# US 9,517,462 B2 · Two-layer-three-way catalyst > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,517,462 B2 - Document ID: US9517462B2 - Status: Granted - Kind: B2 - Application number: 12/530,580 - Filed: 2008-02-16 - Published: 2010-06-03 - Granted: 2016-12-13 - Earliest claimed: 2007-03-19 - Assignees: Umicore AG & Co. KG - Applicants: Martin Roesch; Dieter Linder; Raoul Klingmann; Patrizia Laura De Cola; Joerg-Michael Richter; Marcus Schmidt - Inventors: Martin Roesch; Dieter Linder; Raoul Klingmann; Patrizia Laura De Cola; Joerg-Michael Richter; Marcus Schmidt - Web page: https://patentgrep.com/patent/US9517462B2 ## CPC - B01J 37/0244: {Coatings comprising several layers} - B01D 53/945: {characterised by a specific catalyst} - B01J 23/63: with rare earths or actinides - B01D 2255/1021: Platinum - B01D 2255/1023: Palladium - B01D 2255/1025: Rhodium - B01D 2255/2042: Barium - B01D 2255/407: Zr-Ce mixed oxides - B01D 2255/9022: Two layers - B01J 23/44: Palladium - B01J 23/464: {Rhodium} - Y02A 50/20: Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters - 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) - Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A double-layer three-way catalyst is presented, which is formed from a catalytic coating applied directly to an inert honeycomb and a catalytically active coating thereon, and is suitable especially for cleaning of exhaust gases of motor vehicles with gasoline-operated internal combustion engines. The catalyst contains, in each layer, an active aluminum oxide and a cerium/zirconium mixed oxide, both of which are catalytically activated by palladium. The second layer on the gas side contains not only palladium but also rhodium, which is applied to the active aluminum oxide and the cerium/zirconium mixed oxide of the second layer in addition to the palladium. The cerium/zirconium mixed oxide of the second layer has a higher zirconium oxide content than the cerium/zirconium mixed oxide of the first layer. The catalyst is notable for exceptional activity coupled with outstanding aging stability. ## Claims ### Claim 1 A double-layer three-way catalyst on an inert catalyst support of ceramic or metal for the cleaning of the exhaust gases of internal combustion engines, said double-layer three-way catalyst comprises a first layer containing a first active aluminum oxide and a first cerium/zirconium mixed oxide, which are catalytically activated with palladium and is essentially free of rhodium, and a second layer containing a second active aluminum oxide and a second cerium/zirconium mixed oxide, which are catalytically activated with palladium and rhodium, and wherein the second cerium/zirconium mixed oxide has a higher zirconium oxide content than the first cerium/zirconium mixed oxide. ### Claim 2 (depends on 1) The three-way catalyst as claimed in claim 1, wherein the catalyst support is a honeycomb of ceramic or metal with a volume V, which has parallel flow channels for the exhaust gases of the internal combustion engine, the wall surfaces of the flow channels being coated with the two catalyst layers, and the concentration of the palladium based on the volume of the honeycomb being between 0.1 and 10 g/l. ### Claim 3 (depends on 2) The three-way catalyst as claimed in claim 2, wherein the concentration of the palladium in the second layer is less than the concentration of the palladium in the first layer, based in each case on the volume of the honeycomb. ### Claim 4 (depends on 3) The three-way catalyst as claimed in claim 3, wherein the ratio of the concentration of the palladium in the second layer based on the volume of the honeycomb relative to the concentration of the palladium in the first layer based on the volume of the honeycomb is between 0.001 and 0.9. ### Claim 5 (depends on 4) The three-way catalyst as claimed in claim 4, wherein the first active aluminum oxide and the second cerium/zirconium mixed oxide are additionally surface coated with strontium oxide or barium oxide. ### Claim 6 (depends on 1) The three-way catalyst as claimed in claim 1, wherein the concentration of the rhodium in the second layer based on the volume of the honeycomb is between 0.01 and 1 g/l. ### Claim 7 (depends on 6) The three-way catalyst as claimed in claim 6, wherein the second active aluminum oxide and/or the second cerium/zirconium mixed oxide is additionally catalytically activated with platinum and the concentration of the platinum based on the volume of the honeycomb