Hydrophobic Tungsten-Containing MFI-Type Zeolite Films for Exhaust Gas Detection.

The assembly of highly hydrophobic nanosized tungsten-containing MFI-type zeolite nanocrystals (W-MFI) in films and further use of the films for selective exhaust gas (CO, CO2, NO, and NO2) detection were investigated by operando IR spectroscopy. Because of the hydrophobic nature and presence of tungsten in the framework, the W-MFI films showed excellent sorption capacity toward all analytes, in comparison to the pure silica (Si-MFI) film. The high sensitivity of the W-MFI film toward low concentration of CO2 and NO2 (1-3 ppm) was demonstrated. In addition, the interactions between the analytes and zeolite films have been studied by quantum chemical calculation modeling of the W centers based on the density functional theory method.