Surface-Engineered Wood Fiber with Nano-CeO ₂ for Enhanced Thermal Stability and Catalytic Removal of PM and NOx from Gasoline Engine Exhaust

Wood fibers (WFs) present a sustainable and economically viable option for gasoline particulate filter (GPF) substrates, attributed to their hierarchical porous structure and minimal exhaust back pressure. This study involved the loading of nanoscale cerium oxide (CeO2) onto the WF surface using the sol–gel method to create CeO2/WF composite materials. This approach aims to enhance both the thermal stability of wood fibers and the catalytic activity of cerium oxide. In comparison to the original WF, the residual mass of the CeO2/WF composite material increased by 41.3% under high-temperature conditions, indicating that thermal degradation was successfully mitigated. The altered fibers retained their porous structure, resulting in minimal resistance to flow. At the same time, the evenly distributed CeO2 nanoparticles, rich in oxygen vacancies, enhanced the oxidation of particulate matter (PM) and facilitated NOx reduction through redox cycling between Ce3+ and Ce4+ states. Simulation tests demonstrated a PM removal efficiency of 96% and NOx conversion rate of 52% at 350 °C, surpassing both unmodified WFs and commercial GPF substrates. This study presents a sustainable, high-performance, and low-back-pressure catalytic filter medium, offering a promising pathway for advancing next-generation automotive emission control technologies.