Succinic acid pretreatment of corn cob for production of xylooligosaccharides and biomass pellets

The comprehensive utilization of lignocellulosic biomass (LCB) is crucial for advancing the circular bioeconomy. This study proposes a green biorefinery method based on succinic acid (SA) hydrothermal pretreatment of corncob (CC) to produce xylooligosaccharides (XOS) and biomass pellet fuel for complete biomass utilization. Under optimal pretreatment conditions (150 °C, 40 min, 0.3 M SA), 52.86 % XOS was achieved with a degree of polymerization (DP) of 2–5. Compared to raw CC, the content of cellulose and lignin in the pretreatment residue increased by 27.6 % and 25.5 %, respectively. This compositional change would improve the pellet performance. Lignin acts as a natural binder in biomass pelletizing. Under thermal compression, it softens and bonds, filling the gaps between particles. Simultaneously, it connects cellulose microcrystals through van der Waals forces. Furthermore, the increased crystalline cellulose facilitated mechanical stress dissipation through nanofiber alignment, thereby enhancing pellet density and mechanical strength. Under the pelletizing conditions (80 MPa, 100 °C, 12 % moisture), pellets prepared from pretreated residues showed an 11.99 % increase in density, a 155.78 % rise in compressive strength, a 16.43 % gain in higher heating value (HHV), and a 37.66 % reduction in ash content. The mechanical strength and thermal properties of biomass pellets derived from CC pretreated with SA were significantly enhanced. This environmentally friendly and mild acid pretreatment approach provides an innovative pathway for the efficient, closed-loop utilization of LCB.