Catalytic conversion of raw Dioscorea composita biomass to 5-hydroxymethylfurfural using a combination of metal chlorides in N,N-dimethylacetamide solvent containing lithium chloride

Conversion of Symphytum officinale and Panicum virgatum plant extracts to 5-hydroxymethylfurfural catalysed by metal chlorides in ionic liquids

The present work examined the potential for two plants grown on Canadian soil, Symphytum officinale L. (common comfrey) and Panicum virgatum L. (switchgrass), to produce 5-hydroxymethylfurfural using metal chloride catalysis in two ionic liquids, 1-butyl-3-methylimidazolium chloride or 1-ethyl-3-methylimidazolium chloride. Furthermore, two pre-treatments, namely the dilute sulfuric acid treatment and the methanol extraction, were studied as a way to improve sugar availability and increase 5-hydroxymethylfurfural yields compared with untreated biomass. The 0.5 mol/L H2SO4 hydrolysis under autoclave conditions produced sugar-rich extracts containing 230 ± 23 mg of sugars per gram of hydrolysed biomass for comfrey and 425 ± 13 mg of sugars per gram of hydrolysed biomass for switchgrass. The methanol extraction produced extracts high in simple sugars with concentration of 300 ± 60 mg of sugars per gram of dry extract for comfrey and 202 ± 16 mg of sugars per gram of dry extract for switchgrass. The yield of 5-hydroxymethylfurfural was improved from less than 1% using untreated biomass to 6.04% and 18.0% using dry methanol extracts of comfrey and switchgrass, respectively. These yields, although small, are important, as they show for the first time that a methanol extract could enhance the metal chloride catalysis in ionic liquids for 5-hydroxymethylfurfural production from biomass.

Production of 5-hydroxymethylfurfural from starch-rich food waste catalyzed by sulfonated biochar

Sulfonated biochar derived from forestry wood waste was employed for the catalytic conversion of starch-rich food waste (e.g., bread) into 5-hydroxymethylfurfural (HMF). Chemical and physical properties of catalyst were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area, and elemental analysis. The conversion of HMF was investigated via controlling the reaction parameters such as catalyst loading, temperature, and reaction time. Under the optimum reaction conditions the HMF yield of 30.4 Cmol% (i.e., 22 wt% of bread waste) was achieved in the mixture of dimethylsulfoxide (DMSO)/deionized-water (DIW) at 180 °C in 20 min. The effectiveness of sulfonated biochar catalyst was positively correlated to the density of strong/weak Brønsted acidity (SO₃H, COOH, and OH groups) and inversely correlated to humins content on the surface. With regeneration process, sulfonated biochar catalyst displayed excellent recyclability for comparable HMF yield from bread waste over five cycles.