SSZ-98 Molecular Sieve Synthesis with Dication Template
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Solution Overview
Problem
Current methods for synthesizing ERI framework type molecular sieves lack control over silica-to-alumina ratio, crystal size, and morphology, which are crucial for their applications in catalysis and gas separation.
Innovation Solution
A method involving the use of N,N'-dimethyl-1,4-diazabicyclo[2.2.2]octane dication as a structure directing agent, along with optional 18-crown-6, to synthesize a new crystalline molecular sieve, SSZ-98, which allows for precise control over the silica-to-alumina ratio and morphology, resulting in a molecular sieve with a unique ERI framework type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to synthesize ERI framework type molecular sieves, then the synthesis process is simple, but control over silica-to-alumina ratio, crystal size, and morphology is poor
Solution Approach 1:
The patent employs a specific organic structure directing agent (N,N'-dimethyl-1,4-diazabicyclo[2.2.2]octane dication) and controls hydrothermal synthesis parameters (temperature, time, pH, composition ratios) to precisely regulate the silica-to-alumina ratio, crystal size, and morphology of ERI framework molecular sieves, transforming the synthesis from an uncontrolled process to one with precise parameter control
Solution Approach 2:
The patent introduces an organic structure directing agent (N,N'-dimethyl-1,4-diazabicyclo[2.2.2]octane dication) as an intermediary substance that mediates the self-assembly of inorganic building units into the desired ERI framework structure, enabling precise control over crystal morphology and composition during hydrothermal synthesis
2Manufacturing precision
If ERI framework type molecular sieves are synthesized without specific structure directing agents, then the synthesis process is easier, but the silica-to-alumina ratio and crystal morphology cannot be controlled
Solution Approach 1:
The patent systematically varies synthesis parameters including the Si/Al ratio in the starting gel composition, hydrothermal treatment temperature (100-200°C), and treatment time to achieve precise control over the final silica-to-alumina ratio and crystal morphology of the ERI framework molecular sieve
Solution Approach 2:
The organic structure directing agent (N,N'-dimethyl-1,4-diazabicyclo[2.2.2]octane dication) acts as a template that directs the assembly of silicate and aluminate units into the specific ERI framework structure, enabling control over both the silica-to-alumina ratio and crystal morphology through its molecular structure and interaction with inorganic precursors
3Manufacturing precision
If conventional synthesis methods are used, then fewer additives are required, but crystal size and morphology control is insufficient
Solution Approach 1:
The patent controls crystal size and morphology by adjusting hydrothermal synthesis parameters including temperature (100-200°C), time (several days), pH, and the composition of the starting gel (Si/Al ratio, water content), allowing precise tuning of crystal properties without requiring multiple process steps
Solution Approach 2:
The N,N'-dimethyl-1,4-diazabicyclo[2.2.2]octane dication serves as a structure directing agent that templates the formation of ERI framework crystals with controlled size and morphology, where the organic cation fits within the pores and channels of the framework during synthesis, directing crystal growth along specific orientations
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 method enables the production of SSZ-98 with a controlled silica-to-alumina ratio and specific morphologies, enhancing its performance in catalytic conversions, gas separations, and nitrogen oxide reduction, while minimizing impurities and OFF framework type materials.
Implementation Method 1
a method for preparing SSZ-98 using a N,N'-dimethyl-1,4-diazabicyclo[2.2.2]octane dication as a structure directing agent
Implementation Method 2
The crystal structure defines cavities and pores which are characteristic of the different species
Data Source
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AI summary
Uses for a new crystalline molecular sieve designated SSZ-98 are disclosed. SSZ-98 has the ERI framework type and is synthesized using a N,N'-dimethyl-1,4-diazabicyclo[2.2.2]octane dication as a structure directing agent.