Electronically Heated NOx Adsorber Catalyst

• US 20130111886A1
• Filed: 11/07/2011
• Published: 05/09/2013
• Est. Priority Date: 11/07/2011
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Gonze, Eugene V., Paratore, Michael J. Jr., Solbrig, Charles E.
• Granted Patent: US 8,661,790 B2
• Time in Patent Office: Days
• US Class Current: 60/286
• CPC Class Codes: F01N 2560/026 for measuring or detecting NOx
• CPC Class Codes: F01N 2560/06 the means being a temperature sensor
• CPC Class Codes: F01N 2560/14 having more than one sensor of one kind
• CPC Class Codes: F01N 2900/1404 Exhaust gas temperature
• CPC Class Codes: F01N 3/0814 combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts
• CPC Class Codes: F01N 3/0842 Nitrogen oxides
• CPC Class Codes: F01N 3/106 Auxiliary oxidation catalysts
• CPC Class Codes: F01N 3/108 Auxiliary reduction catalysts
• CPC Class Codes: F01N 3/2013 using electric or magnetic heating means
• CPC Class Codes: F01N 3/2033 using a fuel burner or introducing fuel into exhaust duct
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: F01N 3/208 Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
• CPC Class Codes: F01N 9/00 Electrical control of exhaust gas treating apparatus monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An exhaust gas treatment system for an internal combustion engine is provided, and includes an exhaust gas conduit, an upstream selective catalytic reduction (“SCR”) device, an electrically heated catalyst (“EHC”) device, an oxidation catalyst (“OC”) device, a downstream SCR device, and a control module. The EHC device is in fluid communication with the exhaust gas conduit and is configured to receive the exhaust gas. The EHC device is located downstream of the upstream SCR device and is selectively activated to produce heat. The OC device is in fluid communication with the exhaust gas conduit, and is selectively heated by the EHC device. At least one of the EHC device and the OC device have a NO_x adsorber catalyst disposed thereon for selectively adsorbing NO_x below a threshold temperature and substantially releasing NO_x above the threshold temperature.

Claims

1. An exhaust gas treatment system for an internal combustion engine, comprising:

an exhaust gas conduit in fluid communication with, and configured to receive an exhaust gas from the internal combustion engine, the exhaust gas containing oxides of nitrogen (“

NO_x”

);

an upstream selective catalytic reduction (“

SCR”

) device in fluid communication with the exhaust gas conduit and configured to receive the exhaust gas;

an electrically heated catalyst (“

EHC”

) device in fluid communication with the exhaust gas conduit and configured to receive the exhaust gas, the EHC device located downstream of the upstream SCR device and selectively activated to produce heat, the EHC device including a monolith;

an oxidation catalyst (“

OC”

) device in fluid communication with the exhaust gas conduit, the OC device selectively heated by the EHC device, and wherein at least one of the monolith of the EHC device and the OC device have a NO_x adsorber catalyst disposed thereon for adsorbing NO_x below a threshold temperature and substantially releasing NO_x above the threshold temperature;

a downstream SCR device in fluid communication with the exhaust gas conduit and configured to receive the exhaust gas, the downstream SCR device being located downstream of the OC device, the downstream SCR device including a downstream SCR activation temperature based on a downstream SCR temperature profile, the downstream SCR activation temperature indicating the downstream SCR device is within a specified range of a respective-light-off temperature of the downstream SCR device; and

a control module in communication with the EHC device, comprising;

a control logic for determining the downstream SCR temperature profile; and

a control logic for activating the EHC device if the downstream SCR temperature profile is above the downstream SCR activation temperature.

2. The exhaust gas treatment system of claim 1, further comprising a hydrocarbon supply connected to and in fluid communication with the exhaust gas conduit, wherein the hydrocarbon supply is selectively activated for delivery of a hydrocarbon and formation of an exhaust gas and hydrocarbon mixture therein, the exhaust gas and hydrocarbon mixture delivered to the EHC device and the OC device.

3. The exhaust gas treatment system of claim 2, wherein the control module includes control logic for activating the hydrocarbon supply if the downstream SCR temperature profile is above the downstream SCR activation temperature.

4. The exhaust gas treatment system of claim 1, wherein the OC device and the monolith of the EHC device have at least one of palladium and copper washcoat that are each an oxidization catalyst compound disposed thereon.

5. The exhaust gas treatment system of claim 4, wherein a reductant injector is in fluid communication with the exhaust gas conduit and is in signal communication with the control module, the redutant injector located upstream of the upstream SCR device, wherein the reductant injector is configured for dosing a reductant.

6. The exhaust gas treatment system of claim 1, wherein the NO_x adsorber catalyst is one of a passive NO_x adsorber (“

PNA”

) and a lean NO_x trap (“

LNT”

).

