Pt anchored in the skeleton of rice husk-based ZSM-5 for excellent catalytic VOC oxidation: structure-activity relationship and environmental impact assessment.

ZSM-5 molecular sieves (ZSM-5-T1, ZSM-5-T2, ZSM-5-T3) were synthesized using SiO2, SiO2-8.7% C, and SiO2-23.6% C as templates from rice husk powder, respectively. Pt species were fixed within the ZSM-5 skeleton via the isovolumetric impregnation method, and the resulting catalysts were employed for the efficient oxidation of toluene (C7H8). Notably, Pt/ZSM-5-T2 exhibited the highest C7H8 catalytic oxidation activity (R175 °C = 0.733 µmol g-1 s-1, WHSV = 60 000 mL h-1 g-1) among the three variants. Furthermore, this catalyst displayed excellent water resistance when exposed to various concentrations of water vapor (2 vol%, 5 vol%, 8 vol% and 10 vol%) during the activity test. The characterization results provided insight into the exceptional catalytic performance of the Pt/ZSM-5-T2 catalyst, attributing it to its high specific surface area, appropriate hydrophilicity, abundant Lewis acid sites, and a high Pt0/(Pt0 + Pt2+) ratio. In situ DRIFTS analysis further suggested that the key step in the oxidation of C7H8 to benzyl alcohol involves C-H cleavage on Pt/ZSM-5. Simultaneously, the application of a life-cycle assessment (LCA) revealed that this strategy, involving the substitution of chemicals with biomass, led to a remarkable 41-43% reduction in carbon footprint. This environmentally friendly approach underscores the potential for repurposing rice husk powder waste. Pt/ZSM-5-T2 meets the requirements for practical applications, paving the way for sustainable resource utilization in the realm of environmental preservation. [ABSTRACT FROM AUTHOR]