WO2020183496A1 - Catalyst system for treatment of exhaust gas of automobile and process for making the same - Google Patents

Catalyst system for treatment of exhaust gas of automobile and process for making the same Download PDF

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Publication number
WO2020183496A1
WO2020183496A1 PCT/IN2020/050225 IN2020050225W WO2020183496A1 WO 2020183496 A1 WO2020183496 A1 WO 2020183496A1 IN 2020050225 W IN2020050225 W IN 2020050225W WO 2020183496 A1 WO2020183496 A1 WO 2020183496A1
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WO
WIPO (PCT)
Prior art keywords
brick
substrate
exhaust gas
wash coat
catalyst system
Prior art date
Application number
PCT/IN2020/050225
Other languages
French (fr)
Inventor
Liu XINZHU
Hao Huang
Shau-Lin Frank CHEN
Alok Kumar
Shailendra Kumar Pandey
Original Assignee
Hero MotoCorp Limited
Basf Catalysts (Shanghai) Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hero MotoCorp Limited, Basf Catalysts (Shanghai) Co., Ltd. filed Critical Hero MotoCorp Limited
Priority to CN202080032316.2A priority Critical patent/CN114072223A/en
Publication of WO2020183496A1 publication Critical patent/WO2020183496A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
    • B01D53/945—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/46—Ruthenium, rhodium, osmium or iridium
    • B01J23/464—Rhodium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/63—Platinum group metals with rare earths or actinides
    • B01J35/19—
    • B01J35/56—
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0215—Coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0236—Drying, e.g. preparing a suspension, adding a soluble salt and drying
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/024—Multiple impregnation or coating
    • B01J37/0244—Coatings comprising several layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/024—Multiple impregnation or coating
    • B01J37/0248—Coatings comprising impregnated particles
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1021—Platinum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1023—Palladium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1025—Rhodium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/40—Mixed oxides
    • B01D2255/407—Zr-Ce mixed oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/902—Multilayered catalyst
    • B01D2255/9022—Two layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/903—Multi-zoned catalysts
    • B01D2255/9032—Two zones
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/904—Multiple catalysts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/908—O2-storage component incorporated in the catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/01—Engine exhaust gases
    • B01D2258/014—Stoichiometric gasoline engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2510/00—Surface coverings
    • F01N2510/06—Surface coverings for exhaust purification, e.g. catalytic reaction
    • F01N2510/068—Surface coverings for exhaust purification, e.g. catalytic reaction characterised by the distribution of the catalytic coatings
    • F01N2510/0682—Surface coverings for exhaust purification, e.g. catalytic reaction characterised by the distribution of the catalytic coatings having a discontinuous, uneven or partially overlapping coating of catalytic material, e.g. higher amount of material upstream than downstream or vice versa
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2510/00—Surface coverings
    • F01N2510/06—Surface coverings for exhaust purification, e.g. catalytic reaction
    • F01N2510/068—Surface coverings for exhaust purification, e.g. catalytic reaction characterised by the distribution of the catalytic coatings
    • F01N2510/0684—Surface coverings for exhaust purification, e.g. catalytic reaction characterised by the distribution of the catalytic coatings having more than one coating layer, e.g. multi-layered coatings
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present invention relates to a catalyst system for for treatment of exhaust gas of an automobile. Specifically, the present invention relates to the catalyst system used to abatement of hydrocarbons, carbon monoxide and nitrogen oxides in the motorcycle exhaust gas. Further, the present invention relates to a process for preparing the catalyst. The exhaust gas needs to meet various norms, before letting out into the atmosphere. The present invention also relates to an exhaust gas treatment system incorporating the catalyst unit. The present invention also relates to an exhaust gas treatment process for treating the exhaust gas of the motorcycle.
  • Automobiles which incorporates internal combustion engines, are widely used throughout the world, for transportation.
  • the product or exhaust gas from an internal combustion engine has a number of different components.
  • the product may contain partially converted feed (hydrocarbons), carbon di oxide, carbon monoxide, nitrogen oxides etc.
  • partially converted feed hydrocarbons
  • carbon di oxide carbon di oxide
  • carbon monoxide carbon monoxide
  • nitrogen oxides etc.
  • Exhaust gas from an automobile engine often contains emissions such as hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NO x ). Such emissions are relatively harmful and need to be pretreated before letting out to the atmosphere. Furthermore, the emission treatment norms are becoming stricter year on year. Recently, stricter emission criteria are already required or will be required in many countries to improve the environmental conditions by further limiting emissions such HC, CO, NO x .
  • HC hydrocarbons
  • CO carbon monoxide
  • NO x nitrogen oxides
  • a vehicle such as a motorcycle or scooter is generally provided with an exhaust emission gas purifying device such as a catalyst which purifies exhaust gas discharged from an engine.
  • the purified exhaust gas from the exhaust gas purifying device is then discharged into the atmosphere in a harmless state.
  • a catalyst unit is used as the exhaust gas purifying device.
  • the catalyst unit is disposed either inside the muffler or in the middle of an exhaust pipe having one end thereof connected to an engine and having the other end thereof connected to a muffler.
  • the catalyst unit is used to reduce tailpipe emission levels.
  • the catalyst unit is built in a honeycomb or pellet geometry to expose the exhaust gases to a large surface made of one or more noble metals such as platinum group metals including platinum, palladium rhodium.
  • the catalyst unit is composed of mainly a substrate, a wash coat and one or more layers of noble metals such as platinum, palladium and rhodium.
  • CN105664939A discloses a catalytic converter for treating motorcycle exhaust gas composed of a carrier and a washcoat layer.
  • the said washcoat layer is composed of alumina or an oxygen storage material and precious metals comprising platinum, palladium and rhodium.
  • precious metals are extremely expensive, the high cost of such catalysts is still a critical factor for application of such catalysts. Further, it is essential for the catalyst to treat the exhaust gas in a maximum possible way, for example, a three-way conversion (TWC) catalyst.
  • TWC three-way conversion
  • the present invention provides a improves catalyst system and exhaust treatment process for converting the harmful components of the exhaust gas to less harm full components that can be let out in the atmosphere.
  • This improved catalyst effectively reduces emission, specifically the hydrocarbons present in the exhaust gas.
  • the catalyst system not only gives economic benefit but also addresses the environmental aspect and meeting the emission norms.
  • An object of the present invention is to provide a catalyst effective to catalyze the abatement of HC, CO and NO x from motorcycles exhaust gas.
  • Another object of the present invention is to effectively reduce the emission in the exhaust gas from motorcycles.
  • Yet another object of the present invention is to involve a catalyst system which is cost effective. Yet another object of the present invention is to provide an exhaust gas treatment system for effectively treating the automobile exhaust.
