What is the alternative industrial method to fermentation for producing ethanol?

• A. Fermentation of sugars by yeast
• B. Hydration of ethene (steam) using a catalyst
• C. Electrolysis of water
• D. Cracking of hydrocarbons

Answer: (B)

An industrial alternative to fermentation for making ethanol is the hydration of ethene with steam in the presence of a catalyst. In this process, ethene (CH2=CH2) reacts with water (H2O) to form ethanol (C2H5OH) according to CH2=CH2 + H2O → C2H5OH. This method is used because it can operate continuously at high temperature and pressure with a suitable acid catalyst (often phosphoric acid on a solid support), giving ethanol in high yield and purity. It relies on ethene derived from petroleum rather than crops, making it faster and not dependent on harvests or fermentation constraints such as yeast tolerance to ethanol.

In comparison, electrolysis of water would split water into hydrogen and oxygen, not produce ethanol. Cracking of hydrocarbons breaks larger molecules into smaller ones and doesn’t specifically yield ethanol. Fermentation of sugars by yeast is the biological method being contrasted with the industrial hydration route. It is slower, limited by the sugar supply and yeast tolerance, and generally yields ethanol at lower concentrations requiring extensive purification.