MFS Framework Molecular Sieve Crystal Size Control
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Solution Overview
Problem
Current methods for synthesizing MFS framework type molecular sieves, such as ZSM-57, do not effectively control crystal size and morphology, which are crucial for specific catalytic and separation applications.
Innovation Solution
A method involving a synthesis mixture with controlled water content and the presence of potassium, with or without sodium, to modify the average diameter and thickness of crystalline molecular sieves, allowing for precise control of crystal size and morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional synthesis methods are used to produce MFS framework type molecular sieves, then the molecular sieve can be synthesized, but the crystal size and morphology cannot be effectively controlled
Solution Approach 1:
The patent applies parameter changes by systematically varying the water content (H2O:SiO2 ratio from 10 to 200:1) and alkalinity (OH-:SiO2 ratio from 0.1 to 5:1) of the synthesis mixture to control crystal size and morphology. By adjusting these chemical parameters, the invention achieves precise control over average diameter (0.5-5 microns) and thickness (0.1-1 micron) of ZSM-57 crystals without complicating the synthesis process
Solution Approach 2:
The invention implements dynamics by enabling continuous adjustment of crystal properties during synthesis. The method allows dynamic control of crystal growth by modifying synthesis conditions (water content, alkalinity, temperature, time), producing molecular sieves with tailored sizes and morphologies suitable for different catalytic applications
2Productivity
If the water content and alkalinity of the synthesis mixture are adjusted, then the synthesis yield is optimized, but the crystal size and morphology remain unaffected
Solution Approach 1:
The patent resolves this contradiction by changing multiple parameters simultaneously - not only water content and alkalinity but also their interaction with synthesis temperature and time. This multi-parameter adjustment strategy enables independent control of both yield (through OH-:SiO2 and H2O:SiO2 ratios) and crystal dimensions (through temperature, time, and composition), achieving dual optimization
3Strength
If larger crystal sizes are produced, then the molecular sieve has better mechanical properties, but the catalytic activity and selectivity for specific applications are reduced
Solution Approach 1:
The invention applies parameter changes to produce a range of crystal sizes (average diameter 0.5-5 microns, thickness 0.1-1 micron) that can be selected based on application requirements. By controlling synthesis parameters (water content, alkalinity, temperature, time), the method generates molecular sieves with optimized crystal dimensions that balance mechanical strength and catalytic performance for specific reactions
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
Enables the production of crystalline molecular sieves with controlled average diameter and thickness, enhancing their suitability for catalytic and separation applications by modifying crystal morphology and size.
Implementation Method 1
maintaining said mixture under crystallization conditions until the required zeolite is formed
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A method of making a crystalline molecular sieve of MFS framework type, preferably ZSM-57, from a synthesis mixture comprising at least one source of tetravalent element (Y), at least one source of trivalent element (X), at least one source of alkali metal hydroxide (MOH), at least one structure-directing-agent (R) and water, said alkali metal (M) comprising potassium, and having the following mole composition (expressed in terms of oxide): YO2:(P) X2O3:(q)OH-:(r)R:(s)H2O, wherein (p) is in the range from 0.005 to 0.05, (q) is in the range from 0.01 to 3, (r) is in the range from 0.03 to 2 and (s) is in the range from 10 to 75 (based on total weight of said synthesis mixture); wherein the crystals of molecular sieve formed having an average diameter (D) of less than or equal to 1.5 micron and an average thickness (T) of less than or equal to 300 nanometers.