Kinetics of the isosorbide production from sorbitol using water as solvent and the ion-exchange resin CT-482 as catalyst

Abstract

The chemical industry is subject to various trends and requirements. On the one hand, products must be safe for society. On the other hand, they can replace raw materials from oil or coal, reducing the environmental impact of the processes and reducing energy consumption. The use of bisphenol A has been banned because of the endocrine problems it causes in the population. Bisphenol A is a monomer used to produce polymers that coat the inner surface of tin cans, or was present in the heat-sensitive paper on which supermarket tickets are printed, for example. To replace bisphenol A, the use of isosorbide, a monomer that can polymerize to give polymers of equivalent function to bisphenol A derivatives, has recently been proposed. Isosorbide can be obtained by a process that uses fructose or another sugar as a feedstock and can be produced from biomass after hydrolysis of wood or agricultural residues. Fructose is converted to isosorbide in two stages. In the first, fructose is converted to sorbitol by hydrogenation, and in the second, sorbitol, in the presence of an acid catalyst, forms isosorbide. The aim of the present work was to begin the study of the second reaction, verifying that the reaction is possible using acid ion-exchange resins as catalysts and with special emphasis on obtaining kinetic data. These catalysts are suitable to work at moderate temperatures (below 130 ºC) and, therefore, in interesting conditions for energy saving. A reaction device was used that allowed working with sorbitol in aqueous solution. The working conditions that allow to operate selectively towards the isosorbide avoiding the effects of internal and external matter transfer were determined, using a catalyst previously selected by screening. All this, obtaining a good reaction rate. Finally, the kinetic model that best fitted the experimental results was determined.