Kinetic parameters of the formation of oxygen-containing compounds in the vacuum gas oil oxycracking process

Abstract

The kinetics of the formation of oxygen-containing compounds during oxycracking of vacuum gas oil was experimentally studied. The kinetic parameters of the process of formation of oxygen-containing compounds in five target fractions under oxycracking conditions are established: reaction rates, rate constants, reaction orders, activation energies. The average reaction rate of the formation of oxygen-containing compounds in oxycracking products in the first 600 s is limited by the rate of oxidation of the C10–C12 fraction, further from 600 up to 900 s by the oxidation of the C5–C9 fraction (during this period, the direction/mechanism of the formation of OCC in this fraction changes), and after 900 s—the fractions C1–C4. The presence of the induction period indicates that the formation of oxygen-containing compounds in the C1–C4 fraction occurs according to the unbranched chain mechanism, and C5–C9 and C22–C30—through the chain with degenerate branching. The combination of experimental and calculated data indicates a joint homogeneous heterogeneous oxycracking mechanism of vacuum gas oil, which excludes the single-valued contribution of only the volume or only the surface of the catalyst. It is shown that under oxycracking conditions the process proceeds both in the kinetic and in the internal transition region, depending on the temperature.