Method to regenerate oxygen traps

Patent metadata

Field	Value
Publication number	US-2016177458-A1
Application number	US-201514976288-A
Country	US
Kind code	A1
Filing date	Dec 21, 2015
Priority date	Dec 22, 2014
Publication date	Jun 23, 2016
Grant date	—

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 I m of the current and estimating its derivative dl m /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 (δ s ).

First claim

1 . A method to regenerate an oxygen trap using an electric current, comprising at least the following steps:
a) circulating an electric current in the trap material to reduce this material; b) measuring the value I m of said electric current and estimating its derivative dl m /dt in relation to time; c) estimating the length (δ) of material reduced by said electric current, as a function of the value of said current (I m ) and of its derivative (dl m /dt); d) stopping circulation of the current when the length of reduced material is at least equal to a threshold value (δ s ).

2 . The method according to claim 1 wherein the length of reduced material is a function of the ratio I m 2 /(dl m /dt) between the square of the measured current and its derivative.

3 . The method according to claim 1 wherein 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 as a function of the value of the measured current (I m ), of its derivative (dl m /dt) and of the contribution, to the measured current made by electrochemical reductions of pollutants.

4 . The method according to claim 1 wherein:
the value is also measured of the current (Ip=I(dl/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 (I m ), of its derivative (dl m /dt) and of the value of the current (Ip=I(dl/dt=0)) for a zero or near-zero derivative thereof;
or the instant (maximum) value is estimated of the current when it is interrupted;
or the contribution to measured current by electrochemical reductions of environment pollutants is estimated via fast-scan voltammetry, square-wave potential technique or low frequency complex impedance spectroscopy.

5 . The method according to claim 4 wherein the length of material is a function of the ratio I m (I m −I p )/(dl m /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.

6 . The method according to claim 3 wherein the circulation of current is interrupted and the value of the current (I p =I(dl/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 (I p =(dl/dt=0)), for a zero or near-zero derivative thereof, are performed at regular time intervals for example between 20 s and 100 s.

8 . The method according to claim 1 wherein regeneration 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 device to regenerate an oxygen trap using an electric current comprising at least:
a) a circuit to circulate an electric current in the trap material to reduce this material; b) an ammeter to measure the value of said electric current and to calculate its derivative in relation to time; c) a calculator to estimate the length of material that is reduced as a function of the value of said electric current and its derivative; d) a switch to stop circulation of the electric current when the length of reduced material is equal to a threshold value.

11 . The device according to claim 10 further comprising a calculator to measure or estimate the contribution, to the measured electric current, made by electrochemical reductions of pollutants in the environment of the trap, and to estimate the length (δ) of material reduced as a function of the value of the measured current (I m ), of its derivative (dl m /dt) and of the contribution, to the measured current made by electrochemical reductions of pollutants.

12 . The device according to claim 10 further comprising a calculator:
to measure the value of the current (Ip=I(dl/dt=0)) for a zero or near-zero derivative thereof, and to estimate the length of reduced material as a function of the value of said current (I m ), of its derivative (dl m /dt) and of the value of the current (Ip=I(dl/dt=0)) for a zero or near-zero derivative thereof;
or to estimate the instant (maximum) value of the current when it is interrupted;
or to estimate the contribution towards measured current made by electrochemical reductions of pollutants in the environment, using fast-scan voltammetry, square-wave potential technique or complex low frequency impedance spectroscopy.

13 . The device according to claim 12 further comprising a switch to interrupt the circulation of the current and to measure the value of the current (I p =I(dl/dt=0)) for a zero or near-zero derivative thereof.

14 . The device according to claim 10 , further comprising a clock or a comparator comparing a current estimated as a function of an applied potential and a measured current, which trigger a circuit to cause a current to circulate in the trap material for reduction thereof.

15 . The device according to claim 10 wherein the trap material is a solid ZrYO or ZrScO solution, or 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.

16 . The device according to claim 15 wherein the trap material is:
a zirconium solution such as Zr 1-x Y x O 2-x/2 or Zr 1-x Sc x O 2-x/2 with x between 0.03 and 0.11,
or a solid solution with double substitution such as ZrO 2 (0.86)Y 2 O 3 (0.1)CeO 2 (0.04) or ZrO 2 (0.9)Y 2 O 3 (0.09)CeO 2 (0.01).

17 . The device according to claim 10 , wherein the trap material is of elongate shape e.g. cylindrical or parallelepiped, optionally hollow, or in the form of a pellet or hollow tube for example with circular, rectangular or square cross-section.

18 . The device according to claim 10 wherein the trap material is dense or porous.

19 . A device to regenerate an oxygen trap using an electric current comprising at least:
a) means to circulate an electric current in the trap material to reduce this material; b) means to measure the value of said electric current and to calculate its derivative in relation to time; c) means to estimate the length of material that is reduced as a function of the value of said current and its derivative; d) means to stop circulation of the current when the length of reduced material is equal to a threshold value.

20 . The device according to claim 19 further comprising means to measure or estimate the contribution, to the measured electric current, made by electrochemical reductions of pollutants in the environment of the trap, and to estimate the length (δ) of material reduced as a function of the value of the measured current (I m ), of its derivative (dl m /dt) and of the contribution, to the measured electric current, made by electrochemical reductions of pollutants.

Assignees

• Univ Joseph Fourier
• Centre Nat Rech Scient

Inventors

• Deseure Jonathan
• STEIL CéSAR MARLU

Classifications

• B01J20/06

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

• B01J20/3433

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

• C25B1/00

  Electrolytic production of inorganic compounds or non-metals · CPC title

• B01D2257/104

  Oxygen · CPC title

• B01D53/96

  Regeneration, reactivation or recycling of reactants · CPC title