What is the key difference in oxygen source between Partial Oxidation (POX) and Autothermal Reforming (ATR) processes?

The key difference in oxygen source between Partial Oxidation (POX) and Autothermal Reforming (ATR) processes lies in whether external heat is required to sustain the reaction. In Partial Oxidation (POX), pure or enriched oxygen is directly reacted with a hydrocarbon fuel (e.g., natural gas) in a substoichiometric amount, meaning less oxygen than required for complete combustion. The reaction is exothermic, meaning it releases heat. The heat generated by the partial combustion of the fuel provides the energy needed to drive the endothermic reforming reactions that convert the remaining fuel into hydrogen and carbon monoxide. No external heat source is required. In contrast, Autothermal Reforming (ATR) combines features of both Steam Methane Reforming (SMR) and POX. It involves reacting a hydrocarbon fuel with both steam and oxygen (or air). The partial oxidation reaction provides the heat needed to drive the steam reforming reaction, which is endothermic (requires heat). While ATR uses oxygen (or air) for partial combustion like POX, it also requires an external source of steam, which is not used in POX. The oxygen in ATR serves primarily as an internal heat source by partially oxidizing the fuel, rather than being the sole reactant as in POX. Therefore, POX uses oxygen as a direct reactant and heat source, while ATR uses oxygen primarily as an internal heat source alongside steam for reforming.