Q.How methanol is prepared industrially ? Write the chemical equation.

Preparation of Ethanol by Fermentation

Fermentation is the slow decomposition of sugars into simpler substances by the action of enzymes (biological catalysts secreted by micro-organisms such as yeast). It is the oldest and a major industrial method of manufacturing ethanol, using cheap raw materials like molasses (the residue left after crystallising sugar from sugarcane juice) or starchy grains.

The overall process on cane sugar involves two enzyme-catalysed steps. First, the enzyme invertase (from yeast) hydrolyses sucrose into glucose and fructose:

Then the enzyme zymase, also present in yeast, converts these hexose sugars into ethanol and carbon dioxide:

$C_6H_{12}O_6 \xrightarrow{\text{zymase}} 2\,C_2H_5OH + 2\,CO_2$ …