Claims:WE CLAIM:
1. A process for synthesising a hybrid washcoat, comprising:
generating a washcoat slurry by heating washcoat with platinum group metal (PGM),
wherein heating the washcoat with PGM being carried by microwave irradiation,
wherein the platinum group metal comprises nano sized particles thereby increasing the surface area and consequently increasing catalytic conversion;
uniformly disposing the washcoat slurry onto a substrate to obtain a washcoated substrate;
drying the washcoated substrate to form a layer using a microwave synthesizing technique;
coating one or more catalysts onto the washcoated substrate, using the microwave synthesizing technique, to form plurality of layers of the one or more catalysts impregnated onto the washcoated substrate to obtain the hybrid washcoat,
wherein one or more catalysts comprise the platinum group metal (PGM) and platinum:palladium (Pt:Pd) metal solution,
wherein the plurality of layers of the one or more catalysts comprises a top layer and a bottom layer, and
wherein light off temperature of the one or more catalysts is less than 200ºC.
2. The process as claimed in the claim 1, wherein the platinum group metal comprises range of size of nanoparticles from 10 to 100 nm.

3. The process as claimed in the claim 1, wherein the coating one or more catalysts onto the washcoated substrate comprises coating the Pt: Pd metal solution as an upstream and downstream catalyst in a ratio of 5:1 and 6:1 in the bottom and the top layer, respectively.

4. The process as claimed in the claim 1, wherein the top layer comprises nanosized PGM as upstream catalyst along with Pt:Pd metal solution in a ratio of 1:1 to 2:1, and the bottom layer comprises nanosized and micro sized washcoat along with Pt:Pd metal solution.

5. A catalytic converter system, comprising:
a honeycomb-type refractory carrier member, wherein the honeycomb-type refractory carrier member comprises one of a honeycomb-type silicon carbide (SiC) substrate and honeycomb-type Cordierite type substrate, characterised in that
the honeycomb-type refractory carrier member comprises coating of plurality of layers of one of a diesel oxidation catalyst (DOC) washcoat composition, diesel particulate filter (DPF) washcoat composition, a selective catalytic reduction (SCR) washcoat composition, and an ammonia slip catalyst (ASC) and nano-sized PGM washcoat composition.

6. The catalytic converter system as claimed in claim 5, wherein the ammonia slip catalyst is configured to be coated over 3/4th surface area of the substrate and nano-sized PGM is configured to be coated over 1/4th surface area of the substrate.

Dated this 13th Day of January 2020


Vidya Bhaskar Singh Nandiyal
Patent Agent (IN/PA-2912)
Agent for applicant
, Description:FIELD OF INVENTION
[0001] The present disclosure relates to a catalytic converter and more particularly it relates to a process for synthesizing a hybrid washcoat.

BACKGROUND
[0002] A catalytic converter is an exhaust emission control device that reduces toxic gases and pollutants in exhaust gas from an internal combustion engine into less-toxic pollutants by catalysing a redox reaction (a reduction and an oxidation reaction). Catalytic converters are used with lean-burn engines, kerosene heaters, stoves and internal combustion engines fuelled by either diesel or gasoline.

[0003] Three basic types of catalytic converters are two-way, three-way and three way plus oxidation converters. Three-way catalyst converters further developed into a four-way catalyst converter. The four-way catalyst converter is a technology for vehicles with gasoline engines. The catalyst eliminates the gaseous pollutants, and also solids like particulates from the exhaust gas flow. The four-way catalyst converter occupies much less space as compared to the three-way catalyst converter and the downstream uncoated particulate filter.

[0004] However, component used in catalytic converter such as washcoat is a carrier for the catalytic materials and is used to disperse the materials over a high surface area. Aluminium oxide, silicon dioxide, titanium dioxide, or a mixture of alumina and silica can be used as washcoat. The catalytic materials are suspended in the washcoat prior to applying to the core. Washcoat materials are selected to form a rough, irregular surface, which greatly increases the surface area compared to the smooth surface of the bare substrate.
[0005] Conventional washcoat used in the catalytic converter may not include nano sized and micro sized particles in washcoat. This reduces the surface area thereby reducing catalytic conversion. Also, the process being used for producing washcoated catalyst substrate is tedious due to the conventional heating and drying processes.

[0006] Therefore, there exist a need for an improved and convenient process for synthesizing the hybrid washcoat with nano and micro sized particles, which increases surface area for the catalysts thereby increasing catalytic conversion.

[0007] Present disclosure provides an improved and convenient process for synthesizing the hybrid washcoat with nano and micro sized particles.

