Study on sulfur deactivation of catalysts for DMDS oxidation

In the present research, an industrially aged Pt/Al 2 O 3 catalyst was used as a basis for the study on the sulfur deactivation and the development of more resistant catalytic materials. The catalytic activities of both industrially and laboratory-aged materials in DMDS oxidation were studied in addition to characterization by XRD, XPS, FESEM, TEM and N 2 adsorption. The industrial ageing induced a phase change from γ-Al 2 O 3 towards θ-Al 2 O 3 , formation of aluminum sulfates and an increase in Pt particle size as well as a change in the oxidation state of Pt to a higher state. These changes caused an increase of 30 °C in the light-off temperature for DMDS oxidation. Accelerated ageing in the presence of SO 2 and H 2 O vapor at 400 °C for 5 h decreased the activity of the Pt/Al 2 O 3 at the same level than for the industrially aged catalyst even though smaller sulfur content and no sintering of γ-Al 2 O 3 were observed. Pt sintering (10–20 nm) in both cases was observed. The XPS results confirmed the formation of new sulfate phases and the interaction between sulfur and the active phase as well as the support of the catalyst undergone accelerated ageing. After the accelerated ageing of copper-based catalysts, the 0.3Pt10Cu/Al 2 O 3 ǀ 0.8 SiO 2 ǀ 0.2 catalyst showed an interesting resistance towards sulfur deactivation, as it was expected.