Problem 14 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

An industrial method of preparation of methanol is : (a) catalytic reduction of carbon monoxide in presence of \(\mathrm{ZnO}-\mathrm{Cr}_{2} \mathrm{O}_{3}\) (b) by reacting methane with steam at \(900^{\circ} \mathrm{C}\) with a nickel catalyst (c) by reducing formaldehyde with lithium aluminium hydride (d) by reacting formaldehyde with aqueous sodium hydroxide solution

Step-by-Step Solution

Answer

The industrial method to prepare methanol is catalytic reduction of carbon monoxide in presence of \(\mathrm{ZnO}-\mathrm{Cr}_{2} \mathrm{O}_{3}\) (Option a).

Step 1: Understand the Problem

The problem lists several industrial methods to prepare methanol. Our task is to identify which method correctly describes the industrial preparation process of methanol.

Step 2: Analyze Option (a)

Option (a) suggests catalytic reduction of carbon monoxide with the help of catalysts \(\mathrm{ZnO}-\mathrm{Cr}_{2} \mathrm{O}_{3}\). This is a well-known method used in industry to produce methanol, where carbon monoxide and hydrogen combine to form methanol in the presence of catalysts.

Step 3: Analyze Option (b)

Option (b) discusses the reaction of methane with steam at \(900^{\circ} \mathrm{C}\) in the presence of a nickel catalyst. This process is known as steam reforming, primarily used to produce synthesis gas (a mixture of hydrogen and carbon monoxide) rather than directly producing methanol.

Step 4: Analyze Option (c)

Option (c) involves reducing formaldehyde with lithium aluminium hydride. This reaction is not typically used in industry to produce methanol. Lithium aluminium hydride is a reagent used for nucleophilic reduction, but it's not an industrial-scale method for methanol production.

Step 5: Analyze Option (d)

Option (d) describes reacting formaldehyde with aqueous sodium hydroxide, known as the Cannizzaro reaction. This reaction is not used to produce methanol industrially; instead, it produces alcohol and a salt.

Step 6: Identify the Correct Method

Based on the analysis, option (a) is the widely recognized industrial method for producing methanol: catalytic reduction of carbon monoxide with \(\mathrm{ZnO}-\mathrm{Cr}_{2} \mathrm{O}_{3}\).

Key Concepts

Catalytic Reduction

Catalytic reduction is a chemical process in which a specific catalyst promotes the conversion of reactants to products. In the context of methanol production, this method is particularly essential. Methanol is produced industrially by reducing carbon monoxide in the presence of hydrogen.

• The process requires a catalyst, often made from metal oxides. In this case, zinc oxide (\(\mathrm{ZnO}\)) and chromium oxide (\(\mathrm{Cr}_{2} \mathrm{O}_{3}\)) play a crucial role.
• The catalyst helps lower the energy barrier, allowing the reaction to occur more efficiently at lower temperatures.

The reaction involves binding the carbon monoxide to the catalyst surface, facilitating the combination with hydrogen to ultimately form methanol. This reduction process is both effective and reliable, making it the preferred industrial method for methanol synthesis.

Carbon Monoxide

Carbon monoxide (CO) is a colorless and odorless gas, playing a significant role in the industrial production of methanol. Its molecular structure consists of one carbon atom double-bonded to an oxygen atom.

• In methanol production, CO is a primary feedstock in the catalytic reduction process.
• It reacts with hydrogen when exposed to specific catalysts, such as \(\mathrm{ZnO}\) and \(\mathrm{Cr}_{2} \mathrm{O}_{3}\)

This reaction produces methanol, which is then used in various applications, from fuel to chemical synthesis. Handling CO requires caution, as it is toxic to humans. However, its utility in industrial applications is immense, underlining its importance in chemical manufacturing.

Industrial Chemistry

Industrial chemistry is the branch of chemistry that applies chemical and physical processes to the large-scale manufacture of substances. In the case of methanol production, industrial chemistry optimizes reactions like the catalytic reduction of carbon monoxide.

• This field ensures that chemical processes are cost-effective and environmentally sustainable.
• It involves scaling up reactions from the laboratory to industrial levels while maintaining efficiency and safety.

Understanding industrial processes is critical. It allows for the advancement of technology and fuels innovation in chemical manufacturing, minimizing waste and leveraging resources efficiently.

Synthesis Gas

Synthesis gas, often referred to as syngas, is a mixture of hydrogen and carbon monoxide. It serves as a crucial intermediary in the production of chemicals such as methanol. This gas is often produced through steam reforming, where methane reacts with steam over a nickel catalyst.

• Syngas provides the necessary carbon monoxide and hydrogen for methanol synthesis.
• The composition of syngas can be adjusted to suit the specific needs of different chemical processes.

In industrial settings, syngas generation is a pivotal step. It ensures a steady supply of reactants for processes ranging from ammonia synthesis to fuel production, showcasing its versatility in industrial applications.