Mechanistic kinetic comparison of terrestrial biomass-derived cellulose and marine algae-derived agarose acidic degradation to monosaccharides and 5-hydroxymethylfurfural

Kinetic model is an important approach for quantitative expression of the mechanism of polysaccharide degradation to value-added products. This study conducted a mechanistic kinetic comparison for acidic degradation of terrestrial biomass-derived cellulose and marine algae-derived agarose to monosaccharides and 5-hydroxymethylfurfural (5-HMF). A pseudo-homogeneous first-order reaction kinetic model with Arrhenius-type temperature dependence was applied to interpret acidic degradation process of cellulose and agarose. The subsequent sensitivity analysis of the impact of rate constants on the production of monosaccharides and 5-HMF predicted in the kinetic model was performed. Results showed that rate constant of polysaccharide hydrolysis (k 1 ) exceeded rate constants of monosaccharide dehydration (k 2 ) and 5-HMF degradation (k 3 ) during agarose decomposition process, but was opposite in cellulose depolymerization process. The corresponding activation energy of agarose hydrolysis (64.5 kJ mol −1 ) was much lower than that of cellulose hydrolysis (121.4 kJ mol −1 ). Agarose was demonstrated to be superior to cellulose for producing monosaccharides and 5-HMF. The desired yields of monosaccharides and 5-HMF from agarose were obtained 58.5% and 27.5%, respectively. Subsequent sensitivity analysis revealed that rate constants k 1 and k 3 were the key factors controlling production of monosaccharides and 5-HMF from agarose, respectively.