CHA-type Molecular Sieve Synthesis Using Novel Cyclic Amine SDAs
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Solution Overview
Problem
Existing methods for preparing CHA-type molecular sieves face challenges due to the complexity and limited availability of traditional structure directing agents (SDAs), which hinder large-scale production and require high concentrations, necessitating the development of cheaper, less complex alternatives that can reduce production time.
Innovation Solution
A process using a colloidal aluminosilicate composition in conjunction with novel cyclic nitrogen-containing cationic structure directing agents such as N-cyclohexyl-N-methylpyrrolidinium, N-methyl-N-(3-methylcyclohexyl)pyrrolidinium, and N-ethyl-N-(3-methylcyclohexyl)pyrrolidinium, along with elements from Groups 1 and 2 of the Periodic Table and hydroxide ions, under crystallization conditions to form CHA-type molecular sieves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional structure directing agents are used, then CHA-type molecular sieves can be formed, but the complexity of the SDA increases and availability decreases
Solution Approach 1:
The patent replaces complex, expensive traditional SDAs with simpler, cheaper cyclic nitrogen-containing cations that can be synthesized more easily and are more readily available. These simplified SDAs perform the essential structure-directing function without requiring the complex molecular structures of prior art agents, making them suitable for commercial-scale production.
Solution Approach 2:
The patent identifies and utilizes the essential functional features of traditional SDAs (cationic nature, cyclic structure, nitrogen-containing) while simplifying the overall molecular complexity. The novel SDAs copy the critical structure-directing capabilities without replicating the full complexity of earlier agents, achieving the same crystallization guidance with simpler molecules.
2Reliability
If traditional structure directing agents are used, then CHA-type molecular sieves can be prepared, but the production time increases
Solution Approach 1:
The patent modifies key parameters of the structure directing agent system by using cations with different molecular structures, sizes, and chemical properties compared to traditional SDAs. These parameter changes in the SDA composition lead to altered crystallization kinetics that reduce the time required to form CHA-type molecular sieves while maintaining structural fidelity.
3Reliability
If traditional structure directing agents are used, then CHA-type molecular sieves can be formed, but the concentration required increases production cost
Solution Approach 1:
The patent employs simpler, more economical cyclic nitrogen-containing cations that can be used at lower concentrations compared to traditional SDAs. The enhanced efficiency of these novel agents means less SDA is required to achieve the same structure-directing effect, reducing material costs and improving economic viability for large-scale production.
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
This approach allows for the efficient production of CHA-type molecular sieves with improved scalability, reduced SDA concentration, and shorter production times, while maintaining the desired crystal structure and purity, as evidenced by XRD patterns and post-synthesis treatments like acid leaching.
Implementation Method 1
subjecting the reaction mixture to crystallization conditions sufficient to form crystals of the CHA-type molecular sieve
Data Source
AI summary
The present invention is directed to a process for preparing CHA-type molecular sieves using a colloidal aluminosilicate in the presence of a cationic structure directing agent selected from the group consisting of N-cyclohexyl-N-methylpyrrolidinium, N-methyl-N-(3-methylcyclohexyl)pyrrolidinium, N-ethyl-N-(3-methylcyclohexyl)pyrrolidinium, and mixtures thereof.