Base Metal Catalyst for Exhaust Emission Control
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Solution Overview
Problem
Current precious metal catalysts for exhaust emission control are expensive and ineffective for carbureted motorcycle engines, which require catalysts that can function across a wide range of air-to-fuel ratios and temperatures, and existing base metal catalysts face issues with stability and pollutant reduction.
Innovation Solution
A base metal catalyst composition using a support with at least 10% reducible ceria doped with oxides like Al, Pr, Sm, Zr, Y, Si, Ti, and La, combined with base metals such as Ni, Fe, Mn, Cu, Co, Ba, Mg, Ga, Ca, Sr, V, W, Bi, and Mo, promoting steam reforming and water gas shift reactions to provide H2 as a reductant for NOx abatement, effective under both rich and lean engine conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precious metal catalysts are used for emission control, then effective removal of HC, CO and NOx is achieved, but the cost becomes extremely high
Solution Approach 1:
The patent replaces expensive precious metals (Pt, Pd, Rh) with base metals (Ni, Fe, Mn, Cu, Co, Ba, Mg, Ga, Ca, Sr, V, W, Bi, Mo) that are abundant and much less costly. The catalyst formulation uses base metal oxides supported on reducible ceria to achieve acceptable pollutant removal at a fraction of the cost of precious metal catalysts.
Solution Approach 2:
The patent modifies the catalyst composition parameters by using reducible ceria doped with various oxides (Al, Pr, Sm, Zr, Y, Si, Ti, La) as the support material. This changes the chemical and physical properties of the catalyst to enable base metals to function effectively in emission control, achieving a balance between cost and effectiveness.
2Ease of manufacture
If base metal catalysts are used to reduce cost, then catalyst affordability improves, but pollutant reduction effectiveness and stability deteriorate
Solution Approach 1:
The patent creates a composite catalyst system combining base metal oxides with reducible ceria support doped with multiple oxide components. This composite structure leverages the synergistic effects between the base metals and the doped ceria support to enhance catalytic activity and stability, allowing base metals to achieve performance comparable to precious metals.
Solution Approach 2:
The reducible ceria doped with oxides acts as an intermediary support material that enhances the performance of base metals. The doped ceria provides oxygen storage and transfer capabilities, facilitating the catalytic reactions and improving the overall effectiveness of the base metal catalyst system.
3Adaptability or versatility
If carbureted motorcycle engine emission control is implemented, then wide range air-to-fuel ratio operation is required, but CO conversion activity is lost under rich aging conditions
Solution Approach 1:
The patent employs a dynamic catalyst formulation where reducible ceria can change its oxidation state (Ce4+ to Ce3+) in response to varying air-to-fuel ratios. This dynamic redox behavior allows the catalyst to adapt to both rich and lean conditions, maintaining CO conversion activity across the wide operating range of carbureted motorcycle engines.
Solution Approach 2:
The doped ceria support modifies the chemical parameters of the catalyst system, providing oxygen storage and transfer capabilities that enable the catalyst to maintain effectiveness under varying combustion conditions and resist deactivation during rich aging.
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 catalyst achieves near-complete conversion of hydrocarbons, carbon monoxide, and nitrogen oxides across varying engine conditions, providing thermodynamically limiting oxidants and reductants, enhancing CO conversion performance and stability, and offering a cost-effective solution for carbureted motorcycle engines.
Implementation Method 1
promote a steam reforming reaction of hydrocarbons and a water gas shift reaction to provide H2 as a reductant to abate NOx
Implementation Method 2
promote a steam reforming reaction of hydrocarbons and a water gas shift reaction to provide H2 as a reductant to abate NOx
Implementation Method 3
a support including at least 10% by weight of reducible ceria doped with up to about 60% by weight of one or more of oxides
Implementation Method 4
under what is known in the art as 'lean conditions,' there is excess air supplied, which provides more than enough oxygen for CO and hydrocarbon oxidation
Implementation Method 5
under so-called 'rich conditions,' the air-to-fuel ratio of the exhaust is less than the stoichiometric ratio required for complete oxidation of hydrocarbon and CO and reduction of NOx
Data Source
AI summary
Aspects of the invention relate to a base metal catalyst composition effective to catalyze the abatement of hydrocarbons, carbon monoxide and nitrogen oxides under both rich and lean engine operating conditions comprising a support including at least 10% by weight of reducible ceria doped with up to about 60% by weight of one or more of oxides selected from the group Al, Pr, Sm, Zr, Y, Si, Ti and La; and a base metal oxide on the reducible ceria support, the base metal selected from one or more of Ni, Fe, Mn, Cu, Co, Ba, Mg, Ga, Ca, Sr, V, W, Bi and Mo, the base metal catalyst composition effective to promote a steam reforming reaction of hydrocarbons and a water gas shift reaction to provide H2 as a reductant to abate NOx. Other aspects of the invention relate to methods of using and making such catalysts.