Directional synthesis of furfural compounds from holocellulose catalyzed by sulfamic acid

The coproduction of 5-hydroxymethylfurfural (5-HMF) and furfural (FUR) via the direct hydrolysis of holocellulose analogue composed of cellulose and hemicellulose was investigated. The effects of catalyst amount, solvent type and amount, reaction temperature and time using sulfamic acid with dual active sites as catalyst were also studied. The yields of 5-HMF and FUR at 37.2% and 62.0% were obtained with the volume ratio of γ-valerolactone to water of 25:1 at 180 °C for 3 h. The conversion of corn cob holocellulose and wheat straw holocellulose to furfural compounds was then carried out under the identical conditions. Yields of 5-HMF at 26.6% and 28.5%, and yields of FUR at 34.5% and 26.1% were obtained, respectively. A possible mechanism for the coproduction of 5-HMF and FUR from holocellulose was proposed. It is believed that there is a synergistic effect between the hydrolysis of cellulose and hemicellulose during the conversion of holocellulose. Graphic abstract