Catalytic upgrading of citric acid from fermentation processes
The general aim is to prepare new polyfunctional ester compounds starting from citric acid, directly sourced from the fermentation process. Conversion of citric acid comprises defunctionalisation, e.g. removal of –OH groups, followed by hydrogenation and possibly esterification. An ideal reaction would lead to high yields based on citric acid, would use high concentrations of citric acid, and would be able to deal with raw citric acid, i.e. citric acid that has been minimally purified after the fermentation. Strategies will be developed to facilitate recovery of the hydrogenation catalyst, e.g. by combining the solid hydrogenation catalyst with a soluble Lewis or Brönsted acid catalyst. Besides identifying the most suitable composition of the acid catalyst, due attention will be given to mechanistic aspects. Finally, the optimal procedure will be developed to produce citric acid derived plasticizers, which will then be tested in conditions that are industrially relevant.