The Distribution of Ni and V in Resin and Asphaltene Subfractions and Its Variation During Thermal Processes

Abstract

Ni and V deactivate catalysts and promote coking during heavy oil upgrading. Distribution of metals and metalloporphyrins, and its variation in thermal process, would benefit the more efficient upgrading. Majority of metals concentrate in resins and asphaltenes. To thoroughly study the metals distribution in these fractions, both were subdivided. It is indicated that the interactions between metalloporphyrins and asphaltenes play a significant role in metals distribution. Variation of metals distribution showed that the trend metals concentrated into heavier subfractions and was enhanced by thermal treatment and inhibited by hydrogen sources. Synergism was observed between hydrogen and hydrogen donor for the inhibition.

Microwave-assisted Petroporphyrin Release from Asphaltene Aggregates in Polar Solvents

“…The total vanadium content in the SF after microwave treatment was more than twice that in the asphaltenes, which was almost as high as that in the purified subfractions of a silica gel open column chromatography experiment . By using the integral molar absorptivity of the Soret band published by Strong, the calculated concentration of the porphyrinic vanadium in the SF (using Figure b, red line) was about 1898 ppm, indicating that about 82 wt % of vanadium in the SF presented as the porphyrinic form, which was slightly higher than that in the extracted subfractions of asphaltenes . Although 57 wt % of the total vanadium content in asphaltenes was still retained in the IF, the Soret band of vanadyl porphyrins at 408∼410 nm was completely absent (Figure , blue line), illustrating that all vanadium in the IF should be classified as the nonporphyrinic one.…”

“…20 By using the integral molar absorptivity of the Soret band published by Strong, 30 the calculated concentration of the porphyrinic vanadium in the SF (using Figure 4b, red line) was about 1898 ppm, indicating that about 82 wt % of vanadium in the SF presented as the porphyrinic form, which was slightly higher than that in the extracted subfractions of asphaltenes. 9 Although 57 wt % of the total vanadium content in asphaltenes was still retained in the IF, the Soret band of vanadyl porphyrins at 408∼410 nm was completely absent (Figure 4, blue line), illustrating that all vanadium in the IF should be classified as the nonporphyrinic one. The total nickel content in the SF was only 141 ppm, probably because the low dipole moment of nickel complexes reduced the molecular response to the microwave, which made the petroporphyrin release from asphaltene aggregates more difficult.…”

“…Due to the material differences, it would be farfetched to state that this method was more efficient than the Soxhlet extraction method reported by Xu et al 14 But, the great difference in petroporphyrin contents between two subfractions has rarely been reported. 9,34 Therefore, further comparisons with the Soxhlet extraction method are discussed later in this paper.…”

“…Generally, about 80 wt % of vanadium and 70 wt % of nickel in residues are concentrated in asphaltenes. 8,9 But, few specialized methods have been published to separate petroporphyrins from asphaltenes.…”

“…Among heavy oil fractions, asphaltenes present the highest degree of association and the highest amount of vanadium and nickel. Generally, about 80 wt % of vanadium and 70 wt % of nickel in residues are concentrated in asphaltenes. , But, few specialized methods have been published to separate petroporphyrins from asphaltenes.…”