(651d) Effect of Aromatic Additives on Dilute Acid Pretreatment of Aspen

Authors: 
Sheng, Y., University of Cincinnati
Tu, M., University of Cincinnati
Xia, C., University of Cincinnati
Biomass pretreatment is essential for producing biofuels from lignocellulosic biomass. The aromatic additives (such as p-hydroxybenzoic acid and 2-napthol) have the potential to prevent lignin repolymerization in pretreatment and improve enzymatic hydrolysis. Effects of p-hydroxybenzoic acid and 2-naphthol additives on dilute acid pretreatment were investigated. In this study, we examined the enzymatic hydrolysis of the pretreated substrates and the physicochemical properties and structures of residual lignin. It was observed that p-hydroxybenzoic acid and 2-naphthol improved the 72h hydrolysis yield of dilute acid pretreated substrates by 13% and 17%, respectively. Langmuir adsorption isotherms showed that p-hydroxybenzoic acid and 2-naphthol decreased the residual lignin affinity to cellulase enzymes and reduced the distribution coefficient from 0.232 L/g to 0.124 and 0.084 L/g, respectively. The residual lignin molecular weight was determined by gel permeation chromatography. The potential reaction between lignin and p-hydroxybenzoic acid and 2-naphthol was characterized by HSQC-NMR. The study indicated that aromatic additives could change lignin hydrophobicity and reduce lignin condensation in biomass pretreatment and enhance the enzymatic hydrolysis.