Nanoscale HZSM-5 supported PtAg bimetallic catalysts for simultaneous removal of formaldehyde and benzene

• Simultaneous removal of HCHO and C6H6 by a catalytic cycling process is reported.
• This approach exhibits extremely low energy cost without secondary pollution.
• PtAg/nanoscale HZSM-5 catalyst exhibits excellent activity and stability during 5 consecutive cycles.

ABSTRACTA catalytic process including formaldehyde oxidation and benzene “storage-oxidation” cycling for simultaneously removal of formaldehyde and benzene is proposed, by using HZSM-5 supported PtAg bimetallic catalysts. HZSM-5 with different crystal size supported PtAg bimetallic catalysts were synthesized with the investigation focusing on HCHO oxidation at room temperature, benzene storage capacity at room temperature, and benzene catalytic oxidation at elevated temperature. Crystal size of HZSM-5 zeolite not only influences the dispersion of active metals of PtAg, and therefore influence their catalytic properties for formaldehyde and benzene oxidation, but also has great effects on benzene storage capacity and the thermal stability of the stored benzene, which is directly related to the release of benzene at elevated temperature. The ratio of Pt/Ag has an opposite effect on benzene storage capacity and formaldehyde and benzene oxidation properties. Considering these factors, PtAg (Pt/Ag = 1/1) supported on nanoscale HZSM-5 catalysts were found to be suitable for the proposed cycling process, good carbon balances being obtained for each cycle without the production of secondary pollutants.

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