The role of crystalline structure of molybdenum oxide catalysts onto the activity and stability in sulfoxidation of thioethers

Sulfoxidation of 2-thiomethyl-4,6-dimethyl-pyrimidine and methyl-dodecyl-sulfure was carried out in liquid phase using H 2O 2 in dioxane (6 or 18 wt%) and several molybdenum and mixed antimony–molybdenum oxides such as: Mo 8O 23, MoO 3-basal, MoO 3-iso, Sb 2MoO 6 and a mixture of Sb 2Mo 10O 31 and Sb 4Mo 10O 31 (Sb x Mo 10O 31) phases as catalysts. Both catalytic performances and catalysts stability (structural modifications and leaching) depended on characteristics of the structure. The less active catalysts exhibited a higher leaching. The most stable and thus active catalysts were those for which the leaching is compensated by structural changes going in the direction of the exacerbation of their crystallinity. In the investigated series the most effective were the Mo 8O 23 and Sb 2MoO 6.