Catalyst Sealant Layer for Uniform Washcoat Application
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Solution Overview
Problem
Existing catalysts for exhaust gas treatment, particularly in the automotive sector, face issues with mechanical properties and catalytic activity due to unwanted penetration of washcoat coatings into support body micro-cracks and ion migration between catalytic active materials, leading to non-uniform coatings and reduced catalytic performance over time.
Innovation Solution
A catalyst with a porous ceramic support body and a catalytically active washcoat coating, where a permanent, catalytically inactive inorganic impregnation is applied to reduce surface porosity or form an intermediate layer between the support body and the washcoat, preventing water penetration and ion migration, thus maintaining homogeneous coating and long-term catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a washcoat coating is applied to a porous support body, then catalytic activity is improved, but water penetrates into the support body causing non-uniform coating and reduced mechanical properties
Solution Approach 1:
A sealant composition is applied to the porous support body to form a sealant layer that acts as an intermediary barrier. This sealant layer prevents water from the washcoat coating from penetrating into the porous support body, while still allowing the washcoat to be applied uniformly and maintain catalytic activity. The sealant layer mediates between the porous support structure and the washcoat coating.
Solution Approach 2:
The sealant composition is applied to the porous support body before the washcoat coating is applied. This preliminary action seals the pores and prevents water penetration in advance, ensuring that when the washcoat is subsequently applied, it forms a uniform coating without compromising the mechanical properties or catalytic activity of the final catalyst.
2Reliability
If a washcoat coating is applied to a porous support body, then catalytic activity is improved, but ion migration between catalytic active materials occurs reducing long-term performance
Solution Approach 1:
The sealant layer serves as a protective intermediary between the porous support body and the washcoat coating. It prevents direct contact and interaction between the support body and catalytic active materials, thereby preventing ion migration that would otherwise occur at the interface. This maintains long-term catalytic performance while preserving catalytic activity.
3Manufacturing precision
If the support body porosity is reduced to prevent water penetration, then coating uniformity is improved, but catalytic activity may be reduced
Solution Approach 1:
The support body structure is segmented into two distinct functional zones: the porous support body that provides mechanical strength and structural support, and the sealant layer that provides water barrier functionality. This segmentation allows each layer to perform its specific function optimally - the porous support maintains catalytic activity while the sealant layer ensures coating uniformity by preventing water penetration.
Solution Approach 2:
The sealant layer is applied locally to the surface of the porous support body, creating a localized water barrier only where needed for coating application. The bulk porous structure of the support body remains unchanged, preserving its catalytic activity while the surface sealant layer ensures uniform washcoat application.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution ensures a catalyst with improved mechanical properties and sustained catalytic activity, preventing water infiltration and ion migration, resulting in a uniform washcoat coating and high ammonia conversion rates, thereby maintaining catalytic performance over time.
Implementation Method 1
the porosity of the support body is reduced at least in the region of the surface
Implementation Method 2
A basic distinction is made here between so-called all-active extrudates and coated supports, called 'washcoats'. In the washcoats, a catalytically inert extruded support body is coated with the actual catalytically active catalyst material. This is effected, for example, by dipping the extruded support body into a suspension containing the catalyst material.
Implementation Method 3
The catalyst is in this case particularly designed for exhaust gas treatment, specifically in the automotive field and particularly for nitrogen oxide reduction by the so-called SCR process (selective catalytic reduction)
Implementation Method 4
for oxidizing carbon monoxide to carbon dioxide
Implementation Method 5
for oxidizing unburned hydrocarbons to water (steam) and carbon monoxide
Implementation Method 6
for the cyclic adsorption of nitrogen oxides (NOx) from exhaust gas from a lean burn engine, followed by desorption and reduction of NOx
Data Source
AI summary
A catalyst with a porous, ceramic support body having a porosity which is formed by pores in at least a part of the ceramic support body, and which furthermore has a catalytically active washcoat coating applied to the ceramic support body, which catalytically active washcoat coating having a layer thickness, comprises a permanent catalytically inactive impregnation comprising at least one catalytically inactive inorganic component, and wherein the permanent inactive impregnation has a layer thickness and is present at least partially between a surface of the porous ceramic support body and the catalytically active washcoat coating is present in the pores of the ceramic support body in a region with reduced porosity underneath the surface of the ceramic support body.