7. The exhaust gas treatment system of claim 1, further comprising:

a first temperature sensor situated upstream of the downstream SCR device; and

a second temperature sensor situated downstream of the downstream SCR device.

8. The exhaust gas treatment system of claim 7, wherein the control module includes a control logic for monitoring the first temperature sensor and the second temperature sensor.

9. The exhaust gas treatment system of claim 8, wherein the control module includes a control logic for calculating the downstream SCR temperature profile based on signals from the first temperature sensor and the second temperature sensor, wherein the temperatures of the first temperature sensor and the second temperature sensor are averaged together to create the SCR temperature profile.

10. The exhaust gas treatment system of claim 8, wherein the first temperature sensor is used to calculate an OC temperature of the OC device.

11. The exhaust gas treatment system of claim 10, wherein the control module includes control logic for deactivating the EHC device if the OC temperature is above the threshold temperature.

12. The exhaust gas treatment system of claim 1, further comprising an upstream OC device that is in fluid communication with the exhaust gas conduit, wherein the upstream OC device is located upstream of the upstream SCR device.

13. An exhaust gas treatment system for an internal combustion engine, comprising:

an exhaust gas conduit in fluid communication with, and configured to receive an exhaust gas from the internal combustion engine, the exhaust gas containing oxides of nitrogen (“

NO_x”

) and hydrocarbons;

an upstream oxidation catalyst (“

OC”

) device that is in fluid communication with the exhaust gas conduit, wherein the upstream OC device induces oxidization of hydrocarbons in the exhaust gas;

an upstream selective catalytic reduction (“

SCR”

) device in fluid communication with the exhaust gas conduit and configured to receive the exhaust gas, the upstream OC device located upstream of the upstream SCR device;

an electrically heated catalyst (“

EHC”

) device in fluid communication with the exhaust gas conduit and configured to receive the exhaust gas, the EHC device located downstream of the upstream SCR device and selectively activated to produce heat, the EHC device including a monolith;

a downstream OC device in fluid communication with the exhaust gas conduit, the downstream OC device selectively heated by the EHC device, and wherein at least one of the monolith of the EHC device and the downstream OC device have a NO_x adsorber catalyst disposed thereon for adsorbing NO_x below a threshold temperature and substantially releasing NO_x above the threshold temperature, the NO_x adsorber catalyst being one of a passive NO_x adsorber (“

PNA”

) and a lean NO_x trap (“

LNT”

);

a downstream SCR device in fluid communication with the exhaust gas conduit and configured to receive the exhaust gas, the downstream SCR device being located downstream of the downstream OC device, the downstream SCR device including a downstream SCR activation temperature based on a downstream SCR temperature profile, the downstream SCR activation temperature indicating the downstream SCR device is within a specified range of a respective-light-off temperature of the downstream SCR device; and

a control module in communication with the EHC device, comprising;

a control logic for determining the downstream SCR temperature profile; and

a control logic for activating the EHC device if the downstream SCR temperature profile is above the downstream SCR activation temperature.

14. The exhaust gas treatment system of claim 13, further comprising a hydrocarbon supply connected to and in fluid communication with the exhaust gas conduit, wherein the hydrocarbon supply is selectively activated for delivery of a hydrocarbon and formation of an exhaust gas and hydrocarbon mixture therein, the exhaust gas and hydrocarbon mixture delivered to the EHC device and the downstream OC device.

15. The exhaust gas treatment system of claim 14, wherein the control module includes control logic for activating the hydrocarbon supply if the downstream SCR temperature profile is above the downstream SCR activation temperature.

16. The exhaust gas treatment system of claim 13, wherein the downstream OC device and the monolith of the EHC device have at least one of palladium and copper washcoat that are each an oxidization catalyst compound disposed thereon.

17. The exhaust gas treatment system of claim 16, wherein a reductant injector is in fluid communication with the exhaust gas conduit and is in signal communication with the control module, the redutant injector located upstream of the upstream SCR device, wherein the reductant injector is configured for dosing a reductant.

18. The exhaust gas treatment system of claim 13, further comprising:

a first temperature sensor situated upstream of the downstream SCR device; and

a second temperature sensor situated downstream of the downstream SCR device.

19. The exhaust gas treatment system of claim 18, wherein the control module includes a control logic for monitoring the first temperature sensor and the second temperature sensor.

20. The exhaust gas treatment system of claim 19, wherein the control module includes a control logic for calculating the downstream SCR temperature profile based on signals from the first temperature sensor and the second temperature sensor, wherein the temperatures of the first temperature sensor and the second temperature sensor are averaged together to create the SCR temperature profile.