Engineering CuMn2O4 via waste activated carbon incorporation for low-temperature toluene oxidation: Coupling oxygen vacancies and hierarchical porosity

• Oxygen vacancies in CuMn 2 O 4 were constructed via in-situ WAC incorporation. • Electron distribution and strength of the Mn-O bond changed with WAC incorporation. • The adsorption state of VOCs on the catalyst surface changed to chemisorption. • The replenishment rate of gas phase oxygen to lattice oxygen was accelerated. Developing highly active and cost-effective catalysts for Volatile Organic Compounds (VOCs) removal is yet challenging in the industrial field. Motivated by constructing oxygen vacancy (O v ) and enhancing mass transfer of catalyst for boosting VOCs oxidation, waste activated carbon (WAC) was selected to assist the synthesis of spinel. Herein, the hierarchical porosity and active O v sites were successfully introduced into the spinel skeleton via an in-situ WAC calcinating method, regulating the lattice constant as well. The optimized catalyst achieved 90 % conversion at 212°C, 40 °C lower than the pristine CuMn. Besides, the catalyst delivered satisfactory stability in both wet conditions and long-term reactions. Characterization showed that the O v content of WAC-CuMn increased significantly and changed the electron distribution between Cu and Mn. In situ DRIFTS confirmed that the optimization modified the adsorption state of toluene on the spinel surface. The engineering of numerous O v facilitated the replenishment of gas-phase oxygen to lattice oxygen, enhancing redox cycling and catalytic efficiency. This work provides a new idea for the treatment of WAC and the reasonable design of efficient catalysts for the catalytic oxidation of toluene.