Fluoride-Free CIT-13 Germanosilicate Synthesis
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Solution Overview
Problem
Existing methods for synthesizing CIT-13 molecular sieves often require fluoride ions, which pose safety and cost concerns in commercial-scale operations.
Innovation Solution
A method involving hydrothermal treatment of an aqueous composition containing silicon oxide, germanium oxide, a substituted benzyl-imidazolium organic structure-directing agent, and water, under conditions that crystallize a CIT-13 topology without fluoride ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluoride ions are used in the synthesis mixture, then CIT-13 crystallization is achieved, but safety and cost issues arise in commercial operations
Solution Approach 1:
The patent removes fluoride ions from the synthesis mixture while maintaining CIT-13 crystallization. This is achieved by using alternative mineralizing agents (alkali metal or alkaline earth metal salts) and adjusting the composition ratios of silicon oxide, germanium oxide, and organic structure-directing agents to enable successful crystallization without harmful fluoride ions.
Solution Approach 2:
The patent replaces expensive and hazardous fluoride-containing reagents with cheaper, safer alternative minerals and salts. The use of common alkali metal salts and alkaline earth metal salts substitutes for costly fluoride sources, reducing both material costs and safety risks in commercial-scale operations.
2Object-affected harmful factors
If alternative mineralizing agents are used instead of fluoride ions, then safety and cost improve, but synthesis conditions must be optimized
Solution Approach 1:
The patent systematically adjusts key composition parameters including the molar ratios of silicon oxide to germanium oxide, the amount of organic structure-directing agent, water content, and pH levels to achieve successful CIT-13 crystallization using alternative mineralizing agents. These parameter optimizations enable the use of safer reagents while maintaining product quality.
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 effectively produces CIT-13 compositions without the need for fluoride ions, reducing safety and cost concerns while maintaining the structural integrity and catalytic properties of CIT-13.
Implementation Method 1
hydrothermally treating an aqueous composition comprising: (a) a source of silicon oxide (b) a source of germanium oxide; (c) a hydroxide salt of at least one substituted benzyl-imidazolium organic structure-directing agent (OSDA)
Implementation Method 2
under conditions effective to crystallize a crystalline microporous germanosilicate composition of the CIT-13 topology
Implementation Method 3
heating at a temperature in a range of from about 250°C to about 450°C; or (b) contacting with ozone or other oxidizing agent at a temperature in a range of 25°C to 200°C; for a time sufficient to form a dehydrated or an OSDA-depleted product
Implementation Method 4
contacting with ozone or other oxidizing agent at a temperature in a range of 25°C to 200°C; for a time sufficient to form a dehydrated or an OSDA-depleted product
Implementation Method 5
treating the dehydrated or OSDA-depleted product with an aqueous alkali, alkaline earth, transition metal, rare earth metal, ammonium or alkylammonium salt
Implementation Method 6
the isolated germanosilicate solid products are calcined in air or under inert atmosphere conditions at a temperature in a range of from about 600°C to about 1200°C, preferably about 800°C to about 1000°C, for about 4-8 hours
Data Source
Figure 1(A)~1(C)
Figure 2~3(C)
AI summary
The present disclosure is directed to novel crystalline germanosilicate compositions and methods of producing the same. In particular, the crystalline germanosilicate compositions are extra-large-pore compositions, designated CIT-13 possessing 10- and 14- membered rings. The disclosure describes methods of preparing these compositions using substituted benzyl- imidazolium organic structure-directing agents (OSDAs). Also disclosed are methods of using these crystalline compositions.