Supercritical water hydrolysis of cellulosic biomass as effective pretreatment to catalytic production of hexitols and ethylene glycol over Ru/MCM-48

摘要

The hydrolytic hydrogenation of cellulose was studied using mesoporous Ru/MCM-48 as a catalyst. Supercritical water (SCW) was used as a reaction medium for cellulose hydrolysis, since in this reaction medium it is possible to depolymerize cellulose with a high selectivity towards sugars (70% w/w), avoiding degradation reactions when extremely low reaction times are used. The SCW hydrolysis was carried out at 400 degrees C - 25 MPa and 0.20 s. The hydrogenation of the liquid product from cellulose hydrolysis in SCW was further studied by changing the temperature and reaction time to maximize the yield of hexitols. The results demonstrated the achievement of higher yields of hexitols by the subsequent hydrogenation of the liquid product from cellulose hydrolysis in SCW (49%) rather than using a one-pot catalytic hydrogenation process. Ru/MCM-48 showed better behavior than commercial Ru/C during the hydrogenation process in all cases. Ru/MCM-48 was also employed in the hydrogenation of the product from sugar beet pulp (SBP) hydrolysis in SCW. SBP was used in order to evaluate the behavior of real biomass in this process. A 15% yield of hexitols was achieved from SBP, where ethylene glycol was the main compound in the liquid product and glycerol was obtained as a byproduct too.