Effect of the MoO 3/Al2O3 catalyst fluorination on the propylene metathesis reaction

In the course of this work, fluorinated catalysts MoO3/Al2O3-F for the olefins metathesis have been synthesized. The materials have been characterized by various physicochemical methods and tested in the propylene metathesis reaction. It has been shown that the support fluorination leads to partial replacement of surface hydroxyl groups by F, which is accompanied by an increase in the strength of both Lewis acid sites and residual bridging OH groups. Increasing the fluorine content on γ-Al2O3 up to 3 wt. % leads to an increase in the conversion of propylene in the metathesis reaction by 1.5 times (WHSV = 1.1 h-1, Т = 100 °С, р = 9 atm.) with a selectivity of more than 95%. However, when the reaction is carried out at atmospheric pressure, fluorinated samples show lower activity than unpromoted ones. The results of this work show that the support acidity plays an important role in propylene metathesis. The proposed method of catalyst modification opens up new possibilities for improving classical metathesis catalysts.