Layered Manganese Catalyst for SCR Selectivity
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Solution Overview
Problem
Current catalysts for selective catalytic reduction (SCR) of NOx in combustion exhaust gases face challenges such as high costs, toxicity concerns, and limited performance across a broad temperature range, particularly with vanadium and tungsten oxides, and high selectivity for N2O formation with manganese-based catalysts.
Innovation Solution
A catalyst composition featuring a mixed oxide support of titanium and zirconium with alternating layers of manganese, iron, cerium, or tin oxides and titanium oxide, optimized to improve ammonia selectivity and activity across a range of 250° C. to 450° C., achieved through sequential layering and controlled deposition techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vanadium oxide and tungsten oxide are used as catalyst components, then catalytic performance for NOx reduction is improved, but cost increases and toxicity concerns arise
Solution Approach 1:
The patent removes vanadium oxide and tungsten oxide from the catalyst composition, extracting the harmful and costly components while retaining catalytic functionality through alternative metal oxides (manganese, iron, cerium, or tin) supported on titania with modified isoelectric point
Solution Approach 2:
The patent changes the chemical composition parameters by replacing vanadium/tungsten oxides with alternative metal oxides, and modifies the support properties by adjusting the isoelectric point of titania through added metal oxides, thereby achieving non-toxic, low-cost catalysis with maintained performance
2Productivity
If manganese oxide-based catalysts are used, then low temperature SCR activity is improved, but selectivity for N2O formation increases
Solution Approach 1:
The patent introduces an intermediary layer of titania with modified isoelectric point between the manganese oxide and the support, which mediates the interaction to enhance low temperature activity while suppressing N2O formation through optimized surface properties and acid-base characteristics
Solution Approach 2:
The patent creates a composite catalyst structure combining manganese oxide (or iron, cerium, or tin oxide) with modified titania support, where the composite properties provide both high low-temperature activity and reduced N2O selectivity through synergistic effects of the combined materials
3Ease of manufacture
If conventional titania supported catalysts are used, then manufacturing cost is reduced, but performance across broad temperature range (250°C to 450°C) is limited
Solution Approach 1:
The patent changes the surface property parameters of titania by modifying its isoelectric point through added metal oxides, enabling the catalyst to maintain performance across a broad temperature range (250°C to 450°C) while retaining the cost advantages of titania-based formulation
Solution Approach 2:
The patent enhances the universality of the titania-supported catalyst by optimizing its properties to perform effectively across multiple temperature conditions (250°C to 450°C), making it adaptable to varying operating conditions while maintaining cost-effectiveness
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 solution enhances NOx reduction efficiency and ammonia selectivity at both low and high temperatures, reducing N2O formation, thereby addressing the limitations of existing catalysts and meeting stringent emission requirements.
Implementation Method 1
A catalyst composition having a mixed oxide support containing oxides of titanium and zirconium. A plurality of alternating layers respectively formed of a metal compound and titanium oxide are present on the surface of the mixed oxide support... selective catalytic reduction (SCR) of NOx
Data Source
AI summary
Low temperature activity and high temperature ammonia selectivity of a vanadium-free selective catalytic reduction catalyst are controlled with a mixed oxide support containing oxides of titanium and zirconium, and a plurality of alternating layers respectively formed of a metal compound and titanium oxide present on the surface of the mixed oxide support. The metal compound is selected from the group consisting of manganese oxide, iron oxide, cerium oxide, tin oxide, and mixtures thereof.