# US 9,517,457 B2 · Aftertreatment systems with reduced N2O generation

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- Number: US 9,517,457 B2
- Document ID: US9517457B2
- Status: Granted
- Kind: B2
- Application number: 14/067,814
- Filed: 2013-10-30
- Published: 2015-04-30
- Granted: 2016-12-13
- Earliest claimed: 2013-10-30
- Assignees: Cummins Inc.
- Applicants: Cummins Inc.
- Inventors: Krishna Kamasamudram; Neal W. Currier; Ashok Kumar
- Web page: https://patentgrep.com/patent/US9517457B2

## CPC

- B01J 29/78: containing arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01D 53/9409: {Nitrogen oxides}
- B01D 53/9431: {Processes characterised by a specific device}
- B01J 29/72: containing iron group metals, noble metals or copper
- F01N 3/106: {Auxiliary oxidation catalysts}
- F01N 3/2066: {Selective catalytic reduction [SCR]}
- F01N 13/009: {having two or more separate purifying devices arranged in series}
- F01N 13/0093: {the purifying devices are of the same type}
- B01D 2251/206: Ammonium compounds
- B01D 2255/20723: Vanadium
- B01D 2255/20738: Iron
- B01D 2255/20761: Copper
- B01D 2255/50: Zeolites
- B01D 2255/9032: Two zones
- B01D 2258/012: Diesel engines and lean burn gasoline engines
- F01N 2510/0682: having a discontinuous, uneven or partially overlapping coating of catalytic material, e.g. higher amount of material upstream than downstream or vice versa
- F01N 2570/145: Dinitrogen oxide
- F01N 2900/1404: Exhaust gas temperature
- Y02A 50/20: Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
- Y02C 20/10: of nitrous oxide (N2O)
- Y02T 10/12: Improving ICE efficiencies
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- 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)
- F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16)
- Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Systems, apparatus and methods are disclosed for reducing the amount of nitrous oxide (N2O) produced in a selective catalytic reductant (SCR) catalyst in an exhaust aftertreatment system. The SCR catalysts are arranged to reduce the amount of N2O produced during NOx reduction while not adversely affecting NOx conversion.

## Claims

### Claim 1

A system, comprising:
an internal combustion engine having an exhaust aftertreatment system for receiving an exhaust gas produced from operation of the internal combustion engine; a reductant system including a reductant source; and
a diesel exhaust aftertreatment system that includes at least one selective catalytic reduction (SCR) catalyst positioned downstream of a connection of the reductant source to the exhaust aftertreatment system, wherein the at least one SCR catalyst includes at least three formulations on portions of the SCR catalyst, the at least three formulations including a first formulation, a second formulation, and a third formulation, wherein the first formulation produces less N2O during NOx reduction by the SCR catalyst than the second formulation, wherein:
the first formulation is a vanadium based catalyst formulation, the second formulation is a copper-zeolite catalyst formulation, and the third formulation is an iron-zeolite catalyst formulation, and
a first portion of the SCR catalyst with the first formulation is located upstream of a second portion of the SCR catalyst with the second formulation.

### Claim 2 (depends on 1)

The system of claim 1, wherein the first and second portions of the SCR catalyst comprise one of separate SCR catalysts or portions of a same SCR catalyst.

### Claim 3 (depends on 1)

The system of claim 1, wherein the SCR catalyst includes a length from an upstream end to a downstream end, and the first portion of the SCR catalyst extends along less than half of the length.

### Claim 4

A system, comprising:
an internal combustion engine having an exhaust aftertreatment system for receiving an exhaust gas produced from operation of the internal combustion engine; a reductant system including a reductant source; and
a diesel exhaust aftertreatment system that includes at least one selective catalytic reduction (SCR) catalyst positioned downstream of a connection of the reductant source to the exhaust aftertreatment system, wherein the at least one SCR catalyst includes at least three formulations on portions of the SCR catalyst, the at least three formulations including a first formulation, a second formulation, and a third formulation, wherein the first formulation produces less N2O during NOx reduction by the SCR catalyst than the second formulation, wherein:
the first formulation is a vanadium based catalyst formulation, the second formulation is a copper-zeolite catalyst formulation, and the third formulation is an iron-zeolite catalyst formulation, wherein the first formulation includes a low copper loading washcoat applied to at least a first portion of the SCR catalyst and the second formulation includes a high copper loading washcoat applied to at least a second portion of the SCR catalyst, wherein the first portion is upstream of the second portion.

### Claim 5 (depends on 4)

The system of claim 4, wherein:
the high copper loading washcoat substantially coats the first and second portions of the SCR catalyst; and
the low copper loading washcoat coats the high copper loading washcoat on at least the first portion of the SCR catalyst.

### Claim 6 (depends on 4)

The system of claim 4, wherein the low copper loading washcoat is intermixed with the high copper loading washcoat to form at least one washcoat applied to the SCR catalyst.

### Claim 7

An apparatus for reducing constituents in an exhaust gas, comprising:
at least one selective catalytic reduction (SCR) catalyst including a first portion with a first formulation and a second portion with a second formulation, wherein the first formulation produces a lesser amount of N2O during NOx reduction of the exhaust gas than the second formulation, wherein the first portion is positioned upstream of the second portion so the first portion first receives the exhaust gas, and further comprising a third formulation on the SCR catalyst, wherein:
the first formulation is a vanadium based catalyst formulation;
the second formulation is a copper-zeolite catalyst formulation; and
the third formulation is an iron-zeolite catalyst formulation.

