Emission Control System with Low Precious Metal Loading Oxidation Catalyst
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Solution Overview
Problem
Existing emission control systems in vehicles, particularly those involving selective catalytic reduction (SCR) and diesel oxidation catalysts, generate excessive nitrous oxide (N2O) due to the positioning and interaction of these components, as well as the material composition of the diesel oxidation catalyst (DOC).
Innovation Solution
An emission control system is designed with an oxidation catalyst having a precious metal loading of less than 100 g/ft3 and a SCR catalyst positioned downstream, operated between 150° C. and 300° C., which reduces the formation of N2O through the reaction 2NH3+2NO2→N2O+N2+3H2O, minimizing nitrogen oxide emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the DOC is positioned downstream of the SCR catalyst with high precious metal loading, then the oxidation catalyst can effectively oxidize CO and hydrocarbons, but this configuration generates excessive nitrous oxide emissions due to the interaction between the two components
Solution Approach 1:
The patent inverts the conventional arrangement by positioning the SCR catalyst upstream of the DOC, rather than downstream. This reversal changes the interaction dynamics between the two catalysts, preventing the formation of excessive N2O while maintaining the oxidation function of the DOC for CO and hydrocarbon removal.
Solution Approach 2:
The patent specifies a precise temperature range (150-300°C) for operating the SCR catalyst to optimize its performance while minimizing N2O formation. This parameter control ensures that the SCR reactions proceed efficiently without generating harmful byproducts, resolving the contradiction between emissions reduction and harmful emissions generation.
2Object-generated harmful factors
If the oxidation catalyst has high precious metal loading, then it can effectively perform oxidation reactions, but it contributes to increased generation of nitrogen compounds such as N2O
Solution Approach 1:
The patent specifies a precise temperature range (150-300°C) for operating the SCR catalyst to optimize its performance while minimizing N2O formation. This parameter control ensures that the SCR reactions proceed efficiently without generating harmful byproducts, resolving the contradiction between emissions reduction and harmful emissions generation.
3Productivity
If the SCR catalyst operates outside the specified temperature range, then the system may achieve higher conversion rates, but this increases nitrous oxide formation in the SCR catalyst
Solution Approach 1:
The patent specifies a precise temperature range (150-300°C) for operating the SCR catalyst to optimize its performance while minimizing N2O formation. This parameter control ensures that the SCR reactions proceed efficiently without generating harmful byproducts, resolving the contradiction between emissions reduction and harmful emissions generation.
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 configuration significantly reduces nitrous oxide emissions from the vehicle, thereby minimizing the vehicle's environmental impact by reducing the formation of N2O in the SCR catalyst, with optimal results achieved when the SCR catalyst is maintained within the specified temperature range and the oxidation catalyst has limited precious metal loading.
Implementation Method 1
an oxidation catalyst having a precious metal loading of less than 100 grams (g)/cubic foot (ft3) and a selective catalytic reduction (SCR) component positioned downstream of the oxidation catalyst
Implementation Method 2
the following reaction may take place in the SCR catalyst. 2NH3+2NO2→N2O+N2+3H2O
Implementation Method 3
2NH3+2NO2→N2O+N2+3H2O
Implementation Method 4
diesel oxidation catalysts
Data Source
AI summary
An emission control system is provided. The emission control system includes an oxidation catalyst having a precious metal loading of less than 100 grams (g)/cubic foot (ft3) and a selective catalytic reduction (SCR) component positioned downstream of the oxidation catalyst operated between 150° C. and 300° C. during engine operation to reduce the formation of N2O in the selective-catalytic reduction component.