Batch Reactor Study of the Effect of Aromatic Diluents to Reduce Sediment Formation during Hydrotreating of Heavy Oil

Abstract

The effect of different aromatic diluents on sediment formation during the catalytic hydrotreating of heavy crude oil was studied. The experiments were carried out using a heavy crude oil with 11.69 °API and three aromatic streams from an industrial Fluid Cracking Catalytic plant: light cycle oil, heavy cycle oil, and decanted oil. All tests were performed in a batch reactor at reaction time of 2–4 h, reaction temperature of 380–420 °C, and addition of aromatic diluents in 5 and 10 wt % with respect to the crude oil. The reaction pressure and stirring rate were kept constant at 100 kg/cm2 and 1000 rpm, respectively. The results of the hydrotreating tests showed that the amount of sediment increases as the time and reaction temperature do, being the temperature the variable that has the greatest effect on sediment formation. Light cycle oil provides a greater suppression of sediments. This effect was attributed to the greater amount of total aromatic compounds (mainly diaromatics) able to keep asphaltenes solvated.

Intercriteria Analysis to Diagnose the Reasons for Increased Fouling in a Commercial Ebullated Bed Vacuum Residue Hydrocracker

“…This data shows that the strongest negative consonance of μ = 0.11 (υ = 0.89) has the ATB aromatics content, confirming that increasing the aromatics content by addition of high aromatic FCC gas oils will have a depressing effect on sediment formation rate and consequently on fouling. 9 − 12 Several H-Oil ATB characteristics like Kw-characterizing factor and the colloidal instability indices based on C 5 and C 7 asphaltenes showed a statistically meaningful positive relation to the fouling. This means that their enhancement promotes fouling.…”

“… 5 − 8 Considering the mechanism of coke-like sediment formation, different strategies have been employed to reduce fouling and allow severity enhancement to magnify conversion and meet both key performance indicators in the commercial residue hydrocrackers. 9 − 19 These strategies are (1) an addition of high aromatic oil fractions, 9 − 12 (2) an antifouling additive employment, 13 , 14 (3) a molecularly dispersed nanocatalyst application, 15 − 18 (4) deasphaltization of vacuum residue feed, 19 and (5) a selection of crude oils whose vacuum residues are less prone to sediment formation. 20 , 21 The effect of the different strategies to mitigate fouling can be well defined in the laboratory hydrocrackers.…”

“…Irrespective of the high conversion achievable in the vacuum residue hydrocracking, the formation of coke-like sediments and the related equipment fouling still remain as the main constraint in the aim of increasing both cycle length and conversion in the commercial residue hydrocrackers . The rate of coke-like sediment formation has a complex dependence on the initial aromatic structures in the asphaltenes and vacuum residue, the rate of addition (radical recombination) reactions, and the solubility of reacted asphaltenes and the products of addition reactions. − Considering the mechanism of coke-like sediment formation, different strategies have been employed to reduce fouling and allow severity enhancement to magnify conversion and meet both key performance indicators in the commercial residue hydrocrackers. − These strategies are (1) an addition of high aromatic oil fractions, − (2) an antifouling additive employment, , (3) a molecularly dispersed nanocatalyst application, − (4) deasphaltization of vacuum residue feed, and (5) a selection of crude oils whose vacuum residues are less prone to sediment formation. , The effect of the different strategies to mitigate fouling can be well defined in the laboratory hydrocrackers. However, in the commercial hydrocrackers, a distinction of the effect of the different actions to affect fouling can be strongly obscured.…”

Industrial Investigation of the Combined Action of Vacuum Residue Hydrocracking and Vacuum Gas Oil Catalytic Cracking While Processing Different Feeds and Operating under Distinct Conditions

“…Therefore, in this case, the polycondensed di-and tri-aromatics contained in the FCC HCO seem to be more efficient in sediment formation inhibition than the mono-and di-aromatics contained in the FCC LCO and the tri-, tetra-, and penta-aromatics contained in the FCC SLO. In a study by Tirado and Ancheyta [69], it was shown that mainly di-aromatics containing in the FCC LCO were the best suppressors of sediment formation during the hydroprocessing of a heavy crude oil. The results of Tirado and Ancheyta [69] indicated that the addition of 10 wt.% of FCC SLO led to more sediment formation than the hydrocracking of pure vacuum residue, which is a very convincing indicator of the very complex matter of sediment formation during vacuum residue hydrocracking.…”

“…In a study by Tirado and Ancheyta [69], it was shown that mainly di-aromatics containing in the FCC LCO were the best suppressors of sediment formation during the hydroprocessing of a heavy crude oil. The results of Tirado and Ancheyta [69] indicated that the addition of 10 wt.% of FCC SLO led to more sediment formation than the hydrocracking of pure vacuum residue, which is a very convincing indicator of the very complex matter of sediment formation during vacuum residue hydrocracking. Understandably, such a process is very difficult to model and fully comprehend.…”