Integrated SCR Catalyst Particle Filter for Exhaust Emission Reduction
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Solution Overview
Problem
Existing exhaust gas post treatment systems for internal combustion engines face challenges in simultaneously reducing nitrogen oxide and particle emissions, with issues such as difficulty in quantitative metering of reduction agents, damage to SCR catalysts due to high temperatures, and costly regeneration cycles for particle filters, which lead to increased emissions and system complexity.
Innovation Solution
An exhaust gas post treatment system that combines a particle filter with an SCR catalyst, where the particle filter is charged with SCR-active catalyst material on its outlet side and supplied with ammonia upstream, and an oxidation catalytic converter is used to convert nitric oxide to nitrogen dioxide for continuous particle oxidation, minimizing system size and avoiding damage to the SCR catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a particle filter is used to reduce very fine particles, then particle emissions are reduced, but the filter becomes clogged requiring expensive and complicated regeneration cycles
Solution Approach 1:
The patent combines the particle filter with an SCR catalyst into a single integrated component. The filter structure includes channels for particle separation and catalytic walls with SCR catalyst for nitrogen oxide reduction. This merging eliminates the need for separate regeneration systems, as the SCR catalyst continuously converts nitrogen oxides to nitrogen and water vapor, preventing filter clogging without expensive cyclic regeneration.
Solution Approach 2:
The SCR catalyst enables continuous conversion of nitrogen oxides to harmless substances throughout operation. Instead of periodic regeneration cycles, the system maintains continuous beneficial action by constantly reducing nitrogen oxides in the exhaust gas, preventing accumulation that would require costly cyclic maintenance.
2Productivity
If V2O5 is used as active material for SCR catalyst, then nitrogen oxide conversion is improved, but the catalyst is damaged when exhaust gas temperature exceeds 650°C due to sublimation
Solution Approach 1:
The patent uses composite catalytic materials combining V2O5 with WO3 and TiO2 in a mixed oxide structure. This composite formulation enhances the thermal stability of V2O5, preventing sublimation at temperatures above 650°C while maintaining high nitrogen oxide conversion efficiency. The composite material integrates the benefits of each component for improved performance and durability.
3Object-generated harmful factors
If oxidation catalytic converter is disposed upstream of particle filter to convert NO to NO2, then continuous particle oxidation is enabled, but the system size and complexity increase
Solution Approach 1:
The oxidation catalytic converter functionality is integrated into the catalytic walls of the particle filter itself. The catalytic walls contain both oxidation catalyst and SCR catalyst, eliminating the need for a separate upstream oxidation converter. This merging maintains continuous particle oxidation capability while significantly reducing system size and structural complexity.
Solution Approach 2:
The catalytic walls of the particle filter perform multiple functions: they oxidize particles accumulated in the filter channels and simultaneously reduce nitrogen oxides via SCR catalyst. This multi-functionality eliminates the need for separate dedicated oxidation and reduction components, simplifying the overall system architecture.
4Productivity
If ammonia or ammonia-releasing reduction agent is supplied downstream of particle filter for SCR process, then nitrogen oxide reduction is achieved, but the system requires larger overall size and more complex arrangement
Solution Approach 1:
The SCR catalyst is integrated into the particle filter structure, with catalytic walls containing the SCR catalyst positioned within the filter body. Ammonia or ammonia-releasing reduction agent is supplied directly to this integrated SCR catalyst through injection devices positioned upstream of the filter. This merging eliminates the need for separate downstream SCR catalyst components, reducing system size and arrangement complexity while maintaining effective nitrogen oxide reduction.
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 system effectively reduces nitrogen oxide and particle emissions while maintaining a compact design, preventing damage to SCR catalysts and eliminating the need for expensive regeneration cycles, thus meeting future emissions regulations with reduced harmful byproducts.
Implementation Method 1
The nitrogen oxide reduction is effected via an SCR catalyst... NO+2NH3+NO2→2N2+3H2O
Implementation Method 2
an oxidation catalytic converter is used to convert nitric oxide to nitrogen dioxide... 2NO+O2→2NO2
Implementation Method 3
the particle filter is disposed in the exhaust gas stream of the internal combustion engine... a surface-type particle filter or a deep bed filter
Implementation Method 4
the supply of ammonia or an ammonia-releasing reduction agent is effected upstream of the particle filter... To convert one mol nitric oxide one mol ammonia is required
Data Source
AI summary
An exhaust gas post treatment system for nitrogen oxide and particle reduction of internal combustion engines operated with excess air, comprising a particle filter disposed in the exhaust gas stream of the internal combustion engine. The particle filter is a surface-type particle filter or a deep bed filter, and is charged on an outlet side with an SCR-active catalyst material for reducing nitrogen oxides. Ammonia or an ammonia-releasing reduction agent is supplied to the exhaust gas stream upstream of the particle filter.