UZM-22 Zeolite Synthesis Using Choline Hydroxide Template
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Solution Overview
Problem
The synthesis and utilization of zeolites like ZSM-18 are hindered by the expense and thermal instability of traditional structure directing agents, limiting their application in industrial processes.
Innovation Solution
The development of calcined microporous crystalline zeolites UZM-22 and UZM-22HS, which are thermally stable up to 400°C and synthesized using commercially available structure directing agents like choline hydroxide, overcoming the challenges of cost and stability in zeolite synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional structure directing agents like triquat are used to synthesize zeolites, then the zeolite structure can be formed, but the process becomes expensive and thermally unstable
Solution Approach 1:
The patent changes the chemical parameters of the structure directing agents by using choline hydroxide instead of traditional triquat compounds. This substitution maintains the templating function while improving thermal stability and reducing cost. The choline hydroxide-based synthesis produces zeolites that are stable up to 400°C, resolving the thermal instability issue of traditional agents.
Solution Approach 2:
The patent employs choline hydroxide as a disposable structure directing agent that can be easily removed through calcination. This cheap, readily available compound serves its templating function during synthesis and then decomposes harmlessly, eliminating the need for expensive, difficult-to-remove traditional agents like triquat.
2Ease of manufacture
If choline hydroxide is used as a structure directing agent, then cost is reduced and thermal stability is improved, but the zeolite must be calcined to remove the agent
Solution Approach 1:
The patent utilizes the phase transition and decomposition of choline hydroxide during calcination. The choline hydroxide undergoes thermal decomposition to remove the structure directing agent function, transforming from an organic compound to gaseous products. This phase change enables complete removal of the template while maintaining the zeolite structure.
3Reliability
If conventional zeolite synthesis methods are used, then zeolites can be produced, but they lack the thermal stability required for industrial applications
Solution Approach 1:
The patent creates composite materials by incorporating choline hydroxide into the zeolite synthesis system. This composite approach combines the templating capability of choline hydroxide with the zeolite framework formation, producing a material that inherits both the structural integrity of zeolites and the thermal stability provided by the choline-based template removal process.
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
UZM-22 and UZM-22HS exhibit thermal stability and cost-effectiveness, enabling their use in various industrial applications such as hydrocarbon conversion processes and molecular separation, while being accessible for further modification and customization.
Implementation Method 1
Zeolites are characterized by having pore openings of uniform dimensions, having a significant ion exchange capacity
Implementation Method 2
Zeolites can be used as catalysts for hydrocarbon conversion reactions, which can take place on outside surfaces as well as on internal surfaces within the pore
Data Source
AI summary
Crystalline microporous zeolites designated calcined UZM-22 and UZM-22HS have been synthesized. The calcined UZM-22 is represented by the empirical formula:M1′mn+Al1-xExSiyOz and UZM-22HS has an empirical formula of:M1an+Al(1-x)ExSiy′Oz″where M1 and M1′ are exchangeable cations such as lithium or strontium and E is a framework element such as gallium. Both zeolites are obtained from an as synthesized microporous crystalline composition having an empirical formula of:Mmn+RrAl1-xExSiyOz either by calcination for UZM-22 or by various treatments such as ammonium hexafluorosilicate treatment for UZM-22HS.M is an alkali, alkaline earth, or rare earth metal such as lithium and strontium, R is a singly charged organoammonium cation such as the choline cation and E is a framework element such as gallium.