Fluoride-Free Borosilicate TON Synthesis Using Imidazolium Templates
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Solution Overview
Problem
The existing methods for synthesizing borosilicate TON-framework type molecular sieves require the use of concentrated hydrofluoric acid, which poses hazards and is undesirable on a large scale, necessitating a fluoride-free synthesis approach.
Innovation Solution
A method involving a reaction mixture with silicon, boron, an element from Groups 1 and 2 of the Periodic Table, hydroxide ions, and a structure directing agent such as a 1,3-dimethylimidazolium cation or a 1,4-bis(N-methylimidazolium)butane dication, all in the absence of fluoride, under crystallization conditions to form borosilicate TON-framework type molecular sieves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If concentrated hydrofluoric acid is used as a fluoride source in the synthesis of borosilicate TON-framework type molecular sieves, then the desired crystal structure can be formed, but the process becomes hazardous and unsuitable for large-scale production
Solution Approach 1:
The patent removes the harmful fluoride component from the synthesis system entirely. Instead of using concentrated hydrofluoric acid or other fluoride sources, the invention employs a fluoride-free gel composition containing silicon, boron, alkali metal, alkaline earth metal, and hydroxide ions. This extraction of the harmful element while maintaining the essential crystallization function resolves the contradiction between reliable crystal structure formation and elimination of fluoride hazards.
Solution Approach 2:
The patent changes the chemical parameters of the synthesis system by substituting fluoride ions with hydroxide ions as the key anionic component. The gel composition uses a completely different chemical basis (silicon-boron-hydroxide system instead of silicon-boron-fluoride system), yet achieves the same TON-framework crystal structure. This parameter change eliminates hazards while preserving the desired product structure.
2Object-affected harmful factors
If a fluoride-free synthesis method is used, then hazards are eliminated and large-scale production becomes feasible, but the ability to form the desired TON-framework crystal structure may be compromised
Solution Approach 1:
The patent introduces a specific gel composition as an intermediary medium that enables crystal formation without fluoride. The gel contains silicon source, boron source, alkali metal source, alkaline earth metal source, and hydroxide ions in controlled proportions. This intermediary gel system mediates between the fluoride-free requirement and the crystal structure formation requirement, providing a safe yet effective synthesis pathway that produces the desired TON-framework structure.
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 method successfully synthesizes borosilicate TON-framework type molecular sieves without the need for fluoride, eliminating hazards and enabling large-scale production while maintaining the desired crystal structure and catalytic properties.
Implementation Method 1
maintaining the reaction mixture under crystallization conditions sufficient to form crystals of the molecular sieve
Data Source
AI summary
A method is disclosed for synthesizing borosilicate TON-framework type molecular sieves in a hydroxide media using a 1,3-dimethylimidazolium cation or a 1,4-bis(N-methylimidazolium)butane dication as a structure directing agent.