Reaction of nitrogen and sulphur compounds during catalytic hydrotreatment of shale oil

Pyrolysis oil derived from oil shale was hydrotreated in a stirred reactor at 400°C for a hydrotreatment time of 12 h. The influence of hydrogen pressure at 7, 9, 11 and 15 MPa and the role of catalyst type in the form of nickel–molybdenum and cobalt–molybdenum types was investigated in relation to the yield and composition of the products. The results showed that nitrogen and sulphur contents of the hydrotreated oils were significantly decreased after hydrotreatment and were further decreased with increasing pressure of hydrogen. Correspondingly, detailed analysis of the oils showed that the aromatic nitrogen and sulphur containing compounds were decreased in concentration in the oils as the hydrogen pressure was increased. The comparison of catalyst types showed that there was little difference in the denitrogenation and desulphurisation efficiency of the two catalysts.