A rapid chemical method for production of xylitol from D-xylose as a renewable feedstock from spent aromatic waste

Abstract

Xylitol is occurring naturally as a minor constituent in many fruits and vegetables. Commercially, xylitol is produced by chemical methods from D-xylose for application as an alternative sweetener in food and pharmaceutical products. Although biomass-derived xylose can be used as a potential substrate for xylitol production, its prerequisite purification before a catalytic hydrogenation directly impacts the production cost. In addition, the isolation of xylose falls under a routine pretreatment activity during conversion of biomass to platform chemicals. The resulting hydrolysate often exhibits a low concentration of xylose and other monosaccharides. Concentrating the hydrolysate to a desired level for conversion to xylitol under chemical/biological methods increases the expenditure cost. Many times, concentration by heating may cause the degradation of contained sugars in the hydrolysate. Therefore, this study has been carried out to obtain a mixture of C5/6 sugars, predominantly the D-xylose in a solid dry form (∼10 % yield, >98 % purity) directly from acid hydrolysate of spent aromatic waste. Biomass-derived D-xylose was further transformed to xylitol (100 % conversion) by a fast (10 min), efficient, and solvent-free chemical approach using a modified sodium borohydride (NaBH4) catalyst on a wet silica (SiO2) support at RT. All reagents and solvents used in the process were recovered and recycled, leading to the minimal waste generation.