Catalyst Article Coating with Copper Carbonate for Lower-Energy SCR
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Solution Overview
Problem
Existing methods for preparing metal-loaded molecular sieves for catalytic converters are complex, energy-intensive, and can produce hazardous by-products, while also risking poisoning of downstream ammonia slip catalysts.
Innovation Solution
A method involving the use of copper (II) carbonate as an insoluble active metal precursor, combined with a crystalline molecular sieve in H+ or NH4+ form, is used to form a slurry at ambient temperatures, which is directly applied to a substrate and calcined to create a catalyst layer, avoiding high-temperature heating and additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet ion-exchange or impregnation methods are used to prepare metal-loaded molecular sieves, then metal loading can be achieved, but the process becomes complex, energy-intensive, and produces hazardous by-products
Solution Approach 1:
The invention changes the key parameter from using soluble metal salts requiring aqueous processing to using insoluble metal carbonates that can be directly mixed in slurry form. This parameter change eliminates the need for wet ion-exchange or impregnation steps, reducing process complexity while maintaining metal loading effectiveness through direct incorporation during washcoat application
Solution Approach 2:
The invention extracts and removes the hazardous and complex wet ion-exchange/impregnation steps from the process entirely. By using insoluble metal carbonates that can be directly incorporated into the washcoat slurry, the method eliminates the need for aqueous metal salt solutions, heating steps, and extensive post-processing, thereby simplifying the overall process while maintaining catalytic functionality
2Reliability
If wet ion-exchange or impregnation methods are used, then metal loading can be achieved, but high energy consumption is required for heating and additional processing steps
Solution Approach 1:
The invention changes the physical state parameter of the metal precursor from soluble salts requiring dissolution and heating to insoluble carbonates that can be directly incorporated in dry or slurry form. This eliminates the need for energy-intensive heating steps during metal loading, reducing overall energy consumption while maintaining effective metal incorporation into the molecular sieve structure
Solution Approach 2:
The invention performs preliminary incorporation of the metal carbonate directly into the washcoat slurry before application to the substrate. This preliminary action eliminates the need for subsequent heating and processing steps that would be required for wet ion-exchange or impregnation methods, thereby reducing energy consumption while ensuring proper metal distribution and loading
3Reliability
If metal acetates are used as active metal precursor, then metal loading can be achieved, but hazardous species are generated during calcination
Solution Approach 1:
The invention changes the chemical composition parameter of the metal precursor from metal acetates to metal carbonates. This chemical parameter change is critical because carbonates decompose to metal oxides and carbon dioxide during calcination, eliminating the generation of hazardous acetate by-products while maintaining effective metal loading and catalytic activity
Solution Approach 2:
The invention converts potentially harmful soluble metal salts into insoluble metal carbonates that are safer to handle and process. The carbonate form eliminates hazardous emissions during calcination while the decomposition process itself provides beneficial metal oxide formation in situ, transforming a potential harm into a benefit
4Reliability
If metal-loaded molecular sieves are prepared for SCR catalysts, then catalytic activity can be achieved, but poisoning of downstream ammonia slip catalysts may occur
Solution Approach 1:
The invention changes the metal precursor parameter from soluble salts to insoluble carbonates, which fundamentally alters the release profile and distribution of metal species during calcination. This parameter change prevents excessive metal release that could poison downstream catalysts, while maintaining sufficient metal loading for effective SCR activity through controlled in situ formation of metal oxides
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
This method results in catalysts with comparable SCR activity, reduced energy consumption, and minimizes the generation of hazardous species, while mitigating poisoning effects on ammonia slip catalysts.
Implementation Method 1
a crystalline molecular sieve in H+ or NH4+ form... which is directly applied to a substrate and calcined to create a catalyst layer
Implementation Method 2
which is directly applied to a substrate and calcined to create a catalyst layer
Implementation Method 3
the coated substrate is calcined to form a catalyst layer on the substrate
Data Source
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AI summary
The present disclosure relates to a method for forming a catalyst article comprising: (a) forming a slurry having a solids content of up to 50 wt% by mixing together at least the following components a crystalline molecular sieve in an H+ or NH4+ form, an insoluble active metal precursor and an aqueous solvent at a temperature in the range 10 to 35°C; (b) coating a substrate with the slurry formed in step (a); and (c) calcining the coated substrate formed in step (b) to form a catalyst layer on the substrate. The present disclosure further relates to a catalyst article, particularly a catalyst article which is suitable for use in the selective catalytic reduction of nitrogen oxides, and to an exhaust system.