HYDROPROCESSING OF NARROW-BOILING GAS OIL FRACTIONS - DEPENDENCE OF REACTION-KINETICS ON MOLECULAR-WEIGHT

A heavy gas oil, produced by thermal coking of Athabasca bitumen, was fractionated into six narrow-boiling cuts of nominal 50 °C width and a high-boiling residue. The average molecular weights of the fractions ranged from 187 for the lightest fraction to 653 for the high-boiling residue. The six distillate fractions were catalytically hydroprocessed in a 150-mL CSTR with a commercial Ni/Mo catalyst. Removal of sulfur and nitrogen and conversion of aromatic carbon decreased with increasing average molecular weight (AMW) of the feed. The apparent activation energies for hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) increased with increasing feed AMW. The observed and intrinsic rate constants for HDS and HDN decreased logarithmically with increasing feed AMW and were fitted by a power-law equation. The intrinsic activation energy did not change significantly with increasing feed AMW. The estimated effectiveness factor increased with increasing feed AMW for both reactions and passed through a maximum at a molecular weight of 362 for the feed. © 1990, American Chemical Society. All rights reserved.