Enhanced Removal Performance and Economical Efficiency of Volatile Organic Sulfur Compounds by Silver-Modified ZSM-5 Zeolites under a High-Humidity Environment: A Mechanistic Study of the Adsorption-Plasma Catalytic Process

Dimethyl sulfide (DMS) is a harmful volatile organic sulfur compound (VOSC), which must be effectively controlled. The adsorption-plasma catalytic (APC) process is an efficient and economical route for the elimination of low-concentration VOSCs; however, there are still many challenges in humid environment. In this study, a series of zeolites with different Si/Al ratios and Ag loadings were designed, and were performed for DMS removal by APC process. At 80% relative humidity, the DMS adsorption capacity of Ag5-ZSM25 reached 33.9 mg/g, which was 7.9 times that of ZSM25 and nearly 2 times that of Ag5-ZSM200. Analyses via UV-vis, X-ray photoelectron spectroscopy (XPS), and CO-FTIR confirmed that Ag⁺ was the predominant species for DMS adsorption and degradation in Ag5-ZSM25. DMS-temperature-programmed desorption (TPD) and density functional theory (DFT) calculations indicated that Ag⁺ significantly enhanced the binding energy with DMS and weakened the competitive adsorption impact of H₂O. In the plasma regeneration stage, Ag5-ZSM25 demonstrated an 89% mineralization, with Ag⁺ being crucial for DMS mineralization. Based on the in situ plasma DRIFT spectra, a possible degradation pathway for DMS was proposed. The APC process achieved an energy efficiency of 1.66 g/kWh, tripling that of the continuous plasma catalytic process and providing guidance for low-concentration DMS elimination.