Effect of reaction temperature and time on the products and asphaltene dispersion stability in slurry-phase hydrocracking of vacuum residue

Abstract

The effect of reaction temperature and time on the products and the asphaltene dispersion according to the residue conversion was investigated in a slurry-phase hydrocracking reaction. The experiments were carried out with two different approaches to control the hydrocracking reaction, which the reaction time was changed from 4 h to 20 h (at 410 °C) and the reaction temperature from 430 °C to 453 °C (for 1 h) at 100 bar (at 80 °C) of initial hydrogen pressure and 500 wt.ppm of molybdenum concentration. As a result, it was found that the control of the reaction time and reaction temperature may give different effect to the stability of the asphaltene in the liquid phase in spite of the same VR conversion. In order to understand this, the dipole moments of the liquid product and structural change of the asphaltene was compared. And it was found that enhancing hydrogenation reaction by increasing reaction time at low temperature delayed the time of decreasing point for dipole moments of the liquid phase and increased the length of alkyl chain of remaining asphaltene. Therefore, it is considered that the dispersibility of asphaltene with high polarity is increased. Additionally, it was found that enhancing hydrogenation can also improve the catalyst dispersion in the liquid phase below 80% of residue conversion.