How Silicone is Made: Part ２ –From Metallurgical Silicon to Silane Synthesis
[Super Explanation] From Metallurgical Silicon to Silane Synthesis: The Heart of Silicone Manufacturing
🌐 The Starting Point of Silicone: Metallurgical Silicon
The raw material behind the silicone products around us is actually metallurgical silicon.
However, on its own, it cannot become silicone.
🔀 The key is “organosilane conversion”: introducing methyl groups into Si!
🔬 The Core Technology of Silicone Industry: Müller-Rochow Process
Approximately 90% of global silicone production is made using this method!
🚀 Basic Reaction Formula
- ✅ Gas-solid reaction
- ✅ Catalyst: Copper (Cu)
- ✅ Temperature: 250–350℃
🏭 What Is Produced?
| Product | Chemical Formula | Application |
|---|---|---|
| ⭐ Dimethyldichlorosilane | (CH₃)₂SiCl₂ | Primary raw material for silicone |
| Methyltrichlorosilane | CH₃SiCl₃ | By-product |
| Tetrachlorosilane | SiCl₄ | Semiconductor material, etc. |
| Oligosilanes | – | Impurities |
🔀 The target is to obtain high-purity (CH₃)₂SiCl₂ (DCS)!
🔧 Overall Process Flow
Metallurgical Silicon (Si fine powder) ↓ Organic Synthesis Reactor (Direct Process, Cu catalyst, 300℃) ↓ Chlorosilane Mixture (Gas phase) ↓ Cooling & Condensation ↓ Fractional Distillation Column ↓ High-Purity Dimethyldichlorosilane (DCS)
⚙ The Key Technology: Catalyst Design
| Component | Role |
| Cu | Main catalyst, activates Si surface |
| Zn | Stabilization, suppresses side reactions |
| Sn, B | Additives to improve selectivity |
🔑 Nano-dispersed copper particles have the highest activity!
🔥 Side Reactions and Their Risks
| Reaction | Result |
| Si + 4CH₃Cl → SiCl₄ + 2C + 2CH₄ | Excess SiCl₄ generation |
| (CH₃)₂SiCl₂ → Polymerization | Formation of high-boiling impurities |
🔀 Suppressing these side reactions is the key to high-yield plant performance!
📊 Yield Overview
- Dimethyldichlorosilane selectivity: 75–90%
- World leaders (Shin-Etsu Chemical, Wacker, etc.) achieve over 90%
Selectivity = Profitability itself 🔀 Process optimization = Maximum profitability!
🌟 Technology Dominating the World
- ✅ The only commercial technology to produce Si-C bonds economically
- ✅ Catalyst nano-control determines success or failure
- ✅ A beautifully streamlined integrated process
🔀 This is the “Divine Recipe” of silicone manufacturing.
🚩 Summary Flow Diagram
Metallurgical Silicon (Si) ↓ Organic Synthesis Reactor (Cu catalyst, 300℃) ↓ Chlorosilane Mixture ↓ Cooling & Condensation ↓ Distillation Separation ↓ High-Purity Dimethyldichlorosilane (DCS)
🔎 Topics for Further Deep Dive
- ✅ Hydrolysis Process: DCS → D4
- ✅ Actual Plant Design for Reaction Furnace
- ✅ Japan vs. Overseas Technology Gap
- ✅ Strategic Comparison: Shin-Etsu vs. Dow vs. Wacker
🎯 The Beauty of Technology Lies in Its Simple Perfection
With just a single fixed-bed reactor, this process supports everything from smartphones to artificial hearts and semiconductors worldwide.
This is the core of silicone science.
📚 References & Sources
Müller, E., & Rochow, E. G. (1945). The Direct Synthesis of Organosilicon Compounds. Journal of the American Chemical Society, 67(8), 1633-1634.
Rochow, E. G. (1965). Silicones. Springer-Verlag.
Arkles, B. (2006). Fundamentals of Silicon Chemistry. Gelest Technical Library.
Wacker Chemie AG – Technical Papers on Silicone Manufacturing.
Shin-Etsu Chemical Co., Ltd. – Corporate Technical Reports.
Dow Silicones Corp. – Silicone Manufacturing Process Overview.
Lewis, R. J. (2004). Hawley’s Condensed Chemical Dictionary (14th ed.). Wiley.
Harrod, J. F. (2001). Silicones and Silicone-Modified Materials. In Comprehensive Organometallic Chemistry III (Vol. 11).
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