Phosphoric acid doped polybenzimidazole as an heterogeneous catalyst for selective and efficient dehydration of saccharides to 5-hydroxymethylfurfural

5-Hydroxymethylfurfural (HMF) is considered as a valuable platform chemical for fuels and chemical intermediates. Tremendous efforts have been made on the development of catalysts for the dehydration of saccharides to HMF with high conversion and selectivity. Here we reported a new solid acid, phosphoric acid doped polybenzimidazole (PA-PBI), for the dehydration of fructose to HMF with high selectivity (similar to 94%) at high fructose concentration (50 wt%) in a water-methyl isobutyl ketone (MIBK) biphasic system. PA-PBI was directly obtained by the one-pot polycondensation reaction and was very stable under harsh reaction conditions due to the strong acid-base interaction between PA and imidazole in PBI. PA-PBI was recycled to catalyze the dehydration of fructose four times without the loss of activity and could also catalyze a variety of disaccharides and polysaccharides to produce HMF. The high selectivity and the ease of recycling make PA-PBI a superior catalyst for the dehydration of saccharides to HMF.