Sulfur poisoning of molybdenum dioxide during the partial oxidation of a Jet-A fuel surrogate

The aim of the present work is to investigate the effect that organic sulfur compounds have on the catalytic performance of molybdenum dioxide (MoO2) during the partial oxidation reaction of aviation fuels. N-dodecane and benzothiophene were used as surrogates for Jet-A fuel and as a model sulfur compound, respectively. Activity tests of commercial MoO2 toward the partial oxidation reaction of this model Jet-A fuel were performed at 850 °C. Our studies indicate that MoO2 displays a remarkable tolerance to deactivation by organic sulfur compounds even at concentrations as high as 1000 ppmw, a typical sulfur concentration found in aviation fuels. However, commercial MoO2 catalysts show a significant catalytic performance deactivation as the concentration of organic sulfur compounds increases to 3000 ppmw. TEM and XPS data indicate that the deactivation process starts with the formation of Mo sulfide on the catalyst surface. The sulfide phase appears to reduce the ability of the catalyst to activate hydrocarbon molecules as well as impeding the ability to deliver lattice oxygen to the active surface sites, which leads to the enhancement of side reactions that promote the formation of coking. The catalyst deactivation resulting from the exposure to such high concentrations of organic sulfur compounds appears to be reversible with an air treatment at 850 °C. The catalyst activity of MoO2 recovers approximately 80% of its initial performance as demonstrated by the H2 yield and TEM data.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Influence of sulfur compounds on MoO2 under partial oxidation of dodecane studied. ► MoO2 displays stable performance at benzothiophene concentrations of 1000 ppmw. ► TEM and XPS show the deactivation process of MoO2 under 5 wt% benzothiophene. ► Formation of surface MoS2 promotes coke formation under 5 wt% benzothiophene.