COK-5 Molecular Sieve Synthesis Using Alternative Structure Directing Agents
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Solution Overview
Problem
The synthesis of COK-5 molecular sieve is complex and time-consuming due to its reliance on a single structure directing agent, HEPDD, which limits the production process and increases costs, and there is a need for alternative agents to simplify the synthesis and expand compositional ranges.
Innovation Solution
The use of 1,4-bis(N-propylpyrrolidinium)butane dications, 1,4-bis(N-butylpyrrolidinium)butane dications, and 1,5-bis(N-propylpyrrolidinium)pentane dications as structure directing agents allows for the synthesis of COK-5 in shorter heating periods and across a broader range of Si/Al and Si/B atomic ratios, producing ultra-small crystals with a unique X-ray diffraction pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HEPDD is used as the structure directing agent for COK-5 synthesis, then COK-5 can be obtained, but the synthesis process becomes complex and time-consuming requiring up to 10 days of heating
Solution Approach 1:
The patent changes the chemical structure parameters of the structure directing agent from HEPDD to alternative diquaternary ammonium compounds (such as 1,4-bis(N-propylpyrrolidinium)butane and 1,5-bis(N-propylpyrrolidinium)pentane). This parameter change in the directing agent's molecular structure enables significantly reduced synthesis times while maintaining reliable COK-5 formation, directly resolving the contradiction between successful synthesis and time consumption.
2Reliability
If HEPDD is used as the structure directing agent, then COK-5 synthesis is possible, but the compositional range is limited and production costs increase
Solution Approach 1:
The patent introduces multiple alternative structure directing agents that can universally direct the formation of COK-5 with varying compositional ranges. These agents (1,4-bis(N-propylpyrrolidinium)butane, 1,4-bis(N-butylpyrrolidinium)butane, 1,5-bis(N-propylpyrrolidinium)pentane) provide multi-functionality by enabling synthesis across different Si/Al and Si/B ratios, thereby expanding adaptability while maintaining synthesis capability.
3Reliability
If extensive heating is applied for COK-5 synthesis using HEPDD, then the reaction proceeds to completion, but production costs increase and various difficulties arise
Solution Approach 1:
The patent employs alternative structure directing agents that accelerate the synthesis kinetics, allowing the reaction to reach completion in significantly reduced time (from up to 10 days to much shorter periods). This 'rushing through' the synthesis process with improved directing agents eliminates the need for extensive heating, thereby reducing production costs and avoiding difficulties associated with prolonged heating while maintaining reliable reaction completion.
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 simplifies the synthesis of COK-5, reduces production time, and enables the production of materials with unique properties, including a broader compositional range and smaller crystal size, while maintaining the zeolite's catalytic and adsorption capabilities.
Implementation Method 1
using one or more of 1,4-bis(N-propylpyrrolidinium)butane dications, 1,4-bis(N-butylpyrrolidinium)butane dications and 1,5-bis(N-propylpyrrolidinium)pentane dications as a structure directing agent, it has now been found that COK-5 can be synthesized by simpler processes and in shorter heating periods
Implementation Method 2
COK-5 is a molecular sieve zeolite characterized by very thin crystals from about 6 to 20 nm in thickness and a distinctive X-ray diffraction pattern
Data Source
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AI summary
A molecular sieve having the structure of COK-5 is produced using, as a structure directing agent, at least one diquaternary ammonium compound selected from the group consisting of 1,4-bis(N-propylpyrrolidinium)butane dications, 1,4-bis(N- butylpyrrolidinium)butane dications and 1,5-bis(N-propylpyrrolidinium)pentane dications.