Study on the Structure of Fractional Extraction Components by Different Solvents From Saudi Heavy Vacuum Residue and Their Effects on Performance of Catalytic Conversion Under Hydrogen Atmosphere
Using the soluble and insoluble substances obtained from the fractional extraction of Saudi heavy vacuum residue by four different solvents including methylbenzene,n-pentane,n-heptane,and the mixture of n-heptane and methylbenzene at a volume ratio of 3/1 as raw materials and the deasphalted oil(DAO),catalytic diesel oil(LCO)and FCC-slurry oil as solvent oils,the catalytic hydrogenation thermal conversion were conducted at the temperature of 415 ℃,hydrogen initial pressure of 7 MPa,extraction component mass fraction of 10％,and catalyst mass fraction of 1000 μg/g and reaction time for 1 h.This aims to study the structural characteristics of extraction components,the difference in performance of thermal reaction under hydrogen atmosphere,and the influence of solvent oils on the conversion of pentane asphaltene.The results indicate that the molecular structure of the five extraction components from Saudi heavy vacuum residue is mainly of the isolated island type,with the composition of sulfur compounds accounting for over 70％,and each molecule contains at least 1-2 sulfur atoms.The catalytic thermal reaction under hydrogen atmosphere shows that polysulfide compounds can achieve not only desulfurization but also lightweighting of the components with isolated island type structure through the directed hydrogenation-selective desulfurization reaction path,which can be also converted into aromatic compounds.This is a key reaction for the total conversion rate of five fractionated extraction components,i.e.,n-pentane asphaltene(C5As),n-heptane soluble substance(C7S),n-heptane asphaltene(C7As),mixed solvent 1 soluble substance(M1S),and mixed solvent 1 asphaltene(M1As),to exceed 97％,and the lightweighting rates of C7S,C5As,and M1S are greater than 94％.C7As was obtained after the extraction separation of C7S from C5As,and the condensation rate of C7As was increased by 218％in catalytic conversion under hydrogen atmosphere.Through further research,it has been found that the good solubility and high saturation solubility of C7As in C7S is the essential reason for a significant increase in the condensation rate of C7As in thermal reaction under hydrogen atmosphere after removing C7S.The capability of solvent oils in inhibiting the thermal reaction under hydrogen atmosphere and condensation reaction of pentane asphaltene is listed in the descending order of LCO＞FCC slurry oil＞DAO,which is closely related to the lower saturated component content and the highest pure aromatic content of the solvent oil responsible for hydrogen transfer in reaction process.
fractional extractioncatalytic conversion under hydrogen atmospheresolubility parameterS-containing compoundsisolated island type structure transformationsolvent oil hydrogen transfer
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维普
