Measurement signals during breakdown

Figure 3 Measurement signals recorded during a breakdown of the carrier stream...

There has been some discussion as to whether acoustic signals result from the fracture that occurs when adhesion Is lost at the paint-metal Interface during blistering and cathodic disbonding. In the present study, very sensitive Acoustic Emission measurements have been made In systems exhibiting these types of breakdown. 

The samples are also characterised after the catalytic test. Table 4 shows a low decrease of the surface areas after test except for Pd/HFAU. The catalytic test conditions (water formation during the reaction) could lead to a partial breakdown of zeolites and agglomeration of palladium particles and also to a formation of earbonaeeous eompounds (coke) on the zeolites. EPR measurement (fig.7) is used to make evidenee coke deposit by a signal of carbon radical observed at g=2.003 [13]. Pd/HBEA, Pd/NaBEA and Pd/HFAU present this signal after propene oxidation. Therefore, the acidic character of these zeolites should favour the coke deposition [14]. This result could be also correlated to the highest adsorption energy... 

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