Study On Modification Of Coal-tar Pitch And Microstructure Of The Carbonization Products From Coal Pitch Group Component

In this papar, the coal pitch was divided into TS, TI, ? resin and QI by solvent separation method and then carbonizated corr esponding. The chemical structure, the thermal polycondensation charateristics and the microstructure of their carbonization products were researched. Then, the medium temperature coal-tar pitch was modified by catalytic polycondensation with AlCl₃. The influence of process conditions on component composition and microstructure propert ies of modified coal tar pitch was researched systematically.The chemical structure of coal-tar pitch and its components was researched by FT-IR. The results show that the TS component has a small molecular weight. There are abundant lateral chain and groups in the aromatic hydrocarbons. The molecular weight of ? resin component is big. The lateral chain and groups in the aromatic hydrocarbons are few. The molecular weight of QI component is biggest. They are highly condensation polycyclic aromatic molecules.The thermal polycondensation charateristics of coal-tar pitch and its components was researched by TG-DTA. The results shows that the TS component begins to loss its mass at low temperature with about98 ?. Stability of mo lecules of TS componert is poor and its loss ratio is 79.50%. The ? resin begins to loss its mass at high temperature that is about 208 ? and its loss ratio is 19.2%. The initial loss weiht temperature of Q I component is highest,which is about400?. The weight loss curve of QI component is gentle and its loss ratio is only 7.06%.The microstructure and performances of the ircarbonization products were researched by SEM, TEM and XRD. The research shows that the structure of TS product are mainly the streamline with small content of region. Its microcrystalline is in good orientation and parallel with the layer distances as low as 0.34 0.35 nm. The structure of TI product is concentrated in mosaic and region structure type. The orientation of crystalline is disorder and blend in partial position with the layer distance larger than 0.35 nm. ? resin product is mainly the streamline type while the QI product is constituted with isotropy micron fine particles and the orientation of its micro-crystalline is disordered, which forms the complicated entwined structure.The medium temperature coal-tar pitch was modified with AlCl₃.The effect on basic properties and component composition by the mod ification process conditions was researched. The research shows that the higher modified temperature, the softening point of and the carbon yield of modification coal-tar pitch are higher, and increase greatly a fter the modified temperature is about 260 ?; The higher the content of modified agent, the softening point of and the carbon yield of modification coal-tar pitch are higher, but their growth decelerate after the content of modified agent temperature is 6%; The longer the modified time is, the softening point of and the carbon yield of modification coal-tar pitch are higher.The microstructure of the carbonization products of coal-tar pitch modified at different process conditions was investigated by polarizing microscope and SEM. The results show that with the increase of the modified temperature, the regional structure area of modified coal-tar pitch coking products increased first and then decreased, mosaic structure area decreased first and then increased. With the increase of the content of modified agent, the regional structure area of modified coal-tar pitch coking products increased first and then decreased, mosaic structure area decreased first and then increased. With the increase of the modified time, the regional structure increased and the mosaic structure decreased.The thermal polycondensation charateristics of coal-tar pitch and modification coal-tar pitch was researched by TG-DTG. The results show that the initial loss weight temperature of the coal tar pitch is about 126 ?. Its end loss weight temperature is about 585? and the loss weight ratio is about 60.54%, the modification coal-tar pitch has higher initial loss weight temperature, lower loss rate and lower end loss weight temperature. The value are 158 ?, 50.08%, 572?respectively. The weight loss rate of the fastest temperature is about426 ?and about452? before and after coal-tar pitch before and after modification. The curve of modified pitch shifts to high temperature and ithas better thermal stability.