of methane was studied over calcined, and reduced Pt–Pd/γ-Al2O3 catalysts, in the presence and the absence of SO2 in the CH4–O2 reaction feed. XPS analysis revealed that the presence of Pt(0) may be necessary to prevent the interactions between SO2 and Pd surface species. Long time catalytic tests showed that the activity of a reduced Pt–Pd/γ-Al2O3 catalysts for CH4–O2 reactions remained rather unaffected despite the presence of SO2 in the feed. Evolution of T50 for methane on the CH4 + O2 reaction, with the number of temperature-programmed reaction cycles over reduced 2%Pt–1%Pd/γ-Al2O3, and calcined 2%Pt–1%Pd/γ-Al2O3. Feed: 2000 ppmV CH4, 10% O2, 50 ppmV SO2, balance N2.Figure optionsDownload full-size imageDownload as PowerPoint slide