Cerium Composite Oxide Catalyst for Low-Temperature NOx Adsorption
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Solution Overview
Problem
Conventional exhaust gas purification catalysts fail to achieve sufficient NOx purification performance at low temperatures, limiting their effectiveness in diesel engine exhaust gas treatment.
Innovation Solution
A diesel exhaust gas purification catalyst is developed, comprising a substrate with a catalyst layer containing a composite oxide of cerium and one or more Group III and/or Group IV elements, which is positioned upstream of a denitration catalyst to enhance NOx adsorption at low temperatures and release at higher temperatures, improving overall NOx purification performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional exhaust gas purification catalysts are used, then the catalyst structure is simple and easy to manufacture, but the NOx purification performance is insufficient at low temperatures
Solution Approach 1:
The catalyst is divided into multiple functional layers: a first catalyst layer containing a composite oxide of cerium and Group III/IV elements for low-temperature NOx adsorption, and a second catalyst layer for high-temperature denitration. This segmentation allows each layer to specialize in specific temperature ranges and functions, resolving the contradiction between performance and complexity by organizing complexity into functional modules.
Solution Approach 2:
The patent uses a composite oxide material combining cerium with Group III and/or Group IV elements as the active component in the first catalyst layer. This composite material provides enhanced low-temperature NOx adsorption capability compared to conventional single-oxide catalysts, directly addressing the performance deficiency while maintaining a relatively simple overall structure.
2Adaptability or versatility
If a single catalyst is used for both low-temperature and high-temperature NOx purification, then the device complexity is low, but the purification performance across broad temperature ranges is insufficient
Solution Approach 1:
The catalyst system is segmented into two distinct layers with different functions: the first layer handles low-temperature NOx adsorption, while the second layer handles high-temperature denitration. This functional segmentation enables the system to adapt to broad temperature ranges by having specialized components for each temperature regime.
Solution Approach 2:
The first catalyst layer performs preliminary NOx adsorption at low temperatures before the exhaust gas reaches the second catalyst layer. This preliminary action prepares the exhaust gas for subsequent high-temperature denitration, enabling effective purification across the entire temperature spectrum through staged processing.
3Reliability
If conventional catalysts are used, then the manufacturing cost is low, but the exhaust gas purification effectiveness is insufficient
Solution Approach 1:
The use of composite oxide materials (cerium combined with Group III and/or Group IV elements) provides superior purification effectiveness compared to conventional catalysts. While the material composition is more complex, the manufacturing process remains relatively straightforward by applying coating methods to form the two-layer catalyst structure on a substrate.
Solution Approach 2:
The catalyst is manufactured as a two-layer structured component with distinct functional zones. This segmentation allows for optimized material placement where complex composite oxides are used only where needed (first layer for low-temperature adsorption), while the second layer can use more conventional materials, balancing manufacturing complexity with performance requirements.
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 catalyst system achieves improved NOx purification performance across a broader temperature range by adsorbing NOx at low temperatures and releasing it at higher temperatures, thereby enhancing the denitration catalyst's efficiency.
Implementation Method 1
a catalyst layer formed on the substrate, the catalyst layer comprising a carrier, a noble metal and/or an oxide thereof supported by the carrier, and a composite oxide of cerium and one or more Group III and/or Group IV elements
Implementation Method 2
The catalyst when in use is disposed on an upstream side of an exhaust gas stream with respect to a denitration catalyst
Data Source
AI summary
A diesel exhaust gas purification catalyst contains a substrate, and a catalyst layer formed on the substrate. The catalyst layer contains a carrier, a noble metal and/or an oxide thereof supported by the carrier, and a composite oxide of cerium and one or more Group III and/or Group IV elements. The diesel exhaust gas purification catalyst when in use is disposed on an upstream side of an exhaust gas stream with respect to a denitration catalyst.