Eff ect of the MoO3/Al2O3 catalyst fl uorination on the propylene metathesis reaction

Abstract

In the course of this work, fl uorinated catalysts MoO3 /Al2 O3 -F for the olefi ns 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 fl uorination 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 fl uorine 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, fl uorinated 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 modifi cation opens up new possibilities for improving classical metathesis catalysts.

Keywords

• metathesis
• olefi ns
• ethylene production
• propylene production
• ir spectroscopy
• xps spectroscopy
• catalyst acidity