Methanol is industrially prepared by reduction of CO using H2 and ZnO – Cr2O3.

Methanol, also known as methyl alcohol, is an important organic compound used as a solvent, fuel, and raw material in various industries. It is commonly produced industrially through a process called the catalytic synthesis of methanol.

The correct answer to the given question is option 'D', which states that methanol is prepared by the reduction of CO (carbon monoxide) using H2 (hydrogen) and ZnO – Cr2O3 (zinc oxide – chromium oxide) as catalysts.

Process:

The industrial synthesis of methanol involves several steps, including the following key reactions:

1. Water-gas shift reaction:
CO + H2O ⇌ CO2 + H2

This reaction is carried out to generate hydrogen gas (H2) and carbon dioxide (CO2) from carbon monoxide (CO) and water (H2O). It is an exothermic reaction that occurs at high temperatures in the presence of a suitable catalyst, such as iron oxide.

2. Methanol synthesis:
CO + 2H2 ⇌ CH3OH

In this step, the generated hydrogen gas from the water-gas shift reaction reacts with carbon monoxide to produce methanol. This reaction is known as the methanol synthesis reaction and is catalyzed by a mixture of zinc oxide (ZnO) and chromium oxide (Cr2O3). The catalyst helps in increasing the rate of the reaction and enhancing the selectivity towards methanol formation.

Explanation of the correct option:

Option 'D' states that methanol is prepared by the reduction of CO using H2 and ZnO – Cr2O3. This is the correct answer because the reduction of CO with hydrogen gas in the presence of a suitable catalyst (ZnO – Cr2O3) is a well-established method for the industrial production of methanol. This process allows for the conversion of CO, a byproduct of various industrial processes, into a valuable and versatile chemical compound like methanol.

This method has been widely adopted due to the efficiency and selectivity of the catalyst system, which promotes the formation of methanol while minimizing the formation of unwanted byproducts. The ZnO – Cr2O3 catalyst provides an active surface for the reaction and helps in the dissociation of CO and the subsequent formation of methanol.

By using this process, a large-scale production of methanol can be achieved, meeting the demand for this important chemical compound in various industries.