  • the present invention relates to a catalyst system for aftertreatment of automobile exhaust gas. Specifically, the present invention relates to the catalyst system used to abatement of hydrocarbons, carbon monoxide and nitrogen oxides in the motorcycle exhaust gas. The exhaust gas needs to meet various norms, before letting out into the atmosphere.
  • the present invention also relates to an exhaust gas treatment system incorporating the catalyst unit.
  • the present invention also relates to an exhaust gas treatment process for treating the exhaust gas of the motorcycle.
  • the present invention relates to a catalyst system which effectively catalyze the abatement of HC, CO and NO x from motorcycles exhaust gas.
  • the catalyst system for aftertreatment of motorcycle exhaust gas comprising two bricks 1 and 2 in sequence.
  • the brick- 1 is located upstream comprising washcoat-1 and washcoat-2 coated on substrate-1.
  • the brick-2 located downstream comprising of washcoat-3 coated on substrate-2. All wash coats 1, 2 and 3 comprising noble metal Pt, Pd and Rh.
  • the substrate- 1 and/or substrate-2 having metal substrate (including longitudinal structure) comprising oxygen storage component and refractory metal oxide.
  • the thickness ratio for wash coat of brick-1 and brick-2 is from 1.25 to 1.35.
  • the total average noble metal of the catalyst system is from 35 to 40 g/ft 3 .
  • the PGM loading in brick-1 is 45 to 50 g/ft 3
  • in brick-2 is 25 to 30 g/ft 3 .
  • the present invention relates to an exhaust gas treatment system involving the catalyst system or unit of the invention.
  • the exhaust gas treatment system may have the catalyst unit along with other units for effective treatment.
  • the present invention relates to a process for treating the exhaust gas with a catalyst system.
  • Figure 1 illustrates a schematic representation of catalyst, according to an embodiment of the present invention
  • Figure 2 illustrates a schematic representation of catalyst, according to an embodiment of the present invention
  • Figure 3 illustrates a schematic representation of catalyst, according to an embodiment of the present invention
  • Figure 4 illustrates a schematic representation of catalyst, according to an embodiment of the present invention
  • FIG. 5 shows the total HC (THC) emissions on GVS of Example 1-4;
  • Figure 6 shows the accumulated THC emission of Example 2 and 3
  • Figure 7 shows the accumulated NO x emission of Example 2 and 3
  • Figure 8 shows the accumulated THC emission of Example 5 and 6
  • Figure 9 shows the cumulative hydrocarbon emission of Example 7 and 8;
  • the drawings referred to in this description are not to be understood as being drawn to scale except if specifically noted, and such drawings are only exemplary in nature.
  • vehicle comprises vehicles such as motorcycles, scooters, bicycles, mopeds, scooter type vehicle, all- terrain vehicles (ATV) and the like.
  • ATV all- terrain vehicles
  • a catalyst system for treatment exhaust gas of an automobile comprising, one or more substrate and two or more wash coat layers on the substrate forming one or more bricks, wherein
  • the first brick located in the upstream comprises first wash coat layer and second wash coat layer, coated on the first substrate,
  • wash coat layers comprising noble metal selected from Pt, Pd and Rh, the first substrate and/or the second substrate having a metal substrate comprising oxygen storage component and refractory metal oxide,
  • first brick and second brick are from 1.25 to 1.35.
  • a catalyst system wherein noble metal has a total average loading of the from 35 to 40 g/ft 3 in the catalyst system.
  • a catalyst system wherein the noble metal loading in first brick is 45 to 50 g/ft 3 , and in second brick is 25 to 30 g/ft 3 .
  • Yet another embodiment of the invention involves the catalyst system, wherein Pd/Rh weight ratio in the first brick is from 2.5 to 2.8; and Pd/Rh weight ratio in the second brick is from 1/5 to 1/3.
  • Yet another embodiment of the invention involves a catalyst system, wherein the two bricks system are together with 50 mm away from the engine pipe in motorcycle BS- VI applications.
  • Yet another embodiment of the invention involves a catalyst system, wherein the metal substrate is a longitudinal structure of monoliths.
  • Yet another embodiment of the invention involves a catalyst system, wherein the wash coat layers are applied on a single substrate.
  • Yet another embodiment of the invention involves a catalyst system, wherein the substrate having the oxygen storage component of Ceria and refractory metal oxide components is one or more of Niobium, Molybdenum, Tantalum, Tungsten and Rhenium.
  • the slurry for the first and second wash coat region has at least 40 % solid content
  • the slurry for the third wash coat region has at least 30 % solid content
  • the first brick located in the upstream comprises first wash coat layer and second wash coat layer
  • the second brick located in the downstream comprises the third wash coat layer, characterized in that the thickness ratio of first brick and second brick is from 1.25 to 1.35.
  • a process for preparing the catalyst system wherein the noble metal loading in first brick is 45 to 50 g/ft 3 , and in second brick is 25 to 30 g/ft 3 .
  • Yet another embodiment of the invention a process for preparing the catalyst system, wherein Pd/Rh weight ratio in the first brick is from 2.5 to 2.8; and Pd/Rh weight ratio in the second brick is from 1/5 to 1/3.
  • Yet another embodiment of the invention a process for preparing the catalyst system, wherein the two bricks system are together with 50 mm away from the engine pipe in motorcycle BS-VI applications.
  • Yet another embodiment of the invention a process for preparing the catalyst system, wherein the metal substrate is a longitudinal structure of monoliths.
  • the catalyst system comprising one or more substrate and one or more wash coat layers on the substrate forming two or more bricks, wherein the first brick located in the upstream, comprises first wash coat layer and second wash coat layer, coated on the first substrate,
  • wash coat layers comprising noble metal selected from Pt, Pd and Rh, the first substrate and/or the second substrate having a metal substrate comprising oxygen storage component and refractory metal oxide,
  • first brick and second brick are from 1.25 to 1.35.
  • exhaust gas treatment system is the system as claimed in claims 14.
  • the catalyst system for purifying an exhaust gas of an internal combustion engine comprises at least one substrate; a first washcoat region disposed on upstream side of the at least one substrate, wherein the first washcoat region comprises a first platinum group metal (PGM); a second washcoat region disposed on the substrate adjacent/in sequence to the first washcoat region, wherein the second washcoat region comprises a second platinum group metal (PGM); a third washcoat region disposed over the first washcoat region in the upstream side of the substrate, wherein the third washcoat region comprises a third platinum group metal (PGM); wherein the first PGM, the second PGM and third PGM is selected from the group consisting of platinum, palladium and rhodium.
