Sulphur tolerance of a P-doped Rh/γ-Al2O3 catalyst during the partial oxidation of methane to syngas

A novel monolith catalyst with Rh supported on γ-Al2O3 and doped with phosphorous was prepared by temperature-programmed reduction of oxidic precursors and tested for the first time in the CPO of methane at short contact time and high temperature in the presence of sulphur. The catalyst was characterized by ICP-MS, XRD, TGA, SEM-EDS, BET, H2-TPR, quantitative CO chemisorption measurements and in situ DRIFT of adsorbed CO, performed on freshly reduced samples or after exposures to sulphur species at temperatures and conditions close to those expected under actual CPO of methane. Results were compared with the reference undoped Rh/γ-Al2O3 catalyst and the P-γ-Al2O3 support. Both transient and steady state operation of the CPO reactor were investigated particularly with regards to the effect that the addition/removal of variable S quantities in the feed has on catalyst temperature, on the formation of main reaction products, on the approach to equilibrium and on the apparent reaction rate.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► P-doped Rh/γ-Al2O3 catalyst was tested for the first time in methane CPO to syngas. ► P-doped Rh catalyst shows enhanced tolerance against sulphur poisoning. ► A metallic Rh-P phase is formed by H2-TPR for T > 650 °C. ► P increases Rh dispersion and its CO chemisorption capacity. ► P-doped Rh chemisorbs less S preserving a higher activity for steam reforming.