Sulfidation of a Dispersed Molybdenum Catalyst with Hydrogen Sulfide Formed from Hydroconversion of Petroleum Feedstock

The paper investigates the sulfidation of the precursor of a dispersed molybdenum catalyst consisting of 190-500 nm particles in the hydroconversion of crude oil vacuum residue. The experiments were carried out in a flow-through autoclave reactor system at a hydrogen pressure of 2.5 MPa, in the temperature range of 380-440 degrees C, and with a reaction time of 50-150 min. The catalyst sulfidation was demonstrated to result from a reaction with H2S, which is formed from the thermal decomposition of petroleum feedstock. The sulfidation at 380-400 degrees C is a fairly slow process. At higher hydroconversion temperatures (420-440 degrees C), the H2S concentration in the gas phase grows. However, the formation of compaction products creates a diffusion barrier for H2S transportation to the surface of the catalyst particles and, thus, prevents the precursor from being converted completely to the sulfide form. To enhance the degree of sulfidation, it is preferable to use sulfiding agents that ensure that hydrogen sulfide is formed under the hydroconversion conditions of heavy petroleum feedstock.