MCQ Detailed View

Water gas is a mixture of carbon monoxide (CO) and hydrogen (H₂) obtained by passing steam over hot coke. This mixture is a valuable raw material in industrial chemistry. One of its most important applications is the production of methanol (CH₃OH).

The synthesis takes place under specific conditions: a temperature of about 450 °C, a pressure of nearly 200 atmospheres, and the presence of a catalyst made of zinc oxide (ZnO) and chromium oxide (Cr₂O₃). Under these conditions, carbon monoxide reacts with hydrogen to form methanol according to the equation:

CO + 2H₂ → CH₃OH

The ZnO + Cr₂O₃ catalyst combination is critical. Zinc oxide provides active sites for the adsorption of reactant molecules, while chromium oxide increases durability and prevents the catalyst from breaking down at high temperatures. Together, they make the methanol synthesis process efficient and industrially practical.

Methanol produced from this process has multiple uses. It is widely employed as a solvent, fuel, and antifreeze. It is also used in the manufacture of formaldehyde, acetic acid, plastics, and synthetic fibers. In energy sectors, methanol is gaining attention as an alternative clean fuel and as a feedstock for biodiesel production.

The other options are not correct under these conditions:

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  Ethanol is usually produced by fermentation, not this catalytic process.

  
  


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  Carbonic acid forms when carbon dioxide dissolves in water, not from water gas.

  
  


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  Methane can be formed through methanation, but ZnO + Cr₂O₃ catalyst favors methanol formation instead.

  
  

Therefore, when water gas is treated at high temperature and pressure with ZnO + Cr₂O₃ catalyst, the main product formed is methanol.