Hydrodesulfurization of Cold Lake Diesel Fraction Using Dispersed Catalysts:  Influence of Hydroprocessing Medium and Sources of H₂

Abstract

The hydrodesulfurization (HDS) of a straight-run diesel fraction of a Cold Lake crude was investigated using ammonium tetrathiomolybdate (ATTM) and phosphomolybdic acid (PMA) as dispersed catalysts. The experiments were performed in an autoclave at 340 °C using different hydrotreating media such as H2, H2/H2O, and H2 generated in situ from CO/H2O via the water gas shift reaction (WGSR). The external supply of molecular hydrogen proved to be the most effective medium for HDS with both catalysts, while similar levels of sulfur removal were achieved using either the H2/H2O or the CO/H2O medium. Desulfurization using molecular H2 was thus apparently inhibited by the addition of water to the feed, while H2 generated in situ proved to be at least as efficient at removing sulfur from diesel as using molecular H2 in the presence of water. Under our reaction conditions, ATTM exhibited greater activity for HDS and for the WGSR than PMA. This work demonstrates that Mo-based dispersed catalysts and partial oxidation flue gases containing CO, H2O, CO2, and H2 can be used to achieve satisfactory levels of sulfur removal from an industrial-type feedstock, as well as the feasibility of using dispersed catalysts and recycle streams for the treatment of heavy oil emulsions.

Hydrocracking of Heavy Oil by Means of In Situ Prepared Ultradispersed Nickel Nanocatalyst

“…Ultradispersed (UD) catalysts display a number of characteristic advantages over the supported bulk catalysts, including minor deactivation, high inhibition of coke formation, ease of resulfiding, and a high degree of catalytic metal utilization due to the absence of diffusion limitations. − UD catalysts possess much more accessible reactive sites per unit mass, thereby allowing large complex molecules, including heavy hydrocarbons, to react rather than plugging pores as in supported catalysts . For example, dispersed Mo-based catalyst, derived from MoO 2 (acetylacetonate) 2 , increased the conversion of the extra-heavy crude fractions with boiling points >500 °C to lighter cuts in the presence of methane as a source of hydrogen .…”

Hydrodesulfurization Activity of MoS2 and Bimetallic Catalysts Prepared by in Situ Decomposition of Thiosalt

“…This can be explained as that ATM was dissolved in water which was dispersed in fine droplets in decalin under agitation and then decomposed upon heating under hydrogen pressure to produce finely dispersed MoS 2 catalyst . In addition, water might affect the activity of the catalyst by altering the phase equilibria in the reactor or directly modifying the nature of the active catalytic species …”

Sustainability Effect of Water Gas Shift Reaction (Syngas) in Catalytic Upgrading of Heavy Crude Oil and Bitumen

“…In heavy crude oil and bitumen upgrading where the hydrogen is supplied from syngas, the source is usually from water in-situ [13] or introduced into the reactor alongside feedstock [20,[25][26][27][28][29][30][31]. Irrespective of the method of providing water, the reactor would be pressurized in a neutral environment, usually nitrogen to mimic reservoir conditions.…”