BRIEF DESCRIPTION

[0008] In accordance with an embodiment of the present disclosure, a process for synthesizing a hybrid washcoat is provided. The process includes generating a washcoat slurry by microwave irradiation heating of washcoat with platinum group metal (PGM). The platinum group metal comprises nano sized particles thereby increasing the surface area and consequently increasing catalytic conversion. The process also includes uniformly disposing the washcoat slurry onto a substrate to obtain a washcoated substrate. The process also includes drying the washcoated substrate to form a layer using a microwave drying synthesizing technique. The process further includes coating one or more catalysts onto the washcoated substrate, using the microwave synthesizing technique, to form plurality of layers of the one or more catalysts impregnated onto the washcoated substrate to obtain the hybrid washcoat.

[0009] In accordance with another embodiment of the present disclosure, a catalytic converter system is provided. The catalytic converter system includes a honeycomb-type refractory carrier member, wherein the honeycomb-type refractory carrier member comprises one of a honeycomb-type silicon carbide (SiC) substrate and honeycomb-type Cordierite type substrate. One of the honeycomb-type silicon carbide (SiC) substrate and honeycomb-type Cordierite type substrate includes the honeycomb-type refractory carrier member comprises coating of plurality of layers of one of a diesel oxidation catalyst (DOC) washcoat composition, diesel particulate filter (DPF) washcoat composition, a selective catalytic reduction (SCR) washcoat composition, and an ammonia slip catalyst (ASC) and nano-sized PGM washcoat composition.

[0010] To further clarify the advantages and features of the present invention, a more particular description of the invention will follow by reference to specific embodiments thereof, which are illustrated in the appended figures. It is to be appreciated that these figures depict only typical embodiments of the invention and are therefore not to be considered limiting in scope. The invention will be described and explained with additional specificity and detail with the appended figures.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:

[0011] FIG. 1 represents a flow diagram of process for synthesizing a hybrid washcoat, according to an embodiment of present invention;

[0012] FIG. 2 is schematic representation of uniform disposition of the washcoat slurry onto a substrate using microwave technique, according to an embodiment of present invention;

[0013] FIG. 3 is schematic representation of drying the washcoated substrate using a microwave synthesizing technique, according to an embodiment of present invention;

[0014] FIG. 4 is schematic representation of perspective view of a honeycomb-type refractory carrier member, according to an embodiment of present invention;

[0015] FIG. 5 is schematic representation of horizontal cross-view of downstream side of the honeycomb-type refractory carrier member, according to an embodiment of present invention;

[0016] FIG. 6 is schematic representation of horizontal cross-view of upstream side of the honeycomb-type refractory carrier member, according to an embodiment of present invention;

[0017] FIG. 7 is schematic representation of enlarged partial cross-sectional view of downstream side of the honeycomb-type refractory carrier member, according to an embodiment of present invention;

[0018] FIG. 8 is schematic representation of enlarged partial cross-sectional view of upstream side of the honeycomb-type refractory carrier member, according to an embodiment of present invention;

[0019] FIG. 9 is schematic representation of perspective view of a honeycomb-type silicon carbide (SiC) substrate comprising diesel particulate filter (DPF) washcoat composition, according to an embodiment of present invention;

[0020] FIG. 10 is schematic representation of perspective view of a honeycomb-type cordierite type substrate comprising selective catalytic reduction (SCR) washcoat composition, according to an embodiment of present invention;

[0021] FIG. 11 is schematic representation of perspective view of a honeycomb-type cordierite type substrate comprising varied distribution of ammonia slip catalyst (ASC) washcoat composition and nano-sized platinum group metal (PGM) on surface area of the substrate, according to an embodiment of present invention; and

[0022] FIG. 12 is schematic representation of comparison between traditional way with time-saving microwave synthesis technique provided by the present invention.

[0023] Further, those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the figures with details that will be readily apparent to those skilled in the art having the benefit of the description herein.

DETAILED DESCRIPTION

[0024] For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the disclosure as would normally occur to those skilled in the art are to be construed as being within the scope of the present disclosure.

[0025] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.
[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. The kit and examples provided herein are only illustrative and not intended to be limiting.

[0027] In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.

