In the hydration/filtration method for producing ethanol from ethene, which conditions are described?

In the hydration/filtration method for producing ethanol from ethene, which conditions are described?

• A. One volume of ethene and 0.6 volumes of steam, heated at about 300°C and 60–70 atm with phosphoric acid catalyst; unreacted gases recycled
• B. Ethene and steam at 100°C and 1 atm with sulfuric acid; no recycling
• C. Ethene reacted with oxygen at 200°C under copper catalyst
• D. Ethene with water at room temperature with no catalyst

Answer: (A)

The key idea is that ethene is turned into ethanol by adding water across the carbon–carbon double bond in the presence of an acid catalyst, and doing this efficiently in industry requires high temperature and high pressure with steam as the water source. The phosphoric acid catalyst helps generate the active acidic environment that lets water add across the double bond, while the high temperature increases the reaction rate and the high pressure helps push the equilibrium toward liquid ethanol rather than unreacted gases. Recycling unreacted ethene makes better use of feedstock and improves overall yield. The described conditions match the real industrial setup: a mixture of ethene and steam heated to around 300°C at very high pressure, with phosphoric acid as the catalyst, and a loop to recycle any unreacted ethene. Other options fail because they propose the wrong catalyst (sulfuric acid instead of phosphoric acid), or much lower pressure and no recycling, or scenarios that aren’t hydration at all (oxidation with oxygen) or hydration at room temperature with no catalyst, which would be extremely slow and impractical.

The key idea is that ethene is turned into ethanol by adding water across the carbon–carbon double bond in the presence of an acid catalyst, and doing this efficiently in industry requires high temperature and high pressure with steam as the water source. The phosphoric acid catalyst helps generate the active acidic environment that lets water add across the double bond, while the high temperature increases the reaction rate and the high pressure helps push the equilibrium toward liquid ethanol rather than unreacted gases. Recycling unreacted ethene makes better use of feedstock and improves overall yield.

The described conditions match the real industrial setup: a mixture of ethene and steam heated to around 300°C at very high pressure, with phosphoric acid as the catalyst, and a loop to recycle any unreacted ethene. Other options fail because they propose the wrong catalyst (sulfuric acid instead of phosphoric acid), or much lower pressure and no recycling, or scenarios that aren’t hydration at all (oxidation with oxygen) or hydration at room temperature with no catalyst, which would be extremely slow and impractical.