Three-Way Catalyst with Ruthenium for Low Ammonia Emissions
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Solution Overview
Problem
Three-way catalysts (TWC) in vehicles with equivalence ratio combustion exhibit high ammonia (NH3) emissions, exceeding regulatory standards, which is exacerbated by the addition of ammonia oxidation catalysts (AOC) that increase calibration difficulty and costs.
Innovation Solution
Incorporating ruthenium (Ru) or ruthenium oxide into the three-way catalysts to enhance nitrogen (N2) selectivity and reduce NH3 formation, using a coating material with precious metals like platinum (Pt), palladium (Pd), and rhodium (Rh) on a carrier such as cordierite ceramic, thereby reducing the volume and cost of the catalytic converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If ammonia oxidation catalyst (AOC) is added to purify NH3, then NH3 emission is reduced below 10 ppm, but the calibration difficulty of engine after-treatment system increases, the volume of exhaust purification catalytic converter increases and the cost increases
Solution Approach 1:
The patent combines the NH3 purification function into the TWC itself by adding AOC components (Pt, Pd, Rh) to form a composite catalyst. This integration eliminates the need for separate AOC devices, reducing system complexity and calibration difficulty while maintaining effective NH3 emission control below 10 ppm.
Solution Approach 2:
The modified TWC performs multiple functions simultaneously: it purifies CO, HC, and NOx as a traditional TWC, while also purifying NH3 through the incorporated AOC components. This multi-functionality eliminates the need for separate dedicated NH3 purification devices, reducing overall system volume and complexity.
2Object-generated harmful factors
If ammonia oxidation catalyst (AOC) is added to purify NH3, then NH3 emission is reduced below 10 ppm, but the volume of exhaust purification catalytic converter increases
Solution Approach 1:
The patent merges the AOC functionality into the existing TWC structure, creating a single integrated catalytic converter that handles both TWC and AOC functions. This eliminates the need for separate catalytic converters for each function, thereby reducing the overall volume of the exhaust purification system.
Solution Approach 2:
The composite catalyst performs multiple purification functions (CO, HC, NOx, and NH3) within a single catalytic converter unit. This multi-functional design consolidates what would otherwise require multiple separate devices, reducing the total volume occupied by the exhaust purification system.
3Object-generated harmful factors
If ammonia oxidation catalyst (AOC) is added to purify NH3, then NH3 emission is reduced below 10 ppm, but the cost increases
Solution Approach 1:
The patent combines TWC and AOC into a single composite catalyst, eliminating the need to manufacture and install separate catalyst devices. This integration reduces overall manufacturing costs, installation costs, and maintenance costs compared to using separate TWC and AOC systems.
Solution Approach 2:
The composite catalyst provides multiple purification functions in a single device, replacing what would otherwise require multiple separate catalysts. This reduces the total material costs, manufacturing complexity, and system integration costs associated with deploying multiple separate purification devices.
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 approach significantly decreases NH3 emissions below regulatory limits, improves N2 selectivity, and simplifies the production process, avoiding the need for additional catalysts like AOC, while maintaining high purification efficiency for CO, HC, and NOx.
Implementation Method 1
Incorporating ruthenium (Ru) or ruthenium oxide into the three-way catalysts to enhance nitrogen (N2) selectivity and reduce NH3 formation
Implementation Method 2
The purpose of installing vehicles exhaust purification catalyst is to convert three main pollutants, such as CO, HC and NOx, into harmless substances such as CO2, N2 and H2O
Data Source
AI summary
A three-way catalyst having low NH3 formation is disclosed. The catalyst includes a carrier and a coating material. The coating material includes a precious metal active component and a catalytic material. The precious metal active component includes a first precious metal active component and a second precious metal active component. The first precious metal active component is a composition containing Ru. The second precious metal active component is a composition containing Pt, Pd and Rh. Alternatively, the second precious metal active component is a composition containing Pd and Rh.