Catalytic Glycerol Oxydehydration To Acrylic Acid Over The Vanadium-containing Oxide Supported Montmorillonite

Montmorillonite is a two-dimension layered clay mineral with medium strong acid,which can be used as a solid acid catalyst.Moreover,our group has previously reported that montmorillonite acts as a solid acid catalyst to catalyze the dehydration of glycerol.Therefore,in this paper,montmorillonite was activated by phosphoric acid as an acid catalyst,and vanadium-containing oxide was supported as an oxidation catalyst to catalyze the glycerol oxydehydration to acrylic acid.Using SEM,XRD,FT-IR,NH₃-TPD,and XPS,we investigated the valence and structural characteristics of vanadium oxide,W-V-O,and Mo-V-O oxides supported on montmorillonite as oxidation catalysts,surface acidity,acid strength,and catalytic glycerol oxydehydration.At a reaction temperature of 320°C,20 wt.%of glycerol was used as raw material,and the carrier gas flow rate was 20 ml/min.When W-V-O oxide was supported as an oxidation catalyst,the catalytic performance was worse,15.8%of glycerol conversion and 2.8%acrylic acid selectivtity,compared with vanadium oxide and Mo-V-O oxide.When vanadium oxide was supported as an oxidation catalyst,the best acrylic acid selectivtity was 5.6%with total glycerol conversion over5 wt.%-MMT-500.In contrast,Mo-V-O oxide was most suitable as oxidation catalysts,0.98-MMT-500 with the best catalytic activity,64.0%of glycerol conversion and 8.5%acrylic acid selectivity.And we also have explored that the carrier gas with an O₂/（O₂+N₂）ratio of 0.2 is more suitable for glycerol oxydehydration,in accordance with the Mars-van Krevelen mechanism.