# US 8,465,631 B2 · Purification structure incorporating a biased electrochemical catalyst system

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- Number: US 8,465,631 B2
- Document ID: US8465631B2
- Status: Granted
- Kind: B2
- Application number: 12/682,041
- Filed: 2008-10-02
- Published: 2010-11-18
- Granted: 2013-06-18
- Earliest claimed: 2007-10-08
- Assignees: Saint-Gobain Centre De Recherches Et D'Etudes Europeen
- Applicants: Philippe Vernoux; Abdelkader Hadjar; Ahmed Marouf
- Inventors: Philippe Vernoux; Abdelkader Hadjar; Ahmed Marouf
- Web page: https://patentgrep.com/patent/US8465631B2

## CPC

- B01D 53/944: {Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts (three-way-catalysts [TWC] B01D53/9445)}
- B01D 2255/1021: Platinum
- B01D 2255/1023: Palladium
- B01D 2255/1025: Rhodium
- B01D 2255/104: Silver
- B01D 2255/20738: Iron
- B01D 2255/20746: Cobalt
- B01D 2255/20753: Nickel
- B01D 2255/20761: Copper
- B01D 2258/012: Diesel engines and lean burn gasoline engines
- B01D 2258/014: Stoichiometric gasoline engines
- Y02C 20/10: of nitrous oxide (N2O)
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]

## Abstract

A device for the purification of a polluted gas, for example an exhaust gas from a diesel or gasoline engine, comprising, in combination: A honeycomb structure, comprising at least one porous electron-conductive material forming the walls (1) of said structure and an electrochemical system for treating said gas, comprising a layer (7) of an ionically conductive and electronically insulating material D, a reduction catalyst A (9) for reducing the polluting species of the NOx type and an oxidation catalyst B (4) for oxidizing the polluting species of the soot, hydrocarbon HC, CO or H2 type, said electrochemical system being configured in the form of an electrode W and a counterelectrode CE; and means for applying a voltage or a current between said electrode W and said counterelectrode CE.

## Claims

### Claim 1

A device for purification of a polluted gas, comprising:
a honeycomb structure comprising at least one porous electron-conductive material forming walls of said structure and an electrochemical system for treating said gas, comprising:
a layer of an electronically insulating and ionically conductive material D,
a reduction catalyst A for reducing the polluting species of the NOx type, in contact with the electronically insulating and ionically conductive material D which forms all or part of an electrode W or which is electrically connected to an electrode W and an oxidation catalyst B for oxidizing polluting species selected from the group consisting of soot, hydrocarbons, CO, H2, and mixtures thereof, in contact with the electronically insulating and ionically conductive material D which forms all or part of a counterelectrode CE or which is electrically connected to a counterelectrode CE,
wherein the oxidation catalyst B contacts the electron-conductive material forming the walls of the honeycomb structure, wherein said layer of electronically insulating and ionically conductive material D is between the reduction catalyst A and the oxidation catalyst B so as to electronically isolate each catalyst from the other, and
wherein the honeycomb structure is capable of simultaneously reducing polluting species of the NOx type and oxidizing polluting species selected from the group consisting of soot, hydrocarbons, CO, H2, and mixtures thereof.

### Claim 2 (depends on 1)

The device as claimed in claim 1, in which the porous electron-conductive material forming the walls of the honeycomb structure is a porous inorganic electron-conductive material.

### Claim 3 (depends on 2)

The device as claimed in claim 2, in which the oxidation catalyst B is deposited in pores of the porous inorganic material.

### Claim 4 (depends on 2)

The device as claimed in claim 2, in which the porous inorganic material comprises or is formed by an inorganic electron-conductive material having a structure selected from the group consisting of a carbide structure, a silicide structure, a boride structure, a La1-xSrxMnO3 structure, and a mixed cerium gadolinium oxide structure.

### Claim 5 (depends on 1)

The device as claimed in claim 1, further comprising plugs at one end of channels formed between walls of channels of the honeycomb structure so as to define alternately inlet channels and outlet channels for gas to be purified, said plugs being formed in an electron-conductive material and being in electronic contact with the catalysts A or B, the electrode W of the electrochemical system comprising plugs placed at the inlet of the structure and the counterelectrode CE comprising plugs placed at the outlet of the structure.

### Claim 6 (depends on 1)

The device as claimed in claim 1, in which the electronically insulating and ionically conductive material D is ionically conductive by O2− ions or by H+ ions.

### Claim 7 (depends on 6)

The device as claimed in claim 6, in which the electronically insulating and ionically conductive material D is oxygen-ion conductive having a structure selected from the group consisting of a fluorite structure, a perovskite structure, a BIMEVOX structure, a LAMOX structure, and an apatite structure.

### Claim 8 (depends on 6)

The device as claimed in claim 6, in which the electronically insulating and ionically conductive material D is a proton conductor having a structure selected from the group consisting of a perovskite structure, a BaCe1-xMxO3-α structure and, a compound of LaxSr1-xScO3-α.

### Claim 9 (depends on 1)

The device as claimed in claim 1, in which the porous electron-conductive material comprises silicon carbide.

### Claim 10 (depends on 9)

The device as claimed in claim 9, in which the porous electron-conductive material comprises doped silicon carbide, wherein an electronic resistivity is less than 20 ohms·cm at 400° C.

### Claim 11 (depends on 1)

The device as claimed in claim 1, in which the reduction catalyst A comprises (1) at least one metal selected from the group consisting of Pt, Pd, Rh, Ag and transition metals, and (2) at least one metal or metal oxide of an alkali metal, an alkaline earth, a rare earth or a transition metal.

### Claim 12 (depends on 1)

The device as claimed in claim 1, in which the oxidation catalyst B comprises at least one metal selected from the group consisting of Pt, Pd, Rh and transition metals.

### Claim 13 (depends on 1)

The device as claimed in claim 1, comprising at least one or more of honeycomb monoliths, said monolith or monoliths comprising a set of adjacent ducts or channels of mutually parallel axes which are separated by porous walls and are closed off by plugs at one end to delimit inlet ducts opening onto a gas intake face and outlet ducts opening onto a gas discharge face.

### Claim 14 (depends on 1)

The device as claimed in claim 1, further comprising a continuous negative potential difference source between said electrode W and said counterelectrode CE.

### Claim 15 (depends on 14)

The device as claimed in claim 14, wherein gas to be purified flows through said porous walls.

### Claim 16 (depends on 1)

The device as claimed in claim 1, wherein gas to be purified flows through said porous walls.

### Claim 17 (depends on 16)

The device as claimed in claim 16, in which a current density applied between the electrode and the counterelectrode is greater than 0.01 mA/cm2.

### Claim 18 (depends on 1)

A method for carrying out an on-board check of a catalytic activity of a catalyst, comprising flowing gas through the device as claimed in claim 1 to check of the catalytic activity of the catalyst.

### Claim 19 (depends on 1)

A method of continuous and simultaneous treatment of pollutants comprising continuously and simultaneously reducing polluting species of the NOx type and oxidizing polluting species selected from the group consisting of soot, hydrocarbons, CO, H2, and mixtures thereof in the device as claimed in claim 1.