Pyrolysis of oil sludge with oil sludge ash additive employing a stirred tank reactor

• Addition of oil sludge ash reduced the carbon residue of the oil product from oil sludge pyrolysis process.
• The improvement of the oil product quality was inferred that due to the catalytic effect of the metal oxide composition in the oil sludge ash.
• The possible catalytic mechanism and reaction pathway of the main metal oxide compositions in the oil sludge ash was proposed.

The pyrolysis of oil sludge with addition of oil sludge ash, Al2O3, Fe2O3, CaO and SiO2 was carried out under inert condition employing a stirred tank reactor to investigate the catalytic effect of metal oxides on the oil product quality. Thermogravimetric scale experiments were conducted for searching the optimal reaction temperature. The reaction condition was set at: 450 °C-5 rpm finally. Quality of the oil products was determined based on the results of four main fractions separation method, the H/C mole ratio, the carbon residue and the elemental analysis. Addition of oil sludge ash, Al2O3, Fe2O3 and CaO decreased the carbon residue and the migration of S, N and O from the oil sludge to the oil product. We inferred that these oil quality improvements were due to the catalytic effect of Al2O3, Fe2O3 and CaO composition in oil sludge ash. The possible catalytic mechanism was proposed based on the FTIR (fourier transform infrared spectroscopy), NMR (nuclear magnetic resonance) and GCMS (gas chromatography mass spectrometry) analysis results of the oil product.