Study On Mechanism Of Preparation Of Mesophase Pitch By Naphthenic Heavy Distllates

This research aimed to prepare the mesophase from naphthenic heavy distillates by two-step transformation method,gas stripping method and reforming co-carbonization method The effects of the properties of the raw materials and the preparation conditions on the formation of mesophase pitch were investigated.The structural changes in the mesophase formation were studiedThe influence of pressure modulation on the formation of mesophase structure was studied,and the mesophase pitch with better optical structure was prepared.At the reaction temperature of 480?,the reaction pressure from 9MPa to 6MPa,the large watershed mesophase pitch can be prepared.Through the analysis of polarized structure and sub composition,it is shown that the high temperature and high pressure in the early stage is favorable for the generation of ferrite macromolecules and the orderly arrangement of the small molecules in the free radicals,comparing with no change pressure.The results show that the better mesophase products can be prepared with the periodicity pressureThe mesophase pitch was prepared by gas extraction,and the influence of the physical force on the pellet and the process were investigated.In the process of pressure conversion operation,the nitrogen gas stripping was introduced to obtain the better mesophase pitch XRD of the mesophase pitch showed the interlayer spacing d002?0.3462,the packing height Lc = 2.69,comparing with no gas stripping,the increase of the accumulation of layers indicates that the gas can promote the well-organized accumulation of the planar aromatic hydrocarbon macromolecules greatly.The results show that with the prolonging of the purge time,the ability of the well-organized accumulation of the fused ring aromatic hydrocarbon lamellar molecules was weakened,the lattice parameter interval d002 was increased,the corresponding crystal size Lc,the average number of crystal layers M and the molecular orientation degree Og show a tendency to decrease overall,all that indicate the crystal of the aromatic component was defective and the crystallinity decreases with the prolonging of the purge time,so the stacking structure is more disordered and the preferential orientation is becoming worse.It shows that the stripping process can change the viscosity of the system and provide axial force for the fused ring piling,which makes the crystal orientation of the crystal molecules better and affects the structure of mesophase pitchA mesophase pitch product with better texture structure was prepared by introducing hydrocracking tail oil(HCTO-1)which is a co-carbonization additive in the process of pressurized gas stripping.The XRD analysis of the product shows that the interlayer distance d002 is decreased,but the accumulation of the height Lc is increased,which means that when the interlayer distance is reduced,the number of layers accumulation and the degree of orientation Og become larger,co-carbonization agent can make the plane fused macromolecules accumulate more orderly,the analysis of the co-carbonization agent and the nature of the material oil IR shows that the substituents are few and short,cycloalkyl structure,co-carbonization agent was still a good solvent,The dissolution of the system reduced the viscosity of the system,slowed the change of the viscosity of the carbonization,and caused the small molecule to move to form the macromolecule fused ring.In addition,the hydrogen transfer reaction could produce the free radicals by the early pyrolysis get neutralized and controlled the corresponding carbonation process.A better mesophase structure is prepared.