Passive NOx Adsorber with Electrical Heating for SCR Sync
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Passive nitrogen oxide adsorber catalysts face challenges in synchronizing nitrogen oxide release with the activation temperature of downstream SCR catalysts, leading to potential nitrogen oxide slip due to either premature or delayed release, and struggle with thermal durability and desulfation at high temperatures.
Innovation Solution
A catalyst system comprising a passive nitrogen oxide adsorber coated on a substrate with temperature management capabilities, using palladium supported on cerium oxide, zirconium oxide, or specific zeolites, combined with an electrical heating element to control temperature, ensuring optimal nitrogen oxide storage and release alignment with SCR catalyst activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If passive nitrogen oxide adsorber catalysts are used to store nitrogen oxides at low temperatures, then nitrogen oxide storage capacity is improved, but synchronization of nitrogen oxide release with SCR catalyst activation temperature deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the release temperature characteristics of the passive nitrogen oxide adsorber catalyst through compositional adjustments. By changing the catalyst formulation, the release temperature is tuned to align with the activation temperature of the downstream SCR catalyst, ensuring synchronized operation. This resolves the contradiction by maintaining high storage capacity while achieving proper release timing through parameter optimization.
2Productivity
If passive nitrogen oxide adsorber catalysts operate at high temperatures for nitrogen oxide release, then nitrogen oxide conversion is improved, but thermal durability and desulfation performance deteriorate
Solution Approach 1:
The patent applies dynamics by implementing active temperature management that dynamically controls the operating temperature of the passive nitrogen oxide adsorber catalyst. The system actively heats the catalyst to optimal temperatures for nitrogen oxide release and conversion, then maintains or reduces temperature to preserve thermal durability. This dynamic temperature control enables high conversion efficiency when needed while protecting the catalyst from excessive thermal stress and sulfation.
3Productivity
If active temperature management is implemented, then nitrogen oxide release synchronization and conversion efficiency are improved, but system complexity increases
Solution Approach 1:
The patent applies merging by integrating the temperature management function directly into the catalyst substrate structure. The heating elements are incorporated within or alongside the catalyst monolith, combining the thermal management system with the catalytic converter itself. This integration reduces overall system complexity compared to separate heating systems, while still achieving active temperature control for optimized nitrogen oxide release and conversion.
4Quantity of substance
If passive nitrogen oxide adsorber catalysts are used during cold start, then nitrogen oxide storage is improved, but release timing alignment with SCR catalyst activity deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-heating the passive nitrogen oxide adsorber catalyst during cold start conditions. The active temperature management system initiates heating before the SCR catalyst becomes active, preparing the adsorber for timely nitrogen oxide release. This preliminary thermal preparation ensures that when the SCR catalyst activates, the adsorber is ready to release stored nitrogen oxides immediately, eliminating timing delays and maximizing conversion efficiency during cold start.
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 system effectively stores nitrogen oxides at low temperatures and releases them when the SCR catalyst is active, maintaining high trapping efficiency and thermal durability, preventing nitrogen oxide slip and ensuring full storage capacity during cold starts.
Implementation Method 1
passive nitrogen oxide adsorber catalysts... storing nitrogen oxides in a first temperature window
Implementation Method 2
means to control the temperature of the carrier substrate... electrical heating element to control temperature
Implementation Method 3
releasing them as soon as the SCR catalyst is operative... releasing nitrogen oxides stored in step a) as soon as the first SCR catalyst has reached its operating temperature range
Implementation Method 4
selective catalytic reduction with ammonia in the presence of an SCR catalyst. This method comprises conversion of nitrogen oxides to be removed from the exhaust gas with ammonia as reductant into nitrogen and water
Data Source
AI summary
The present invention relates to a catalyst comprising a carrier substrate of the length L, a passive nitrogen oxide adsorber and means to control the temperature of the carrier substrate, as well as a process for cleaning of an exhaust gas emitted from a lean burn engine.