Which of the following is an industrial method of preparation of methanol?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → By catalytic hydrogenation of carbon monoxide
Most methanol today is made from carbon monoxide and hydrogen, which combine at high pressure and temperature over a \( \ce{ZnO-Cr2O3} \) catalyst:
\( \displaystyle \ce{CO + 2H2} \xrightarrow[\text{high pressure, high temperature}]{\ce{ZnO-Cr2O3}} \ce{CH3OH} \)
Why the other options are incorrect
Option (2) By fermentation of molasses — Incorrect. The sugar in molasses is fermented by the enzymes of yeast to ethanol, not methanol.
Option (3) By reduction of HCHO with LiAlH4 — Incorrect. This reduction does give methanol (an aldehyde gives a primary alcohol), but \( \ce{LiAlH4} \) is an expensive reagent used for special chemicals only, not for making methanol on a large scale.
Option (4) By heating HCHO with concentrated NaOH — Incorrect. This is the Cannizzaro reaction: only half of the methanal becomes methanol, the other half is oxidised to sodium methanoate, so it is not the industrial route.
\( \displaystyle \ce{2HCHO + NaOH} \xrightarrow{\Delta} \ce{CH3OH + HCOONa} \)
NCERT (2026-27 edition):
7.5 Some Commercially Important Alcohols – “… Today, most of the methanol is produced by catalytic hydrogenation of carbon monoxide at high pressure and temperature and in the presence of ZnO – Cr2O3 catalyst.”