Ultra-Fast Selective Fructose Dehydration Promoted by a Kraft Lignin Sulfonated Carbon Under Microwave Heating

In this work, a highly acidic sulfonated carbon was obtained from eucalyptus kraft lignin, a byproduct from paper industry, and then used as catalyst in fructose dehydration. Reactions were performed employing dimethylsulfoxide (DMSO) as low cost/toxicity solvent and under microwave heating. The main product obtained was 5-hydroxymethylfurfural (5-HMF), a versatile platform compound that can be converted to several products of industrial interest. The catalyst is highly active to fructose dehydration and is able to convert 93.3% of the fructose (in a 10% m/v DMSO solution) with 98% of selectivity for 5-HMF in just 10 s at 393 K. Investigations about the catalyst dosage, reaction temperature and substrate concentration were carried out. In addition, the low-cost catalyst produced outperformed expensive commercial catalysts under the same conditions. After a simple regeneration process, the catalyst produced also can be recycled without significant loss in its catalytic activity.