Study On The Preparation Of Meso-Pitch Microbeads By Suspention

The developments of preparation and application of Meso-carbon microbeads (MCMBs) was introduced. On the basis of that, polymerization and suspension were chose to prepare meso-pitch and Meso-pitch microbeads (MPMBs). MPMBs were applied as precursors of MCMBs. The influences of raw materials and process technologies on MPMBs' microcosmic figure and diameter distribution were investigated.We chose petroleum pitch as raw material to prepare mesophase pitch by polymerization. Under the conditions of 370℃ for 20h, 380℃ for 20h and 400℃ for 10h, the mesophase pitches labeled as AMP-1, AMP-2 and AMP-3 respectively were prepared. They were characterized by FI-IR, XRD, TG-DTA and optical microscope. The results of FT-IR and optical microscope show that the content of mesophase of AMP-1, AMP-2 and AMP-3 is 96.1%, 98.2% and 99.0% respectively. The results of XRD indicate that the interlayer spacing d₀₀₂ of AMP-1, AMP-2 and AMP-3 decreases and the crystallite height Lc increases sequentially. TG-DTA shows that carbon yields of AMP-1, AMP-2 and AMP-3 minish. Element analysis indicate that H/C ratio of the three mesophase pitches are 0.73, 0.68, 0.61 respectively. Solubility analyses indicate that they can well dissolve in THF, toluene, pyridine and quinoline. Characters mentioned above indicate the mesopitches should meet the demand of preparing MPMBs by suspensionSuspension was used to prepare MPMBs. Scanning electron microscope (SEM) and diameter distribution analysis were applied to study the MPMBs' appearance and diameter distribution effected by heat-treatment medium, raw material, solvent, concentration and ratio, stirring speed, heat-treatment temperature and time. The experimental results show that good sphericity and narrow diameter distribution is obtained when silicon-oil is chosen as heat-treatment medium. Comparing with other two mesophase pitches, AMP-2 can produce MPMBs with higher yield and smallersize. When quinoline is used as solvent, the diameter distribution is narrowest and the average diameter is smallest. However, because of high power-cost and toxicity, quinoline is instead by toluene that can also be used to prepare MPMBs with smaller diameter. With the increasing of concentration and ratio of solution to heat-treatment medium, MPMBs' average diameter increases. MPMBs with good sphericity, high yield and small diameter is obtained when the ratio is 10:1 in our experiments. With the increasing of stirring speed, MPMBs' average diameter becomes larger. However, too low and too high stirring speeds lead to difficult separation of MPMBs. MPMBs felt each other if higher heat-treatment temperature or longer heat-treatment time be applied. It is discovered that MPMBs can be well separate when the mesopitch is heat-treated at 270 °C for 35 min.