u00b0 f to 500 u00b0 f from about 100 u00b0 f to 600 u00b0 f overall 100 u00b0 f to 400 u00b0 f typical operating temperatures for the top bed 31 a 300 u00b0 f to 500 u00b0 f typical operating temperatures for the bottom bed 31 b a suitable catalyst family widely known and used in industry that is suitable for this hydrodesulfurization process is a combination of group vi and group vii elements in the periodic table of elements typically the cobalt and molybdenum are supported on a substrate base of alumina to form the catalysts suitable catalyst types include cobalt molybdenum nickel molybdenum and nickel tungsten the initial fractionation column or main column 10 separates the reactor effluent 11 produced in a fluid catalytic cracking unit not shown into gases and different boiling range liquid products typical boiling ranges are as follows for cat naphtha c 5 to 430 u00b0 f light cycle oil lco 430 u00b0 f to 650 u00b0 f and for heavy cycle oil hco slurry 650 u00b0 f the side stream distillation column reactor 30 contains at least two beds 31 a 31 b provided with hydrotreating type catalyst in a distillation type structure the feed to column 30 is withdrawn from.