Efficient Preparation of C6 Carbohydrate into 5‐Hydroxymethylfurfural with a Combination of Monoclinic FePO4 and Carbon‐Based Solid Acid Catalyst Prepared from Papermaking Sludge

Abstract A bifunctional and high‐efficiency solid acid catalyst(S‐SBC) was prepared from papermaking sludge by calcining and sulfonation with concentrated sulfuric acid. The monoclinic FePO 4 was added to assist S‐SBC to improve HMF yield. The structure characterization of S‐SBC and its catalytic performance for 5‐hydroxymethylfurfural(HMF) preparation from fructose, glucose and cellulose were investigated. Metal ions and −SO 3 H in the S‐SBC had synergistic effects on the HMF yield. The HMF yield from fructose, glucose and cellulose were respectively 90.3 %, 73.7 % and 28.8 % with S‐SBC alone. The combination of monoclinic FePO 4 and S‐SBC could effectively improve the yield of HMF from glucose and cellulose. The highest yield of HMF from glucose and cellulose were respectively 89.5 % and 53.3 % with the binary catalysts. The mechanism of the synergistic action of the binary catalysts was proposed. Bronsted acid from metal ions hydrolysis and ‐SO 3 H, ‐COOH, ‐OH grafted on the surface of biochar promoted hydrolysis of cellulose to glucose, which was then coordinated with Lewis acids and isomerized to fructose. Finally, HMF was obtained by dehydrating from fructose.