NOx-decomposing electrode and NOx concentration-measuring apparatus
AssigneeNGK Insulators, Ltd.
InventorsKunihiko Nakagaki, Hideyuki Suzuki, Sang Jae Lee, Osamu Nakasone
Life of this patent
Estimating the term…
Abstract
A detecting electrode comprises a first cermet electrode layer formed directly on a solid electrolyte layer and a second cermet electrode layer formed on the first cermet electrode layer. A ratio between an alloy of Pt—Rh and ZrO2 in the first cermet electrode layer ranges from 20:80 to 50:50 by volume ratio. On the other hand, a ratio between an alloy of Pt—Rh and ZrO2 in the second cermet electrode layer ranges from 60:40 to 50:50 by volume ratio.
Claims5
A NOx-decomposing electrode for decomposing or reducing NOx, wherein said electrode decomposes NOx to produce oxygen:
- said electrode having a plurality of cermet electrode layers each of which comprise an alloy of Pt—Rh and a ceramic component;
- and
- said respective cermet electrode layers having different ratios between said alloy of Pt—Rh and said ceramic component.
A NOx concentration-measuring apparatus comprising:
- a first oxygen pump means for introducing a measurement gas from the outside of said apparatus into a first hollow space to adjust a partial pressure of oxygen in said measurement gas;
- and
- a second oxygen pump means for pumping out oxygen contained in said measurement gas from said measurement gas having said partial pressure of oxygen controlled by said first oxygen pump means and controlling said partial pressure of oxygen to have a predetermined value at which a NOx component is reduced or decomposed to pump out oxygen produced when said NOx component contained in an atmosphere in a second hollow space is reduced or decomposed, wherein:
- a concentration of NOx in said measurement gas is detected by measuring a pumping current due to a pumping action of said second oxygen pump means of said NOx concentration-measuring apparatus;
- a NOx-decomposing electrode of said second oxygen pump means for reducing or decomposing said NOx component has a plurality of cermet electrode layers each of which comprise an alloy of Pt—Rh and a ceramic component;
- and
- said respective cermet electrode layers have different ratios between said alloy of Pt—Rh and said ceramic component.
Dependencies are inferred from the claim text.