Regeneration of deactivated activated carbon honeycomb catalysts for VOC removal: structural evolution and activity...

The deactivation problem of honeycomb catalysts used for industrial volatile organic compound treatment will greatly restrict their long-term effectiveness and lower the overall economic benefits. The long-term operational data shows that the adsorption efficiency has gradually decreased from the original 90 to 95% to 82 to 88%, accompanied by greater fluctuations and more low efficiency situations, indicating that the catalyst is gradually becoming deactivated. In this study, a regeneration process including physical cleaning, chemical washing, and thermal treatment was used for deactivated activated carbon honeycomb catalysts. After regeneration, the catalyst structure and catalytic performance were recovered. BET results showed that the specific surface area increased from 29.57 to 54.44 m² g^-1, and the micropore area increased from 11.85 to 25.90 m² g^-1. SEM images showed that surface deposits were removed and blocked pore channels were reopened. XRD results indicated that the carbon framework and active phases remained structurally stable during regeneration. XPS results demonstrated variations in surface chemical composition, including the partial removal of sulfur- and chlorine-containing deposits, while maintaining the overall carbon framework. Furthermore, TGA analysis confirmed a decrease in thermally stable carbonaceous residues after regeneration, indicating the removal of accumulated organic contaminants. Based on the structural characterization results, a deactivation-regeneration mechanism involving contaminant deposition, pore blockage, active site shielding, and pore reopening was proposed. The reconstructed hierarchical pore structure significantly improved pore accessibility and re-exposed active sites, resulting in the recovery of catalytic performance. These research results can provide reliable regeneration methods for honeycomb catalysts used in the treatment of volatile organic compounds in industry.