Toluene adsorption on a novel hydrophobic ZSM-5(300)@LDH: Material synthesis, adsorption performances and moisture-resistant characteristics

Volatile organic compounds (VOCs), particularly toluene, pose significant environmental and health challenges. This study addresses the limitations of ZSM-5 zeolite in humid environments by integrating Si/Al ratio optimization with hydrophobic modification via layered double hydroxide (LDH) coatings. H-ZSM-5 zeolites with Si/Al ratios of 25, 85, and 300 were synthesized using hydrothermal methods, revealing that higher Si/Al ratios enhance specific surface area (387.67 m 2 /g for Si/Al = 300) and mesopore volume (66.4 %). However, humidity reduced the adsorption capacity (e.g., ZSM-5(300) decreased from 85.37 ± 3.60 to 65.76 ± 2.26 mg/g at 80 % RH). To mitigate moisture interference, three LDH-coated composites were fabricated: self-assembled (ZZ-300@LDH), co-precipitated (GC-300@LDH), and sol-gel-derived (RN-300@LDH). Among these, GC-300@LDH exhibited superior hydrophobicity (water contact angle: 53°) and a hierarchical pore structure (mesopore volume: 0.3688 cm 3 /g), achieving a toluene adsorption capacity of 94.43 ± 1.43 mg/g under 80 % RH—43.6 % higher than ZSM-5(300). The dual adsorption sites and enhanced surface roughness contribute to prolonged breakthrough time (6.6 ± 0.3 min) and stable regeneration over five cycles. Comparative analysis with industrial zeolites highlights GC-300@LDH's potential for integration into zeolite rotor-RTO systems, offering a scalable solution for humid industrial VOC treatment.