Five experimental runs were conducted as a part of the temperature and catalyst zoned concept. These experiments were conducted at 10.3 MPa (1500 psig), with the bottom zone reactor at 400/sup 0/C (752/sup 0/F), LHST of 1.9 h, with 20% (wt) of the catalyst in the top zone and utilizing a variable temperature in the top zone 400 to 500/sup 0/C (752 to 932/sup 0/F). Excessive reactor plugging occurred when the top zone was operated at 500/sup 0/C (932/sup 0/F). This suggests an upper limit when utilizing the feedstock of 15% (wt) mixture of SRC in a coal liquefaction process solvent, and with a commercial grade catalyst, Armak KF-153-S, a Ni-Mo type. All temperature zoning combinations showed a loss in catalyst activation over the experimental run durations of 72 h. Activity loss was rapid in the first 30 to 40 h and gradual thereafter. This activity loss was caused by carbonaceous material and metals deposition. Increasing the top zone temperature from 400 (752/sup 0/F) to 450/sup 0/C (842/sup 0/F) provided a beneficial effect on HDN and HDM activity. A further temperature increase was detrimental because of excessive coking and possible thermodynamic equilibrium limitations. The one reference run that was conducted …