An anti-humidity palladium-containing MFI composite as a robust ethylene scavenger

Abstract

The inhibition of ethylene exposure is necessary for preserving the quality of postharvest fruit and vegetables. In this study, we report a rational design of Pd-based MFI composite adsorbents consisting of Pd-ZSM-5 and S-1 zeolites with high ethylene adsorption capacity even in the humid environment. The effects of S-1 incorporation on the morphology, apparent surface area, Pd nanoparticles distribution, and the hydrophobicity of the MFI composite were investigated in relation to their ethylene adsorption performance in dry and humid environments. Our finding reveals a synergistic effect between the Si-rich layer and Pd nanoparticles on moisture protection and ethylene capture, respectively, leading to an exceptional ethylene adsorption ability of S-1/Pd-ZSM-5 under high relative humidity. Compared with the conventional ZSM-5-supported Pd adsorbent, S-1/Pd-ZSM-5 exhibited a two-fold enhancement in ethylene removal in the presence of moisture (0.195 mmol/g vs. 0.416 mmol/g). In particular, the secondary crystallization of S-1 achieved by 72 h of hydrothermal treatment gave an excellent confinement over the Pd-ZSM-5 structure. This novel design of S-1/Pd-ZSM-5 provides the valuable applicability of the composite zeolite for ethylene regulation in postharvest crops in the future.