# US 7,607,291 B2 · Engine system arrangement with on-board ammonia production and exhaust after treatment system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,607,291 B2 - Document ID: US7607291B2 - Status: Granted - Kind: B2 - Application number: 11/242,589 - Filed: 2005-10-03 - Published: 2007-04-05 - Granted: 2009-10-27 - Earliest claimed: 2005-10-03 - Assignees: Caterpillar Inc. - Inventors: Josh Driscoll; Wade J. Robel - Web page: https://patentgrep.com/patent/US7607291B2 ## CPC - F01N 3/0821: {combined with particulate filter} - F01N 3/2066: {Selective catalytic reduction [SCR]} - F01N 2250/02: filtering and catalytic conversion - F01N 2610/02: the substance being ammonia or urea - Y02T 10/12: Improving ICE efficiencies - 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 An engine system includes first and second combustion chamber groups that supply exhaust to respective first and second exhaust passages. NOx in the exhaust of the first combustion group is converted to ammonia, such as by enriching the exhaust with fuel and then passing the mixture over an appropriate catalyst. Particles are trapped and continuously oxidized through appropriate placement of one or more particle traps coated with an appropriate oxidizing catalyst. NOx in the second passage from the second combustion group is combined with ammonia produced in the first passage and converted to nitrogen and water in a merged passage before being vented to atmosphere. This conversion is accomplished by passing the merged exhaust over an appropriate selective catalytic reduction catalyst. ## Claims ### Claim 1 A method of operating an engine system, comprising the steps of: supplying exhaust from a first combustion chamber group to a first exhaust passage; supplying exhaust from a second combustion chamber group to a second exhaust passage; converting NOx to ammonia in the first exhaust passage; oxidizing particles with NOx in the second exhaust passage; merging the first and second exhaust passages into a third exhaust passage; including a step of reacting NOx with ammonia in the third exhaust passage to produce nitrogen and water; wherein the oxidizing step is performed at least in part with a second catalyst; and oxidizing particles in the first exhaust passage at least in part with a first catalyst that is chemically different from the second catalyst. ### Claim 2 (depends on 1) The method of claim 1 including a step of reacting NOx with ammonia in the third exhaust passage to produce nitrogen and water. ### Claim 3 (depends on 2) The method of claim 2 including a step of supplying fuel into the first exhaust passage; reforming hydrocarbons in the first exhaust passage upstream from the converting step. ### Claim 4 (depends on 2) The method of claim 2 including a step of rotating a turbine with gas flow in at least one of the first, second and third exhaust passages. ### Claim 5 (depends on 2) The method of claim 2 wherein the oxidizing step is performed passively and continuously during the supplying steps. ### Claim 6 (depends on 2) The method of claim 2 including a step of fluidly connecting the third passage only to the first exhaust passage, the second exhaust passage and atmosphere. ### Claim 7 A method of treating combustion exhaust comprising the steps of: splitting the exhaust of a merged exhaust passage between a first passage and a second passage; enriching exhaust in the first passage relative to exhaust in the second passage; converting NOx, hydrocarbons and oxygen in the first passage to ammonia, carbon monoxide and hydrogen; re-merging the first passage with the second passage into a merged passage; converting NOx, carbon monoxide and hydrogen to ammonia in the merged passage. ### Claim 8 (depends on 7) The method of claim 7 including a step of oxidizing hydrocarbons in the second passage. ### Claim 9 (depends on 7) The method of claim 7 including a step of enriching exhaust in the second passage. ### Claim 10 (depends on 7) The method of claim 7 including a step of leaving exhaust in the second passage untreated and unenriched. ### Claim 11 (depends on 7) The method of claim 7 wherein the enriching step includes injecting fuel into the first passage. ### Claim 12 (depends on 11) The method of claim 11 wherein the splitting step includes a step of routing more exhaust into the second passage than the first passage. ### Claim 13 (depends on 11) The method of claim 11 wherein the converting step in the first passage includes a step of passing enriched exhaust over a catalyst. ### Claim 14 A method of operating a combustion exhaust aftertreatment system, comprising the steps of: reacting exhaust NOx with an excess amount of reductant, which includes at least one of urea and ammonia, to produce nitrogen, excess reductant and water; splitting an upstream exhaust passage into a first exhaust passage and a second exhaust passage; converting a portion of the excess reductant to NOx in the second exhaust passage; merging the first and second exhaust passages into a merged exhaust passage; and reacting NOx with an other portion of the excess reductant in the merged exhaust passage to produce nitrogen and water. ### Claim 15 (depends on 14) The method of claim 14 wherein the reductant is ammonia. ### Claim 16 (depends on 14) The method of claim 14 wherein the step of reacting exhaust NOx with a reductant is performed upstream from the splitting step. ### Claim 17 (depends on 14) The method of claim 14 wherein the step of reacting exhaust NOx with a reductant is performed in both the first and second exhaust passages. ### Claim 18 (depends on 14) The method of claim 14 wherein the splitting step includes routing more exhaust to one of the first and second exhaust passages than the other of the first and second exhaust passages. ### Claim 19 (depends on 14) The method of claim 14 including a step of supplying a reductant overdose into the upstream exhaust passage.