Researchers at the Isfahan University of Technology (Iran), have demonstrated the use of a dilute acid hydrolysis process to convert rice straw—a cheap, abundant and mainly unused ag waste—to 5-Hydroxymethylfurfural (HMF) and furfural. Both furans are components for production of different chemicals and fuels.
|Rice straw to furans via dilute acid hydrolysis. Source: Amiri et al. Click to enlarge.|
A paper on their work was published in the journal Carbohydrate Research.
The highest yield of HMF in a single-phase hydrolysis was 15.3 g/kg straw, attained at 180 °C during 3 h with 0.5% sulfuric acid, while the maximum yield of furfural, 59 g/kg straw, was obtained at 150 °C during 5 h.
Different extracting solvents, including 2-PrOH, 1-BuOH, methyl isobutyl ketone (MIBK) and acetone at 180 °C for 3 h as well as tetrahydrofuran (THF) at 150 °C for 5 h were examined in biphasic systems.
Use of the solvents generally improved the production of HMF compared to the single aqueous phase process. The best results of HMF production, more than 59 g/kg straw, were obtained in the systems containing either 2-PrOH or 1-BuOH. Using THF as an extracting solvent, a relatively high furfural yield, 118.2 g/kg straw, was obtained and 96% of furfural produced in this system was extracted into THF during the process.
Hamid Amiri, Keikhosro Karimi, and Shapoor Roodpeyma (2010) Production of furans from rice straw by single-phase and biphasic systems. Carbohydrate Research. In press. doi: 10.1016/j.carres.2010.07.032