Medium Temperature Coal Tar Pitch Research Articles

Complex research of the components of the coal tar pitch

The composition, structure and morphology of particles of β-and α2-fraction powders of medium-temperature coal tar pitch were studied using the methods of electron microscopy, adsorption porosimetry, NMR, IR-EPR spectroscopy, X-ray diffractometry, thermal analysis, and chromatography-mass spectrometry. The morphology and structure of coke residues were investigated depending on the heating temperature. It has been established that polyaromatic hydrocarbons in the composition of volatile products of thermolysis of coal tar pitch are formed mainly during the decomposition of the β-fraction components. The results obtained are of interest from the point of view of the directions of using the isolated fractions of coal tar pitch as precursors for obtaining functional carbon materials.

Зависимость модификации структуры каменноугольного пека от различных углеродных добавок

The work is devoted to the study of changes in the basic structural characteristics of coal tar pitch during carbonization with various carbon additives that have different textural characteristics. An industrial medium-temperature coal tar pitch with a softening temperature of 87 °C was taken as a starting material, nanosized carbon material "Kemerit", nanotubes, activated carbon, and thermally expanded graphite are considered as carbon additives. It was found in the work that the entire range of considered carbon additives significantly increases the yield of coke residue, while it was noted that a decrease in the amount of released volatile products during the destruction of pitch during its thermal transformation was observed, which is very important for carcinogenic compounds. Of the selected series of carbon additives, the maximum amount of solid residue is formed when nanostructured carbon additives (nanotubes and nanosized carbon material "Kemerit") are introduced into coal tar pitch. The structural characteristics of coal tar pitch before and after the carbonization process, as well as all carbon additives considered in the work, were investigated by the complex of X-ray diffraction methods (X-ray phase and X-ray structural methods of analysis). It was revealed that the formed carbon material, when nanotubes and Kemerite are added to coal tar pitch, is characterized by a more disordered structure when compared with the structure of individual coal tar pitch. The addition of thermally expanded graphite into coal tar pitch promotes the formation of graphite-like structures during pitch carbonization and reduces the amount of volatile carcinogenic compounds during thermal destruction to a greater extent when compared with amorphous carbon additives.

Получение графитоподобных материалов из каменноугольного пека

In the research, the study of precursors of graphite-like materials obtained from medium-temperature coal tar pitch was carried out on the individual components of coal tar pitch by separating the multicomponent composition of the pitch into separate fractions. Such approach, to study the physicochemical characteristics of the individual components of coal tar pitch, contributes to both the determination of the contribution of individual pitch components to the process of its structuring during carbonization and the development of new environmentally friendly methods for the synthesis of functional materials for various applications. The β-fraction was precipitated with n-hexane from toluene extract of coal tar pitch. γ-fraction was isolated from n-hexane by solvent evaporation. α2-fraction was isolated from the residue, insoluble in toluene, by quinoline extraction. The composition and structure of the isolated individual fractions of coal tar pitch were studied by physicochemical methods of analysis. The shape and morphology were investigated by electron microscopy. To study the composition and structure, the methods of elemental analysis, infrared spectroscopy, electron-paramagnetic resonance, XRD-analysis, and thermoanalysis were used in combination with methods of derivative analysis, chromatography, and mass spectrometry. The authors of the work propose new approaches to the use of individual fractions of coal tar pitch in order to obtain new graphite-like materials on their basis.

High performance sulphur-doped pitch-based carbon materials as anode materials for sodium-ion batteries

Sulfur-doped pitch-based carbon materials with a high sulfur content were prepared by a two-step heat treatment method using medium-temperature coal tar pitch as the carbon source and sublimated sulfur as the sulfur source. The effect of the final carbonization temperature on the composition, microstructure and electrochemical properties of the materials suitability as anode materials for sodium ion batteries were investigated. Results show that by increasing the final carbonization temperature the sulfur content of the materials decreases significantly, and the specific surface area and interlayer spacing gradually increase. Among the carbons obtained at different final carbonization temperatures, the sulfur content of the carbon at 800 oC was 20.19 wt.% and its interlayer spacing 0.368 nm, and its reversible capacity was 482.8 mAh/g at 0.1 A/g for the first cycle and had values of 245.9 and 103.7 mAh/g at 0.5 and 5 A/g, respectively after 500 cycles. The excellent sodium storage performance of the carbon at 800 oC is attributed to its high sulfur content, large interlayer spacing and suitable pore structure.

