Fundamental Research On Classified Utilization Of High-temperature Coal Tar Pitch

With the rapid development of carbon materials industry,high-temperature coal tar pitch was generally used as the high-quality precursor to produce carbon materials.What's more,using separation method to obtain varied raw materials with different properties has been a hot topic in the high value-added carbon materials production field.In order to achieve the optimal utilization of pitch resources,series fundamental research works had been carried out on the classified utilization of high-temperature coal tar pitch in this paper.Briefly,the basic properties and application directions of different pitch components obtained by extraction and separation had been explored in detail.The results showed that:(1)Refined pitch and heavy-phase pitch(quinoline insoluble content was 0.16%and 6.75%,respectively)were obtained by extraction and separation of high-temperature coal tar pitch.Compared with the heavy-phase pitch,the refined pitch had a lower degree of aromatic condensation and rich branched chains.The non-isothermal pyrolysis kinetics research showed that the pyrolysis activation energies of refined pitch and heavy-phase pitch were 62.81kJ·mol^-1 and 104.69kJ·mol^-1,respectively.The pyrolysis mechanism model was in accord with random nucleation and its subsequent growth.Furthermore,the content of leaflet and fibrous structure in thermal conversion product from refined pitch was as high as 95.26%,and the crystalline structure tended to be more orderly.However,"honeycomb"appeared on the surface of the thermal conversion product of heavy-phase pitch,which presented more mosaic structure in the optical structure,and the micro-strength reached 85%.(2)Submicron green balls which with a yield of 50.98%were obtained after polymerization and separation of heavy-phase pitch,the volatile content was only10.82%,and had terrific thermal stability.After calcination at 1400?,the average diameter(D50)of the submicron carbon balls was 0.369?m,the contents of ideal graphite microcrystalline and amorphous carbon were 13.59%and 10.31%,respectively.The lateral size of microcrystalline was 2.06nm.In particular,removal rate of COD from coking wastewater(COD=1730.32mg·L^-1)could reach 100%when the Fenton-reaction was carried out by using the iron-based carbon electrode prepared by submicron carbon balls.(3)Modified pitch could be directly molded to produce green carbon blocks after pretreatment,and the bulk density could reach 1.304g·cm^-3.The bulk density of the carbon blocks increased continuously during the process of calcination,when the calcination temperature reached 600?,bonding interface between the particles of carbon block began to become blurred,sintering nodes appeared as the temperature rises,and the compact carbon block was finally formed.After calcination at 1400?,the bulk density reached 1.606g·cm^-3,even more to the point,the maximum compressive strength was 170.30MPa.During the calcination process,the D/G band ratio decreased gradually,it meant that carbon structure in the material tend to be orderly.(4)Four pitch components obtained by separation and modification method were prepared into pitch derived carbons and its graphitization properties were related as follows:RP-Coke>DP-Coke>Carbon blocks>Submicron carbon balls.The"stacking fault"phenomenon leaded to the evolution of the layer spacing of pitch derived carbons increasing at first and then decreasing in the calcination process.The L_c and N of four pitch derived carbons showed"inflection point"at 1000?,and the microcrystalline size decreased slightly.With the increase of calcination temperature,the D band gradually narrowed and the peak position shifted back.The content of ideal graphite microcrystalline in the four pitch derived carbons kept increasing,what's more,the content of defective graphite microcrystalline gradually decreased and changed to ideal graphite microcrystalline.