Morpholinium-Based AEI Zeolite Plate Morphology
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Solution Overview
Problem
Conventional processes for producing AEI framework zeolites, such as SSZ-39, often result in crystals with suboptimal morphology, leading to reduced catalytic activity due to large size, thick dimensions, and poor access to inner pores, which increases costs.
Innovation Solution
Replacing conventional ammonium-based organic structure-directing agents (OSDAs) with 2,4,4,6-tetramethyl morpholinium hydroxide (MOPEY) to produce nano-sized, plate-shaped crystals with a high aspect ratio, enhancing access to catalytic sites and reducing the formation of competing phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional ammonium-based OSDAs (e.g., PIPPY) are used to make AEI framework zeolites, then the zeolite crystals form with conventional morphology, but the crystals become too thick or too big, reducing catalytic activity
Solution Approach 1:
The patent changes the chemical structure parameters of the OSDA by replacing conventional ammonium-based OSDAs (like PIPPY) with morpholinium-based OSDAs. This parameter change in the OSDA structure directly influences the crystal growth parameters, resulting in thinner crystal morphology (reduced thickness) while maintaining the AEI framework. The morpholinium cation's specific structural parameters enable better control over crystal thickness, thereby improving catalytic activity.
2Ease of operation
If conventional OSDAs are used, then the synthesis process is well-established, but the surface area to volume ratio is too small, making inner pores inaccessible
Solution Approach 1:
The patent applies parameter changes by substituting the OSDA type from ammonium-based to morpholinium-based. This change fundamentally alters the crystal morphology parameters, producing a shape with enhanced surface area to volume ratio. The new morphology exposes more inner pores to the external environment, improving accessibility for reactants and products, thus enhancing ease of operation in catalytic applications.
3Reliability
If conventional OSDAs are used, then the synthesis follows known procedures, but competing phases form reducing product purity
Solution Approach 1:
The patent changes the OSDA parameter from conventional ammonium-based to morpholinium-based, which fundamentally alters the synthesis pathway. This parameter change suppresses the formation of competing phases by directing the crystallization exclusively toward the desired AEI framework structure. The morpholinium cation's specific properties create a more reliable synthesis process with higher phase purity, eliminating the harmful effect of competing phase formation.
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
The new morphology, referred to as SAZ-1, improves catalytic activity by providing better access to inner pores and reducing the formation of competing phases, leading to more efficient and cost-effective catalytic applications.
Implementation Method 1
Zeolites such as SSZ-39 are made with organic structure-directing agents (OSDAs), sometimes referred to as templates, which are usually organic bases which guide or direct the molecular shape and pattern of the zeolite framework. The OSDAs act something like a frame around which the zeolite crystals form
Implementation Method 2
reacting a mixture comprising an oxide of silicon, an oxide of aluminum, a quaternary ammonium compound, an alkali metal hydroxide and water at a temperature of at least 100°C. for a time sufficient to form crystals of an aluminosilicate zeolite
Data Source
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AI summary
An aluminosilicate zeolite comprising at least 90% phase pure AEI zeolite crystals, the crystals having a plate-shaped morphology. In embodiments, at least 50% of the crystals have at least one ratio in at least one pair of dimensions in the range from 3:1 to 20:1, and thickness of 30-100 nm. A process of making the AEI zeolite comprising reacting an oxide of silicon, faujasite, a quaternary ammonium compound comprising 2,4,4,6-tetramethylmorpholinium cation, alkali metal hydroxide and water at at least 100C. to form crystals of a zeolite having an AEI framework. A crystalline AEI zeolite having pores comprising a 2,4,4,6-tetramethylmorpholinium cation. The zeolite may comprise at least 90% phase pure AEI zeolite with the 2,4,4,6-tetramethylmorpholinium cation within pores of the zeolite. In some embodiments the zeolite comprises crystals having a plate-shaped morphology and with the 2,4,4,6-tetramethylmorpholinium cation within pores of the AEI zeolite.