Kasper, G.

Neubauer, N.

Seipenbusch, M.

English

KITopen

  Specific detection of palladium nanoparticles in presence of a SiO2 background aerosol  N. Neubauer1, M. Seipenbusch1 and G. Kasper1  1Institut für Mechanische Verfahrenstechnik und Mechanik, Karlsruhe Institute of Technology (KIT),  76131 Karlsruhe, Germany Keywords: specific detection, background distinction, catalytically active nanoparticles, (quasi) real-time Presenting author email: nicole.neubauer@kit.edu  Introduction The on-line discrimination of engineered nanoparticles from the background aerosol of the workplace still remains a challenge. In a recent publication (Neubauer, 2011) we introduced a new measurement technique based on catalysis for the material-specific detection of nanoparticles with a high sensitivity. We now present first results with regard to a real-time discrimination of catalytically active nanoparticles from a non-active background aerosol. Experimental Palladium nanoparticles both directly after their production by spark discharge and after mixing them with SiO2 background particles were sampled onto glass fibre filters for a fixed time interval. Afterwards they were exposed to gaseous reaction educts which initiate the catalytic reaction. The hydrogenation of ethene was chosen as a specific catalytic test reaction for the detection of palladium. The conversion of ethene to ethane due to the catalytic activity of the palladium nanoparticles is measured online by infrared spectroscopy. Both the palladium and the background particles as well as their mixture were characterized by an electrical mobility spectrometer and by electron microscopy. The specific surface area of the catalytically active palladium nanoparticles was determined by nitrogen BET. Results Electron microscopy analysis resulted in a median primary particle size of 3.2 nm for the palladium nanoparticles. They are arranged in agglomerates with a mode of the mobility equivalent diameter of 74 nm. The SiO2 background particles also form agglomerates (xmob,mod 163 nm) of primary particles with a median size of 48 nm. The nitrogen BET analysis of the palladium nanoparticles gave a specific surface area of 87 g/m2.  The catalytic experiments showed a proportional dependence of the catalytic activity of the pure palladium nanoparticles on their mass. After the addition of the background aerosol the smaller palladium agglomerates are attached to the SiO2 particles due to coagulation (cf. Figure 1) and disappear from the particle size distribution. Nevertheless, it was possible to detect them via their catalytic behaviour – even in the attached state.             200 nm Figure 1: Palladium agglomerates attached to a background agglomerate of SiO2   Conclusion  The presented measurement technique enables the detection and quantification of palladium nanoparticles based on their catalytic activity. Besides, the method is suitable for a discrimination of catalytically active particles from a non-active background aerosol in (quasi) real-time.   The research leading to these results has received funding from the European Commission's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 211464-2 (Nanodevice).  Neubauer N., Weis F., Binder A., Seipenbusch M. and Kasper G. (2011) Journal of Physics: Conference Series 304 (1) 

Specific detection of palladium nanoparticles in presence of a SiO2 background aerosol

https://publikationen.bibliothek.kit.edu/1000034238/2514937

Specific detection of palladium nanoparticles in presence of a SiO2 background aerosol

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