Experimental study and molecular simulation of the influence of air humidity on ethylene adsorption performance

Ethylene is a cause of the rotting of fruits and vegetables. Purification of ethylene in high-humidity environments is challenging. In order to improve the purification performance of potassium permanganate impregnated materials in high humidity environments, it is necessary to understand the influence of carrier properties on competitive adsorption behaviour. In this study, ZSM-5 zeolites with different SiO 2 /Al 2 O 3 ratios (25, 50, and 80) were used as carriers for KMnO 4 impregnation. Ethylene adsorption experiments were carried out under different humidity conditions (40% and 80%). It was found that in high-humidity environments, carriers with higher KMnO 4 loading did not necessarily exhibit higher ethylene purification capacity. The competitive adsorption mechanism between ethylene and water vapour in zeolite pores was analysed by GCMC molecular simulation. Under high concentration water vapour, the purification process can be divided into two stages: ethylene first reacts with potassium permanganate on the outer surface, then diffusion into pores is hindered, causing pore-loaded KMnO 4 to fail. This study revealed that specific surface area can dominate water vapour adsorption capacity, while the SiO 2 /Al 2 O 3 ratio controls ethylene adsorption through acid sites. The findings provide fundamental guidance for carrier selection in high-humidity environments and demonstrate that higher loading does not guarantee better performance under competitive adsorption conditions.