Making ethanol two ways: fermentation and hydration sim
Run a fermentation tank and an ethene hydration plant side by side, day by day. Set the temperature, keep the air out, choose the pressure, and watch a comparison table and a graph build: rate, purity, raw material, energy, batch or continuous, carbon dioxide.
Organic chemistry: making ethanol by fermentation and by the hydration of ethene, and comparing the two · covers the GCSE, IGCSE, O-Level topic
What the sim shows
Ethanol is made in two ways. Fermentation: sugar from plants (glucose) and yeast, at about 25–35 °C with no air, in batches: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. It is slow, stops at about 15 % ethanol when the yeast dies, and the product must be fractionally distilled (to about 95 %). Too hot and the yeast's enzymes are denatured; let air in and the yeast respires instead, and bacteria turn the ethanol into ethanoic acid. Hydration: ethene (from cracking crude oil) with steam over a phosphoric acid catalyst at about 300 °C and 60 atm, continuously: C₂H₄ + H₂O ⇌ C₂H₅OH. Only about 5 % reacts on each pass, so the unreacted ethene is recycled; the product is pure ethanol once the water is removed. The reaction gives out heat, so a lower temperature turns more of each pass into ethanol but more slowly: 300 °C is a compromise. Fermentation uses a renewable raw material and little energy but is slow and impure; hydration is fast, continuous and pure but uses a non-renewable raw material and a lot of energy. The fermentation rates are the library's own (the fermentation figure); the hydration conditions match the reactions-of-ethene figure. Model limits: a 400 m³ tank and 20 t of ethene an hour through the reactor are illustrative sizes; time moves only when you press Wait one day.
- Left: fermentation tank, air lock, column
- Right: reactor, heater, compressor, separator
- Recycle pipe: unreacted ethene goes round again
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