NOx Trap Catalyst Support Material Stability Against BaAl2O4 Formation
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Solution Overview
Problem
Current NOx-trap catalysts using cerium oxide doped Mg/Al mixed oxide support materials degrade due to the formation of BaAl2O4 when combined with barium compounds, leading to reduced nitrogen oxide storage efficiency during thermal aging.
Innovation Solution
A method involving the sequential addition of manganese oxide to the cerium oxide doped Mg/Al mixed oxide, followed by calcination, to form a support material that prevents the formation of BaAl2O4, maintaining the catalyst's efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cerium oxide doped homogenous Mg/Al mixed oxide is used as support material, then the nitrogen oxide storage efficiency and thermal stability are improved, but the formation of inactive BaAl2O4 occurs during thermal aging, reducing long-term durability
Solution Approach 1:
Manganese oxide is introduced as an intermediary substance that mediates between the barium storage component and the Mg/Al mixed oxide support. It preferentially reacts with barium to form BaMnO3, preventing the direct reaction between barium and aluminum oxide that would form inactive BaAl2O4. This intermediary approach preserves both the high nitrogen oxide storage efficiency of cerium oxide doping and the long-term durability by blocking the harmful reaction pathway.
Solution Approach 2:
The chemical composition parameter of the support material is changed by adding manganese oxide to the cerium oxide doped Mg/Al mixed oxide system. This compositional modification alters the reaction chemistry during thermal aging, shifting the product from inactive BaAl2O4 to active BaMnO3, thereby maintaining catalytic functionality over time while preserving the beneficial properties of cerium oxide doping.
2Temperature
If the support material reacts with barium compound to form BaAl2O4, then the thermal aging process proceeds, but the nitrogen oxide storage efficiency deteriorates due to loss of active storage material
Solution Approach 1:
The harmful reaction between barium and aluminum oxide that forms inactive BaAl2O4 is converted into a beneficial reaction by introducing manganese oxide. The barium preferentially reacts with manganese oxide to form BaMnO3, which is an active nitrogen oxide storage material. This converts the originally harmful reaction pathway into a beneficial one, maintaining storage efficiency while achieving thermal aging resistance.
Solution Approach 2:
Manganese oxide acts as an intermediary that intercepts barium during thermal aging, preventing the formation of inactive BaAl2O4. By introducing this intermediate substance, the reaction pathway is redirected to form BaMnO3, which maintains nitrogen oxide storage functionality even after thermal aging, thus resolving the contradiction between thermal stability and storage efficiency.
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 support material remains stable against BaAl2O4 formation even after thermal aging, ensuring high NOx trap efficiency and durability by converting barium into non-detrimental BaMnO3, which interacts positively with nitrogen oxides.
Implementation Method 1
converting barium into non-detrimental BaMnO3, which interacts positively with nitrogen oxides
Implementation Method 2
a material that is able to store NOx, e.g. as a nitrate under lean conditions
Data Source
AI summary
The present invention relates to a method for the production of a support material for a nitrogen oxide storage component that is applicable in catalysts for treating exhaust gases from lean-burn engines and a support material made according to said process that is stable against the reaction with a Barium compound to form BaAl2O4.