ANS:C - partial oxidation

Partial oxidation is a process in which a hydrocarbon fuel, such as natural gas or liquid fuel oil, is partially combusted with a limited amount of oxygen or air to produce synthesis gas (syngas), which consists mainly of hydrogen (H2) and carbon monoxide (CO). Unlike complete combustion, where the fuel is fully oxidized to produce carbon dioxide (CO2) and water (H2O), partial oxidation stops short of complete combustion, leading to the formation of syngas. Here's how the process generally works:

1. Fuel and Oxygen: A hydrocarbon fuel, such as natural gas (methane, CH4) or liquid fuel oil, is mixed with a controlled amount of oxygen or air.
2. Combustion: The fuel and oxygen mixture is then ignited in a reaction chamber or burner. The combustion reaction is allowed to proceed, but it is intentionally limited to prevent complete oxidation of the fuel.
3. Formation of Syngas: In the partial oxidation process, only a portion of the fuel is oxidized completely to carbon dioxide and water vapor. The remaining fuel undergoes partial oxidation, resulting in the formation of a mixture of hydrogen (H2) and carbon monoxide (CO). This mixture is known as syngas.
4. Chemical Reactions:
   • Complete Combustion: CH4 + 2O2 → CO2 + 2H2O
   • Partial Oxidation: CH4 + O2 → CO + 2H2
5. Product Composition: The composition of the syngas produced through partial oxidation depends on factors such as the ratio of fuel to oxygen, the temperature of the reaction, and the presence of catalysts. Typically, syngas produced by partial oxidation contains varying proportions of hydrogen and carbon monoxide, with smaller amounts of other gases such as methane, carbon dioxide, and nitrogen.