Hydrothermal treatment of biomass using phosphorous acid as an additive

Instead of using as a solvent, phosphorous acid can be also used as a catalyst for biomass pretreatment.

Based on the study in Japan, the yield of monosaccharide obtained from the rice straw using hydrothermal treatment was low. but when 50 mM phosphoric acid solution was used to hydrothermal system, most of xylan in rice straw was successfully hydrolyzed to xylose and some amount of glucan was also converted into glucose at 160 °C for 15 min. The maximum xylose and glucose yields were 54.1 and 15.0 % at this condition, respectively.

The remained cellulose residue after hydrothermal treatment with phosphoric acid at 160 °C for 15 min was easily saccharified to glucose by enzymatic hydrolysis. After the enzymatic saccharification, the glucose yield was 81.6 %.

After neutralization of hydrolysate with NaOH, the salt formed is sodium phosphate. This salt used as nutrient by microorganisms.