A contribution to the study of the fructose to isosorbide conversion reaction

Abstract

The search for an alternative to the rejection of petroleum derivatives as raw materials is one of the most important challenges facing the chemical industry. The increasing stringency of environmental legislation and the need to eliminate harmful products from industry present biomass as a viable and promising resource. Isosorbide is a molecule of particular interest which can be obtained from agricultural and forestry waste. It can be used in a wide range of applications, such as the bioplastic production, and allows the substitution of bisphenol A, a monomer used, until recently, in some packaging in the food industry and which is harmful to consumers. For the production of isosorbide, a reaction mechanism is taking part. The final stage, a double dehydration of sorbitol that requires an acid catalyst, is the one under study. Currently, to obtain acceptable selectivity and yield values, sulphuric acid or a similar strong mineral acid is used. These homogeneous catalysts have present disadvantages due to energy consumption, the need for subsequent separation and neutralisation treatments, and the costs derived from the equipment corrosion. For this reason, the main interest is the search for heterogeneous catalysts that allow obtaining a good yield and selectivity with moderate conditions that promote energy costs savings. The experiments carried out in this study have proved the viability of using acidic ion exchange resins as catalysts evaluating their catalytic behaviour. Resins with a lower cross-linking degree and a higher specific volume of swolling polymer have given the best results. CT-482 resin has shown the best activity, obtaining a maximum isosorbide yield of 70% for a temperature of 180ºC. In addition, sorbitol solubility has been studied to determine possible substitutes for water. Regarding this, protic solvents with a higher polarity are the ones that have provided the best solubility values.