Effect Of Ultrasonic Treatment On Composition And Properties Of Heavy Oils

Due to the imbalance between oil supply and demand,and the declining quality of crude oil,many reasons force people to focus on the processing and utilization of heavy oil.But the complexity of heavy oil structure and the fact that most of the processing processes need to be carried out under high temperature and pressure conditions,the energy consumption and technical requirements of heavy oil treatment process are increased.Ultrasonic processing,as a green and efficient processing method,has attracted extensive attention in the processing of heavy oil.In this paper,the effects of ultrasonic power on the properties of Marei atmospheric residual oil(MRAR)were investigated by ultrasonic treatment.It was found that the medium power(40%)ultrasonic treatment condition was sufficient to produce ultrasonic effect.Saudi Arabia vacuum residuum(STVR)and Venezuela atmospheric residuum(WNAR)were treated by medium power ultrasound.SARA component analysis and simulated distillation analysis were used.The results showed that with the increase of ultrasonic time,the content of saturated fraction first decreased and then increased,the content of aromatic fraction and resin first increased and then decreased,the content of asphaltene significantly decreased;the content of heavy fraction decreased gradually and the content of light fraction gradually increased,which could realize the process of conversion from heavy component to light component.In this paper,the colloidal stability before and after STVR ultrasonic treatment was explored.The results showed that the ultrasonic treatment can effectively improve the stability of the colloidal stability.The elemental content,relative molecular weight,~1H-NMR and structural parameters of STVR dispersive media before and after ultrasonic treatment were analyzed.The results showed that ultrasonic treatment can change the composition of colloidal dispersion medium.After ultrasonic treatment,the saturated fraction contained desorbed small molecule structure,asphaltene fracture structure and"asphaltene like"fracture structure.The converted heavy component contained aromatic ring structure.The aromatic naphthenic rings undergo a ring-opening reaction,most of the adsorbed saturated fractionals were desorbed,and most of the adsorbed asphaltene fracture structures are retained in the components.The side chain structure of the resin was broken,and a small part of the aromatic ring structure was shed off.Most of the adsorbed asphaltene fracture structures were desorbed,and most of the adsorbed saturated sub-fracture structures were retained in the components.The molecular structure change of STVR asphaltene before and after ultrasonic treatment was investigated by the same characterization method as that of dispersion medium.The results showed that the molecular structure of asphaltene can be destroyed by ultrasonic treatment,and the ring opening and fracture reaction of naphthenic ring can be carried out,and the aromatic ring structure can be detached.However,the association between unit lamellaes is enhanced.The STVR and WNAR asphaltenes before and after ultrasonic treatment were analyzed by SEM,FT-IR and XRD.The results showed that the degree and way of structural change of asphaltenes from different sources are different by ultrasonic treatment.Although the association of unit flakes was enhanced for the two kinds of residue,STVR asphaltenes were more prone to naphthenic ring opening fracture reactions,while WNAR asphaltenes were more prone to side chain fracture reactions.And the degree of damage is less than STVR,and the reduction of alkyl side chain is lower.