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It has been widely accepted that oxygen vacancies are critical to catalytic oxidation activities. However, the effects of Ce–O bond strength on the formation of oxygen vacancies and the oxidation rate of styrene remain ambiguous. Herein, a series of CeO2 (CeO2-100, CeO2-140, CeO2-180) were synthesized to uncover the effects of Ce–O bond strength on surface chemical properties and unravel the oxidation mechanism of styrene via comprehensive characterization techniques and theoretical calculations. DFT calculations showed a positive correlation between the Ce–O bond strength and the formation of oxygen vacancies. The CeO2-100 catalyst exhibited a lower styrene degradation temperature (T 100 = 223 °C) and the lowest apparent activation energy (E a = 19.12 kJ/mol). This is due to the fact that weakening the Ce–O bond strength would make it easier to generate oxygen vacancies. More oxygen vacancies facilitate the adsorption of styrene and the formation of surface adsorbed oxygen, thereby accelerating styrene oxidation. In situ DRIFTS demonstrated that more oxygen vacancies can accelerate the oxidation of important intermediate products and further promote the deep oxidation of styrene to CO2 and H2O. Furthermore, the CeO2-100 catalyst showed better activity stability at 223 °C and good water resistance in the presence of 10 vol % water.

BACKGROUND: Coal gangue causes a series of environmental problems due to its low utilization rate and high amount of hoarding. However, the preparation of porous materials with coal gangue is an effective method of resource utilization. Mesoporous silica and meso-microporous ZSM-5 were prepared with alkali melting activation-acid leaching and hydrothermal synthesis, respectively. The orthogonal experiment was used to explore the optimal preparation conditions for mesoporous silica. Meso-microporous ZSM-5 were characterized with instruments. The adsorption and desorption performance of the porous material was explored by dynamic adsorption/desorption on volatile organic compounds (VOCs).RESULTS: The optimal preparation conditions for mesoporous silica are a roasting temperature of 800 °C, mass ratio of coal gangue to sodium carbonate of 1:0.6, and sulfuric acid leaching of 4 mol L −1 . The characterization results show that the molecular sieve has a superior specific surface and a certain amount of mesoporous pores due to the addition of the appropriate mesoporous template. The results of toluene dynamic adsorption experiments show that the meso-microporous ZSM-5 (ZSM-5-0.025PAC) has excellent adsorption and desorption performance (the adsorption capacity is up to 47.02 mg g −1 ), water resistance (the adsorption capacity decreased only 4.64%), and renewability (the adsorption and desorption efficiency is up to 95% and 97%).CONCLUSION: The porous materials prepared presented excellent VOCs ad/desorption performance, which has good industrial application prospects. The research provides a novel approach for the utilization of coal gangue.