Performance evaluation of SO_x (x = 2,3) gas sensors using Ag- β″-alumina solid electrolyte

摘要

Fully solid state SO_x sensors have been investigated with a galvanic cell of Pt, Ag/Ag-β″-alumina/SO_3, SO_2, O_2, Pt using tubular Ag-β″-alumina as solid electrolyte, metal silver as solid reference electrode, and porous Pt as working electrode. The values of electric motive force (EMF) of the sensors are consistent with the theoretically calculated ones at temperatures above 550℃ in the p_(SO_x) range of at least 10-50 000 ppm. Applying catalysts such as Pt-net and V_2O_5 in the gas upstream considerably improves the sensor performance and extend its working temperature down to 450℃. The reproducible EMF values are obtained in the gas flow velocity of 0.2-0.4 cm/s. The response time of the sensors is 50-100 s as the p_(SO_x) changes. The sensors exhibit a good selectivity to SO_x against hundred-fold concentrations of CO_2, NO_2 and H_2O.