  • the total loading/density of the second PGM is greater than the total loading/density of the first PGM, and the total loading/density of the first and third PGM together is greater than the total loading/density of the second PGM. Furthermore, the ratio of the thickness first wash coat layer to the second wash coat layer is from 1.25 to 1.35.
  • Figure 1 illustrates a schematic representation of catalyst, according to an embodiment of the present invention.
  • the catalyst (100) of the invention comprises a first substrate (101), a second substrate (102), a first washcoat region (201), a second washcoat region (202), a third washcoat region (203).
  • the second substrate (102) is disposed on adjacent to the first substrate (101) along the downstream of the first substrate (101).
  • the second substrate (102) is disposed adjacent to the first substrate (101) along the downstream of the first substrate (101) with a predetermined space gap‘x’ therebetween.
  • the first washcoat region (201) is disposed on the first substrate (101).
  • the second washcoat region (202) is disposed on the first substrate (101).
  • the first washcoat region (201) comprises a first platinum group of metals (PGM) selected from the group consisting of platinum, palladium and rhodium.
  • PGM platinum group of metals
  • the Palladium/Rhodium weight ratio in the first substrate is from 2.5 to 2.8.
  • the second washcoat region (202) is disposed on the second substrate (102) adjacent to the first substrate (101) and along a direction downstream of the first substrate (101).
  • the Palladium/Rhodium weight ratio in the second substrate is from 1/5 to 1/3.
  • the second washcoat region (202) comprises a second platinum group of metals selected from the group consisting of platinum, palladium and rhodium.
  • the third washcoat region (203) is disposed on the first washcoat region (201) on the first substrate (101).
  • the third washcoat region (203) comprises a first platinum group of metals selected from the group consisting of platinum, palladium and rhodium.
  • the thickness ratio of first and third washcoat region together in the first substrate and of the second washcoat region in the second substrate is from 1.25 to 1.35.
  • the total loading of first and the third PGM is 45 to 50 g/ft 3 In an embodiment, the loading of the third PGM is 25 to 30 g/ft 3 In an embodiment, the length of the first substrate (101) and the second substrate (102) are equal. In another embodiment, as shown in figure 3, the first substrate (101) and the second substrate (102) is an integral substrate (103). In an embodiment, as shown in figure 04, there is a space gap of‘x’ provided between the first substrate (101) and (102). This space gap‘x’ between the first substrate (101) and second substrate (102) is provided to improve uniformity index of flow and maintain turbulent flow in second substrate (102) leading to better purification efficiency of the catalyst system (100). In an embodiment, the space gap is in the range of 10 mm to 20mm.
  • the substrate is a metal substrate (including longitudinal structure) comprising oxygen storage component and refractory metal oxide.
  • the commonly used oxygen storage component is cerium oxide or a mixed oxide containing cerium, e.g. ceria-zirconia mixed oxide.
  • the refractory metal oxide is selected from alumina, silica, zirconia, titania, ceria and mixtures thereof.
  • the catalyst system comprising different Pd/Rh ratio in different bricks of the catalyst.
  • the Pd/Rh weight ratio in brick- 1 is from 2.5 to 2.8; and Pd/Rh weight ratio in brick-2 is from 1/5 to 1/3.
  • Another aspect of the invention provides a catalyst system applied on a two bricks system together with 50 mm away from the engine pipe in motorcycle BS-VI applications.
  • the coating of noble metals on the substrate and the arrangement on the substrate plays an important part in the overall performance of the engine. If the coating of noble metal on the substrate is very thick then it may increase the back pressure in the exhaust system affecting performance of the engine. Further, the coating of noble metal increases the cost. Therefore, the coatings of noble metal on the substrate has to be done in optimize way such as it does not affect the engine performance and also meets the emission norms for the vehicle. At the same time, the coating of noble metal should be cost effective for the catalyst.
  • the preparation method as described below, are used to prepare the catalyst system of the invention in example 1 to 8:
  • Step 1 preparation and coating of wash coat 1 :
  • Soluble rhodium solution was diluted with water to reach incipient wetness for the impregnation of alumina, cerium and zirconium oxide particles.
  • the impregnated sample was then mixed with water, soluble platinum solution to form a slurry with ⁇ 40 wt % solid content.
  • the above mixture was applied to a metal substrate (40x60 mm DxL, cell density is 200 cpsi), and was dried and calcined at 550°C for 2 hours.
  • Step 2 preparation and coating of wash coat 2:
  • Soluble palladium and rhodium solutions were diluted with water to enable incipient wetness impregnation of alumina and cerium and zirconium oxide.
  • the impregnated sample was then mixed with water to form a slurry with ⁇ 30 wt % solid content.
  • the mixture was applied onto washcoat-1 and was dried and calcined at 550°C for 2 hours
  • Step 3 preparation and coating of wash coat 3 :
  • Soluble palladium and rhodium solutions were diluted with water to allow incipient wetness impregnation of alumina and cerium and zirconium oxide particles.
  • the impregnated sample was then mixed with water and soluble platinum solution to form a slurry with ⁇ 40 wt % solid content.
  • the above mixture was applied to a metal substrate (40x 60 mm DxL, cell density is 200 cpsi), and was dried and calcined at 550°C for 2 hours.
  • Example 1 Example 1 :
  • the catalyst of the comparative example 1 is same as that of the inventive example 1, except that the ratio of thickness in brick 1 to brick 2 is 0 8
  • the catalyst of the comparative example 1 is same as that of the inventive example 1, except that the ratio of thickness in brick 1 to brick 2 is 1.
  • the catalyst of the comparative example 1 is same as that of the inventive example 1, except that the ratio of thickness in brick 1 to brick 2 is 1.5.
  • the amount THC/CO/NO x are determined by TCD, FID and FTIR infrared spectroscopy. Results are shown in Figure 5.
  • the catalysts of inventive examples 2 and 3 are used for further studies of the NO x performance.
  • the test was carried on an automobile with World motorcycle Test Cycle (WMTC) cycle.
  • the WMTC cycle is a standard cycle wherein the catalyst is tested by varying the speed, time.
  • the Catalyst were coated on full size substrate (40 mm D * 60 mm L *2) and assembled on an automobile muffler.
  • the amount THC/CO/NOx are determined by TCD, FID and FTIR infrared spectroscopy. Results are shown in Figure 6 and 7.
  • the gray color denotes the actual speed of the engine.
  • the P8 (yellow color) denotes the example 3
  • P80H blue color
  • the example 2 wash coat loading provides better emission control (THC and NO x reduction) than the example 2 wash coat loading.
  • the catalysts of inventive examples 5 and 6, are used for further studies of the THC performance.
  • the test was carried on an automobile with World motorcycle Test Cycle (WMTC) cycle.
