Hydroprocessing of a Maya residue. Intrinsic kinetics of sulfur-, nitrogen-, nickel-, and vanadium-removal reactions

A residue from a Maya crude was processed in a hydrotreating unit with a co ntinuous stirred tank reactor at high temperatures (375-415 degrees C) and hydrogen pressures (10-15 MPa). A commercial guard-bed demetalation catalys t Ni-Mo supported on gamma-Al2O3 was used. In this paper, the intrinsic kin etics of the sulfur-, nitrogen-, nickel-, and vanadium-removal reactions ar e reported. The sulfur-removal reactions fit second-order kinetics, the nit rogen-removal reactions half-order kinetics, the nickel-removal reactions f irst-order kinetics, and the vanadium-removal reactions half-order kinetics . The nickel-removal reactions showed the highest value for the activation energy. The sulfur-removal reactions were the only ones that had a dependen ce on the hydrogen pressure in every range of hydrogen pressures studied, 1 0-15 MPa, and a kinetic order of 0.4 has been observed. For nitrogen-, nick el-, and vanadium-removal reactions, an increase of the pseudokinetic const ants was only observed between 10 and 12.5 MPa. The percentages of sulfur-r emoval range from 22% to 79.3%, nitrogen conversion from 3.7% to 50.9%, nic kel conversion from 32.1% to 98.8%, and vanadium conversion from 40.1% to 9 9.7% at 375 degrees C, 10 MPa, and 7.1 Uh g(cat) and 415 degrees C, 12.5 MP a, and 3.3 L/h g(cat). The relationships between the percentages of sulfur- removal and metal-removal were studied.