Integrated NOx Storage Catalyst and Diesel Particulate Filter
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Solution Overview
Problem
Existing diesel exhaust gas treatment systems require multiple nitrogen oxide storage catalysts, which are space and economically inefficient, and lack optimal integration of catalysts and filters to meet stringent emission standards like Euro 6.
Innovation Solution
A catalyst system comprising a nitrogen oxide storage catalyst with a higher noble metal loading and a diesel particulate filter, both containing catalytically active noble metals like platinum and palladium, optimally distributed to effectively remove CO, NOx, and particulates, with the nitrogen oxide storage catalyst handling NOx and CO conversion and the particulate filter focusing on HC and particulate filtration and regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple nitrogen oxide storage catalysts are used to meet stringent emission standards, then NOx conversion performance is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent combines the nitrogen oxide storage catalyst and diesel particulate filter into a single integrated component with alternating flow channels. The filter walls are coated with a catalytic layer containing nitrogen oxide storage material and noble metals, enabling both NOx storage/reduction and particulate filtration functions in one device, thereby reducing the number of separate catalyst components while meeting stringent emission standards
Solution Approach 2:
The integrated catalyst-filter component performs multiple functions simultaneously: particulate filtration through the wall flow structure, NOx storage on basic compounds during lean operation, NOx reduction during rich regeneration, and CO/HC oxidation on noble metal sites. This multi-functionality eliminates the need for separate nitrogen oxide storage catalysts while maintaining high conversion performance
2Reliability
If multiple nitrogen oxide storage catalysts are used to ensure effective NOx removal, then emission standards are met, but space requirements and manufacturing costs increase
Solution Approach 1:
The patent merges the nitrogen oxide storage catalyst and diesel particulate filter into one integrated component, eliminating the need for separate catalyst housings and mounting spaces. The alternating flow channel design with catalytic-coated walls maximizes the use of available volume for active filtration and catalysis functions
Solution Approach 2:
The catalytic layer containing nitrogen oxide storage material and noble metals is nested within the filter walls themselves. The storage material and catalysts are deposited on the internal surface of the filter walls, effectively nesting the catalyst function within the structural framework of the filter, thereby minimizing overall system volume
3Reliability
If multiple nitrogen oxide storage catalysts are used to achieve high NOx conversion, then treatment effectiveness is improved, but manufacturing costs increase
Solution Approach 1:
The patent combines nitrogen oxide storage catalyst and diesel particulate filter into a single integrated component, eliminating the need for separate catalyst assemblies and their associated mounting hardware. This integration reduces manufacturing steps, assembly operations, and overall system cost while maintaining high NOx conversion efficiency through the coordinated action of storage material and noble metals in the catalytic layer
Solution Approach 2:
The integrated component performs multiple emission control functions (particulate filtration, NOx storage, NOx reduction, CO and HC oxidation) in a single device, eliminating the need for multiple separate catalyst components. This multi-functionality reduces the total amount of expensive noble metals required and simplifies manufacturing while achieving high conversion efficiency for all pollutants
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 CO and NOx emissions while efficiently managing particulate filtration and regeneration, meeting Euro 6 standards without the need for additional space or economic burdens, demonstrating superior performance in engine tests.
Implementation Method 1
storage of the nitrogen oxides by the storage material of the storage catalyst, predominantly in the form of nitrates
Implementation Method 2
They are deposited on suitable support materials in very high dispersion to create a large interaction area with the exhaust gas
Implementation Method 3
the filter can be coated with a catalyst layer capable of lowering the soot ignition temperature
Implementation Method 4
oxidation of the filtered soot particles... burning off the soot... with oxygen
Implementation Method 5
oxidizing NO to NO2, and CO and HC to CO2 under lean conditions
Implementation Method 6
carbon monoxide (CO), gaseous hydrocarbons (HCs) and any organic agglomerates adhering to the soot particles... can be removed oxidatvely with the aid of oxidation catalysts
Implementation Method 7
The particulate-containing exhaust gas flowing into the inflow channels is forced by a gas-tight closure plug present on the exit side to pass through the porous wall, and exits from the wall flow filter substrate again from the outflow channels
Implementation Method 8
honeycombs having alternate inflow and outflow channels which are sealed gas-tight, bounded by porous walls
Data Source
AI summary
The present invention relates to a catalyst system for treatment of diesel exhaust gas, comprising, in flow direction of the exhaust gas,a nitrogen oxide storage catalyst containing a nitrogen oxide storage component and noble metal anda diesel particulate filter containing noble metal selected from the group of platinum, palladium, and platinum and palladium,characterized in that the noble metal loading of the nitrogen oxide storage catalyst is 100 to 180 g/ft3 (3.53 to 6.36 g/L) and the noble metal loading of the diesel particulate filter is 5 to 35 g/ft3 (0.18 to 1.24 g/L).