  • WMTC cycle is a standard cycle wherein the catalyst is tested by varying the speed, time
  • the catalysts were aged for 24 hours at 550°C in air and were coated on core substrate (1-inch D * 1-inch L *2).
  • the catalysts of inventive examples 7 and 8 are used for further studies of the THC performance.
  • the test was carried on motorcycle with WMTC cycle. Catalyst were coated on full size substrate (40 mm D * 90 mm L *2) and assembled on motorcycle muffler. The amount THC/CO/NOx are determined by TCD, FID and FTIR infrared spectroscopy. Results are shown in figure 9.
  • the gray color denotes the actual speed of the engine.
  • the 4 (green color) denotes the example 8 and 0.25 (magenta color) denotes the example 7. It can be seen that the example 7 wash coat loading provides better emission control (Cumulative hydrocarbon) than the example 8 wash coat loading.

Abstract

The present invention relates to a catalyst system for after treatment of automobile exhaust gas. The present invention also relates to an exhaust gas treatment system incorporating the catalyst unit. The present invention also relates to an exhaust gas treatment process for treating the exhaust gas of the motorcycle. The exhaust gas needs to meet various norms, before letting out into the atmosphere. The catalyst system of the invention effectively reduces the harmful hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx) into less harmful components to meet the emission norms. The catalyst system has the advantages of being economical and efficient, reduced back pressure and at the same time meeting the emission norms, optimal usage of the noble metals in the catalyst resulting in the cost reduction.

Description

“CATALYST SYSTEM FOR TREATMENT OF EXHAUST GAS OF AUTOMOBILE AND PROCESS FOR MAKING THE SAME”
Technical Field
The present invention relates to a catalyst system for for treatment of exhaust gas of an automobile. Specifically, the present invention relates to the catalyst system used to abatement of hydrocarbons, carbon monoxide and nitrogen oxides in the motorcycle exhaust gas. Further, the present invention relates to a process for preparing the catalyst. The exhaust gas needs to meet various norms, before letting out into the atmosphere. The present invention also relates to an exhaust gas treatment system incorporating the catalyst unit. The present invention also relates to an exhaust gas treatment process for treating the exhaust gas of the motorcycle.
Background
Automobiles, which incorporates internal combustion engines, are widely used throughout the world, for transportation. The product or exhaust gas from an internal combustion engine has a number of different components. The product may contain partially converted feed (hydrocarbons), carbon di oxide, carbon monoxide, nitrogen oxides etc. The wider usage of the automobiles leads to wider product of these products.
Exhaust gas from an automobile engine often contains emissions such as hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx). Such emissions are relatively harmful and need to be pretreated before letting out to the atmosphere. Furthermore, the emission treatment norms are becoming stricter year on year. Recently, stricter emission criteria are already required or will be required in many countries to improve the environmental conditions by further limiting emissions such HC, CO, NOx.
A vehicle such as a motorcycle or scooter is generally provided with an exhaust emission gas purifying device such as a catalyst which purifies exhaust gas discharged from an engine. The purified exhaust gas from the exhaust gas purifying device is then discharged into the atmosphere in a harmless state. In an example, a catalyst unit is used as the exhaust gas purifying device. The catalyst unit is disposed either inside the muffler or in the middle of an exhaust pipe having one end thereof connected to an engine and having the other end thereof connected to a muffler. The catalyst unit is used to reduce tailpipe emission levels. Generally, the catalyst unit is built in a honeycomb or pellet geometry to expose the exhaust gases to a large surface made of one or more noble metals such as platinum group metals including platinum, palladium rhodium. The catalyst unit is composed of mainly a substrate, a wash coat and one or more layers of noble metals such as platinum, palladium and rhodium.
It is well known in the art that various catalysts and exhaust gas purification systems have been developed and used in the automobile, to resolve the challenging emission control problems. However, there is always a room for improvement and advancement of the catalyst system.
Reference is made to the CN patent application CN105664939A, which discloses a catalytic converter for treating motorcycle exhaust gas composed of a carrier and a washcoat layer. The said washcoat layer is composed of alumina or an oxygen storage material and precious metals comprising platinum, palladium and rhodium. First of all, as precious metals are extremely expensive, the high cost of such catalysts is still a critical factor for application of such catalysts. Further, it is essential for the catalyst to treat the exhaust gas in a maximum possible way, for example, a three-way conversion (TWC) catalyst. Hence, it is desired to develop a catalyst system with limited precious metals used, while could meet the increasingly stringent regulations simultaneously.
Further reference is made to US patent application US20120128558 Al, which discloses a TWC catalyst of at least two front layers and two rear layers in conjunction with a substrate. This document discloses that all layers comprise a platinum group metal component, and the rear bottom layer is substantially free of a ceria-containing oxygen storage component. Even though this catalyst system could meet the emission norms there is still a need to reduce the hydrocarbons from the exhaust gas. Furthermore, there is a requirement to develop a catalyst having improved conversion of the reactant exhaust gas.
Although the prior arts disclose various catalyst system to treat the exhaust gas stream, the systems know are either not satisfactory or very costly. Thus, there is still a need for cost effective, well designed catalyst system for aftertreatment of motorcycles exhaust gas.
In view of this, the inventors of the present disclosure felt a need to develop a catalyst system which overcomes all the problems of the prior arts and is cost effective. Particularly there is a need to improve the efficiency of the catalyst i.e. the conversion of the hydrocarbons. The present invention provides a improves catalyst system and exhaust treatment process for converting the harmful components of the exhaust gas to less harm full components that can be let out in the atmosphere. This improved catalyst effectively reduces emission, specifically the hydrocarbons present in the exhaust gas. The catalyst system not only gives economic benefit but also addresses the environmental aspect and meeting the emission norms.
An object of the present invention is to provide a catalyst effective to catalyze the abatement of HC, CO and NOx from motorcycles exhaust gas.
Another object of the present invention is to effectively reduce the emission in the exhaust gas from motorcycles.
Yet another object of the present invention is to involve a catalyst system which is cost effective. Yet another object of the present invention is to provide an exhaust gas treatment system for effectively treating the automobile exhaust.
Summary of the Invention
The present invention relates to a catalyst system for aftertreatment of automobile exhaust gas. Specifically, the present invention relates to the catalyst system used to abatement of hydrocarbons, carbon monoxide and nitrogen oxides in the motorcycle exhaust gas. The exhaust gas needs to meet various norms, before letting out into the atmosphere. The present invention also relates to an exhaust gas treatment system incorporating the catalyst unit. The present invention also relates to an exhaust gas treatment process for treating the exhaust gas of the motorcycle.
