Effect of water density and air pressure on partial oxidation of bitumen in supercritical water

► Bitumen was partially oxidized in supercritical water for selective CO formation. ► The bitumen - supercritical water - air system consisted of two phases. ► The CO selectivity increased and the amount of total gas tended to decrease with increasing water/oil ratio. ► The increase in air pressure increased the amount of CO and CO2 and decreased the CO selectivity. ► Temperature, water/oil ratio and air pressure were important factors to govern partial oxidation of bitumen.