n-Tetrasilane Purification via Freezing Point Separation
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Solution Overview
Problem
Current methods for producing high-purity n-tetrasilane are economically inefficient due to high wastewater treatment costs, equipment corrosion, and the difficulty in separating n-tetrasilane from i-tetrasilane isomers, which requires multiple distillation columns and excessive energy consumption.
Innovation Solution
A purification method involving cooling a tetrasilane isomeric mixture to a temperature between the freezing points of n-tetrasilane and i-tetrasilane, allowing for the solidification of n-tetrasilane and subsequent vacuum separation, followed by distillation to achieve high purity with reduced energy and equipment costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple distillation columns are used to separate n-tetrasilane from i-tetrasilane, then purification effectiveness is improved, but equipment capital and operational cost increase
Solution Approach 1:
The patent utilizes the freezing point difference between n-tetrasilane (-90°C) and i-tetrasilane (-99.4°C) to separate the isomers through controlled freezing. By cooling the mixture to a temperature between these two freezing points, n-tetrasilane crystallizes while i-tetrasilane remains liquid, enabling separation with a single equipment unit rather than multiple distillation columns.
Solution Approach 2:
The invention changes the separation parameter from boiling point difference (which is only 6.4°C and requires multiple distillation columns) to freezing point difference (which is 9.4°C and can be exploited with a single freezing point separation unit). This parameter change simplifies the equipment configuration while maintaining high purification effectiveness.
2Manufacturing precision
If multiple distillation columns are used to separate n-tetrasilane from i-tetrasilane, then purification effectiveness is improved, but energy consumption increases
Solution Approach 1:
The patent employs freezing point separation where n-tetrasilane is selectively frozen and separated from liquid i-tetrasilane. This phase transition-based separation requires less energy input compared to multiple distillation operations, as freezing typically consumes less energy than repeated vaporization-condensation cycles required for distillation.
Solution Approach 2:
The invention performs preliminary separation through freezing before any potential distillation steps. By removing a significant portion of n-tetrasilane in the freezing step, the subsequent purification requires less energy-intensive distillation, thereby reducing overall energy consumption while maintaining high purification effectiveness.
3Quantity of substance
If silicon-magnesium alloy method with ammonium chloride is used, then higher silanes production is achieved, but wastewater treatment cost and equipment corrosion increase
Solution Approach 1:
The patent extracts and utilizes the beneficial aspect of the silicon-magnesium alloy method (production of higher silanes) while eliminating the harmful aspect (acidic wastewater generation). By using magnesium silicide reacting with water instead of ammonium chloride in acidic solution, the process produces higher silanes without generating corrosive wastewater requiring expensive treatment.
Solution Approach 2:
The invention converts a potentially harmful process (silicon-magnesium alloy reaction) into a beneficial one by changing the reaction conditions. Instead of using acidic ammonium chloride solution that causes corrosion and wastewater issues, the patent uses water as the reactant, transforming the process into one that is environmentally friendly while still producing higher silanes effectively.
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 achieves 99.99% purity of n-tetrasilane with lower operational costs and energy consumption, simplifying the separation process and reducing equipment requirements.
Implementation Method 1
cooling the tetrasilane (Si4H10) to a predetermined temperature with a refrigerant at the solidifying purification tank, maintaining the predetermined temperature between the freezing temperature of the i-tetrasilane (i-Si4H10) and the n-tetrasilane (n-Si4H10) to condense the n-tetrasilane (n-Si4H10) into its solid form
Implementation Method 2
vacuuming the liquid i-tetrasilane (i-Si4H10) in the tetrasilanes isomeric mixture for separation
Data Source
AI summary
A high-purity n-tetrasilane purification method includes: introducing a tetrasilane (Si4H10) isomeric mixture into a solidifying purification tank, cooling the tetrasilane (Si4H10) to a predetermined temperature with refrigerant in the solidifying purification tank, maintaining the predetermined temperature between the freezing temperature of the n-tetrasilane (n-Si4H10) and of the i-tetrasilane (i-Si4H10), solidifying the n-tetrasilane (n-Si4H10) in the tetrasilane (Si4H10) isomeric mixture into solid state, and vacuuming the i-tetrasilane (i-Si4H10) from the mixture for separation.