Method to regenerate oxygen traps

Patent metadata

Field	Value
Publication number	US-10428433-B2
Application number	US-201514976288-A
Country	US
Kind code	B2
Filing date	Dec 21, 2015
Priority date	Dec 22, 2014
Publication date	Oct 1, 2019
Grant date	Oct 1, 2019

Abstract

A method is described to regenerate an oxygen trap, comprising at least the following steps: circulating a current in the trap material (2) to reduce this material; measuring the value Im of the current and estimating its derivative dIm/dt in relation to time; estimating the length (δ) of material reduced by the current as a function of the value of the current and its derivative; stopping circulation of the current when the length of reduced material is at least equal to a threshold value (δs).

First claim

The invention claimed is:

1. A method to regenerate an oxygen trap using an electric current, comprising at least the following steps:
a) circulating, by a circuit and a voltage source, an electric current in a material of the trap to reduce the material;
b) measuring, by an ammeter, a value Im of said electric current and estimating a derivative dIm/dt of the measured current Im in relation to time;
c) estimating, by a calculator, a length (δ) of material reduced by said electric current, as a function of the value of said current (Im) and of said derivative (dIm/dt);
d) stopping, by a switch, circulation of the current when the length of reduced material is at least equal to a threshold value (δs).

2. The method according to claim 1 wherein the length of reduced material is a function of the ratio Im 2 /(dIm/dt) between the square of the measured current and its derivative when the derivative dIm/dt is not zero.

3. The method according to claim 1 further comprising measuring or estimating a contribution, to the measured current, made by electrochemical reductions of pollutants in the environment of the trap, wherein the length (δ) of reduced material is estimated in step c) as a function of the value of the measured current (Im), of the estimated derivative (dIm/dt), and of the measured or estimated contribution, to the measured current, made by the electrochemical reductions of pollutants.

4. The method according to claim 1 wherein a value is also measured of the current (Ip=I(dI/dt=0)) for a zero or near-zero derivative thereof, and wherein the length of reduced material is estimated as a function of the value of said current (Im), of its derivative (dIm/dt) and of the value of the current (Ip=I(dI/dt=0)) for a zero or near-zero derivative thereof.

5. The method according to claim 4 wherein the length of material is a function of the ratio Im(Im−Ip)/(dIm/dt) between the product of the electric current and the electric current corrected for the current value when the current is substantially constant, and the derivative of the current when the derivative dIm/dt is not zero.

6. The method according to claim 3 wherein the circulation of current is interrupted and the value of the current (Ip=I(dI/dt=0)) is measured for a zero or near-zero derivative thereof.

7. The method according to claim 6 wherein the interruption of the current and measurement of the value of the current (Ip=(dI/dt=0)), for a zero or near-zero derivative thereof, are performed at regular time intervals.

8. The method according to claim 1 wherein regenerating the oxygen trap takes place at a temperature between 600° C. and 900° C.

9. The method according to claim 1 wherein the trap material is a solid ZrYO or ZrScO solution, or a ThO 2- and LaGaO 3- structure with or without double substitutions of Y 2 O 3 or Sc 2 O 3 by CeO 2 or Al 2 O 3 , or a 8(Y 2 O 3 ).10(Al 2 O 3 ) mixture.

10. A method to regenerate an oxygen trap using an electric current, comprising at least the following steps:
a) circulating, by a circuit and a function generator, an electric current in a material of the trap to reduce the material;
b) measuring, by an oscilloscope, a value Im of said electric current and estimating its derivative dIm/dt in relation to time;
c) estimating, by a calculator, a length (δ) of material reduced by said electric current, as a function of the value of said current (Im) and of its derivative (dIm/dt);
d) stopping, by a switch, circulation of the current when the length of reduced material is at least equal to a threshold value (δs),
wherein, owing to said oscilloscope, a measurement or estimate is calculated of the contribution, to the measured current, made by electrochemical reductions of pollutants in the environment of the trap, and the length (δ) of reduced material is estimated in step c) as a function of the value of the measured current (Im), of the derivative (dIm/dt), and of the contribution, to the measured current made by the electrochemical reductions of pollutants.

11. The method according to claim 1 wherein the instant (maximum) value is estimated of the current when it is interrupted.

12. The method according to claim 1 wherein a contribution to the measured current by electrochemical reductions of environment pollutants is estimated via fast-scan voltammetry, square-wave potential technique or low frequency complex impedance spectroscopy.

Assignees

• Univ Grenoble Alpes
• Centre Nat Rech Scient

Inventors

• Deseure Jonathan
• STEIL CéSAR MARLU

Classifications

• B01J20/3433

  of sorbents or filter aids other than those covered by B01J20/3408 - B01J20/3425 · CPC title

• B01J20/06

  comprising oxides or hydroxides of metals not provided for in group B01J20/04 · CPC title

• B01D53/96

  Regeneration, reactivation or recycling of reactants · CPC title

• B01J20/02

  comprising inorganic material · CPC title

• B01D2257/104

  Oxygen · CPC title