CHA-type Molecular Sieve Synthesis Using Novel Cationic Structure Directing Agents

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Solution Overview

Problem

The preparation of CHA-type molecular sieves is hindered by the complexity and limited availability of traditional structure directing agents, which are costly and difficult to produce in sufficient quantities, necessitating the development of cheaper, less complex alternatives that can reduce production time and minimize agent concentration.

Innovation Solution

A method involving the use of alkali metal silicate, oxides of trivalent and pentavalent elements, elements from Groups 1 and 2 of the Periodic Table, and specific cationic structure directing agents such as N-cyclohexyl-N-methylpyrrolidinium and its derivatives, under crystallization conditions to form CHA-type molecular sieves, with optional post-crystallization processing for achieving the target molecular sieve.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional structure directing agents (N-alkyl-3-quinuclidinol, N,N,N-trialkyl-1-adamantammonium, N,N,N-trialkyl-2-exoaminonorbornane) are used to prepare CHA-type molecular sieves, then the desired crystal structure is obtained, but the complexity and cost of the agents increase and their availability decreases

Engineering Contradiction:

Improvecrystal structure formationVSAvoidstructure directing agent complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex, expensive traditional SDAs with simpler, cheaper quaternary ammonium salts that can be produced more easily and in larger quantities. These alternative SDAs perform the necessary structure-directing function temporarily during synthesis but are not required to be complex or stable long-term, embodying the principle of using simple disposable agents rather than complex persistent ones.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the chemical parameters of the structure directing agents by using quaternary ammonium salts with different molecular structures (such as N-cyclohexyl-N-methylpyrrolidinium, N-ethyl-N-(3-methylcyclohexyl)pyrrolidinium) compared to traditional agents. This parameter change in molecular structure, charge distribution, and steric properties enables the same crystal structure formation with simpler, more available reagents.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If traditional structure directing agents are used, then CHA-type molecular sieves are formed, but the production time increases and agent concentration must be high

Engineering Contradiction:

Improvecrystal structure formationVSAvoidcrystallization time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent changes the chemical parameters of the structure directing agents to achieve faster crystallization kinetics. The quaternary ammonium salts used (such as N-cyclohexyl-N-methylpyrrolidinium and its derivatives) have different solubility, reactivity, and template effects compared to traditional agents, enabling the same CHA structure to form in shorter times with potentially lower concentrations.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If traditional structure directing agents are used, then CHA-type molecular sieves are prepared, but the cost and difficulty of producing sufficient quantities increase

Engineering Contradiction:

Improvecrystal structure formationVSAvoidagent production ease

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent employs simple quaternary ammonium salts that can be synthesized through straightforward chemical routes from readily available starting materials, unlike the complex traditional SDAs that require multi-step syntheses. These simpler agents can be manufactured at lower cost and in larger quantities, removing the bottleneck of SDA availability while maintaining their temporary structure-directing function during the crystallization process.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 availability and reduced costs, utilizing novel structure directing agents that simplify the synthesis process and minimize impurities, while maintaining the desired crystal structure and properties.

Implementation Method 1

subjecting the reaction mixture to crystallization conditions sufficient to form crystals of the CHA-type molecular sieve

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentUS9216911B2Method for preparing CHA-type molecular sieves using an alkali metal silicate precursor and novel structure directing agents

Publication Date: 2015.12.22 CHEVRON USA INC

AI summary

The present invention is directed to a process for preparing CHA-type molecular sieves using a colloidal aluminosilicate composition containing a cationic structure directing agent selected from the group consisting of N-cyclohexyl-N-methylpyrrolidinium, N-cyclohexyl-N-ethylpyrrolidinium, N-methyl-N-(3-methylcyclohexyl)pyrrolidinium, N-ethyl-N-(3-methylcyclohexyl)pyrrolidinium, N-methyl-N-(2-methylcyclohexyl)-pyrrolidinium, N-ethyl-N-(2-methylcyclohexyl)pyrrolidinium, and mixtures thereof.