Which process uses steam and a catalyst to produce ethanol industrially?

Which process uses steam and a catalyst to produce ethanol industrially?

• A. Fermentation
• B. Distillation
• C. Hydration of ethene
• D. Cracking

Answer: (C)

The idea being tested is that ethanol can be produced industrially by adding water to ethene in the presence of a catalyst and steam. This hydration of ethene is an addition reaction across the carbon–carbon double bond, so ethene plus water yields ethanol (C2H4 + H2O → C2H5OH). The catalyst, typically phosphoric acid on a solid support, and the high temperature and pressure used in industry drive the reaction to give a good yield, allowing large-scale continuous production. Fermentation uses yeast and sugar and happens at much milder conditions without steam or a similar catalyst, and distillation is just a purification step, not a reaction. Cracking breaks larger hydrocarbons into smaller ones, which isn’t how ethanol is made.

The idea being tested is that ethanol can be produced industrially by adding water to ethene in the presence of a catalyst and steam. This hydration of ethene is an addition reaction across the carbon–carbon double bond, so ethene plus water yields ethanol (C2H4 + H2O → C2H5OH). The catalyst, typically phosphoric acid on a solid support, and the high temperature and pressure used in industry drive the reaction to give a good yield, allowing large-scale continuous production. Fermentation uses yeast and sugar and happens at much milder conditions without steam or a similar catalyst, and distillation is just a purification step, not a reaction. Cracking breaks larger hydrocarbons into smaller ones, which isn’t how ethanol is made.