Acetalization reaction between glycerol and n-butyraldehyde using an acidic ion exchange resin. Kinetic modelling

The acetalization reaction between glycerol and n-butyraldehyde using Amberlyst 47, an acidic ion exchange resin catalyst, was studied. These acetals can be obtained from renewable sources and seem to be good candidates for different applications such as oxygenated diesel additives. Amberlyst 47 acidic ion exchange showed good activity and stability after five consecutive cycles of reuse. Therefore, 100% of selectivity towards the formation of acetals and butyraldehyde conversions between 92% and 98% were obtained for different molar feed ratios of glycerol:aldehyde. For glycerol:aldehyde molar ratios lower than the stoichiometric one, 2,4,6-tripropyl-1,2,3-trioxane is also detected as product when glycerol is almost totally consumed. Moreover, a pseudo-homogeneous kinetic model able to explain the reaction mechanism was adjusted and the corresponding overall reaction order was determined. The addition of around 15 wt% of water in the feed produces only a slight decrease in the butyraldehyde conversion, and it improves the mixing and transport properties of the reaction mixture.