In one aspect of the disclosure, the present invention relates to a catalyst system which effectively catalyze the abatement of HC, CO and NOx from motorcycles exhaust gas. The catalyst system for aftertreatment of motorcycle exhaust gas comprising two bricks 1 and 2 in sequence. The brick- 1 is located upstream comprising washcoat-1 and washcoat-2 coated on substrate-1. The brick-2 located downstream comprising of washcoat-3 coated on substrate-2. All wash coats 1, 2 and 3 comprising noble metal Pt, Pd and Rh. The substrate- 1 and/or substrate-2 having metal substrate (including longitudinal structure) comprising oxygen storage component and refractory metal oxide. The thickness ratio for wash coat of brick-1 and brick-2 is from 1.25 to 1.35. The total average noble metal of the catalyst system is from 35 to 40 g/ft3. The PGM loading in brick-1 is 45 to 50 g/ft3, and in brick-2 is 25 to 30 g/ft3.
The inventors of the present invention have surprisingly found that by providing the catalyst including various features along with the thickness ratio for wash coat of brick- 1 and brick-2, a cost effective catalyst system which effectively reduces the emission in the exhaust gas can be obtained. In another aspect of the disclosure, the present invention relates to an exhaust gas treatment system involving the catalyst system or unit of the invention. The exhaust gas treatment system may have the catalyst unit along with other units for effective treatment.
In another aspect of the disclosure, the present invention relates to a process for treating the exhaust gas with a catalyst system.
Brief Description of the Drawings:
The invention itself, together with further features and attended advantages, will become apparent from consideration of the following detailed description, taken in conjunction with the accompanying drawings. One or more embodiments of the present invention are now described, by way of example only wherein like reference numerals represent like elements and in which:
Figure 1 illustrates a schematic representation of catalyst, according to an embodiment of the present invention;
Figure 2 illustrates a schematic representation of catalyst, according to an embodiment of the present invention;
Figure 3 illustrates a schematic representation of catalyst, according to an embodiment of the present invention;
Figure 4 illustrates a schematic representation of catalyst, according to an embodiment of the present invention;
Figure 5 shows the total HC (THC) emissions on GVS of Example 1-4;
Figure 6 shows the accumulated THC emission of Example 2 and 3;
Figure 7 shows the accumulated NOx emission of Example 2 and 3;
Figure 8 shows the accumulated THC emission of Example 5 and 6;
Figure 9 shows the cumulative hydrocarbon emission of Example 7 and 8; The drawings referred to in this description are not to be understood as being drawn to scale except if specifically noted, and such drawings are only exemplary in nature.
Detailed Description of the Invention
While the invention is susceptible to various modifications and alternative forms, an embodiment thereof has been shown by way of example in the drawings and will be described here below. It should be understood, however that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the invention.
The terms“comprises”,“comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, structure or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or structure or method. In other words, one or more elements in a system or apparatus proceeded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
For the better understanding of this invention, reference would now be made to the embodiment illustrated in the accompanying Figures and description here below, further, in the following Figures, the same reference numerals are used to identify the same components in various views.
While the present invention is illustrated in the context of a vehicle, however, exhaust system and aspects and features thereof can be used with other type of vehicles as well. The terms“vehicle”,“two wheeled vehicle” and“motorcycle” have been interchangeably used throughout the description. The term “vehicle” comprises vehicles such as motorcycles, scooters, bicycles, mopeds, scooter type vehicle, all- terrain vehicles (ATV) and the like. Furthermore, it is to be understood that the invention is not limited to the details of construction or process steps set forth in the following description. The invention is capable of other embodiments and of being practiced or being carried out in various ways.
The following terms, used in the present description and the appended claims, have the following definitions:
Expressions“a”,“an”,“the”, when used to define a term, include both the plural and singular forms of the term.
All percentages and ratios are mentioned by weight unless otherwise indicated.
In one aspect of the invention, provides a catalyst system for treatment exhaust gas of an automobile comprising, one or more substrate and two or more wash coat layers on the substrate forming one or more bricks, wherein
the first brick located in the upstream, comprises first wash coat layer and second wash coat layer, coated on the first substrate,
the second brick located in the downstream comprising of third wash coat layer, coated on second substrate,
wherein the wash coat layers comprising noble metal selected from Pt, Pd and Rh, the first substrate and/or the second substrate having a metal substrate comprising oxygen storage component and refractory metal oxide,
characterized in that the thickness ratio of first brick and second brick is from 1.25 to 1.35.
In an embodiment of the invention a catalyst system is disclosed, wherein noble metal has a total average loading of the from 35 to 40 g/ft3 in the catalyst system.
In another embodiment of the invention a catalyst system is disclosed, wherein the noble metal loading in first brick is 45 to 50 g/ft3, and in second brick is 25 to 30 g/ft3. Yet another embodiment of the invention involves the catalyst system, wherein Pd/Rh weight ratio in the first brick is from 2.5 to 2.8; and Pd/Rh weight ratio in the second brick is from 1/5 to 1/3.
Yet another embodiment of the invention involves a catalyst system, wherein the two bricks system are together with 50 mm away from the engine pipe in motorcycle BS- VI applications.
Yet another embodiment of the invention involves a catalyst system, wherein the metal substrate is a longitudinal structure of monoliths.
Yet another embodiment of the invention involves a catalyst system, wherein the wash coat layers are applied on a single substrate.
Yet another embodiment of the invention involves a catalyst system, wherein the substrate having the oxygen storage component of Ceria and refractory metal oxide components is one or more of Niobium, Molybdenum, Tantalum, Tungsten and Rhenium.
In an embodiment of the invention a process for preparing the catalyst system for aftertreatment of automobile exhaust gas comprising steps of
preparing and coating of one or more wash coat layers on one or more substrate forming two or more bricks, comprising
a. diluting the soluble noble metal solution with water to reach incipient wetness.
b. Impregnating the alumina, cerium and zirconium oxide particles on the Noble metal solution.
c. Addition of the water and another soluble noble metal solution to form a slurry. d. The slurry is applied on a metal substrate.
e. Drying and calcination at a temperature of 500°C -600°C for at least 2 hours.
wherein the slurry for the first and second wash coat region has at least 40 % solid content, the slurry for the third wash coat region has at least 30 % solid content, the first brick located in the upstream, comprises first wash coat layer and second wash coat layer,
the second brick located in the downstream comprises the third wash coat layer, characterized in that the thickness ratio of first brick and second brick is from 1.25 to 1.35.
In another embodiment of the invention a process for preparing the catalyst system, wherein the noble metal loading in first brick is 45 to 50 g/ft3, and in second brick is 25 to 30 g/ft3.
