Asphaltene characterization as function of time on-stream during hydroprocessing of Maya crude

Determining a series of physical parameters has allowed the behavior of the asphaltene constituents to be monitored during hydrotreating of Maya crude oil. In keeping with the thermal behavior of the asphaltenes constituents, the observations are the aromaticity of the asphaltene increases with time-on-stream and the number and length of the alkyl chains decreases. Sulfur and nitrogen constituents tend to accumulate in the asphaltene before giving rise to carbenes, carboids, and coke. As the reaction progresses, the nickel and vanadium concentrate in the asphaltene fraction, but only to a point (up to 700-h on-stream). After 700-h on-stream, the nickel and vanadium contents of the asphaltene fraction are reduced presumably because the nickel and vanadium concentrate on the coke that is laid down on the catalyst.