In-situ Copper Ion-Exchange on Zeolitic Catalyst
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Solution Overview
Problem
Existing processes for preparing catalysts with zeolitic materials containing copper do not achieve optimal catalytic activities, particularly for NOx conversion at both low and high temperatures.
Innovation Solution
A process involving the preparation of an aqueous mixture with a zeolitic material having a framework type CHA, copper, alumina, silica, and a copper source, followed by deposition on a substrate and calcination, enhances catalytic activity by optimizing the composition and structure of the catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid-phase ion-exchange process is used to prepare copper-exchanged zeolitic catalyst, then copper ions are introduced into the zeolite framework, but the catalytic activity for NOx conversion at both low and high temperatures is not optimal
Solution Approach 1:
The patent divides the copper introduction process into two distinct stages: (1) pre-exchange of copper ions into the zeolite framework using liquid-phase ion-exchange, and (2) subsequent in-situ ion-exchange during catalyst preparation where copper source compounds are deposited and calcined. This segmentation allows optimization of each stage independently, achieving both high catalytic activity and process simplicity.
Solution Approach 2:
The patent performs preliminary copper ion exchange into the zeolite framework before final catalyst preparation. This preliminary action creates a pre-exchanged zeolitic material that serves as an optimized precursor, enabling the final catalyst to achieve superior NOx conversion activity at both low and high temperatures while maintaining ease of manufacture.
2Temperature
If in-situ ion-exchange process is used with copper precursor, Zr-acetate and deionized water, then high temperature performance is enhanced, but further improvement in catalytic activity for NOx conversion is still needed
Solution Approach 1:
The patent modifies the in-situ ion-exchange process by changing key parameters: using a mixture of deionized water and alcohol (methanol/ethanol) instead of pure deionized water, adjusting the copper-to-zeolite ratio, and optimizing calcination conditions. These parameter changes enable the catalyst to achieve both enhanced high-temperature performance and improved low-temperature NOx conversion activity.
Solution Approach 2:
The patent creates a composite catalyst system combining pre-exchanged zeolitic material (CHA framework) with copper ions introduced through controlled in-situ ion-exchange. The composite structure of pre-exchanged zeolite plus additional copper from precursor compounds during calcination achieves synergistic effects, improving catalytic activity across the full temperature range while maintaining high-temperature performance.
3Ease of manufacture
If traditional copper ion-exchange methods are used, then the preparation process is simple, but the catalyst does not achieve high catalytic activities across wide temperature ranges
Solution Approach 1:
The patent ensures continuous useful action by performing copper ion exchange in-situ during the catalyst preparation process itself, rather than as a separate pre-treatment step. The copper source compounds are deposited on the zeolitic material and then converted to active copper species during the standard calcination step, maintaining process simplicity while achieving broad temperature range performance.
Solution Approach 2:
The patent creates a universal catalyst preparation method that can achieve optimal performance across both low and high temperature applications. The pre-exchanged zeolitic material serves multiple functions: it provides the structural framework, pre-loads copper ions, and acts as a substrate for additional copper deposition during in-situ ion-exchange, making the process adaptable to various operating conditions.
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 results in a catalyst with improved NOx conversion capabilities across a wide temperature range, demonstrating higher catalytic activity compared to traditional methods.
Implementation Method 1
Liquid-phase ion-exchange processes are know for the ion-exchange of zeolitic materials with copper and/or iron
Implementation Method 2
calcining the substrate obtained in (ii)
Data Source
AI summary
A process for preparing a catalyst comprising a zeolitic material comprising copper, the process comprising (i) preparing an aqueous mixture comprising water, a zeolitic material comprising copper, a source of copper other than the zeolitic material comprising copper, and a non-zeolitic oxidic material selected from the group consisting of alumina, silica, titania, zirconia, ceria, a mixed oxide comprising one or more of Al, Si, Ti, Zr, and Ce and a mixture of two or more thereof; (ii) disposing the mixture obtained in (i) on the surface of the internal walls of a substrate comprising an inlet end, an outlet end, a substrate axial length extending from the inlet end to the outlet end and a plurality of passages defined by internal walls of the substrate extending therethrough; and optionally drying the substrate comprising the mixture disposed thereon; (iii) calcining the substrate obtained in (ii).