Yet another embodiment of the invention a process for preparing the catalyst system, wherein Pd/Rh weight ratio in the first brick is from 2.5 to 2.8; and Pd/Rh weight ratio in the second brick is from 1/5 to 1/3.
Yet another embodiment of the invention a process for preparing the catalyst system, wherein the two bricks system are together with 50 mm away from the engine pipe in motorcycle BS-VI applications.
Yet another embodiment of the invention a process for preparing the catalyst system, wherein the metal substrate is a longitudinal structure of monoliths.
In an embodiment of the invention an exhaust gas treatment system for treating the exhaust gas of an automobile comprising one or more catalyst system
the catalyst system comprising one or more substrate and one or more wash coat layers on the substrate forming two or more bricks, wherein the first brick located in the upstream, comprises first wash coat layer and second wash coat layer, coated on the first substrate,
the second brick located in the downstream comprising of third wash coat layer, coated on second substrate,
wherein the wash coat layers comprising noble metal selected from Pt, Pd and Rh, the first substrate and/or the second substrate having a metal substrate comprising oxygen storage component and refractory metal oxide,
characterized in that the thickness ratio of first brick and second brick is from 1.25 to 1.35.
In an embodiment of the invention an exhaust gas treatment process for treating the exhaust gas of an automobile comprising steps of
sending the exhaust gas from the automobile engine to an exhaust gas treatment system to convert the harmful hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx) into less harmful components to meet the emission norms,
wherein the exhaust gas treatment system is the system as claimed in claims 14.
In an embodiment of the invention use of the catalyst system as claimed in claim 1 for aftertreatment of automobile exhaust gas.
In an embodiment of the invention use of the catalyst system as claimed in claim 16 having reduced back pressure and optimum usage of the noble metals.
The catalyst system for purifying an exhaust gas of an internal combustion engine, comprises at least one substrate; a first washcoat region disposed on upstream side of the at least one substrate, wherein the first washcoat region comprises a first platinum group metal (PGM); a second washcoat region disposed on the substrate adjacent/in sequence to the first washcoat region, wherein the second washcoat region comprises a second platinum group metal (PGM); a third washcoat region disposed over the first washcoat region in the upstream side of the substrate, wherein the third washcoat region comprises a third platinum group metal (PGM); wherein the first PGM, the second PGM and third PGM is selected from the group consisting of platinum, palladium and rhodium. The total loading/density of the second PGM is greater than the total loading/density of the first PGM, and the total loading/density of the first and third PGM together is greater than the total loading/density of the second PGM. Furthermore, the ratio of the thickness first wash coat layer to the second wash coat layer is from 1.25 to 1.35.
The terms“rear / rearward / back / backward”,“up / upper / top”,“down / lower / lower ward / downward, bottom”,“left / leftward”,“right / rightward” used therein represents the directions as seen from a vehicle driver sitting astride and these directions are referred by arrows Fr, Rr, U, Lr, L, R in the drawing Figures.
Figure 1 illustrates a schematic representation of catalyst, according to an embodiment of the present invention.
The catalyst (100) of the invention comprises a first substrate (101), a second substrate (102), a first washcoat region (201), a second washcoat region (202), a third washcoat region (203). The second substrate (102) is disposed on adjacent to the first substrate (101) along the downstream of the first substrate (101).
In another embodiment, as shown in figure 4, the second substrate (102) is disposed adjacent to the first substrate (101) along the downstream of the first substrate (101) with a predetermined space gap‘x’ therebetween. The first washcoat region (201) is disposed on the first substrate (101). The second washcoat region (202). The first washcoat region (201) is disposed on the first substrate (101). The first washcoat region (201) comprises a first platinum group of metals (PGM) selected from the group consisting of platinum, palladium and rhodium. In an embodiment, the Palladium/Rhodium weight ratio in the first substrate is from 2.5 to 2.8. Further, the second washcoat region (202) is disposed on the second substrate (102) adjacent to the first substrate (101) and along a direction downstream of the first substrate (101).
In an embodiment of the invention, the Palladium/Rhodium weight ratio in the second substrate is from 1/5 to 1/3. The second washcoat region (202) comprises a second platinum group of metals selected from the group consisting of platinum, palladium and rhodium. Furthermore, the third washcoat region (203) is disposed on the first washcoat region (201) on the first substrate (101). The third washcoat region (203) comprises a first platinum group of metals selected from the group consisting of platinum, palladium and rhodium. In an embodiment, the thickness ratio of first and third washcoat region together in the first substrate and of the second washcoat region in the second substrate is from 1.25 to 1.35. In an embodiment, the total loading of first and the third PGM is 45 to 50 g/ft3 In an embodiment, the loading of the third PGM is 25 to 30 g/ft3 In an embodiment, the length of the first substrate (101) and the second substrate (102) are equal. In another embodiment, as shown in figure 3, the first substrate (101) and the second substrate (102) is an integral substrate (103). In an embodiment, as shown in figure 04, there is a space gap of‘x’ provided between the first substrate (101) and (102). This space gap‘x’ between the first substrate (101) and second substrate (102) is provided to improve uniformity index of flow and maintain turbulent flow in second substrate (102) leading to better purification efficiency of the catalyst system (100). In an embodiment, the space gap is in the range of 10 mm to 20mm.
In another aspect of the invention, the substrate is a metal substrate (including longitudinal structure) comprising oxygen storage component and refractory metal oxide. The commonly used oxygen storage component is cerium oxide or a mixed oxide containing cerium, e.g. ceria-zirconia mixed oxide. The refractory metal oxide is selected from alumina, silica, zirconia, titania, ceria and mixtures thereof. In preferable embodiments, the catalyst system comprising different Pd/Rh ratio in different bricks of the catalyst. Preferably, the Pd/Rh weight ratio in brick- 1 is from 2.5 to 2.8; and Pd/Rh weight ratio in brick-2 is from 1/5 to 1/3.
Another aspect of the invention provides a catalyst system applied on a two bricks system together with 50 mm away from the engine pipe in motorcycle BS-VI applications.
The invention itself, together with further features and attended advantages, will become apparent from consideration of the following detailed description, taken in conjunction with the accompanying drawings. One or more embodiments of the present invention are now described, by way of example only wherein like reference numerals represent like elements and in which:
EXAMPLES
There are many variations and combinations that can be made based on this disclosure to make catalyst systems for aftertreatment of motorcycle exhaust gas without departure from the spirit of this disclosure. The following examples and embodiments are given as illustration purposes only that should not be used as limit to the invention.
