4.4.4 SCRCatalyst Materials for Exhaust Gas Detection

14th International Meeting on Chemical Sensors - IMCS 2012
2012-05-20 - 2012-05-23
Nürnberg/Nuremberg, Germany
4.4 EU NetAir (Special Session) I
D. Schönauer-Kamin, R. Moos - University of Bayreuth, Functional Materials (Germany)
387 - 390


The application of SCR-catalyst materials like vanadia-doped tungsten-titania (VWT) and ironexchanged zeolites (Fe-ZSM-5) for analyte detection in exhaust gases is investigated. Three detection modes are covered by this overview: the detection of certain gas concentrations with sensing devices comprising SCR-materials, the measurement of the electrical properties of the catalyst materials itself, and the direct determination of the catalyst status during operation by microwave method (an inoperando method). In this work, an overview on the suitability of SCR materials for gas detection at high temperatures (500 – 600 °C) is given. Various sensing principles, like mixed-potential, impedimetric, or resistive sensing, are discussed with respect to NH3 and SO2 response. A promising NH3 sensor behavior was found in case of a mixed-potential sensor with a VWT catalyst layer. Additionally, an impedimetric sensor with a VWT functional layer provides a selective NH3 response with marginal NO cross interference. Initial results of an impedimetric Fe-ZSM5 sensor indicate a strong NH3 dependency but a high NOx interfering effect is observed. For SO2 detection in coal combustion processes, two promising sensor setups utilizing VWT are investigated. Furthermore, the applicability of contactless radio-frequency method for direct determination of the amount of stored ammonia in a zeolite-based catalyst is shown.