[0028] Embodiment of the present disclosure relates to a process for synthesizing a hybrid washcoat. The present disclosure provides an improved and convenient process for synthesizing the hybrid washcoat with nano and micro sized particles, which increases surface area for catalysts thereby increasing catalytic conversion. The process enables to reduce duration for one or more catalysts impregnation onto the hybrid washcoat and utilizes lesser platinum group metal as compared to conversional impregnation. The process provides better loading and uniform distribution of the one or more catalysts thereby enhancing performance. A four-way catalytic converter comprising the hybrid washcoat is used for applications in commercial trucks for oxidation of hydrocarbons, carbon monoxide, nitrogen oxide and the like into less or non-environmentally harmful compositions, such as carbon dioxide, water, nitrogen, oxygen and the like.

[0029] FIG. 1 illustrates a flow chart representing steps involved in the process for synthesizing a hybrid washcoat in accordance with an embodiment of the present disclosure. The process mainly comprises, impregnating one or more catalysts on the hybrid washcoat by a microwave synthesizing technique. As used herein the term “washcoat” refers to a carrier for the catalytic materials and is used to disperse the materials over a high surface area. As used herein the term “microwave synthesizing technique” refers to the process which uses a high-frequency wave to heat synthesize or an ion-exchange or reducing the materials to a high temperature in a short time.
[0030] The process for synthesizing a hybrid washcoat begins with heating microwave irradiating a washcoat with platinum group metal (PGM) for generating a washcoat slurry at step 102. The platinum group metal comprises nano sized particles thereby increasing the surface area and consequently increasing catalytic conversion. The platinum group metal comprises range of size of nanoparticles from 10 to 100 nm. In an exemplary embodiment, platinum group metal comprises range of size of nanoparticles 20 to 50 nm.

[0031] In an embodiment, the generated washcoat slurry is uniformly disposed onto a substrate to obtain a washcoated substrate at step 104. The uniform disposition of the washcoat slurry is configured to increase porosity and surface area for the catalytic conversion.

[0032] In an embodiment, the washcoated substrate is dried to form a layer using the microwave synthesizing technique at step 106. Drying the washcoated substrate enables fixing uniform disposition over substrate surface which increases its life and performance by increasing surface area without creating any cracks in washcoat or active catalyst layer.

[0033] In an embodiment, one or more catalysts are coated onto the washcoated substrate, using the microwave synthesizing technique, to form plurality of layers of the one or more catalysts impregnated onto the washcoated substrate to obtain the hybrid washcoat at step 108. The one or more catalysts comprise platinum group metal (PGM) and platinum: palladium (Pt:Pd) metal solution. The PGM replaces the rare earth oxide or refractory oxides which are used in the convention methods. In such embodiment, the plurality of layers of the one or more catalysts comprises a top layer and a bottom layer, wherein the top layer comprises nanosized PGM as upstream catalyst along with Pt:Pd metal solution in a ratio of 1:1 to 2:1, wherein the Pt:Pd metal solution is in a ratio of 3:1, and the bottom layer comprises nanosized and micro sized washcoat along with Pt:Pd metal solution. The coating one or more catalysts onto the washcoated substrate comprises coating the Pt: Pd metal solution as an upstream and downstream catalyst in a ratio of 5:1 and 6:1 in the bottom and the top layer, respectively.

[0034] In such embodiment, light off temperature of the one or more catalysts is less than 200ºC. As used herein the term “light off temperature” refers to the temperature at which catalytic reactions are initiated within a catalytic converter.

[0035] FIG. 2 is a schematic representation of uniform disposition of the washcoat slurry onto a substrate using microwave technique, according to an embodiment of present invention. The uniform disposition of the washcoat slurry is configured to increase porosity and surface area for the catalytic conversion.

[0036] FIG. 3 is a schematic representation of drying the washcoated substrate using a microwave synthesizing technique, according to an embodiment of present invention. Drying the washcoated substrate enables fixing uniform disposition over substrate surface which increases its life and performance by increasing surface area without creating any cracks in washcoat or active catalyst layer.

[0037] FIG. 4 is schematic representation of perspective view of a honeycomb-type refractory carrier member, according to an embodiment of present invention. The honeycomb-type refractory carrier member comprises diesel oxidation catalyst (DOC) washcoat composition with nano-sized PGM and Pt: Pd metal solution.

[0038] FIG. 5 is schematic representation of horizontal cross-view of downstream side of the honeycomb-type refractory carrier member, according to an embodiment of present invention. The horizontal cross-view of downstream side of the honeycomb-type refractory carrier member depicts the plurality of layers of Pt: Pd metal solution and washcoat composition coated onto the substrate.

[0039] FIG. 6 is schematic representation of horizontal cross-view of upstream side of the honeycomb-type refractory carrier member, according to an embodiment of present invention. The horizontal cross-view of upstream side of the honeycomb-type refractory carrier member depicts the plurality of layers of the one or more catalysts coated onto the substrate.

