Synergistic effect of metal oxidation states and surface acidity enhanced the trace ethylene adsorption of Ag/ZSM-5

Abstract

Trace ethylene in a storage environment induces softening and ripening of fruits, causing short storage life and food wastage. Adsorption is regarded as a promising technology for the removal of trace ethylene, but the design and development of high-performance adsorbents still remain challenging. Herein, Ag/ZSM-5 adsorbents with different Si/Al ratios were prepared for removing 100 ppm of ethylene from the air stream. Among all the adsorbents, Ag/ZSM-5 with a Si/Al ratio of 130 exhibited the best ethylene adsorption performance, achieving a capacity of 5.14 L kg_ads⁻¹ at 20 °C and more than 99.9% of removal rate. According to characterization, Ag/ZSM-5(130) possesses a higher silver ion content and larger number of weak Lewis acid sites. Therefore, it shows the strongest electron-acceptability, enhancing the π-complexation ability between ethylene molecules and the adsorbents, which promotes the adsorption of trace ethylene. A post-harvest banana storage experiment was conducted and it proved the excellent potential of Ag/ZSM-5 in practical applications. Regulating adsorption through changing the zeolite Si/Al ratio maybe a novel idea for improving the performance of zeolite-based ethylene adsorbents.