Patent
Potentiometric CO.sub.2 sensor having an open titanate- or stannate-based reference electrode
| العنوان: | Potentiometric CO.sub.2 sensor having an open titanate- or stannate-based reference electrode |
|---|---|
| Patent Number: | 5,910,239 |
| تاريخ النشر: | June 08, 1999 |
| Appl. No: | 08/765,087 |
| Application Filed: | December 23, 1996 |
| مستخلص: | The invention relates to a a reference electrode for electrolytic cells, comprising a combination of (a) titanium dioxide and an alkali-metal or alkaline-earth-metal titanate or (b) tin dioxide and an alkali-metal or alkaline-earth-metal stannate as a homogeneous mixture. |
| Inventors: | Maier, Joachim (Wiernsheim, DEX); Sitte, Werner (Graz, ATX); Holzinger, Michael (St. Veit an der Glan, ATX) |
| Assignees: | Max-Plank-Gesellschaft Zur (Munich, DEX) |
| Claim: | We claim |
| Claim: | 1. A galvanic cell for measuring a gas comprising |
| Claim: | (a) a reference electrode comprising a combination of (i) titanium dioxide and an alkali-metal or alkaline-earth-metal titanate or (ii) tin dioxide and an alkali-metal or alkaline-earth-metal stannate in intimate mixture, said reference electrode not being isolated from a gas medium to be measured; |
| Claim: | (b) a measuring electrode containing a compound which is in thermodynamic equilibrium with the gas to be measured; and |
| Claim: | (c) an ion-conducting solid electrolyte contacting the reference electrode and with the measuring electrode. |
| Claim: | 2. The galvanic cell of claim 1 wherein the alkali-metal or alkaline-earth-metal titanate of the reference electrode has the composition X.sub.m Ti.sub.n O.sub.2n+1, where X is an alkali-metal ion and m equals 2 or X is an alkaline-earth-metal ion and m equals 1, and n is a natural number from 1 to 20. |
| Claim: | 3. The galvanic cell of claim 2 wherein the alkali-metal or alkaline-earth-metal titanate has the composition X.sub.m Ti.sub.6 O.sub.13. |
| Claim: | 4. The galvanic cell of claim 1 wherein the alkali-metal or alkaline-earth-metal stannate of the reference electrode has the composition X.sub.m Sn.sub.n O.sub.2n+1, where X is an alkali-metal ion and m equals 2 or X is an alkaline-earth-metal ion and m equals 1, and n is a natural number from 1 to 20. |
| Claim: | 5. The galvanic cell of claim 4 wherein the alkali-metal or alkaline-earth-metal stannate has the composition X.sub.m SnO.sub.3. |
| Claim: | 6. The galvanic cell of claim 1 wherein the titanate or stannate is an alkali-metal titanate or stannate. |
| Claim: | 7. The galvanic cell of claim 1 wherein titanate or stannate is sodium titanate or stannate. |
| Claim: | 8. The galvanic cell of claim 7 wherein the titanate is Na.sub.2 Ti.sub.6 O.sub.13. |
| Claim: | 9. The galvanic cell of claim 7 wherein the stannate is Na.sub.2 SnO.sub.3. |
| Claim: | 10. The galvanic cell of claim 1 wherein the reference electrode further comprises a metallic substance which is intimately mixed with said combination of (i) or (ii). |
| Claim: | 11. The galvanic cell of claim 10 wherein the metallic substance is a precious metal. |
| Claim: | 12. The galvanic cell of claim 1 wherein the reference electrode comprises titanium dioxide and the titanate, or tin dioxide and the stannate in proportions of at least 10 vol. % of each. |
| Claim: | 13. The galvanic cell of claim 12 wherein the reference electrode comprises said titanium dioxide and the titanate, or tin dioxide and the stannate in approximately equal proportions by volume. |
| Claim: | 14. The galvanic cell of claim 1 wherein the reference electrode is in the form of a press-formed piece. |
| Claim: | 15. A gas sensor comprising a galvanic cell according to claim 1 and a reference electrode holder. |
| Claim: | 16. The sensor of claim 15 wherein the ion-conducting solid electrolyte is conductive for alkali-metal or alkaline-earth-metal ions. |
| Claim: | 17. The sensor of claim 16 wherein the solid electrolyte is a sodium-ion conductor. |
| Claim: | 18. The sensor of claim 17 wherein the measuring electrode (b) contains (i) an alkali-metal or alkaline-earth-metal carbonate, (ii) an alkali-metal or alkaline-earth-metal nitrate, or (iii) an alkali-metal or alkaline-earth-metal sulfate. |
| Claim: | 19. The sensor of claim 18 for measuring CO.sub.2 wherein the measuring electrode contains an alkali-metal or alkaline-earth-metal carbonate. |
| Claim: | 20. The sensor of claim 19 wherein the measuring electrode contains sodium carbonate. |
| Claim: | 21. The sensor of claim 17 wherein the measuring electrode further comprises a metallic substance which is mixed intimately with said compound which is in thermodynamic equilibrium with the gas to be measured. |
| Claim: | 22. The sensor of claim 21 wherein the metallic substance is a precious metal. |
| Claim: | 23. A method for measuring a gas in order to provide a signal which is independent of the partial pressure of the oxygen in a gas medium to be measured comprising contacting the sensor of claim 1 with a gas to be measured. |
| Claim: | 24. The method of claim 23 wherein the gas to be measured is selected from the group consisting of CO.sub.2, NO.sub.x, and SO.sub.x. |
| Claim: | 25. The method of claim 23 wherein the gas to be measured is CO.sub.2. |
| Current U.S. Class: | 205/781; 204/424; 204/426; 204/435; 205/784; 2057/865 |
| Current International Class: | G01N 27407 |
| Patent References Cited: | 4505804 March 1985 Mase et al. 4715944 December 1987 Yanagida et al. 5454923 October 1995 Nachlas et al. 5545468 August 1996 Koshiba et al. |
| Other References: | Science and Technology of Fast Ion Conductors, ed. by Harry L. Tuller and Minko Balkanski (Plenum Publishing Corp., 1989) Month Unavailable, Joachim Maier, pp. 299-301. Electrical Sensing of Complex Gaseous Species by Making Use of Acid-Base Properties, J. Maier, Solid State Ionics 62 (1993) Month Unavailable pp. 105-111, North Holland. Thermodynamic Investigations of Na.sub.2 ZrO.sub.3 by Electrochemical Means Joachim Maier and Udo Warhus, J. Chem. Thermodynamics 1986, Month Unavailable, pp. 309-316, M-1884. |
| Primary Examiner: | Tung, T. |
| Attorney, Agent or Firm: | Fulbright & Jaworski, LLP. |
| رقم الانضمام: | edspgr.05910239 |
| قاعدة البيانات: | USPTO Patent Grants |
| الوصف غير متاح. |