NOx Catalyst Production via Potassium Compound Calcination
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Solution Overview
Problem
Conventional NOx storage-reduction catalysts deteriorate at high temperatures, leading to a decrease in NOx purification performance due to the migration of potassium-containing NOx storage material from the catalyst layer to the honeycomb substrate.
Innovation Solution
A method involving the use of potassium compound particles such as oteracil potassium, potassium tetranitroacridone, potassium tetraphenylborate, and potassium tetranitrophenothiazine-9-oxide, which are insoluble in water, are supported on catalyst support particles and calcined to form larger potassium carbonate particles that do not migrate at high temperatures, maintaining NOx storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional NOx storage material (potassium hydrogen tartrate) is used, then high NOx storage performance is achieved, but the material migrates to honeycomb substrate at high temperatures causing deterioration
Solution Approach 1:
The patent changes the chemical composition parameters of the NOx storage material from conventional potassium hydrogen tartrate to specific potassium compounds (potassium tetraphenylborate, potassium tetranitroacridone, potassium tetranitrophenothiazine-9-oxide, or oteracil potassium). These alternative compounds have different thermal stability properties that prevent migration at high temperatures while maintaining NOx storage capability, thus resolving the contradiction between performance and stability.
2Loss of substance
If poorly water-soluble hydrogen tartrate salt is used, then elution is prevented, but migration to low specific surface area particles occurs at high temperatures
Solution Approach 1:
The patent changes the chemical identity of the potassium compound from hydrogen tartrate salt to compounds with specific molecular structures (tetraphenylborate, tetranitroacridone, tetranitrophenothiazine-9-oxide, or oteracil). These structural modifications provide both water insolubility (preventing elution) and thermal stability (preventing migration), simultaneously addressing both loss and distribution stability issues.
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 approach inhibits the migration of NOx storage material to the honeycomb substrate, thereby maintaining NOx purification performance even after exposure to high temperatures, as the potassium carbonate remains in the catalyst layer.
Implementation Method 1
supporting potassium compound particles on catalyst support particles by using a potassium dispersed water containing the potassium compound particles
Implementation Method 2
calcining the catalyst support particles supporting the potassium compound particles
Data Source
AI summary
An object of the present disclosure is to provide a method for producing a NOx storage-reduction catalyst capable of inhibiting decreases in NOx purification performance following exposure to high temperatures. The present disclosure achieves the aforementioned object with a method for producing a NOx storage-reduction catalyst, comprising: (A) supporting potassium compound particles on catalyst support particles by using an potassium dispersed water containing the potassium compound particles, and (B) calcining the catalyst support particles supporting the potassium compound particles; wherein, the potassium compound particles are at least one type selected from the group consisting of oteracil potassium, potassium tetranitroacridone, potassium tetraphenylborate, and potassium tetranitrophenothiazine-9-oxide.