Effect of air flow rate on oxidative cracking of fuel and formation of chemical transformation products

The effect of air flow rate and pressure on the air-assisted oxidative conversion of fuel oil was experimentally investigated at 440 °C. Fuel oil containing fractions boiling up to 360 °C was used as the feedstock. Air was supplied at flow rates of 0.2-1.0 l min⁻¹ kg⁻¹ of fuel oil, and experiments were additionally performed at pressures of 0.5-1.0 MPa. Increasing the air flow rate from 0.2 to 0.8 l min⁻¹ kg⁻¹ increased the yield of light fractions boiling below 360 °C from 24.5 to 44.5 wt%, whereas a further increase to 1.0 l min⁻¹ kg⁻¹ resulted in a slight decrease to 43.8 wt%. At an air flow rate of 0.8 l min⁻¹ kg⁻¹, the highest liquid-product yield among the investigated pressures was obtained at 0.8 MPa. Under the selected operating conditions of 440 °C, 0.8 MPa, and 0.8 l min⁻¹ kg⁻¹ air flow rate, the material balance comprised 3.4 wt% gases, 23.7 wt% gasoline-range fraction, 9.5 wt% kerosene-range fraction, 18.4 wt% diesel-range fraction, and 45.0 wt% oxidized residue. FTIR analysis indicated the presence of aliphatic, aromatic, olefinic, and oxygen-containing functional groups in the liquid products. The observed enhancement of light-fraction formation is consistent with the participation of oxygen-mediated radical-chain reactions combined with thermal decomposition. The study demonstrates the potential of controlled air addition for intensifying the conversion of fuel oil into light fractions; however, further physicochemical characterization and techno-economic assessment are required before commercial application can be evaluated.