Basic Research On Preparation And Application Of Binder Pitch

Coal tar pitch is a complex organic compound composed of many kinds of thick cyclic aromatic hydrocarbons.It has the characteristics of high carbon content,excellent physical and chemical properties and a wide range of sources.It is widely used in many fields such as the preparation of artificial carbon/graphite materials.As a kind of special pitch,binder pitch is used as a binder in the production process of carbon materials because of its excellent bonding characteristics,which affects the strength of carbon materials,electrical and thermal conductivity properties.With the rapid development of economy,the quality requirements of carbon materials（especially graphite electrodes and negative electrode materials of lithium ion batteries）are becoming higher and higher in the market,so higher requirements are put forward for the quality of binder pitch.How to improve the quality of binder pitch and improve and optimize the preparation process become one of the important issues in the carbon material production industry.In this thesis,medium temperature pitch is selected as raw material,and the optimum reaction conditions for preparing binder pitch is selected by controlling reaction temperature,reaction time,air flow,gas type.The best reaction conditions is used to explore the influence of different sources of raw pitch on the properties and coking of binder pitch,and to explore the bonding performance of binder pitch.The results showed that:（1）The two step process of oxidative polymerization and thermal condensation can effectively improve the softening point,QI,TI and coking value of pitch.In the modification process,the raw pitch is oxidized by air at 280℃for 3 h（air flow is 0.04m³/h）,then heated up to 360℃for 1 h（N₂flow is 0.06 m³/h）to obtain binder pitch（softening point is 144℃,QI content is 0.46%,TI is 26.74%,coking value is 51.53%,volatile component is 56.65%）,which improve the aromatic condensation degree of pitch,and the small and medium molecular branched chain structure of asphalt is reduced.In this case,the residual carbon content of asphalt after pyrolysis is the highest,which is 45.12%.（2）Four kinds of refined pitch from different sources are selected to prepare a series of binder pitch through the optimum reaction conditions.The macro indexes of the four binders are very similar,but there are some differences in molecular structure.After pitch modification,the temperature range of asphalt pyrolysis became smaller,the total weight loss rate of AS-MP samples is the highest,reaching 66.89%,while KL-MP is the lowest,reaching 51.32%.The coking of binder pitch is mainly composed of sheet structure,the content is about 70%and there are some coarse fibrous structures with few mosaic structures.The microcrystalline structures of AG-MP,XJ-MP and AS-MP tend to be more regular while the content of I_greached about 90%,the microcrystalline arrangement of KL-MP is relatively irregular.Four kinds of binder pitch coke skeleton strength is better,the microscopic strength is about 70%.（3）A series of carbon blocks are prepared by mixing and carbonizing a series of binder pitch and needle coke aggregate in a certain proportion.The yield of carbon block decreases with the increase of pitch content.When the pitch content is 50%,the carbon block is the most complete and the drum strength is the highest reached about104.The change of microscopic strength gradually increases with the increase of pitch content,but KL-C is smaller than the other three kinds.The microcrystalline structure of the mixed coke with XJ-C-50,AG-C-40 and KL-C-30 ratios is the most orderly,while the microcrystalline structure of AS-MP becomes irregular after mixing with the needle coke,which can be concluded that its own bonding properties and the resulting product properties are poor.