The coating of noble metals on the substrate and the arrangement on the substrate plays an important part in the overall performance of the engine. If the coating of noble metal on the substrate is very thick then it may increase the back pressure in the exhaust system affecting performance of the engine. Further, the coating of noble metal increases the cost. Therefore, the coatings of noble metal on the substrate has to be done in optimize way such as it does not affect the engine performance and also meets the emission norms for the vehicle. At the same time, the coating of noble metal should be cost effective for the catalyst. The preparation method as described below, are used to prepare the catalyst system of the invention in example 1 to 8:
Step 1 : preparation and coating of wash coat 1 :
Soluble rhodium solution was diluted with water to reach incipient wetness for the impregnation of alumina, cerium and zirconium oxide particles. The impregnated sample was then mixed with water, soluble platinum solution to form a slurry with ~40 wt % solid content. The above mixture was applied to a metal substrate (40x60 mm DxL, cell density is 200 cpsi), and was dried and calcined at 550°C for 2 hours. Step 2: preparation and coating of wash coat 2:
Soluble palladium and rhodium solutions were diluted with water to enable incipient wetness impregnation of alumina and cerium and zirconium oxide. The impregnated sample was then mixed with water to form a slurry with ~30 wt % solid content. The mixture was applied onto washcoat-1 and was dried and calcined at 550°C for 2 hours
Step 3 : preparation and coating of wash coat 3 :
Soluble palladium and rhodium solutions were diluted with water to allow incipient wetness impregnation of alumina and cerium and zirconium oxide particles. The impregnated sample was then mixed with water and soluble platinum solution to form a slurry with ~40 wt % solid content. The above mixture was applied to a metal substrate (40x 60 mm DxL, cell density is 200 cpsi), and was dried and calcined at 550°C for 2 hours. Example 1 :
Above preparation method was used to prepare the catalyst system, the resulted catalyst system with washcoat loading 1.4 g/in3 in washcoat 1, washcoat loading 1.0 g/in3 in washcoat 2 and washcoat loading 3 g/in3 in washcoat 3. The ratio of the thickness of the brick 1 to brick 2 is 1.26. Example 2:
Above preparation method was used to prepare the catalyst system, the resulted catalyst system with washcoat loading 2.0 g/in3 in washcoat 1, washcoat loading 1.0 g/in3 in washcoat 2 and washcoat loading 3 g/in3 in washcoat 3. The ratio of the thickness of the brick 1 to brick 2 is from 1.25 to 1.35.
Example 3 :
Above preparation method was used to prepare the catalyst system, the resulted catalyst system with washcoat loading 2.0 g/in3 in washcoat 1, washcoat loading 1.0 g/in3 in washcoat 2 and washcoat loading 2.4 g/in3 in washcoat 3. The ratio of the thickness of the brick 1 to brick 2 is from 1.25 to 1.35.
Example 4:
Above preparation method was used to prepare the catalyst system, the resulted catalyst system, the resulted catalyst with washcoat loading 2.0 g/in3 in washcoat 1, washcoat loading 1.0 g/in3 in washcoat 2 and washcoat loading 2.0 g/in3 in washcoat 3. The ratio of the thickness of the brick 1 to brick 2 is from 1.25 to 1.35.
Example 5:
Above preparation method was used to prepare the catalyst system, the resulted catalyst system with Pd/Rh ratio 2.7 in brick 1, and Pd/Rh ratio 0.4 in brick 2. The ratio of the thickness of the brick 1 to brick 2 is from 1.25 to 1.35.
Example 6:
Above preparation method was used to prepare the catalyst system, the resulted catalyst system with Pd/Rh ratio 1.7 in brick 1, and Pd/Rh ratio 0.4 in brick 2. The ratio of the thickness of the brick 1 to brick 2 is from 1.25 to 1.35. Example 7:
Above preparation method was used to prepare the catalyst system, the resulted catalyst system with Pd/Rh ratio 2.7 in brick 1, and Pd/Rh ratio 0.25 in brick 2. The ratio of the thickness of the brick 1 to brick 2 is from 1.25 to 1.35.
Example 8:
Above preparation method was used to prepare the catalyst system, the resulted catalyst system with Pd/Rh ratio 2.7 in brick 1, and Pd/Rh ratio 4.0 in brick 2. The ratio of the thickness of the brick 1 to brick 2 is from 1.25 to 1.35.
Comparative example 1 :
The catalyst of the comparative example 1 is same as that of the inventive example 1, except that the ratio of thickness in brick 1 to brick 2 is 0 8
Comparative example 2:
The catalyst of the comparative example 1 is same as that of the inventive example 1, except that the ratio of thickness in brick 1 to brick 2 is 1.
Comparative example 3 :
The catalyst of the comparative example 1 is same as that of the inventive example 1, except that the ratio of thickness in brick 1 to brick 2 is 1.5.
Test of THC (Total Hydrocarbon) performance of Example 1 and Comparative examples E 2 and 3 :
The catalysts were aged for 24 hours at 550°C in air and were coated on core substrate (1-inch D * 1-inch L *2). Testing was performed at GVS (gasoline vehicle simulator) and the space velocity was dynamic which reached to max 85,000 h 1 and lambda swing at 0.80 to 1.20; HC is from 0-20,000 ppm, CO is from 0-35,000 ppm and NOx (NO/NO2) is from 0-8,000 ppm, H2O = 10%, CO/NOx/02 varies base on lambda. The amount THC/CO/NOx are determined by TCD, FID and FTIR infrared spectroscopy. Results are shown in Figure 5.
As show in figure 5, the THC (Total Hydrocarbon) is effectively reduced when the ratio of the thickness of the brick 1 to brick 2 is between the claimed range (example 1). On the other hand, if the ratio of the thickness of the brick 1 to brick 2 outside the claimed range (comparative examples 1 to 3), the desired reduction in the THC is not obtained. Hence, the rest of example 1 and comparative examples 1 to 3 clearly shows the enhanced performance of the catalyst system of the invention.
Test of THC and NOx performance of Example 2 and 3 :
The catalysts of inventive examples 2 and 3, are used for further studies of the NOx performance. The test was carried on an automobile with World Motorcycle Test Cycle (WMTC) cycle. The WMTC cycle is a standard cycle wherein the catalyst is tested by varying the speed, time. The Catalyst were coated on full size substrate (40 mm D * 60 mm L *2) and assembled on an automobile muffler. The amount THC/CO/NOx are determined by TCD, FID and FTIR infrared spectroscopy. Results are shown in Figure 6 and 7. The gray color denotes the actual speed of the engine. The P8 (yellow color) denotes the example 3 and P80H (blue color) denotes the example 2. It can be seen that the example 3 wash coat loading provides better emission control (THC and NOx reduction) than the example 2 wash coat loading.
