# US 7,743,602 B2 · Reformer assisted lean NOx catalyst aftertreatment system and method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,743,602 B2 - Document ID: US7743602B2 - Status: Granted - Kind: B2 - Application number: 11/514,544 - Filed: 2006-09-01 - Published: 2008-03-06 - Granted: 2010-06-29 - Earliest claimed: 2005-06-21 - Assignees: ExxonMobil Research and Engineering Company; Caterpillar Inc. - Inventors: Mohan Kalyanaraman; Paul W. Park; Christie S. Ragle - Web page: https://patentgrep.com/patent/US7743602B2 ## CPC - B01D 53/9409: {Nitrogen oxides} - F01N 3/2066: {Selective catalytic reduction [SCR]} - F01N 13/0097: {the purifying devices are arranged in a single housing} - B01D 2251/202: Hydrogen - B01D 2251/208: Hydrocarbons - B01D 2255/104: Silver - B01D 2255/50: Zeolites - B01D 2258/012: Diesel engines and lean burn gasoline engines - F01N 2240/30: a fuel reformer - F01N 2610/03: the substance being hydrocarbons, e.g. engine fuel - F01N 2610/04: the substance being hydrogen - Y02T 10/12: Improving ICE efficiencies - 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) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A method and apparatus for catalytically processing a gas stream passing therethrough to reduce the presence of NOx therein, wherein the apparatus includes a first catalyst composed of a silver-containing alumina that is adapted for catalytically processing the gas stream at a first temperature range, a second catalyst composed of a copper-containing zeolite located downstream from the first catalyst, wherein the second catalyst is adapted for catalytically processing the gas stream at a lower second temperature range relative to the first temperature range, a hydrocarbon compound for injection into the gas stream upstream of the first catalyst to provide a reductant, and a reformer for reforming a portion of the hydrocarbon compound into H2 and/or oxygenated hydrocarbon for injection into the gas stream upstream of the first catalyst. The second catalyst is adapted to facilitate the reaction of reducing NOx into N2, whereby the intermediates are produced via the first catalyst reacting with NOx and hydrocarbons. ## Claims ### Claim 1 An apparatus for catalytically processing a gas stream passing therethrough to reduce the presence of NOx therein, said apparatus comprising: a combination catalyst having first and second catalysts positioned in a staged arrangement for catalytically processing the gas stream, said combination catalyst including: a first catalyst for catalytically processing the gas stream being selected from the group consisting of metal-containing alumina, metal oxide-containing alumina, or a combination thereof, wherein the metal is selected from the group consisting of silver, indium, gallium, tin and cobalt and mixtures thereof, said first catalyst having a first temperature at which peak catalytic activity occurs, said first catalyst being adapted for both converting a portion of NOx directly to N2 and another portion to nitrogen-containing intermediates with a portion of NOx remaining; and a second catalyst being located downstream from the first catalyst for catalytically processing the gas stream subsequent to the first catalyst, said second catalyst being selected from the group consisting of a metal-containing zeolite, metal oxide-containing zeolite, or a combination thereof, wherein the metal is selected from the group consisting of copper, iron, cobalt, and silver and mixtures thereof, said second catalyst having a second temperature at which peak activity occurs, said second catalyst being adapted to facilitate the reaction of the remaining NOx and intermediates for further reduction into N2, wherein the value of the second temperature is lower than the value of the first temperature; a source of reductant for injection of reductant into said gas stream upstream of said combination catalyst, said reductant being a hydrocarbon compound; an activator selected from the group consisting of hydrogen (H2), oxygenated hydrocarbon, or a combination thereof, for injection thereof upstream of said combination catalyst, for activating said reductant to improve low temperature NOx conversion; and a reformer for providing said activator by converting a portion of said hydrocarbon from said source of reductant into at least one of H2 and oxygenated hydrocarbon. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein said gas stream consists of exhaust from a lean burn internal combustion engine, and said reductant consists of diesel fuel. ### Claim 3 (depends on 1) The apparatus of claim 1, further including: controller means responsive to both the speed and exhaust temperature of said engine for controlling the amount of diesel fuel and activator injected into said gas stream. ### Claim 4 (depends on 1) The apparatus of claim 1, further including: controller means responsive to the temperature of said gas stream for adjusting the amounts of said reductant and activator injected into said gas stream. ### Claim 5 (depends on 1) The apparatus of claim 1, wherein the first and second catalysts are abutted against one another. