The Measurement of Sulfur Chemical Potential Differences Using a Calcium Fluoride Solid Electrolyte

Abstract

Calcium fluoride has been conventionally used as a solid electrolyte to measure fluorine chemical potentials in high temperature systems. However in this investigation, this electrolyte has been used as a sulfur sensor. Opencircuit emf measurements have been carried out with the following four galvanic cellsnormalCu,Cu2S,normalCaS|CaF2|normalFe,normalFeS,normalCaS normalCu,Cu2S,normalCaS|CaF2|normalAg,Ag2S,normalCaS normalCu,Cu2S,normalCaS|CaF2|normalMn,normalMnS,normalCaS normalCu,Cu2S,normalCaS|CaF2|normalCr,normalCrS,normalCaSThe cells were investigated in the temperature range, 500°–900°C. Using Richardson and Antill's data for the standard Gibbs energy of formation of Cu2S , the standard Gibbs energies of formation of normalFeS , Ag2S , normalMnS , and normalCrS have been determined.

Sulfur Gas Sensor Using a Calcium Fluoride Solid Electrolyte

“…The steady emf observed agreed well (to within + 1%) with the calculated emf from Eq. [5]. The emf remained stable for longer times at lower temperatures and at lower Ps2 than at higher temperatures and at higher Ps> The cell was active for about two days at 650~ even when the H2S/H~ ratios were frequently changed from 0.1 to oo (pure H2S).…”

“…In (Ps211/Ps~ I) (PsJ 1 > Ps2 ~) [5] By using JANAF Tables (12), the Ps2 values in the H2S + H2 mixture, which corresponds to Ps~ ~ in Eq. [5], were calculated (18,19) from the reactions…”

“…1/2 H= + 1/2 S= = HS [7] The estimated emfs were obtained from Eq. [5], and Ps=" values were derived from Eq. [1] and [2].…”

Thermodynamic Calculations of Phase Equilibria in the Fe-Cr-S System.

“…2. [19][20][21][22][23] The formation energy results of Hager and Elliott, 19) Rau,21) and Ramanarayanan and Worrell 23) are in good agreement with one another even though the experimental methods adopted were different. Fujisawa et al 24) calculated the formation energy of CrS from the solubility of S in stainless steel and their result is also in good agreement with the results of Hager and Elliott.…”

Measurement of the standard molar Gibbs free energy of formation of Ag2S using Ag+β-alumina solid electrolyte

“…The agreement with the measurements of Thompson et al (6) is within 1 kJ·mol −1 . The reported temperature of fusion of Ag 2 S is 1103 K. (11) Although two experimental points were measured above this temperature, it can be seen from (6) ----, Ramanarayanan et al; (8) --, Rosenqvist.…”