Chlorosilane Purification via Cinnamaldehyde Impurity Conversion
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Solution Overview
Problem
Conventional methods for purifying chlorosilanes face challenges in efficiently removing donor and acceptor impurities, such as phosphorus, arsenic, boron, and aluminum, due to limitations in selecting organic matter with lone pair electrons, which can decompose or form polymers, and require complex facilities like adsorption columns.
Innovation Solution
A method involving a hydrogenation or chlorination step followed by an impurity conversion step using a cinnamaldehyde derivative to convert impurities into high-boiling substances, allowing for their separation through distillation, eliminating the need for complex facilities and waste treatment issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional organic matter with lone pair electrons is used to remove impurities, then impurity removal effectiveness is improved, but the organic matter decomposes or forms polymers causing operational problems
Solution Approach 1:
The patent uses cinnamaldehyde derivative as a consumable reagent that is added in controlled amounts to react with impurities. The reagent is intentionally designed to be used up in the reaction process, converting impurities into separable high-boiling substances, rather than being a permanent catalyst or adsorbent that requires regeneration or replacement.
Solution Approach 2:
The patent changes the chemical structure parameter of the aldehyde compound from simple aromatic aldehydes (which form polymers) to cinnamaldehyde derivatives (which have the alpha-beta unsaturated structure). This structural parameter change prevents polymerization while maintaining the lone pair electron capability for impurity removal. The specific parameter changed is the molecular structure configuration that prevents cross-linking.
2Manufacturing precision
If adsorption columns or complex facilities are used to remove impurities, then purification effectiveness is improved, but device complexity and waste treatment requirements increase
Solution Approach 1:
The patent replaces mechanical/physical separation systems (adsorption columns, complex distillation trains) with a chemical reaction-based purification method. The cinnamaldehyde derivative chemically reacts with impurities to transform them into high-boiling substances that can be separated through simple distillation, substituting complex mechanical separation with a simpler thermal separation process.
Solution Approach 2:
The patent converts impurities into high-boiling substances through chemical reaction, allowing them to be discarded in the distillation residue rather than requiring complex adsorption media or regeneration systems. The cinnamaldehyde derivative itself can be recovered from the distillate and reused, implementing a discard-recover cycle that simplifies the overall process.
3Ease of manufacture
If simple distillation is used to purify chlorosilanes, then process simplicity is maintained, but donor and acceptor impurities remain in the final product
Solution Approach 1:
The patent performs a preliminary chemical conversion step before the final distillation. The cinnamaldehyde derivative is added to the chlorosilane mixture beforehand to react with and convert donor and acceptor impurities into high-boiling substances. This preliminary action transforms the impurities into a form that can be easily separated during the subsequent simple distillation process.
Solution Approach 2:
The cinnamaldehyde derivative acts as an intermediary reagent that mediates between the impurities and the distillation process. It temporarily binds to impurities through chemical reaction, transforming them into high-boiling complexes that are then separated during distillation. The intermediary facilitates the separation without requiring complex equipment.
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 removes impurities, producing high-purity chlorosilanes suitable for semiconductor-grade polycrystalline silicon production without forming polymers or requiring adsorption columns, ensuring continuous operation and simplified waste handling.
Implementation Method 1
an impurity conversion step of treating the chlorosilane distillate obtained in the hydrogenation step or chlorination step in the presence of a cinnamaldehyde derivative to convert donor impurities and acceptor impurities contained in the chlorosilane distillate to a high-boiling substance
Implementation Method 2
a purification step of separating purified chlorosilanes from the chlorosilane distillate which has been subjected to the impurity conversion step and recovering the purified chlorosilanes outside the system, wherein the purification step is carried out using at least one distillation column
Implementation Method 3
a hydrogenation step of reacting chlorosilanes mainly comprising tetrachlorosilane with hydrogen in the presence of a metal-grade silicon to obtain a chlorosilane distillate containing trichlorosilane
Implementation Method 4
a chlorination step of reacting a metal-grade silicon with hydrogen chloride to obtain a chlorosilane distillate containing trichlorosilane
Data Source
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AI summary
The method comprises at least three steps of a hydrogenation step (101) and/or a chlorination step (102), an impurity conversion step (103), and a purification step (104). In the impurity conversion step (103), an aldehyde compound represented by the general formula Ar-R-CHO (Ar; denotes a substituted or unsubstituted aryl group, R; denotes an organic group having two or more carbon atoms) is added to convert donor impurities and acceptor impurities contained in a chlorosilane distillate to a high-boiling substance. The chlorosilane distillate after the donor impurities and acceptor impurities have been converted to a high-boiling substance is sent to the purification step (104). In the purification step (104), high purity chlorosilanes from which the donor impurities and acceptor impurities have been thoroughly removed are obtained by using a distillation column or the like, where the high purity chlorosilanes are recovered outside the system from the top of the column.