[0040] FIG. 7 is schematic representation of enlarged partial cross-sectional view of downstream side of the honeycomb-type refractory carrier member, according to an embodiment of present invention. The enlarged partial cross-sectional view of downstream side of the honeycomb-type refractory carrier member depicts the plurality of layers of Pt: Pd metal solution and washcoat composition coated onto the substrate.

[0041] FIG. 8 is schematic representation of enlarged partial cross-sectional view of upstream side of the honeycomb-type refractory carrier member, according to an embodiment of present invention. The enlarged partial cross-sectional view of upstream side of the honeycomb-type refractory carrier member depicts the plurality of layers of the one or more catalysts coated onto the substrate.

[0042] FIG. 9 is schematic representation of perspective view of a honeycomb-type silicon carbide (SiC) substrate comprising diesel particulate filter (DPF) washcoat composition, according to an embodiment of present invention. The diesel particulate filter (DPF) washcoat composition is configured to trap particles of soot in the flow of exhaust gases from diesel vehicles and convert them into carbon dioxide.

[0043] FIG. 10 is schematic representation of perspective view of a honeycomb-type cordierite type substrate comprising selective catalytic reduction (SCR) washcoat composition, according to an embodiment of present invention. The selective catalytic reduction (SCR) washcoat composition reduces levels of nitrogen oxide using ammonia as a reductant within a catalyst system.

[0044] FIG. 11 is schematic representation of perspective view of a honeycomb-type cordierite type substrate comprising varied distribution of ammonia slip catalyst (ASC) washcoat composition and nano-sized platinum group metal (PGM) on surface area of the substrate, according to an embodiment of present invention. The ammonia slip catalyst is configured to be coated over 3/4th surface area of the substrate and nano-sized PGM is configured to be coated over 1/4th surface area of the substrate.

[0045] FIG. 12 is schematic representation of comparison between traditional way with time-saving microwave synthesis technique provided by the present invention. The microwave synthesis technique enables to reduce duration for one or more catalysts impregnation onto the hybrid washcoat and utilizes lesser platinum group metal as compared to traditional impregnation which in turns reduces the cost for conversion.

[0046] In another embodiment of the present disclosure, a catalytic converter system is provided. The catalytic converter is an exhaust emission control device that reduces toxic gases and pollutants in exhaust gas from an internal combustion engine into less-toxic pollutants by catalysing a redox reaction (a reduction and an oxidation reaction). Catalytic converters are used with lean-burn engines, kerosene heaters, stoves and internal combustion engines fuelled by either diesel or gasoline.

[0047] The catalytic converter system includes a honeycomb-type refractory carrier member, wherein the honeycomb-type refractory carrier member comprises one of a honeycomb-type silicon carbide (SiC) substrate and honeycomb-type Cordierite type substrate.

[0048] In such embodiment, one of the honeycomb-type silicon carbide (SiC) substrate and honeycomb-type Cordierite type substrate comprises coating of plurality of layers of one of a diesel oxidation catalyst (DOC) washcoat composition, diesel particulate filter (DPF) washcoat composition, a selective catalytic reduction (SCR) washcoat composition, and an ammonia slip catalyst (ASC) and nano-sized PGM washcoat composition. The ammonia slip catalyst is configured to be coated over 3/4th surface area of the substrate and nano-sized PGM is configured to be coated over 1/4th surface area of the substrate.
[0049] The process provides, the catalyst impregnated hybrid washcoat with nano and micro sized particles, which increases surface area for catalysts thereby increasing catalytic conversion. The process enables reduction of duration for one or more catalysts impregnation onto the hybrid washcoat and utilizes lesser platinum group metal as compared to conversional impregnation which in turns reduces the cost for conversion. The process provides better loading and uniform distribution of the one or more catalysts thereby enhancing performance. A four-way catalytic converter comprising the hybrid washcoat is used for applications in commercial trucks for oxidation of hydrocarbons, carbon monoxide, nitrogen oxide and the like into less or non-environmentally harmful compositions, such as carbon dioxide, water, nitrogen, oxygen and the like. The catalytic converter system disclosed by the present invention exhibits improved catalytic conversion of hydrocarbons, carbon monoxide, nitrogen oxide into less environmentally harmful compositions as compared to conventional catalytic converter.

[0050] While specific language has been used to describe the invention, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.

[0051] The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, order of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts need to be necessarily performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples.