KINETIC MODELING OF HYDROTREATING.

摘要

Only recently have detailed kinetic studies of the hydrotreating reactions been undertaken. In previous studies, the pseudo first-order kinetics of hydrodenitrogenation, hydrosulfurization, and hydrogenation in single and binary systems were determined along with some correlations of competitive adsorption inhibition effects. In the present work, additional kinetic studies were carried out in a batch autoclave at 350(DEGREES)C and 34 atm over presulfided commercial Ni-Mo/(gamma)-Al(,2)O(,3) catalyst. A systematic numerical and experimental strategy was developed to use the experimental data from both the present study and a past study to develop Langmuir-Hinshelwood expressions to model the kinetics of the hydrodenitrogenation of quinoline and indole, the hydrodesulfurization of dibenzothiophene, and the hydrogenation of naphthalene, both separately and in binary and ternary mixtures. Naphthalene hydrogenation and the desulfurization of dibenzothiophene to biphenyl were used as model hydrogenation and hydrogenolysis reactions to formulate the Langmuir-Hinshelwood expressions for the kinetic models. The models and the values of their adsorption parameters were determined from studies of inhibition by nitrogen-containing, sulfur-containing, and aromatic compounds. Total nitrogen removal, sulfur removal, and hydrogen consumption during hydrotreating were also predicted from the kinetic models developed. Quinoline, indole, dibenzothiophene, napthalene and their products were categorized into 5 kinetically-significant adsorption groups to account for the interactions among the nitrogen-containing, sulfur-containing, and aromatic compounds during catalytic hydrotreating. Basic nitrogen-containing compounds adsorb two orders of magnitude more strongly than sulfur-containing or aromatic compounds and are the strongest inhibitor, indicating the importance of acidic sites in hydrotreating reactions. The patterns of inhibition suggest that while hydrogenation, denitrogenation, and desulfurization occur on the acidic catalytic sites, desulfurization and possibly denitrogenation appear to also occur on less acidic sites. The Langmuir-Hinshelwood kinetic models developed imply that hydrogen adsorbs on yet another type of sites. The resulting kinetic models are adequate in fitting the data.