Purifying Silicon Compounds via Amine-Metal Complexation
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Solution Overview
Problem
Current methods are inadequate for effectively reducing high levels of metal impurities, such as aluminum and titanium, in fluid silicon compounds like direct process residue (DPR) to below 50 ppm, which is necessary to prevent catalyst poisoning and enable recycling of halosilane monomers and high boiling components.
Innovation Solution
A process involving a mixture of fluid silicon compounds and metal impurities combined with a tertiary amine to form an amine-metal complex, followed by adsorption with bituminous coal-based activated carbon, achieving significant reduction of metal impurities to low levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If activated carbon is used to remove metal impurities from silicon compounds, then certain metal impurities are removed to low levels, but this is only effective when starting with silicon compounds already containing low levels of the impurities
Solution Approach 1:
A tertiary amine is introduced as an intermediary substance that selectively complexes with metal impurities (aluminum and titanium) to form amine-metal complexes. These complexes are then adsorbed by activated carbon, enabling effective removal of high levels of metal impurities that activated carbon alone cannot remove. The amine acts as a mediator that enhances the affinity between the activated carbon and the metal impurities.
Solution Approach 2:
The invention changes the chemical state of metal impurities from free metal ions to amine-metal complexes through chemical complexation. This parameter change (from free ions to complexed form) significantly alters the adsorption characteristics, making the impurities removable by activated carbon even at high concentration levels (≥500 ppm).
2Productivity
If metal impurities are not removed from halosilane monomers and high boiling components, then the components can be recycled and reused, but metal impurities act as catalyst poisons and are detrimental to reactivity
Solution Approach 1:
The invention extracts metal impurities (aluminum and titanium) from the silicon compound mixture through a two-step process: first, tertiary amine selectively complexes with the metal impurities to form amine-metal complexes; second, activated carbon adsorbs these complexes, effectively separating and removing the impurities from the recyclable halosilane monomers and high boiling components. This extraction enables both high productivity through recycling and high reliability by eliminating catalyst poisons.
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 process effectively reduces metal impurities in fluid silicon compounds to ≤50 ppm, enabling their reuse and minimizing waste, thereby improving the reactivity of halosilane and high boiling components for further processing.
Implementation Method 1
combining B) a tertiary amine; thereby forming C) a product comprising i) the fluid silicon compound and iii) an amine-metal complex
Implementation Method 2
combining C) the product formed in step 1), and D) an activated carbon; thereby adsorbing the amine-metal complex with the activated carbon
Data Source
AI summary
A process for removing metallic impurities from halogenated silicon compounds, such as chlorosilane monomers and/or chlorinated polysilanes is disclosed. The process involves treating a halogenated silicon compound with a tertiary amine and thereafter a suitable grade of activated carbon.