is between 0.01 and 1 g/l. ### Claim 8 (depends on 1) The three-way catalyst as claimed in claim 1, wherein the active aluminum oxides of the two layers are each stabilized with 1 to 10% by weight of lanthanum oxide, based on the total weight of the aluminum oxide. ### Claim 9 (depends on 1) The three-way catalyst as claimed in claim 1, wherein the cerium/zirconium mixed oxides of the two layers are each stabilized with 1 to 15% by weight of metal oxides, based on the total weight of the mixed oxides, said metal oxides being those of the metals selected from the group consisting of iron, manganese, titanium, silicon, yttrium, lanthanum, praseodymium, neodymium, samarium and mixtures thereof. ### Claim 10 (depends on 9) The three-way catalyst as claimed in claim 9, wherein the first cerium/zirconium mixed oxide has a weight ratio of cerium oxide to zirconium oxide of 0.8 to 1.2, and the second cerium/zirconium mixed oxide has a weight ratio of cerium oxide to zirconium oxide of 0.5 to 0.1. ### Claim 11 (depends on 10) The three-way catalyst as claimed in claim 10, wherein the first layer additionally comprises a third cerium/zirconium mixed oxide with a weight ratio of cerium oxide to zirconium oxide of 0.5 to 0.1. ### Claim 12 (depends on 11) The three-way catalyst as claimed in claim 11, wherein the second layer additionally comprises zirconium oxide. ### Claim 13 (depends on 12) The three-way catalyst as claimed in claim 12, wherein the zirconium oxide is stabilized with 1 to 30% by weight of rare earth oxide, based on the total weight of the zirconium oxide. ### Claim 14 (depends on 13) The three-way catalyst as claimed in claim 13, wherein the zirconium oxide contains not more than 10% by weight of cerium oxide, based on the total weight of the stabilized zirconium oxide. ### Claim 15 (depends on 1) The three-way catalyst as claimed in claim 1, wherein the first layer additionally comprises lanthanum oxide or neodymium oxide. ### Claim 16 (depends on 1) A process for cleaning exhaust gases of a gasoline engine comprising passing said gases in contact with the catalyst according to claim 1 as a close-coupled starter catalyst or as an underfloor main of a motor vehicle equipped with said gasoline engine. ### Claim 17 (depends on 1) The three-way catalyst of claim 1, wherein the first layer is catalytically activated with only palladium. ### Claim 18 (depends on 1) The three-way catalyst of claim 1, wherein the second layer is catalytically activated with only palladium and rhodium. ### Claim 19 (depends on 1) The three-way catalyst of claim 1, wherein the first layer is catalytically activated with only palladium and the second layer is catalytically activated with only palladium and rhodium. ### Claim 20 A double-layer three-way catalyst on an inert catalyst support of ceramic or metal for the cleaning of the exhaust gases of internal combustion engines, said double-layer three-way catalyst comprises a first layer containing a first active aluminum oxide and a first cerium/zirconium mixed oxide, which are catalytically activated with palladium, wherein the palladium is dispersed throughout the first layer, and a second layer containing a second active aluminum oxide and a second cerium/zirconium mixed oxide, which are catalytically activated with palladium and rhodium, and wherein the second cerium/zirconium mixed oxide has a higher zirconium oxide content than the first cerium/zirconium mixed oxide. ### Claim 21 (depends on 20) The double-layer three-way catalyst of claim 20, wherein the amount of palladium in the first layer is greater than an amount of rhodium. ### Claim 22 (depends on 21) The double-layer three-way catalyst of claim 21, wherein the first layer is substantially free of rhodium. ### Claim 23 A double-layer three-way catalyst on an inert catalyst support of ceramic or metal for the cleaning of the exhaust gases of internal combustion engines, said double-layer three-way catalyst comprises a first layer containing a first active aluminum oxide and a first cerium/zirconium mixed oxide, which are catalytically activated with palladium and does not contain rhodium, and a second layer containing a second active aluminum oxide and a second cerium/zirconium mixed oxide, which are catalytically activated with palladium and rhodium, wherein the second cerium/zirconium mixed oxide has a higher zirconium oxide content than the first cerium/zirconium mixed oxide, and wherein the first layer is designed not to contain rhodium.