Microwave-Assisted Plasma Catalytic Conversion of Tar to Hydrocarbon Products

Rapid conversion of tar from the Nizhnekamsk Oil Refinery in the plasma catalytic mode stimulated by microwave radiation (MWR, 2.45 ± 0.05 GHz) was studied. A quartz reactor arranged in the installation waveguide was charged with tar mixed with 15 wt % catalytic system characterized by high dielectric loss. Microwave radiation gives rise to breakdown effects on the surface of the catalytic system, followed by the plasma generation. In the plasma catalytic mode at optimum temperature of the reaction zone, 650–700°С, the tar undergoes rapid degradation with the formation of gaseous (9.3 wt %) and liquid (75.7 wt %) products and of a carbon residue containing the catalytic system (15 wt %). The maximal tar conversion is 85% upon 20-min irradiation. Analysis by gas chromatography–mass spectrometry and IR spectroscopy shows that the tar conversion products consist mainly of alkanes, alkenes, alkynes, and alkyl-substituted aromatic hydrocarbons. The solid iron-containing residue separated from the tar hydrogenation products exhibits increased ability to absorb MWR and can be used repeatedly.