TWC Catalyst Hydrogen Enrichment for Cold-Start Emissions
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Solution Overview
Problem
Existing three-way conversion (TWC) catalysts for gasoline engines are ineffective in reducing nitrogen oxides (NOx) emissions during the cold-start period when exhaust gas temperatures are low, and there is a need for improved systems to manage CO, HC, and NOx emissions at low engine exhaust temperatures.
Innovation Solution
Introducing a controlled amount of hydrogen gas (H2) into the exhaust gas stream upstream of the TWC catalyst during the cold-start period, using a feedback sensor to modulate H2 introduction, enhancing catalyst activity and minimizing NMHC+NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a TWC catalyst is used to treat exhaust gas, then CO, HC, and NOx emissions can be abated under stoichiometric conditions, but the catalyst is ineffective during cold-start period when exhaust temperatures are low
Solution Approach 1:
The system introduces hydrogen gas into the exhaust stream before the catalyst during cold-start conditions to pre-activate the catalyst and promote CO oxidation, enabling the catalyst to become effective at lower temperatures than traditionally required
Solution Approach 2:
The system changes the chemical composition parameter of the exhaust gas by adding hydrogen, which modifies the catalytic reaction environment and enables the catalyst to function effectively at lower temperatures during cold-start operation
2Productivity
If hydrogen gas is introduced into the exhaust gas stream, then TWC catalyst activity is enhanced and NMHC+NOx emissions are minimized, but system complexity increases due to H2 source and control mechanisms
Solution Approach 1:
The system uses the engine's own exhaust gas as the source of hydrogen through reforming processes, eliminating the need for external hydrogen storage tanks and supply systems, thereby reducing overall system complexity while maintaining the benefits of hydrogen-enhanced catalysis
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
Enhances TWC catalyst activity and reduces non-methane hydrocarbon and nitrogen oxide emissions by introducing a small amount of hydrogen gas, improving pollutant abatement during the cold-start period.
Implementation Method 1
The systems and method use hydrogen as a reductant in the exhaust gas stream. introducing H2 from the H2 source into the exhaust gas stream upstream of the catalyst article during a cold-start period can enhance TWC activity
Implementation Method 2
The systems and method use hydrogen as a reductant in the exhaust gas stream
Data Source
AI summary
The disclosure provides a system for treating an exhaust gas stream from a gasoline engine. The system is configured to introduce controlled quantities of hydrogen gas into the exhaust gas stream upstream of a catalyst article during a cold-start period. Further provided are related methods of treating such exhaust streams. Such systems and methods are useful in reducing a level of one or more of hydrocarbons, carbon monoxide, and nitrogen oxide in a gaseous exhaust stream from a gasoline engine.