Hydrogen Injection for Cold-Start Catalyst Regeneration
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Solution Overview
Problem
Current emission gas treatment systems for internal combustion engines are inadequate in reducing CO emissions during cold-start conditions and struggle with the regeneration of precious metals in diesel oxidation catalysts, leading to inefficient NOx conversion and increased nitrate formation.
Innovation Solution
An on-board vehicle system for hydrogen generation and injection into the exhaust gas stream, using ammonia decomposition to produce hydrogen, which is then stored and introduced upstream of catalytic articles during cold-start periods to aid in the oxidation of CO, HC, and NOx, and to regenerate precious metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diesel oxidation catalyst is used to treat exhaust gas, then hydrocarbon and carbon monoxide emissions are converted, but the catalyst is less effective during cold-start periods due to insufficient temperature
Solution Approach 1:
The patent introduces hydrogen into the exhaust stream before it reaches the diesel oxidation catalyst during cold-start periods. This preliminary action provides additional fuel for combustion that raises the exhaust gas temperature, enabling the catalyst to reach its light-off temperature and become effective sooner than it would with cold exhaust gas alone.
2Productivity
If hydrogen is introduced to raise exhaust temperature during cold-start, then catalytic conversion efficiency is improved, but nitrate formation increases which inhibits precious metals
Solution Approach 1:
The patent utilizes the nitrate formation that would normally be harmful as an intermediate step. The stored nitrates on the catalyst surface are subsequently reduced by hydrogen to produce nitrogen and water, converting the harmful nitrate accumulation into a beneficial nitrogen reduction reaction that occurs after the initial temperature boost.
3Reliability
If hydrogen is used to regenerate precious metals in the catalyst, then catalyst performance is enhanced, but hydrogen storage and injection system complexity increases
Solution Approach 1:
The system uses onboard hydrogen storage that can be integrated with existing vehicle hydrogen infrastructure (such as fuel cell vehicles). The hydrogen injection is controlled based on exhaust temperature and catalyst state, allowing the system to self-regulate hydrogen dosing to maintain catalyst performance without requiring complex external control systems.
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
The system effectively increases the conversion of CO, HC, and NOx by up to 60% during cold-start conditions, enhances precious metal regeneration, and minimizes nitrate formation, thereby improving the overall efficiency of emission reduction and catalyst performance.
Implementation Method 1
an ammonia decomposition article configured to generate hydrogen, the ammonia decomposition article comprising an ammonia/ organic solvent reservoir or an ammonia storage tank, and a catalytic reactor configured to decompose ammonia into hydrogen and nitrogen from ammonia
Implementation Method 2
oxidation catalysts comprising a precious metal, such as platinum group metals (PGM), dispersed on a refractory metal oxide support, such as alumina, are known for use in treating the exhaust of diesel engines in order to convert both hydrocarbon and carbon monoxide gaseous pollutants by catalyzing the oxidation of these pollutants to carbon dioxide and water
Data Source
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AI summary
Systems for abatement of pollutants in an exhaust gas stream of an internal combustion engine including a hydrogen injection article configured to introduce hydrogen upstream of a catalytic article are effective for the abatement of carbon monoxide and/or hydrocarbons and/or nitrogen oxides. The introduction of hydrogen may be intermittent and/or during a cold-start period.