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the first and second catalysts are spaced apart at a distance from one another. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the first and second catalysts are present in an amount ratio ranging from about 1:2 to 2:1. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein the first and second catalysts are present in an amount ratio of about 1:1. ### Claim 9 (depends on 1) The apparatus of claim 1, wherein the alumina is derived from a sol-gel synthesis process. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein the metal is present in an amount of from about 1 to 15 weight percent based on the total weight of the first catalyst. ### Claim 11 (depends on 1) The apparatus of claim 1, wherein the metal is present in an amount of from about 2 to 5 weight percent based on the total weight of the first catalyst. ### Claim 12 (depends on 1) The apparatus of claim 1, wherein the first catalyst is silver-containing alumina. ### Claim 13 (depends on 1) The apparatus of claim 1, wherein the zeolite is selected from the group consisting of ZSM-5, ZSM-11, ZSM-35, MCM-22, MCM-49, MCM-56, Beta, ITQ-13, and MCM-68. ### Claim 14 (depends on 1) The apparatus of claim 1, wherein the metal is present in an amount of from about 2 to 15 weight percent based on the total weight of the second catalyst. ### Claim 15 (depends on 1) The apparatus of claim 1, wherein the metal is present in an amount of from about 3 to 11.5 weight percent based on the total weight of the second catalyst. ### Claim 16 (depends on 1) The apparatus of claim 1, wherein the second catalyst is copper-containing zeolite. ### Claim 17 (depends on 1) The apparatus of claim 1, wherein the first and second catalysts are in the forms selected from powders, pellets, monoliths, fluidized beds, and combinations thereof. ### Claim 18 A method for reducing NOx contained in a gas stream resulting from a combustion process, said method comprising the steps of: passing said gas stream through a combination catalyst having first and second catalysts positioned in a staged arrangement for catalytically reducing the NOx, said combination catalyst comprising: said first catalyst far catalytically processing the gas stream being selected from the group consisting of metal-containing alumina, metal oxide-containing alumina, or a combination thereof, wherein the metal is selected from the group consisting of silver, indium, gallium, tin and cobalt and mixtures thereof, said first catalyst having a first temperature at which peak catalytic activity occurs, said first catalyst being for both converting a portion of NOx directly to N2 and another portion to nitrogen-containing intermediates with a portion of NOx remaining; and said second catalyst being located downstream from the first catalyst for catalytically processing the gas stream subsequent to the first catalyst, said second catalyst being selected from the group consisting of a metal-containing zeolite, metal oxide-containing zeolite, or a combination thereof, wherein the metal is selected from the group consisting of copper, iron, cobalt, and silver and mixtures thereof, said second catalyst having a second temperature at which peak activity occurs, said second catalyst being adapted to facilitate the reaction of the remaining NOx and intermediates for further reduction into N2, wherein the value of the second temperature is lower than the value of the first temperature; injecting a reductant from a reductant source into said gas stream upstream of said combination catalyst; reforming a portion of a reductant from the reductant source to obtain an activator selected from the group consisting of hydrogen (H2), oxygenated hydrocarbon, or a combination thereof; and injecting the activator into said gas stream upstream of said combination catalyst, to activate said reductant to improve low temperature NOx conversion. ### Claim 19 (depends on 18) The method of claim 18, wherein said reductant consists of a hydrocarbon compound. ### Claim 20 (depends on 18) The method of claim 18, wherein said gas stream consists of exhaust gas from a lean burn internal combustion engine, and said injecting step includes using diesel fuel for said reductant. ### Claim 21 (depends on 20) The method of claim 20, wherein said activator injecting step includes the step of reforming a portion of said diesel fuel to obtain the required amount of one of the group consisting of H2, oxygenated hydrocarbon, or a combination thereof, at any given time. ### Claim 22 (depends on 20) The method of claim 20, further including the step of controlling individually the amounts of activator and diesel fuel injected into the gas stream, as a function of the temperature of said exhaust gas and engine speed. ### Claim 23 (depends on 21) The method of claim 21, wherein said reforming step uses a reformer, and said method further includes the step of: controlling individually the amounts of activator from said reformer and diesel fuel injected into said exhaust gas as a function of its temperature and the engine speed at any given time. ### Claim 24 (depends on 18) The method of claim 18, further including the step of spacing apart said first and second