ANS:B - steam reforming

Ammonia synthesis gas is produced from natural gas by a process called steam reforming. Steam reforming, also known as steam methane reforming, is a widely used industrial process for the production of hydrogen and synthesis gas (syngas) from hydrocarbons, such as natural gas or methane. In this process, natural gas is reacted with steam in the presence of a catalyst to produce a mixture of hydrogen, carbon monoxide, and carbon dioxide. This mixture, known as synthesis gas, can then be further processed to produce ammonia through the Haber process or used for other chemical synthesis applications. Steam reforming, also known as steam methane reforming (SMR), is a chemical process used to produce hydrogen and synthesis gas (syngas) from hydrocarbons, particularly natural gas or methane. It is one of the most common methods for industrial hydrogen production. The process involves several steps:

1. Reaction: Natural gas (primarily methane, CH4) is mixed with steam (H2O) and heated to high temperatures (typically between 700°C to 1000°C) in the presence of a catalyst, such as nickel or cobalt. The steam reacts with methane in an endothermic reaction, producing hydrogen (H2) and carbon monoxide (CO). 𝐶𝐻4+𝐻2𝑂→𝐶𝑂+3𝐻2CH4​+H2​O→CO+3H2​
2. Water-gas Shift Reaction: In a subsequent step, the water-gas shift reaction may occur, where carbon monoxide reacts with steam to produce additional hydrogen and carbon dioxide. 𝐶𝑂+𝐻2𝑂→𝐶𝑂2+𝐻2CO+H2​O→CO2​+H2​
3. Product Separation: The resulting mixture of hydrogen, carbon monoxide, carbon dioxide, and unreacted methane is cooled, and the water and excess steam are condensed and removed from the gas stream. This separation is essential to avoid further reactions and to recover the water for reuse.
4. Purification: The syngas is then purified to remove impurities, such as sulfur compounds and other trace contaminants, which can interfere with downstream processes.

The resulting product, synthesis gas (syngas), typically consists of hydrogen (H2) and carbon monoxide (CO) in varying proportions, depending on the process conditions and the desired application. Syngas is a versatile intermediate product used in various chemical synthesis processes, including the production of ammonia (NH3), methanol (CH3OH), and Fischer-Tropsch liquids (synthetic fuels). Steam reforming is favored for hydrogen and syngas production due to its high efficiency, relatively low cost, and ability to utilize abundant feedstocks, such as natural gas. It plays a crucial role in the chemical industry, providing essential feedstocks for a wide range of industrial processes.