Polyvinyl sulfonated catalyst and the effect of sulfonic sites on the dehydration of carbohydrates

Several biobased platform chemicals have been identified as potential replacements of oil-based product, such as fuels and polymers. One of them, 5-hydroxymethylfurfural (HMF), has the potential to be transformed in a myriad of products, such as fungicides, fuels, and plastics. Environmentally and financially sustainable production of HMF has been one of the main bottlenecks for its commercialization at the industrial level. Here is presented a low-cost, tunable polyvinyl-based solid catalyst capable of efficiently transforming carbohydrates into HMF. The catalyst was produced using polyvinyl alcohol and sulfosuccinic acid (SSA) as the crosslinker. Adjusting crosslinking concentration had measurable effects on the physical properties and the efficiency of the catalyst. The crosslinking degree was observed to affect the thermal stability, the crystallinity, and the functional sites, providing an opportunity to fine tune the material to the reaction’s needs. At the highest SSA concentration, SO3H functional sites reached 1.7 mmol/g, and 3.6 mmol/g total acid sites. HMF synthesis was tested in ionic liquid [BMIM][Cl] and water. The use of ionic liquids reduced considerably the reaction temperature and time needed for quantitative yields from fructose. Optimal reaction conditions were found by response surface methodology, resulting in an HMF yield of 94.3% after 4 min at 125 °C from fructose. A kinetic model showed that HMF degradation proceeded via HMF self-condensation or self-etherification, and not through rehydration. The PVA-SSA catalyst was also tested on glucose and sucrose, with moderate yields (25% and 63.9% respectively) for both. The material shows promise as a highly tunable, recyclable catalyst