catalysts. ### Claim 25 A method for catalytically processing the exhaust gas stream from an internal combustion engine to reduce the presence of NOx therein, said method comprising the steps of: delivering the gas stream to a first catalyst being selected from the group consisting of metal-containing alumina, metal oxide-containing alumina, or a combination thereof, wherein the metal is selected from the group consisting of silver, indium, gallium, tin and cobalt and mixtures thereof for catalytically processing the gas stream, said first catalyst having a first temperature at which peak catalytic activity occurs, said first catalyst being adapted for both converting a portion of NOx directly to N2 and another portion to nitrogen-containing intermediates with a portion of NOx remaining; conveying the gas stream from the first catalyst to a second catalyst located downstream from the first catalyst in a staged arrangement, said second catalyst being selected from the group consisting of a metal-containing zeolite, metal oxide-containing zeolite, or a combination thereof, wherein the metal is selected from the group consisting of copper, iron, cobalt, and silver and mixtures thereof, for catalytically further processing the gas stream subsequent to the first catalyst, said second catalyst having second temperature at which peak activity occurs, said second catalyst being adapted to facilitate the reaction of the remaining NOx and intermediates for further reduction into N2, wherein the value of the second temperature is lower than the value of the first temperature; injecting a hydrocarbon compound reductant from a hydrocarbon reductant source into said exhaust gas stream upstream of said first catalyst; reforming a portion of a hydrocarbon reductant from the hydrocarbon reductant source to obtain an activator selected from the group consisting of hydrogen (H2), oxygenated hydrocarbon, or a combination thereof; and injecting the activator into said exhaust gas stream upstream of said first catalyst to activate said reductant in a low temperature range relative to said exhaust gas stream to facilitate the reduction of NOx in the gas stream. ### Claim 26 (depends on 25) The method of claim 25, further including the step of spacing apart said first and second catalysts. ### Claim 27 (depends on 25) The method of claim 25, further including the steps of: controlling the amount of hydrocarbon compound injected as a function of both the exhaust gas stream temperature and engine speed; and controlling the amount of activator injected as a function of both the exhaust gas stream temperature and engine speed. ### Claim 28 (depends on 25) The method of claim 25, wherein said reductant consists of diesel fuel. ### Claim 29 An apparatus for catalytically processing the exhaust gas stream from a lean burn internal combustion engine to reduce the presence of NOx therein, said apparatus comprising: a combination catalyst having first and second catalysts positioned in a staged arrangement for catalytically processing the gas stream, said combination catalyst including: said first catalyst for catalytically processing the gas stream, being selected from the group consisting of metal-containing alumina, metal oxide-containing alumina, or a combination thereof, wherein the metal is selected from the group consisting of silver, indium, gallium, tin and cobalt and mixtures thereof, said first catalyst having a first temperature at which peak catalytic activity occurs, said first catalyst being adapted for both converting a portion of NOx directly to N2 and another portion to nitrogen-containing intermediates with a portion of NOx remaining; and said second catalyst being located downstream from the first catalyst for catalytically processing the gas stream subsequent to the first catalyst, being selected from the group consisting of a metal-containing zeolite, metal oxide-containing zeolite, or a combination thereof, wherein the metal is selected from the group consisting of copper, iron, cobalt, and silver and mixtures thereof, said second catalyst having a second temperature at which peak activity occurs, said second catalyst being adapted to facilitate the reaction of the remaining NOx and intermediates for further reduction into N2, wherein the value of the second temperature is lower than the value of the first temperature; a source of hydrocarbon compound reductant for injecting the same into said gas stream upstream of said first catalyst; an activator selected from the group consisting of hydrogen (H2), oxygenated hydrocarbon, or a combination thereof, for injection into said gas stream upstream of said first catalyst, for activating said reductant to improve NOx reduction in a low temperature range of said exhaust gas stream relative to the overall temperature range thereof; a reformer adapted for reforming a portion of said reductant into said activator; and a controller for individually adjusting the amounts of said reductant and activator injected as a function of both the temperature of the exhaust gas stream and engine speed. ### Claim 30 (depends on 29) The apparatus of claim 29, wherein said reductant consists of diesel fuel.