Cu-Fe Exchanged CHA Zeolite SCR Catalyst for Low N2O Emissions
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Solution Overview
Problem
Existing SCR catalysts face challenges in maintaining high NOx conversion while minimizing N2O emissions, especially under aging conditions, which are exacerbated by the increasing NOx conversion requirements of modern diesel engines.
Innovation Solution
A process involving the preparation of an Fe-CHA catalyst slurry with a small amount of copper loading, followed by coating and calcination, to enhance NOx conversion and reduce N2O emissions, utilizing a zeolitic material with specific framework structures and ion exchange methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Fe-CHA catalyst is used to achieve high NOx conversion, then NOx conversion activity is improved, but N2O emissions increase
Solution Approach 1:
The patent combines Fe-CHA and Cu-CHA zeolites into a single catalyst system where Fe provides high NOx conversion activity and Cu suppresses N2O formation. The two metal-exchanged zeolites are integrated at the molecular level through co-ion exchange, creating a synergistic effect that resolves the contradiction between NOx conversion and N2O emissions.
Solution Approach 2:
The invention creates a composite catalytic material by incorporating both Fe and Cu ions into the CHA zeolite framework. This bimetallic composite catalyst leverages the complementary properties of Fe (high activity) and Cu (low N2O formation) to achieve both high NOx conversion and low N2O emissions simultaneously.
2Productivity
If Fe-CHA catalyst is used to maintain high NOx conversion, then NOx conversion is improved, but performance deteriorates after aging
Solution Approach 1:
The Cu component is incorporated into the catalyst structure in advance to prevent N2O formation and stabilize the catalyst against aging effects. The Cu ions act as a protective element that maintains catalyst performance stability over time, cushioning against the natural deactivation that would otherwise occur with Fe-CHA catalysts under aging conditions.
3Object-generated harmful factors
If small amount of copper is added to Fe-CHA catalyst, then N2O emissions are reduced, but catalyst complexity increases
Solution Approach 1:
The patent applies local quality by introducing Cu ions at specific locations within the CHA zeolite framework through targeted ion exchange. Rather than uniformly distributing all metals throughout the structure, the Cu is locally incorporated into Fe-CHA sites where it most effectively suppresses N2O formation, optimizing the catalyst with minimal additional complexity.
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 process significantly reduces N2O emissions and enhances NOx conversion activity, maintaining high performance even after aging, particularly under standard SCR conditions.
Implementation Method 1
subjecting the zeolitic material provided in (1) to an ion exchange procedure with one or more iron(II) and/or iron (III) containing compounds
Implementation Method 2
A process for preparing a catalyst for the selective catalytic reduction of nitrogen oxide
Data Source
AI summary
The present disclosure relates to a process for preparing a catalyst for the selective catalytic reduction of nitrogen oxide. The process includes providing a zeolitic material including SiO2 and X2O3 in its framework structure, wherein X is a trivalent element; subjecting the zeolitic material to an ion exchange procedure with one or more iron (II) and/or iron (III) containing compounds; preparing a slurry including the Fe ion-exchanged zeolitic material, one or more copper (II) containing compounds, and a solvent system; providing a substrate and coating the slurry onto the substrate; and calcining the coated substrate. Furthermore, the present disclosure relates to a catalyst for the selective catalytic reduction of nitrogen oxide, an exhaust gas treatment system for the treatment of exhaust gas exiting from an internal combustion engine, and a method for the selective catalytic reduction of nitrogen oxides.