High temperature thermodynamic study of chromium carbide and carbon dioxide utilizing solid electrolytes

Both calcia-stabilized zirconia (CSZ) and yttria-doped thoria (YDT) were utilized in measuring the electromotive forces (e.m.f.) produced in chromium carbide thermodynamic cells. Available experimental data for the free energy of formation of chromium carbide (Cr{dollar}sb3{dollar}C{dollar}sb2{dollar}) indicate that the present cell configuration produces oxygen pressures that are unsuitable for use with CSZ. The best values obtained for the free energy of formation using YDT consist of: {dollar}Delta{dollar}G{dollar}sp{lcub}rm 0{rcub}sb{lcub}rm Crsb3Csb2{rcub}{dollar}({dollar}pm{dollar}208 cal/mole) = {dollar}-{dollar}6248 {dollar}-{dollar} 11.39 T R{dollar}sp2{dollar} = 0.76 (1088 to 1208 K); {dollar}Delta{dollar}G{dollar}sp{lcub}rm 0{rcub}sb{lcub}rm Crsb3Csb2{rcub}{dollar}({dollar}pm{dollar}208 cal/mole) = {dollar}-{dollar}5427 {dollar}-{dollar} 10.77 T R{dollar}sp2{dollar} = 0.83 (1124 to 1353 K); An alternate cell configuration is recommended which replaces the solid three-phase cathode with gaseous oxygen to eliminate any difficulty in reaching equilibrium. The anode would consist of a solid-gas phase mixture.; Yttria-stabilized zirconia (YSZ) was used in measuring the electromotive force created by the oxidation of carbon monoxide to carbon dioxide. Mixtures dilute in either component produced results which were sensitive to polarization at the anode. The mixtures which consisted of significant amounts of both CO and CO{dollar}sb2{dollar} provided the best results which agreed fairly closely with accepted values. For the reaction CO + {dollar}1over 2{dollar}O{dollar}sb2{dollar} = CO{dollar}sb2{dollar} the best value obtained was: {dollar}Delta{dollar}G{dollar}sp{lcub}rm 0{rcub}(pm{dollar}95 cal/mole) = {dollar}-{dollar}65807 {dollar}-{dollar}19.64 T R{dollar}sp2{dollar} = 0.99 (781 to 1423 K). (Abstract shortened by UMI.)...