Study of physico-chemical characteristics of the bitumen obtained by aerobic catalytic oxidation of oil tar

The article considers the way to improve the quality of bitumen. In order to improve the quality characteristics of bitumen, the authors propose introducing special additive (catalyst-modifier) into the tar during its oxidation. The effect of a manganese-containing catalyst synthesized on the basis of petroleum acids on the rate of obtaining road bitumen from petroleum tar by means of a liquid-phase oxidation process was studied. The conducted studies have established that the introduction of the catalyst in various concentrations (0.1-0.5 wt.%) and a change in the amount of supplied air (0.3-0.6 l/min) leads to an increase in the rate of bitumen production. Based on the obtained experimental data, the optimal amount of catalyst (0.3 wt.%) and air supply rate (0.6 l/min) at the most acceptable oxidation process temperature of 260±2 °C were determined. Analysis of the elemental composition of the initial tar and the obtained bitumen samples showed that the oxidation process significantly increases the amount of oxygen and reduces the amount of hydrogen. In particular, during oxidation in the presence of a catalyst, the amount of oxygen reaches its maximum level, which confirms the effectiveness of the reaction. The results of structural-group analysis show significant changes in the structure of molecules that occur during oxidation: chain rupture, changes in the ratio of saturated and unsaturated fragments, an increase in the number of substitutions in aromatic nuclei. Thus, the oxidation process carried out in the presence of a catalyst has a more effective and profound effect in terms of structural changes. Keywords: tar; liquid-phase oxidation; manganese-containing catalyst; road bitumen.