Acetic Acid Pretreatment Modulates Pyrolysis of Invasive Wetland Biomass: Insights from a Three-Parallel-Reaction Model

High Resolution Image Download MS PowerPoint Slide Effects of chemical pretreatment on biomass minerals and their roles in pseudo-component's pyrolysis kinetics, mechanisms, and thermodynamics remain unclear. This study investigates the effect of acetic acid pretreatment on the pyrolysis behaviors of Phragmites karka (PK) and Actinoscirpus grossus (AG) using fixed-bed pyrolysis, spectroscopic characterizations, and thermogravimetric kinetic analyses. The results reveal that pretreatment decreases char yield and significantly increases gas production in AG, with almost no liquid products, due to the activation of AG following partial removal of inherent high calcium content. Conversely, pretreatment of PK slightly increases char yield while decreasing gas and liquid yields and promoting levoglucosan formation. For PK, activation energies increased after pretreatment (pseudo-hemicellulose: 164.8 to 279.0; pseudo-cellulose: 200.1 to 242.7; pseudo-lignin: 191.8 to 238.4 kJ·mol −1 ), indicating catalytic effects of inherent minerals. In AG, pretreatment decreased activation energies for pseudo-hemicellulose (178.3 to 156.9 kJ·mol −1 ) and pseudo-cellulose (214.2 to 116.0 kJ·mol −1 ), with minimal change for pseudo-lignin (149.4 to 148.0 kJ·mol −1 ), reflecting the activation of AG. Order-based models describe pseudo-hemicellulose and AG pseudo-cellulose devolatilization, while PK and treated PK pseudo-cellulose follow random scission, with variable order for lignin devolatilization. Thermodynamic parameters supported kinetic results, highlighting how mineral contents and pretreatment modulate reaction chemistry and kinetics during biomass pyrolysis.