Pressurized HCl gas/solid system for efficient degradation of cellulose polymorphs into monosugars

Activity: Talk or presentation typesConference presentation

Description

As cellulose is the main polysaccharide in biomass, countless efforts have been devoted to degrading this recalcitrant polysaccharide, particularly in the context of biofuels and renewable nanomaterials. Previously, we have shown that pressurized HCl gas in a solid/gas system is able to efficiently hydrolyze cellulose in fibers, reaching the so-called leveling-off degree of polymerization (LODP) in less than 1.5 h.[1] LODP marks the point where the disordered portions of cellulose microfibrils have been degraded and only the crystalline portions remain, generally signaling the end of cellulose degradation unless remarkably high concentrations are used (e.g., 72% H2SO4). Increasing the water content of the fibers to 30-50% markedly boosts the hydrolysis rate and can take the hydrolysis further beyond the LODP. Simultaneously, however, the harmful formation of strongly chromophoric humins is strongly increased. Here, we show that the humin formation can be suppressed by a simple addition of chlorite into the reaction system where the degradation of several cellulose polymorphs was trialed (Figure 1). 50–70% glucose yields were obtained from cellulose I and II polymorphs while >90% monosaccharide conversion was acquired from cellulose IIIII after a mild post-hydrolysis step.[2] Besides that, purification of the products was relatively unproblematic from a gas-solid mixture, and a gaseous catalyst was easier to recycle than the aqueous or liquid counterpart. The results lay down a basis for future practical solutions in cellulose hydrolysis where side reactions are controlled, conversion rates are efficient, and the recovery of products and reagents is effortless.
Period26 Sept 202328 Sept 2023
Event titleInternational Cellulose Conference
Event typeConference
Conference number5
LocationHiroshima, JapanShow on map
Degree of RecognitionInternational