Effect of Catalyst Zoning on Hydrodemetalation of a Petroleum Residue

Abstract

This study was concerned with the effect of catalyst zoning on the hydrodemetalation of a petroleum residue. A residue was hydrodemetalizedover combinations of commercial Ni-Mo-Al203 catalysts in a two-zone, trickle-bed reactor system. Experiments were carried out varying catalyst activity in both the top and the bottom zones. The hydrodemetalation activities of five catalyst combinations were examined at 380�C, 10.3 MPa, and 1.0 h-1 LHSV for 72 h. Analyses were performed on liquid products, and on spent and regenerated catalysts in an effort to determine the optimum hydrodemetalation combination. Metal removal activities and coke deposition rates in graded catalyst beds were favored by higher total promotor and active metals contents and larger catalyst pore diameters. The upstream hydrodemetalation catalysts minimized physical property loss in the downstream catalyst in spite of increasing its coke content. Boiling point reduction activities were also favored by increasing the total promotor and active metals contents in graded catalyst beds.