### Claim 8 (depends on 7)

The apparatus of claim 7, wherein the at least one SCR catalyst includes a length and the first portion extends along less than one half of the length.

### Claim 9 (depends on 7)

The apparatus of claim 7, wherein the first and second portions are separate first and second SCR catalysts.

### Claim 10 (depends on 7)

The apparatus of claim 7, wherein the second formulation is a high copper loading copper-zeolite catalyst formulation.

### Claim 11

An apparatus for reducing constituents in an exhaust gas, comprising:
a selective catalytic reduction (SCR) catalyst including a top washcoat and a bottom washcoat, wherein:
the bottom washcoat includes a high copper loading SCR catalyst formulation;
the top washcoat includes a low copper loading SCR catalyst formulation and substantially coats the bottom washcoat;
further comprising a third catalyst formulation on the SCR catalyst, wherein:
the top washcoat includes a vanadium based catalyst formulation;
the bottom washcoat is a copper-zeolite catalyst formulation; and
the third catalyst formulation is an iron-zeolite catalyst formulation.

### Claim 12 (depends on 11)

The apparatus of claim 11, wherein:
the copper-zeolite catalyst formulation includes a high copper loading; and
the top washcoat includes a low copper loading.

### Claim 13

A method for treating an exhaust gas, comprising:
exposing the exhaust gas to a selective catalytic reduction (SCR) catalyst including first catalyst formulation and a second catalyst formulation;
wherein the first catalyst formulation produces less N2O during NOx reduction by the SCR catalyst than the second formulation, and further comprising a third catalyst formulation on the SCR catalyst, wherein:
the first catalyst formulation is a vanadium based formulation;
the second catalyst formulation is a copper-zeolite formulation; and
the third catalyst formulation is an iron-zeolite formulation, wherein exposing the exhaust gas to the first and second catalyst formulations of the SCR catalyst results at high exhaust gas temperatures results in a decrease in N2O formation over an SCR catalyst including the second catalyst formulation alone.

### Claim 14 (depends on 13)

The method of claim 13, wherein the high exhaust gas to temperature is 350° C. or more.

### Claim 15

A method for treating an exhaust gas, comprising:
exposing the exhaust gas to a selective catalytic reduction (SCR) catalyst including first catalyst formulation and a second catalyst formulation;
wherein the first catalyst formulation produces less N2O during NOx reduction by the SCR catalyst than the second formulation, and further comprising a third catalyst formulation on the SCR catalyst, wherein:
the first catalyst formulation is a vanadium based formulation;
the second catalyst formulation is a copper-zeolite formulation;
the third catalyst formulation is an iron-zeolite formulation;
the first catalyst formulation includes a low copper loading that is less than 75% copper; and
the second catalyst formulation includes a high copper loading that is more than 75% copper.

### Claim 16 (depends on 13)

The method of claim 13, wherein the first catalyst formulation includes a low copper loading that is less than 50% copper and the second catalyst formulation includes a high copper loading that is more than 50% copper.

### Claim 17 (depends on 13)

The method of claim 13, wherein the first catalyst formulation includes a low copper loading that is less than 25% copper and the second catalyst formulation includes a high copper loading that is more than 25% copper.

### Claim 18

A method for treating an exhaust gas, comprising:
exposing the exhaust gas to a selective catalytic reduction (SCR) catalyst including first catalyst formulation and a second catalyst formulation;
wherein the first catalyst formulation produces less N2O during NOx reduction by the SCR catalyst than the second formulation, and further comprising a third catalyst formulation on the SCR catalyst, wherein:
the first catalyst formulation is a vanadium based formulation;
the second catalyst formulation is a copper-zeolite formulation;
the third catalyst formulation is an iron-zeolite formulation;
the selective catalytic reduction (SCR) catalyst includes a first portion with the first formulation and a second portion with the second formulation;
the first portion is positioned upstream of the second portion so the first portion first receives the exhaust gas.

### Claim 19

A system, comprising:
an internal combustion engine having an exhaust aftertreatment system for receiving an exhaust gas produced from operation of the internal combustion engine; a reductant system including a reductant source; and
a diesel exhaust aftertreatment system that includes at least one selective catalytic reduction (SCR) catalyst positioned downstream of a connection of the reductant source to the exhaust aftertreatment system,
the selective catalytic reduction (SCR) catalyst including a top washcoat and a bottom washcoat, wherein:
the bottom washcoat includes a high copper loading SCR catalyst formulation;
the top washcoat includes a low copper loading SCR catalyst formulation and substantially coats the bottom washcoat;
further comprising a third catalyst formulation on the SCR catalyst, wherein;
the top washcoat includes a vanadium based catalyst formulation;
the bottom washcoat is a copper-zeolite catalyst formulation; and
the third catalyst formulation is an iron-zeolite catalyst formulation.

### Claim 20

A method for treating an exhaust gas, comprising:
exposing the exhaust gas to a selective catalytic reduction (SCR) catalyst, the selective catalytic reduction (SCR) catalyst including a top washcoat and a bottom washcoat, and further comprising a third catalyst formulation on the SCR catalyst, wherein:
the bottom washcoat includes a high copper loading SCR catalyst formulation;
the top washcoat includes a low copper loading SCR catalyst formulation and substantially coats the bottom washcoat;
the top washcoat includes a vanadium based catalyst formulation;
the bottom washcoat is a copper-zeolite catalyst formulation; and
the third catalyst formulation is an iron-zeolite catalyst formulation.