The Catalytic Effect of Rice Husk Ash on Pine Pyrolysis Based on a Three-Component System

Biomass is characterized by its diversity and wide availability. Co-pyrolysis technology is considered a promising approach for high-quality conversion and high-value utilization of biomass, representing a critical pathway toward environmental sustainability. This study selected rice husk and pine as representative herbaceous and woody biomass materials. Using a thermogravimetric analyzer (TGA) and Py-GC/MS, we systematically investigated the synergistic effects during co-pyrolysis, examined their underlying mechanisms, and analyzed changes in product distribution. The results indicate that the blend containing 30% rice husk exhibited the most pronounced synergistic effect. Specifically, the experimental char yield and pyrolysis activation energy were 9.7% and 10.5% lower than the theoretically calculated values, respectively. Both the blending ratio and heating rate were found to significantly influence these synergistic interactions. The observed synergy is attributed to the migration of alkali metals from rice husk ash, which enhances reaction rates and promotes specific pathways such as cellulose ring-opening cleavage and hemicellulose deacetylation. Consequently, the product distribution shifts toward lighter compounds, including aldehydes, ketones, and alcohols. This study clarifies the central catalytic role of herbaceous biomass ash and highlights the critical function of alkali metal migration in regulating product selectivity, thereby providing theoretical support for efficient pyrolytic conversion.