Layered Ammonia Oxidation Catalyst for Low Slip and NOx Purification
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Solution Overview
Problem
Existing ammonia oxidation catalyst devices struggle to achieve a balance between ammonia slip performance and NOx purification performance, with either low adsorption capacity leading to decreased NOx purification efficiency or excessive adsorption resulting in ammonia slip.
Innovation Solution
The ammonia oxidation catalyst device comprises a substrate with a first catalyst coating layer containing inorganic oxide particles and a catalyst precious metal, and a second catalyst coating layer with a NOx selective reduction catalyst and proton zeolite, arranged in a specific positional relationship to optimize ammonia adsorption and NOx purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the adsorbent material has a low ability to adsorb ammonia, then the ammonia slip discharged as-is increases, but the efficiency of NOx purification by reaction with ammonia decreases
Solution Approach 1:
The catalyst device is divided into two distinct catalyst coating layers: a first layer containing inorganic oxide particles and a catalyst precious metal for ammonia oxidation, and a second layer containing a NOx selective reduction catalyst and a proton zeolite for ammonia adsorption and NOx purification. This segmentation allows each layer to perform its specific function optimally, resolving the contradiction between ammonia slip control and NOx purification efficiency.
Solution Approach 2:
The invention uses composite material structures in both layers: the first layer combines inorganic oxide particles with catalyst precious metal, and the second layer combines NOx selective reduction catalyst with proton zeolite. These composite materials provide synergistic effects that simultaneously achieve ammonia oxidation and controlled adsorption, balancing ammonia slip performance with NOx purification efficiency.
2Productivity
If the amount of ammonia adsorbed by the adsorbent material is excessively large, then the ammonia slip concentration increases during acceleration, but the NOx purification efficiency improves
Solution Approach 1:
The proton zeolite in the second catalyst coating layer provides dynamic ammonia adsorption and desorption capabilities. During normal operation, it adsorbs ammonia to maintain high NOx purification efficiency. During acceleration when ammonia slip occurs, the zeolite releases stored ammonia to continue the purification reaction. This dynamic behavior allows the system to adapt to varying operating conditions and maintain balance between ammonia slip control and NOx purification efficiency.
3Device complexity
If a single catalyst layer is used, then the device structure is simple, but the balance between ammonia slip performance and NOx purification performance cannot be achieved
Solution Approach 1:
The catalyst device is divided into two distinct catalyst coating layers: a first layer containing inorganic oxide particles and a catalyst precious metal for ammonia oxidation, and a second layer containing a NOx selective reduction catalyst and a proton zeolite for ammonia adsorption and NOx purification. This segmentation allows each layer to perform its specific function optimally, resolving the contradiction between ammonia slip control and NOx purification efficiency.
Solution Approach 2:
The second catalyst coating layer performs multiple functions: the proton zeolite adsorbs ammonia while the NOx selective reduction catalyst purifies NOx. This multi-functionality in the second layer, combined with the ammonia oxidation function of the first layer, achieves both ammonia slip performance and NOx purification performance within a unified two-layer structure.
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 device achieves a high NOx purification rate with minimal ammonia slip by utilizing proton zeolites for controlled ammonia adsorption and a first catalyst layer for ammonia oxidation, resulting in improved overall performance.
Implementation Method 1
the second catalyst coating layer contains a NOx selective reduction catalyst and a proton zeolite
Implementation Method 2
the first catalyst coating layer contains inorganic oxide particles and a catalyst precious metal carried on the inorganic oxide particles
Implementation Method 3
Ammonia oxidation catalyst devices have a function of oxidizing and removing ammonia discharged from SCR devices
Implementation Method 4
the second catalyst coating layer contains a NOx selective reduction catalyst
Implementation Method 5
selective catalytic reduction (SCR) is a technology in which NOx purification is carried out by supplying ammonia or an ammonia precursor such as urea to exhaust gas to catalytically react NOx (conventionally, NO+NO2) with ammonia (NH3) to convert it into nitrogen (N2) and water (H2O)
Data Source
AI summary
An ammonia oxidation catalyst device, including a substrate, a first catalyst coat layer and a second catalyst coat layer, wherein: the first catalyst coat layer includes inorganic oxide particles and a catalytic noble metal supported on the inorganic oxide particles; the second catalyst coat layer includes an NOx selective reduction catalyst and a proton zeolite H-Zeolite; the first catalyst coat layer is present on the substrate; and the second catalyst coat layer is present on the first catalyst coat layer.