Formation kinetics of hydrocarbon compounds in the vacuum gas oil oxycracking process

Abstract

The kinetics of the formation of oxygen-free hydrocarbon compounds obtained during the process of oxidation of vacuum gas oil at 450–550 °C for 2700 s of conducting of the process was studied. It was established that the highest rate of hydrocarbon formation was noted for the C₁–C₄ fraction starting from the moment the process started and up to 900 s (1.76 × 10⁻⁸ – 4.58 × 10⁻⁸). For other fractions, reaction rate maximums were noted: for C₅–C₉—300 s from the start of the process; for C₁₀–C₁₂—in the interval between 300 and 900 s, i.e. at 600 s process duration; for the raw fractions C₂₂–C₃₀, C₃₁–C₃₅ and C₃₆–C₄₀, grew after 1800s. The data on the influence of the process temperature on the rate of hydrocarbon formation allowed us to establish that the oxycracking process is limited by the formation of C₁₀–C₁₆ hydrocarbon fractions. The increase in contact time to a greater extent affects the rate of formation of hydrocarbons C₁–C₄ and C₁₇–C₂₁. The features of the rate of hydrocarbon production as a function of the amount of oxygen were found out: the rate of formation of hydrocarbons C₁–C₄ and C₁₇–C₂₁ increases with increasing oxygen content (in the case of C₁₇–C₂₁ it passes through a minimum); C₅–C₉ and C₁₃–C₁₆—monotonously decreases; C₁₀–C₁₂ passes through a maximum at an oxidation state of 1%, which undoubtedly indicates the role of oxygen in the destructive processes of the formation of hydrocarbons that do not contain oxygen under oxycracking conditions.