Test of THC performance of Example 5 and 6:
The catalysts of inventive examples 5 and 6, are used for further studies of the THC performance. The test was carried on an automobile with World Motorcycle Test Cycle (WMTC) cycle. The WMTC cycle is a standard cycle wherein the catalyst is tested by varying the speed, time The catalysts were aged for 24 hours at 550°C in air and were coated on core substrate (1-inch D * 1-inch L *2). Testing was performed at GVS (gasoline vehicle simulator), and the space velocity was dynamic which reached to max 85,000 h 1 and lambda swing at 0.80 to 1.20; HC is from 0-20,000 ppm, CO is from 0-35,000 ppm and NOx (NO/NO2) is from 0-8,000 ppm, H2O = 10%, CO/NOx/02 varies base on lambda. The amount THC/CO/NOx are determined by TCD, FID and FTIR infrared spectroscopy. Results are shown in figure 8. The 2.7 (red color) denotes the example 5 and 1.7 (blue color) denotes the example 6. It can be seen that the example 5 wash coat loading provides better emission control (THC reduction) than the example 6 wash coat loading.
Test of THC performance of Example 7 and 8:
The catalysts of inventive examples 7 and 8, are used for further studies of the THC performance.
The test was carried on motorcycle with WMTC cycle. Catalyst were coated on full size substrate (40 mm D * 90 mm L *2) and assembled on motorcycle muffler. The amount THC/CO/NOx are determined by TCD, FID and FTIR infrared spectroscopy. Results are shown in figure 9. The gray color denotes the actual speed of the engine. The 4 (green color) denotes the example 8 and 0.25 (magenta color) denotes the example 7. It can be seen that the example 7 wash coat loading provides better emission control (Cumulative hydrocarbon) than the example 8 wash coat loading.
Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention include modifications and variations that are within the scope of the appended claims and their equivalents. Advantages:
The catalyst unit and the emission treatment system of the invention has the following advantages:
• Economical and efficient.
• Effective reduction of hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx) from the exhaust gas of automobiles.
• Reduced back pressure and at the same time meeting the emission norms.
• Optimal usage of the noble metals in the catalyst resulting in the cost reduction.

Claims

The Claims:
1. A catalyst system for treatment of exhaust gases of an automobile comprising, one or more substrate and one or more wash coat layers on the substrate forming two or more bricks, wherein
the first brick located in the upstream, comprises first wash coat layer and second wash coat layer, coated on the first substrate,
the second brick located in the downstream comprising of third wash coat layer, coated on second substrate,
wherein the wash coat layers comprising noble metal selected from Pt, Pd and Rh, the first substrate and/or the second substrate having a metal substrate comprising oxygen storage component and refractory metal oxide,
characterized in that, the thickness ratio for wash coat layer of the first brick and the second brick is from 1.25 to 1.35.
2. The catalyst system as claimed in claim 1, wherein noble metal in the catalyst system has a total average loading in a range of 35 to 40 g/ft3.
3. The catalyst system as claimed in claims 1 or 2, wherein the noble metal loading in the first brick is 45 to 50 g/ft3, and in the second brick is 25 to 30 g/ft3.
4. The catalyst system as claimed in claim 1, wherein Pd/Rh weight ratio in the first brick is in a range of 2.5 to 2.8; and Pd/Rh weight ratio in the second brick is in a range of 1/5 to 1/3.
5. The catalyst system as claimed in any one of claims 1 to 4, wherein the two bricks system are together in an exhaust pipe with 50 mm away from an exhaust port of an engine of the automobile.
6. The catalyst system as claimed in claims 1, wherein the metal substrate is a longitudinal structure of monoliths.
7. The catalyst system as claimed in claim 1 or 6, wherein the wash coat layers are applied on a single substrate.
8. The catalyst system as claimed in claims 1 or 6, wherein the substrate having the oxygen storage component of Ceria and refractory metal oxide components is one or more of Niobium, Molybdenum, Tantalum, Tungsten and Rhenium.
9. A process for preparing the catalyst for aftertreatment of automobile exhaust gas comprising steps of preparing and coating of one or more wash coat layers on one or more substrate forming two or more bricks, comprising
a. diluting the soluble noble metal solution with water to reach incipient wetness.
b. Impregnating the alumina, cerium and zirconium oxide particles on the Noble metal solution.
c. Addition of the water and another soluble noble metal solution to form a slurry.
d. The slurry is applied on a metal substrate.
e. Drying and calcination at a temperature of 500°C -600°C for at least 2 hours.
wherein the slurry for the first and second wash coat region has at least 40 % solid content, the slurry for the third wash coat region has at least 30 % solid content, the first brick located in the upstream, comprises first wash coat layer and second wash coat layer,
the second brick located in the downstream comprises the third wash coat layer, characterized in that the thickness ratio for wash coat layer of the first brick and second brick is from 1.25 to 1.35.
10. The process as claimed in claims 9, wherein the noble metal loading in first brick is 45 to 50 g/ft3, and in second brick is 25 to 30 g/ft3.
11. The process as claimed in claim 9 or 10, wherein Pd/Rh weight ratio in the first brick is in a range of 2.5 to 2.8; and Pd/Rh weight ratio in the second brick is in a range of 1/5 to 1/3.
12. The process as claimed in any one of claims 9 to 11, wherein the two bricks system are together with 50 mm away from the engine pipe in motorcycle.
13. The process as claimed in claim 9, wherein the metal substrate is a longitudinal structure of monoliths.
14. An exhaust gas treatment system for treating the exhaust gas of an automobile comprising a one or more catalyst system comprising one or more substrate and one or more wash coat layers on the substrate forming two or more bricks, wherein the first brick located in the upstream, comprises first wash coat layer and second wash coat layer, coated on the first substrate,
the second brick located in the downstream comprising of third wash coat layer, coated on second substrate,
wherein the wash coat layers comprising noble metal selected from Pt, Pd and Rh, the first substrate and/or the second substrate having a metal substrate comprising oxygen storage component and refractory metal oxide,
characterized in that the thickness ratio for wash coat layer of the first brick and the second brick is from 1.25 to 1.35.
15. An exhaust gas treatment process for treating the exhaust gas of an automobile comprising steps of
sending the exhaust gas from the automobile engine to an exhaust gas treatment system to convert the harmful hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx) into less harmful components to meet the emission norms, wherein the exhaust gas treatment system is the system as claimed in claims 14.
16. Use of the catalyst system as claimed in claim 1 for aftertreatment of automobile exhaust gas.
17. Use of the catalyst system as claimed in claim 16 having reduced back pressure and optimum usage of the noble metals.
PCT/IN2020/050225 2019-03-11 2020-03-11 Catalyst system for treatment of exhaust gas of automobile and process for making the same WO2020183496A1 (en)

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