Cerium Oxide Catalyst Morphology for Non-Toxic NOx Reduction
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Solution Overview
Problem
Current catalysts for nitrogen oxide (NOx) reduction in mobile sources, such as vanadium pentoxide on tungsten oxide/titania, are toxic and costly, and existing alternatives do not demonstrate superior performance or cost-effectiveness, with little attention paid to optimizing catalyst performance through morphology modification.
Innovation Solution
A catalyst comprising cerium oxide and anatase titanium dioxide with two distinct morphologies: colloidal cerium oxide agglomerates interdispersed among titanium dioxide particles and cerium oxide islands on the surface, formed by specific methods of combining colloidal CeO2 and soluble Ce salts with the titanium dioxide support, enhancing NOx removal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vanadium pentoxide is used as the catalyst, then NOx removal effectiveness is improved, but toxicity and volatility increase
Solution Approach 1:
The patent extracts and removes the harmful vanadium component from the catalyst system while retaining the beneficial NOx removal functionality through alternative metal compositions that are non-toxic and non-volatile
Solution Approach 2:
The patent employs base metal oxides such as cerium, zinc, and manganese which are more abundant and less expensive than vanadium, creating a cost-effective catalyst that maintains performance without the environmental hazards of vanadium
2Reliability
If zeolite based catalysts are used, then NOx removal effectiveness is improved, but cost increases significantly
Solution Approach 1:
The patent replaces expensive zeolite-based catalysts with affordable base metal oxide compositions, achieving comparable or superior NOx removal performance at a fraction of the cost through careful selection of common metals like cerium, zinc, and manganese
Solution Approach 2:
The patent optimizes catalyst performance by adjusting compositional parameters and morphology of the base metal oxides, demonstrating that cost-effective materials can achieve high effectiveness through proper formulation rather than relying on expensive proprietary materials
3Productivity
If catalyst morphology is not optimized, then manufacturing simplicity is maintained, but NOx conversion rates decrease
Solution Approach 1:
The patent systematically varies morphological parameters of the catalyst particles and optimizes the composition ratios of base metal oxides to maximize NOx conversion rates, demonstrating that controlled morphology development can be achieved through standard ceramic processing techniques
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 a significant increase in NOx conversion rates, providing a non-toxic, cost-effective alternative with superior performance compared to commercial iron on beta zeolite and vanadia on tungsten oxide/titania catalysts, maintaining activity even after aging and at high temperatures.
Implementation Method 1
Selective catalytic reduction (SCR) has been used as an alternative for NOx removal from the emissions of vehicles employing lean burn technologies such as diesel engines
Implementation Method 2
A catalyst for removing nitrogen oxides, which has a high activity and thermal stability, and is efficient for the removal of NOx from exhaust gas even at high temperatures and after aging
Implementation Method 3
The present invention relates to a catalyst for removing nitrogen oxides, which has a high activity and thermal stability, and is efficient for the removal of NOx from exhaust gas even at high temperatures and after aging
Data Source
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AI summary
A catalyst for removal of NOx from exhaust gas, containing cerium oxide and titanium dioxide, wherein a first portion of the cerium oxide forms at least one agglomerate of cerium oxide crystallites interdispersed in the titanium dioxide, and a second portion of the cerium oxide forms at least one island on a surface of the titanium dioxide, a method for producing the catalyst, a process for selectively reducing NOx levels in an exhaust gas using the catalyst, and an SCR canister containing the catalyst therein.