Sulfur Gas Sensor Using a Calcium Fluoride Solid Electrolyte

Abstract

The sulfur gas potentials in the H2S + H2 buffer gases were measured by a galvanic ell Ps2(g), Au(Pt)I(MoS2 + CaS)ICaF21(Cu + Cu2S + CaS)[Au(Pt) in the temperature ange from 650 ~ to 950 ~ and Ps ~ region from 10-2 to 10-' ~ atm. A quick response time (within 5 to 10 min) in emf with the change of Ps2 at a given temperature was observed by placing a MoS ~ and CaS mixed pellet auxiliary electrode at the bottom of the cylindrical single-crystal CaF2 electrolyte. The observed emf's agreed well with those calcu-lated from the Nernst equation. Using this sensor, Ps2 values in the SOs + H2 + H2S gas system were also evaluated from the measured emf at 827 ~ and were found to be in close agreement with those calculated from the thermochemical t bles. Recently, the application of in situ solid-state sensors at high temperatures has drawn great attention as a method for monitor ing the sulfur-bearing species in a number of technologies. A galvanic ceil using a solid electrolyte is very desirable for such a sensor. However, unlike the oxygen potentials, which can be measured i-rectly using oxide ion conductors uch as ZrO2(CaO)