Gradient Catalyst for Exhaust Gas Temperature Control
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Solution Overview
Problem
Existing methods for purifying exhaust gas from internal-combustion engines, particularly diesel engines, face challenges in efficiently removing particulates and sulfur compounds due to hydrocarbon poisoning and the need for high temperature exhaust gas, which can lead to engine stoppages and decreased NOx purification performance.
Innovation Solution
A method involving a temperature-raising catalyst with a concentration gradient of catalytically active components, such as platinum, palladium, or rhodium, supported on a refractory three-dimensional structure, is introduced to efficiently combust high concentration hydrocarbons, raising exhaust gas temperature and preventing hydrocarbon poisoning, thereby enabling stable regeneration of diesel particulate filters and NOx storage catalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large quantity of hydrocarbon is supplied to raise temperature for regeneration, then particulate combustion efficiency is improved, but hydrocarbon poisoning of the catalyst occurs
Solution Approach 1:
The catalyst employs a concentration gradient of noble metal components along the flow direction, with higher concentration at the upstream side and lower concentration at the downstream side. This local quality variation allows the upstream region to efficiently combust high-concentration hydrocarbon while the downstream region prevents excessive hydrocarbon accumulation, thereby resolving the contradiction between combustion efficiency and catalyst poisoning.
Solution Approach 2:
The invention changes the concentration parameter of catalytically active components along the flow direction, creating a gradient distribution rather than uniform distribution. This parameter change enables different regions of the catalyst to perform different functions: high combustion activity upstream and hydrocarbon poisoning prevention downstream, thus resolving the technical contradiction.
2Productivity
If high temperature exhaust gas is used for filter regeneration, then particulate removal is improved, but engine stoppages and decreased NOx purification performance occur
Solution Approach 1:
The invention optimizes the temperature parameter by using a controlled hydrocarbon combustion process that raises exhaust temperature to the necessary range for particulate combustion (above 200°C) without excessive temperature increase. The concentration gradient catalyst enables this controlled temperature rise, achieving effective regeneration while avoiding engine stoppages and maintaining NOx purification performance.
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 stabilizes the combustion of hydrocarbons, raises exhaust gas temperature effectively, and maintains long-term regeneration of filters and NOx storage catalysts, improving purification performance and reducing the risk of engine stoppages.
Implementation Method 1
A method involving a temperature-raising catalyst with a concentration gradient of catalytically active components, such as platinum, palladium, or rhodium, supported on a refractory three-dimensional structure, is introduced to efficiently combust high concentration hydrocarbons
Implementation Method 2
efficiently combust high concentration hydrocarbons, raising exhaust gas temperature
Implementation Method 3
combust high concentration hydrocarbons, raising exhaust gas temperature
Data Source
AI summary
Provided is a method for extending a temperature range enabling combustion of high concentration hydrocarbon, or for rapidly supplying high temperature gas to a later stage catalyst. Provided is a method for purification of exhaust gas from an internal-combustion engine comprised by: providing a temperature-raising catalyst for exhaust gas from an internal-combustion engine in an exhaust gas passage of the internal-combustion engine, along flow of said exhaust gas, at the upstream side of a purification catalyst for said exhaust gas; and introducing hydrocarbon in an amount of 1,000 to 40,000 ppm, as converted to methane, from the upstream side of the temperature-raising catalyst, wherein said temperature-raising catalyst has catalytically active components supported onto a refractory three-dimensional structure, wherein concentration of said components has a gradient such that said concentration gradually becomes lower from the inflow side toward the outflow side of said exhaust gas.