The hydrotreating (HT) and mild hydrocracking (MHC) of gas oil derived from Athabasca bitumen have been performed in a micro trickle-bed reactor, using a commercial NiMo/Al2O3 catalyst. The operating conditions were varied as follows:  temperature range, 340−420 °C; reactor pressure, 6.5−11.0 MPa; liquid hourly space velocity (LHSV) range, 0.5−2.0 h-1; and hydrogen/gas oil ratio, 600 mL/mL. The removal values of sulfur and total nitrogen, basic nitrogen, and non-basic nitrogen obtained under optimum conditions were 99, 92, 99, and 88 wt %, respectively. The highest selectivities for sulfur and basic nitrogen removal occurred at the lowest temperature and pressure and the highest LHSV values (i.e., 340 °C, 6.5 MPa, and 2 h-1, respectively), whereas those for total and non-basic nitrogen removal occurred at the highest temperature and pressure and the lowest LHSV values (i.e., 420 °C, 11 MPa, and 0.5 h-1, respectively). High levels of aromatic saturation were also observed (22.7 wt % aromatics at 400 °C and 11 MPa). The overall boiling point of each product fraction decreased over the entire temperature range, because of (i) the conversion of sulfur and nitrogen heteroatoms at lower temperatures (≤380 °C) and (ii) MHC at higher temperatures (>380 °C). The yield and selectivities of gasoline, kerosene, and light gas oil (LGO) increased as the operating severity increased. The highest yield of gasoline (10 wt %), kerosene (12 wt %), and LGO (19 wt %) were obtained at the highest severity of 420 °C. Vacuum gas oil (VGO) was the main fraction of the gas oil feed that apparently underwent conversion. No apparent significant change was observed in the net content of the heavy gas oil (HGO) fraction under all operating conditions. A reaction pathway is postulated for the conversion of the gas oil to products via heteroatom removal, saturation of aromatics, and hydrocracking.

Hydrotreating (HT) kinetics of Athabasca bitumen‐derived gas oil has been studied between 340 to 420°C using a commercial NiMo/γ‐Al2O3 catalyst. The kinetics analyses included overall conversion of high‐boiling species into low‐boiling products, hydrodenitrogenation (HDN) of total, basic and non‐basic nitrogen compounds and hydrodesulfurization (HDS). Three temperature regimes were marked out for the kinetic analyses: low (340‐370°C), intermediate (370‐400°C) and high (400‐420°C). The mechanism for the conversion of high to low‐boiling species was observed to change from one temperature regime to the other, giving rise to different activation energies. HDS and HDN activation energies increased in the order: high < low < intermediate severity temperature regime.

Two-stage hydrodenitrogenation (HDN)−hydrodesulfurization (HDS) of heavy gas oil, derived from Athabasca bitumen, has been carried out in a trickle-bed microreactor using a commercial NiMo/Al2O3 catalyst. The operating conditions for the experiments were varied as follows:  temperature range of 340−420 °C, reactor pressure of 950−1600 psig, liquid hourly space velocity range of 0.5−2.0 h-1, and hydrogen to heavy gas oil ratio of 600 mL/mL. Variation in the catalyst loading between stages I and II was also studied. Stage I products were stripped off any generated hydrogen sulfide and further hydrotreated in stage II to see the impact of hydrogen sulfide interstage removal on the hydrotreating activities. A comparison of the two-stage results to those of the single-stage results shows an enhancement in the hydrotreating activities. For instance, a 12.6 wt % increase in the conversion of nonbasic nitrogen was observed. The optimum conditions for higher gain in HDN and HDS due to hydrogen sulfide removal were found to be 380 °C, 7.6 MPa, and 1:3 (w/w) catalyst loading. A Langmuir−Hinshelwood model developed for the hydrogen sulfide inhibition predicts sufficiently the observed data of the two-stage process.