EBL-fabricated model catalysts

Fig. 4.33. Measured CO oxidation rate on EBL-fabricated model catalysts with different support materials and particle sizes (a) The inlet gas mixture represented by the parameter (3 = Pco/ Pco + P02) has been scanned up/down at a constant temperature of 450 K, and the rate of CO2 production has been monitored during the gas scan in j3. This has been made for three different samples (a) 750-nm Pt/Si02 (blue), (b) 750-nm Pt/CeOj, (black), and (c) Pt/CeOj, sample (200mn, red, disintegrated particles). Results both from experiments (filled circles) and simulations solid lines) are shown. The arrows indicate which reaction rate branch that has been observed while scanning up/down in (3. A bistable region (hysteresis) is observed for all samples, (b) The bistability diagrams determined from a series of measurements as those shown in (a) at different temperatures (Pt/Si02, blue and open squares) Pt/CeOj, black hatch marks and crosses and the 200-nm Pt/CeOj, red hatched area and open squares). The observed differences can be traced back to a pronounced O-spillover effect on ceria. Note the logarithmic scale for the /3-value (from [29])...

In the second examples, we present results of reactivity measurements performed on Pd/Si02 EBL samples in combination with in situ vapor deposited samples employing a combination of state-of-the-art UHV techniques. The EBL-fabricated model catalyst consisted of hexagonally arranged Pd towers with an aspect ratio of 1. These towers were 500-nm high and 500 nm... 

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