HC-SCR Catalyst Regeneration Using Nitrogen-Based Reductant
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Solution Overview
Problem
Hydrocarbon selective catalytic reduction (HC-SCR) systems for internal combustion engines are susceptible to deactivation by sulfur oxides, requiring high-temperature regeneration that reduces catalyst life and fuel efficiency, while nitrogen-based SCR systems are complex and costly with less available reductant agent.
Innovation Solution
A method and system that reintroduces a nitrogen-based reductant agent to convert sulfur oxides on the HC-SCR catalyst to hydrogen sulfides, using a nitrogen-based agent injector and controller to manage regeneration, allowing for periodic regeneration at lower temperatures and conserving the nitrogen-based reductant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature regeneration is used to remove sulfur oxides from the HC-SCR catalyst, then the catalyst activity is restored, but the catalyst life is reduced and fuel efficiency decreases
Solution Approach 1:
The patent changes the chemical parameters of the exhaust gas by introducing a nitrogen-based reductant agent (ammonia or urea) to create a reducing atmosphere during regeneration. This chemical parameter change allows sulfur oxide removal at lower temperatures (below 600°C) compared to conventional thermal regeneration, thereby extending catalyst life while maintaining regeneration effectiveness.
Solution Approach 2:
The nitrogen-based reductant agent acts as an intermediary substance that facilitates the removal of sulfur oxides from the catalyst surface. Instead of directly applying high heat to remove sulfur, the reductant agent chemically reacts with sulfur oxides to form removable compounds, serving as a mediator that enables gentle regeneration and preserves catalyst structure.
2Duration of action of stationary object
If a nitrogen-based reductant agent is introduced to regenerate the HC-SCR catalyst, then the regeneration temperature is reduced and catalyst life is extended, but the system complexity increases due to additional storage and injection requirements
Solution Approach 1:
The nitrogen-based reductant agent serves multiple functions: it acts as a reductant for removing sulfur oxides during regeneration, and it also functions as the active ingredient in selective catalytic reduction for nitrogen oxide emissions control. This multi-functionality reduces the need for separate systems and justifies the added complexity by providing dual benefits.
Solution Approach 2:
The system uses the engine's own exhaust gas stream to deliver the nitrogen-based reductant agent to the catalyst, leveraging the existing exhaust flow infrastructure. The reductant is injected directly into the exhaust stream where it automatically mixes and reaches the catalyst without requiring separate delivery mechanisms, reducing overall system complexity.
3Device complexity
If hydrocarbon reductant agent is used for SCR, then the system is simple and fuel is readily available, but the catalyst is susceptible to deactivation by sulfur in the exhaust gasses
Solution Approach 1:
The nitrogen-based reductant agent serves as a protective intermediary that prevents sulfur deactivation of the HC-SCR catalyst. By introducing this agent periodically, it creates a reducing environment that removes sulfur oxides before they can permanently deactivate the catalyst, thereby protecting the catalyst while maintaining system simplicity.
Solution Approach 2:
Instead of continuously adding complex components, the system applies nitrogen-based reductant agent periodically during regeneration cycles. This periodic intervention is sufficient to remove accumulated sulfur oxides and prevent deactivation, maintaining catalyst reliability while keeping the system simple and avoiding continuous complexity.
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
Extends the life of the HC-SCR catalyst, reduces nitrogen oxide emissions, and conserves the nitrogen-based reductant agent by regenerating the catalyst periodically with lower temperature treatments and utilizing the N-based SCR system to manage newly created nitrogen oxides.
Implementation Method 1
decomposing the nitrogen-based reductant agent to nitrogen oxides and hydrogen
Implementation Method 2
selective catalytic reduction (SCR) methods in which the quantity of nitrogen oxides in the exhaust gasses are reduced through chemical reactions that occur in the presence of a catalyst
Implementation Method 3
converting the sulfur oxides and the hydrogen to hydrogen sulfides
Data Source
AI summary
A hydrocarbon selective catalytic reduction (HC-SCR) catalyst is regenerated using a nitrogen-based reductant agent. The HC-SCR catalyst is in communication with a power system such as an internal combustion engine and receives exhaust gasses from the internal combustion engine. Sulfur in the exhaust gasses may deactivate the HC-SCR catalyst by sulfur oxides forming thereon. To remove the sulfur oxides, a nitrogen-based reductant agent is introduced to the exhaust gasses. The nitrogen-based reductant agent decomposes to nitrogen oxides and hydrogen. The hydrogen reacts with the sulfur oxides to form hydrogen sulfides thereby removing the sulfur oxides from the HC-SCR catalyst.