Kinetic study on catalytic cracking of Brazilian high-boiling-point petroleum fractions

Abstract

This work proposed a technique to estimate the kinetic parameters of cracking reaction. High-boiling-point petroleum fractions (>623.15 K) were analyzed. The experiments were performed using a thermal analysis system with a differential scanning calorimetry module at different linear heating rates (15, 20, 25, and 30 K min−1) in the temperature range from 303.15 to 823.15 K. The Arrhenius, Kissinger, and Flynn–Ozawa–Wall methods were used to determine the kinetic parameters. The compensation effect and the dependence on the activation energy of the conversion degree were evaluated. The catalyst used was a typical FCC regenerated catalyst containing 48.3 mass% of alumina, and particle size of 67 μm. The effect of catalyst loading was studied using 3, 5, and 10 mass%. Analysis of the DSC curves showed a major transitional stage between 693.15 and 723.15 K, identified as an endothermic region of high temperature oxidation (HTO). Empirical kinetic models were produced and data were obtained from the kinetic analysis of the HTO region. Under non-isothermal heating conditions higher activation energies were found as the API gravity of the high-boiling-point petroleum fraction decreased. On the other hand, the results showed consistent effects for the dependence of the activation energy on the extent of cracking conversion under non-isothermal conditions, showing a decrease with the extent of conversion. The catalytic loading effect is remarkable, and provides an alternative route for the cracking with lower activation energy with increasing catalyst weight. The kinetic parameters formulated will be used in the mathematical modeling of the reactive molecular distillation process for upgrading high-boiling-point petroleum fractions.