The gas used in the manufacture of urea fertilizer is ?

Urea fertilizer is one of the most important nitrogen-containing fertilizers used in agriculture. The production of urea involves two main raw materials — ammonia (NH₃) and carbon dioxide (CO₂). Both of these are derived from methane (CH₄), which makes methane the essential gas in urea manufacturing.

The process begins with steam reforming of methane, where methane reacts with steam at high temperature in the presence of a nickel catalyst:
CH₄ + H₂O → CO + 3H₂

The hydrogen gas (H₂) produced in this reaction is then used in the Haber process to synthesize ammonia:
N₂ + 3H₂ → 2NH₃

At the same time, carbon dioxide (CO₂) formed as a byproduct in the reforming process is captured and combined with ammonia to form urea:
2NH₃ + CO₂ → NH₂CONH₂ + H₂O

Thus, methane indirectly provides both key ingredients — hydrogen (for ammonia) and carbon (for carbon dioxide) — necessary for the formation of urea.

Reasons methane is used:

• 
  

  It is a primary component of natural gas, making it easily available and economical.

  
  


• 
  

  It produces pure hydrogen upon reforming, which is crucial for ammonia synthesis.

  
  


• 
  

  It ensures high yield and energy efficiency in industrial fertilizer plants.

  
  

Summary of steps:

1. 
   

   Methane → Hydrogen + CO

   
   


2. 
   

   Hydrogen + Nitrogen → Ammonia (Haber process)

   
   


3. 
   

   Ammonia + CO₂ → Urea

   
   

Because of its central role in supplying hydrogen and carbon for urea synthesis, methane (CH₄) is the gas used in the manufacture of urea fertilizer.

✅ Correct Option: D) CH₄ (Methane)