OPTIMIZATION OF THE 2-STAGE HYDROTREATMENT FOR A COAL LIQUID HEAVY DISTILLATE USING SOME COMMERCIAL CATALYSTS AT EACH STAGE

Catalytic up-grading of a coal liquid heavy distillate was examined using several commercial catalysts under variable conditions at hydrogen pressure of 150 atm (15. 2 MPa). Some particular catalysts (Ni-Mo/Al//2O//3) exhibited much higher activities for denitrogenation in the two-stage hydrotreatment of 380 degree C for 3 h and 420 degree C for 3 h, although all Ni-Mo catalysts examined had similar activities for the cracking of paraffins in the distillate. Combinations of a Ni-Mo catalyst in the first stage (380 degree C for 3 h) with a silica-alumina or with a Co-Mo/Al//2O//3 in the second stage (420 degree C for 3 h) exhibited the highest activities for paraffin cracking (conversion 61%) or denitrogenation (96% removal), respectively. By optimization of the two-stage hydrotreatment, especially in terms of catalyst combination and reaction temperature, the total reaction time could be reduced to a practically acceptable one (3 h) by achieving satisfactory levels of paraffin cracking and denitrogenation.