The effect of platinum clusters in the zeolite micropores of a zeolite-based potentiometric hydrocarbon gas sensor

The gas sensitive ZSM-5 zeolite phase of a potentiometric hydrocarbon gas sensor is modified by introduction of Pt clusters into the micropores of the zeolite. The response of the sensors with and without Pt and with two different electrodes (Au and Cr) to propane (0.1–3 kPa) is measured at 723 K in O2/CO2/N2 base gas. Catalytic oxidation causes a reversible drop of the cell voltage in the vicinity of the stoichiometric concentration ratio (O2/C3H8 = 5). The potentiometric sensor effect is observed for propane concentrations below this point. The influence of the zeolite and electrode materials on the sensing characteristics is explained by different electrode reactions at Au and Cr electrodes and by the effect of the Pt on the gas sorption equilibria in the zeolite micropores.