Work

Catalyst in-situ regeneration for polychlorinated biphenyl tail gas degradation and catalytic activity recovery mechanisms

Year: 2025

Type: article

Abstract: • The in-situ catalyst regeneration in the degradation of PCB-209 was explored. • Coke removal mechanism and optimize regeneration conditions were revealed. • Water vapor reacted with activated carbon to generate reducing gases H2 and CO. • Coke gasification process and activation of active components were proposed. • The optimum content of water vapor and temperature enhanced catalyst regeneration. To address the problems with catalytic degradation, such as poisoning and inactivation, a simple and efficient gas purging regeneration technique was developed for iron-based catalyst in-situ regeneration. Specifically, the effects of carrier gas types, regeneration temperatures, and granular activated carbon (GAC) addition on iron-based catalyst regeneration were investigated. The Fe 3 O 4 /γ-Al 2 O 3 regenerated at 550 °C with additional GAC and 15 % water vapor exhibited the optimal degradation efficiency towards polychlorinated biphenyls (PCBs), with an increase from 41.2 % to 93.5 %, compared with non-regenerated Fe 3 O 4 /γ-Al 2 O 3 . In addition, the 60-hour stability test revealed a well-recovered catalytic activity. During the Fe 3 O 4 /γ-Al 2 O 3 regeneration, the coke on the catalyst surface was oxidized and removed in the form of CO 2 , and meanwhile the oxidized Fe(III) was reduced into Fe(II) in the catalyst. This study provides a safe and efficient iron-based catalyst regeneration technology for PCB off-gas degradation and reveals the catalytic activity recovery mechanism during catalyst regeneration.

Source: Journal of Environmental Sciences

DOI: 10.1016/j.jes.2025.03.041