Ag/Eggshell Nanocatalyst for Sustainable Ethylbenzene Oxidation: Synthesis, Characterization, and Performance

Abstract

Catalytic oxidation is one of the most effective technologies for controlling volatile organic compounds (VOCs) due to its environmental friendliness and energy efficiency. Supported noble metal nanostructures are among the most commonly used catalysts, exhibiting high activity, durable stability, poison tolerance, and easy regeneration. The solid, hierarchical, and porous structure of eggshell makes it an excellent support for dispersing and stabilizing nanoparticles. In this study, an Ag/eggshell catalyst was synthesized by the impregnation method in an aqueous medium and characterized using SEM, TEM, XRD, and FTIR. The XRD results revealed the diffraction peaks of silver nanoparticles, and TEM analysis showed an average nanoparticle size of 52 ± 11 nm. The effects of different synthesis and operational factors on the catalytic activity for ethylbenzene oxidation were investigated in a gas matrix at various temperatures. Catalysts synthesized with Ag/Ca molar ratios of 10.8%, 19.9%, and 34.3% resulted in t₉₀ (temperature for 90% conversion) at 204, 226, and 283 °C, respectively. An increase in relative humidity from 0 to 40% led to an increase in t₉₀ from 201 to 275 °C. In conclusion, Ag/eggshell catalysts demonstrate significant potential for the oxidation of airborne ethylbenzene in occupational settings.