Ethanol Separation Membrane for Lean NOx Reduction
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Solution Overview
Problem
Conventional methods for reducing nitrogen oxides (NOx) in lean combustion engine exhausts are inefficient, often requiring separate reducing agents like urea, which increase costs and complexity, and struggle to maintain fuel efficiency while minimizing NOx emissions.
Innovation Solution
A method and system that separates ethanol from oxygenate-containing fuels using membrane separation techniques, generating an ethanol-enriched fraction which is then used as a reducing agent in a catalyst system to reduce NOx levels in the exhaust, comprising a first reducing catalyst and a second oxidation catalyst, optionally with a third catalyst for further treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lean combustion conditions are used to improve fuel efficiency, then fuel efficiency is improved, but nitrogen oxide emissions increase
Solution Approach 1:
The patent converts the harmful effect of excess oxygen in lean combustion (which causes NOx formation) into a beneficial effect by using that same excess oxygen to oxidize ethanol in the exhaust stream. The ethanol, when oxidized by the oxygen-rich lean exhaust, produces water and carbon dioxide while simultaneously reducing NOx through catalytic reactions, thus transforming the harmful excess oxygen into a useful oxidizing agent for emissions control
Solution Approach 2:
The system uses the engine's own fuel (ethanol-containing gasoline) to provide the reducing agent needed for NOx control. By separating and injecting ethanol from the fuel, the system makes the fuel itself serve dual purposes: as combustion fuel and as a reducing agent for emissions control, eliminating the need for separate urea systems
2Object-generated harmful factors
If separate reducing agents like urea are used to reduce nitrogen oxides, then nitrogen oxide emissions are reduced, but system complexity and cost increase
Solution Approach 1:
The patent makes ethanol serve multiple functions: it acts as the fuel component providing energy, as the separating target to create an ethanol-enriched stream, and as the reducing agent for NOx control. This multi-functionality eliminates the need for separate urea storage, handling, and injection systems, significantly reducing system complexity while maintaining effective NOx reduction
Solution Approach 2:
The system extracts ethanol from the gasoline fuel stream using membrane separation technology. This extracted ethanol-enriched fraction is then injected into the exhaust stream where it serves as the reducing agent. By taking out only the necessary component (ethanol) from the fuel, the system avoids the complexity of handling entire fuel systems or separate chemical storage systems
3Quantity of substance
If membrane separation is used to separate ethanol from fuel, then ethanol-enriched fraction is obtained, but additional processing steps are added
Solution Approach 1:
The patent replaces complex mechanical separation systems (such as distillation columns requiring heat input and complex controls) with membrane separation technology. The membrane system uses selective permeability to separate ethanol from gasoline based on molecular size and polarity differences, achieving high ethanol concentration in the permeate stream without mechanical moving parts, thermal processing, or complex control systems
Solution Approach 2:
The system employs porous membrane materials with specific pore sizes and surface properties that selectively allow ethanol molecules to pass through while retaining larger gasoline molecules. The membrane's porous structure provides the separation mechanism based on molecular dimensions and interaction properties, achieving efficient ethanol enrichment in a single processing step without complex equipment
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 approach effectively reduces NOx concentrations in engine exhausts to 50 wppm or less, maintaining fuel efficiency by utilizing the ethanol within the fuel as a reducing agent, eliminating the need for external urea and minimizing fuel usage.
Implementation Method 1
separating a fuel containing ethanol, such as 5 vol % or more of ethanol, into at least an ethanol-enriched fraction and a second fraction
Implementation Method 2
exposing at least a portion of the combustion exhaust to a catalyst system in the presence of a post-combustion-addition portion of the ethanol-enriched fraction
Implementation Method 3
The catalyst system can include a first reducing catalyst. Exposing the combustion exhaust to the first reducing catalyst can form a reduced exhaust fraction
Implementation Method 4
At least a portion of the reduced exhaust fraction can be exposed to a second oxidation catalyst to form a treated exhaust
Implementation Method 5
a second oxidation catalyst to form a treated exhaust
Data Source
AI summary
Systems and methods are provided for performing selective catalytic reduction on engine exhaust using ethanol from the engine fuel as the reducing agent. Fuel from a fuel tank or other fuel source can be passed through a separation module to produce a fuel stream with a reduced ethanol content and an ethanol-enriched fraction. After combustion of fuel under lean conditions, the combustion exhaust can be exposed to a catalyst system in the presence of the ethanol-enriched fraction.