SCR Catalytic Converter Without External Reducing Agent Injection
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Solution Overview
Problem
Conventional SCR catalytic converters require external injection of ammonia or urea, leading to installation complexities and ammonia slip issues, making them ineffective for lean burn diesel engines and non-compliant with stringent NOx emission regulations.
Innovation Solution
An SCR catalytic converter design without external reducing agents, featuring a front portion with modified catalysts, a middle portion with ammonia synthesis catalysts, and a rear portion with SCR reducing catalysts, allowing for internal NOx reduction without external ammonia injection, using known catalyst compositions supported on porous partition walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external ammonia or urea injection is used in SCR catalytic converter, then NOx reduction efficiency is improved, but device complexity and installation difficulty increase
Solution Approach 1:
The catalytic converter generates its own reducing agent (ammonia) through an onboard ammonia synthesis catalyst that reacts exhaust gas components (NO, CO, HC) to produce ammonia in situ. This eliminates the need for external ammonia or urea injection systems, thereby maintaining high NOx reduction efficiency while significantly simplifying device structure and installation complexity
Solution Approach 2:
The ammonia synthesis catalyst is positioned upstream in the exhaust flow to pre-generate ammonia before the exhaust reaches the SCR catalyst. This preliminary generation of reducing agent ensures that ammonia is available when needed for NOx reduction, maintaining effectiveness without requiring external injection infrastructure
2Reliability
If external ammonia injection is used in SCR catalytic converter, then NOx reduction efficiency is improved, but ammonia slip occurs
Solution Approach 1:
By generating ammonia internally through controlled reaction of exhaust components on the ammonia synthesis catalyst, the system produces exactly the amount of ammonia needed for SCR reduction. This eliminates excess ammonia injection that causes ammonia slip, while still providing sufficient reducing agent for effective NOx conversion
Solution Approach 2:
The system controls ammonia generation by adjusting reaction conditions (temperature, reactant concentrations) on the ammonia synthesis catalyst to match the exact stoichiometric requirements of the SCR reaction. This precise parameter control ensures complete ammonia utilization without slip, while maintaining optimal NOx reduction efficiency
3Reliability
If conventional SCR system with external reducing agent is used, then NOx emission standards are met, but control system complexity increases
Solution Approach 1:
The catalytic converter autonomously generates its own reducing agent through chemical reactions of exhaust components, eliminating the need for external ammonia storage tanks, injection pumps, dosing control units, and associated sensors. This self-sufficient approach ensures emission compliance while dramatically simplifying the control system to passive thermal management only
Solution Approach 2:
The system replaces mechanical injection systems (pumps, valves, nozzles) with a passive chemical generation system. The ammonia synthesis catalyst uses thermal energy from exhaust gas to drive chemical reactions that produce ammonia in situ, substituting complex mechanical control infrastructure with a simpler thermal-chemical process that inherently complies with emission standards
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
Enables easy installation, eliminates ammonia slip, and achieves economic efficiency by internally synthesizing ammonia for NOx reduction, thus complying with strict emission standards without external reducing agent systems.
Implementation Method 1
a middle portion, in which second supports that support ammonia synthesis catalyst components are applied on the inner surfaces of porous partition walls
Implementation Method 2
a rear portion, in which third supports that support SCR reducing catalyst components are applied on the inner surfaces of porous partition walls
Data Source
Figure 1~2
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AI summary
The present invention relates to a Selective Catalytic Reduction (SCR) catalytic converter that does not require the injection of a reducing agent, and, particularly, to an open-flow type or wall- flow type SCR catalytic converter that does not require the injection of a reducing agent, which includes a front portion 41, in which first supports supporting modified catalyst components are applied on the inner surfaces of porous partition walls, a middle portion, in which second supports supporting ammonia synthesis catalyst components are applied on the inner surfaces of porous partition walls, and a rear portion, in which third supports supporting SCR reducing catalyst components are applied on the inner surfaces of porous partition walls. More par¬ ticularly, the present invention relates to a catalytic converter, which can improve a reduction rate of NOx without requiring the injection of an ammonia reducing agent from the outside.