Integrated SCR Catalyst Particulate Filter for Exhaust Purification
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Solution Overview
Problem
Conventional exhaust gas purification systems face challenges in small vehicles due to space constraints and rapid degradation of selective reduction catalysts, which occurs when the particulate filter regeneration temperature exceeds 800°C, damaging both the catalyst and filter.
Innovation Solution
The system coats a selective reduction catalyst on the particulate filter and uses an oxygen storage capacity material, such as cerium or ferrous chemicals, to lower the regeneration temperature of the particulate filter, preventing catalyst degradation by injecting these materials into the exhaust gas, either mixed with or separate from the reducing agent like urea or ammonia, to promote soot oxidation at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the particulate filter is mounted with a predetermined distance from the SCR catalyst to prevent degradation, then the SCR catalyst degradation is prevented, but the mounting space for the exhaust gas purification system becomes insufficient in small vehicles
Solution Approach 1:
The patent combines the SCR catalyst and particulate filter into a single integrated component. The SCR catalyst is coated on the inner surface of the particulate filter, allowing both functions to be performed by one device. This merging eliminates the need for separate mounting positions and reduces the overall space required for the exhaust gas purification system while preventing catalyst degradation by maintaining appropriate distance from the fuel injector.
2Productivity
If the inlet temperature of the particulate filter is raised to at least 600°C to regenerate the filter, then the soot trapped in the particulate filter is burned, but the inner temperature of the particulate filter is raised to higher than 800°C which causes rapid degradation of the SCR catalyst
Solution Approach 1:
The patent introduces a thermal insulation layer as an intermediary between the fuel injector and the SCR catalyst. This thermal insulation layer acts as a heat barrier that prevents excessive heat generated during soot combustion from reaching the SCR catalyst. The thermal insulation layer allows the particulate filter to be regenerated at high temperatures while protecting the SCR catalyst from thermal degradation, thus enabling both efficient soot burning and catalyst preservation.
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 reduces the mounting space required for the exhaust system by integrating the selective reduction catalyst with the particulate filter and prevents catalyst degradation by regenerating the filter at lower temperatures, maintaining the catalyst's effectiveness while improving fuel economy by avoiding the need for heating to prevent freezing of the reducing agent.
Implementation Method 1
a first injector adapted to inject the reducing agent containing an oxygen storage capacity material
Implementation Method 2
a selective reduction catalyst which is adapted to reduce nitrogen oxides contained in the exhaust gas by an injection of a reducing agent
Implementation Method 3
a particulate filter for filtering particulate matters (or soot) contained in the exhaust gas
Implementation Method 4
Reducing agents such as urea, ammonia, carbon monoxide, and hydrocarbon (HC) react better with nitrogen oxides than with oxygen in the SCR catalyst
Data Source
AI summary
A system for purifying an exhaust gas and an exhaust system having the same while preventing degradation of a selective reduction catalyst may include an exhaust pipe connected to an engine, the exhaust gas generated at the engine passing through the exhaust pipe, a particulate filter mounted on the exhaust pipe, coated with a selective reduction catalyst adapted to reduce nitrogen oxides contained in the exhaust gas by an injection of a reducing agent, and adapted to trap particulate matters contained in the exhaust gas, and one or more injectors adapted to inject the reducing agent and/or oxygen storage capacity material together or separately into the exhaust gas passing through the exhaust pipe.