Superior performance in catalytic combustion of toluene over mesoporous ZSM-5 zeolite supported platinum catalyst

• 0.5% Pt-R/Meso-KZSM-5 catalyst is prepared by incipient wetness impregnation.
• Pt-R/Meso-KZSM-5 gives the T98 of 1000 ppm toulene at only 175 °C.
• Pt-R/Meso-KZSM-5 exhibits good water and CO2 tolerance.
• Pt0 species could be the active centers for the conversion of toluene to CO2 and H2O.
• Pt0 concentration increases with decreasing electronegativity of the zeolite cations.

Catalytic combustion over zeolite supported platinum catalysts is regarded as one of the efficient methods for removal of volatile organic compounds (VOCs). In this work, we show a preparation of Pt loaded mesoporous ZSM-5 zeolite (Pt/Meso-ZSM-5) with various cations. The sample N2 sorption isotherms and TEM image show abundant mesoporosity existing in the zeolite crystals. The catalytic toluene combustion tests show that the Pt/Meso-ZSM-5 catalysts have higher activities than conventional ZSM-5 supported Pt catalysts (Pt/ZSM-5), which is related to their difference in the concentration of active sites Pt0 and the rate of mass transfer. Particularly, after reduction with hydrogen at 300 °C, the Pt nanoparticles supported on Meso-ZSM-5 with K+ and Cs+ cations (Pt-R/Meso-KZSM-5 and Pt-R/Meso-CsZSM-5) exhibit much higher activities than those on Meso-ZSM-5 with Na+ and H+ cations, which is well consistent with their order of the Pt0 concentration. For example, Pt-R/Meso-KZSM-5 gives the temperature for conversion of 98% toluene (T98) at only 175 °C, while Pt-R/Meso-HZSM-5 shows the T98 at 190 °C. More importantly, Pt-R/Meso-KZSM-5 has a long life, and its activity cannot be influenced by the water and CO2. These features are critically important for practical applications of these catalysts in the future.

K+-exchanged mesoporous ZSM-5 zeolite supported 0.5% platinum catalyst (Pt-R/Meso-KZSM-5) is very active, giving T98 at 175 °C, negligible inhibition effect of water and CO2, and extraordinary long life in catalytic combustion of 1000 ppm toluene. These features would be potentially important for the catalytic combustion of VOCs in the future.Figure optionsDownload high-quality image (246 K)Download as PowerPoint slide