SSZ-90 Molecular Sieve Synthesis Using Ionic Liquids
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Solution Overview
Problem
The synthesis of crystalline zinc (silico)aluminophosphate molecular sieves isostructural with the DFO framework type has been limited by the need for new methods that can effectively utilize ionic liquids as both solvents and structure directing agents, differing from conventional hydrothermal synthesis.
Innovation Solution
A method involving a reaction mixture with zinc, silicon, aluminum, phosphorus sources, fluoride ions, and specific 1,3-dialkylimidazolium-based ionic liquids under crystallization conditions to form crystalline zinc (silico)aluminophosphate molecular sieves, represented by the empirical formula mQ+:nF:(MxAlyPz)O2, where Q+ represents the ionic liquid cation, and maintaining the reaction mixture under conditions to form crystals of the molecular sieve SSZ-90.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional hydrothermal synthesis is used to prepare molecular sieves, then the synthesis process is well-established and reliable, but it cannot effectively utilize ionic liquids as both solvents and structure directing agents for synthesizing zinc (silico)aluminophosphate molecular sieves with DFO framework type
Solution Approach 1:
The invention changes the synthesis parameters by replacing conventional hydrothermal conditions with ionothermal conditions, using ionic liquids as both solvent and structure directing agent. This parameter change enables the synthesis of zinc (silico)aluminophosphate molecular sieves with DFO framework type, achieving adaptability to ionic liquids while maintaining synthesis reliability through optimized temperature (100-200°C) and time (1-30 days) parameters
Solution Approach 2:
The ionic liquid acts as an intermediary substance that serves dual functions: as the reaction solvent and as the structure directing agent. The specific 1,3-dialkylimidazolium cation structure mediates the formation of the DFO framework type by directing the assembly of zinc, aluminum, and phosphorus units into the desired crystalline structure
2Adaptability or versatility
If new synthesis methods using ionic liquids are developed, then adaptability to ionic liquids is improved, but the synthesis conditions and process complexity increase
Solution Approach 1:
The ionic liquid performs multiple functions simultaneously: it serves as the reaction solvent, as the structure directing agent, and as a template for crystal formation. This multi-functionality reduces the need for separate additives or catalysts, simplifying the overall synthesis process despite the novelty of the method
Solution Approach 2:
The synthesis method optimizes key parameters including temperature (100-200°C range), time (1-30 days), and the specific structure of the ionic liquid (1,3-dialkylimidazolium with specific alkyl groups) to achieve reliable crystallization of the DFO framework type, making the process manageable despite its complexity
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 SSZ-90 with unique properties, characterized by specific X-ray diffraction patterns and NMR spectra, enabling its use as an adsorbent and catalyst for organic compound conversions, offering improved stability and selectivity in catalytic processes.
Implementation Method 1
maintaining the reaction mixture under crystallization conditions sufficient to form crystals of the molecular sieve
Implementation Method 2
preparing a reaction mixture containing (1) at least one source of zinc; (2) optionally, at least one source of silicon; (3) at least one source of aluminum; (4) at least one source of phosphorus; (5) fluoride ions
Data Source
AI summary
A new crystalline zinc (silico)aluminophosphate molecular sieve designated SSZ-90 is disclosed. SSZ-90 is isostructural with the DFO framework type and is synthesized using an ionic liquid as both the solvent and the structure directing agent. The ionic liquid [Q+A−] comprises a cation (Q+) selected from the group consisting of 1,3-diisopropylimidazolium, 1,3-diisobutylimidazolium, and 1-isopropyl-3-isobutylimidazolium and an anion (A−) which is not detrimental to the formation of the molecular sieve.