Removal of QI from Medium-temperature Coal Tar Pitch and Preparation of Needle Coke through Carbonization

Removal of QI from Medium-temperature Coal Tar Pitch and Preparation of Needle Coke through Carbonization

Preparation and pyrolysis behavior of modified coal tar pitch as C/C composites matrix precursor

Medium-temperature coal tar pitch (CPT) which is used as C/C composites matrix precursor is modified by phenolic resin (PF) in the presence of p-toluene sulfuric (PTS) acid as catalyst. Fourier transform Infrared (FT-IR) spectroscopy techniques, polarized-light microscopy and thermaogravimetric analysis (TGA) are employed to study on structure and thermal behavior of the modified CPT, respectively. Results show that the high molecular weight aromatic species in modified CPT is found and also confirmed by the results from FT-IR and TGA analysis. Otherwise, coking yield of modified CTP has improved by 13% and soft point decreased by 25°C compared with raw CPT. Moreover, the modification contributes to an improvement in the optical textures of resultant matrix precursor materials of C/C composites.

Реологические особенности компактирования изделий электротехники из коксопековых и графитопластовых композиций

The analysis of the well-known compaction curves and rheological models of coke-pitch composition compaction (CCC), including PPSC coke and artificial graphite as a filler and medium temperature coal tar pitch as a binder, is performed. As a result, the polytrophic type compaction curves received by pressing of samples in a heated mold. It was revealed that the increase of pressure from 5 MPa to 35 MPa leads to an density increase of the samples to 6,92%. The compaction curves stages characterized the features of CCCs and Lethersich rheological model describing the compaction process is considered as well as the main methods of compaction: compaction in the mold and extrusion through a die. The compaction curves, rheological model obtained by the authors and the new and original ways of the graphiteplaste compositions compaction (GCC), containing graphite as a filler made of waste electrode production and novolak resin as a binder, is described. The compaction curves obtained by compression of samples in a heated mold at a pressure from 5 to 50 MPa, and their appearance is described by the polytrophic equation, the initial branch which is a straight when it loaded to the efforts of 35 MPa. The upgraded rheological model obtained on the basis of the Lethersich model which takes into account such phenomena as the aftereffect, relaxation and heredity property.

Preparation of high quality impregnating pitch by new route

High quality impregnating pitch with low quinoline insoluble (QI) content and high coking value (CV) is required during the production of ultrahigh power graphite electrodes and C/C composites. High quality impregnating pitch using medium temperature coal tar pitch as raw material was prepared by a new route. The medium temperature pitch was first thermally treated to increase the CV and the β-resin content, then the QI was separated and removed by sedimentation with mixed solvent. For the traditional process technology, thermal polymerisation is operated after the removal of QI. The effects of sedimentation temperature, solvent ratio, aromatic/aliphatic ratio and sedimentation time on QI content, softening point (SP) and CV of impregnating pitch were discussed. The optimal process conditions were determined. The samples of high quality impregnating pitch with 82°C of SP, <0·14% of QI content and >52·22% of CV were obtained by adjusting the operating conditions. The CV of 52·22% was significantly higher than that of the impregnating pitch by the traditional process technology using medium temperature coal tar pitch as raw material.

The Preparation of Coal Pitch Slurry with Coking Wastewater

This study explored the feasibility of using coking wastewater and coal pitch powder to make coal pitch wastewater slurry. The medium temperature coal tar pitch powder was prepared by freezing and pulverizing coal tar pitch. The dispersant, JL-C01 medium-breaking emulsifier, had a large adsorption value on the coal pitch surface. At the same time, the Zeta potential on the coal pitch having added dispersant had a big increase. On the basics of that, putting some dispersants and wastewater into the powder under high speed stirring, the coal pitch wastewater slurry was obtained. The slurryability, rheological behavior, and static stability of coal pitch wastewater slurry were investigated at different dispersant dosages and slurry concentrations. The results showed that the apparent viscosity decreased with increasing the shearing rate. The rheological behavior of the slurry exhibited pseudo-plasticity. The biggest slurryability could be up to 70%. When the slurry concentration was 70%, the slurry could be kept for 28 d. At last, considering the test methods for quality of coal water mixture, the combustion analysis of the slurry was carried out and many indexes accorded with the national standard. The low heat value, the ash content, and the volatile matter met the coal water slurry first grade standard, and the sulfur content met the second grade standard.

Changes of centrosome and related protein in malignant transformation of BEAS-2B cell induced by coal tar pitch smoke extracts

To analyze the centrosome abnormalities in the malignant transformation of human bronchial epithelial cells (BEAS-2B) induced by coal tar pitch smoke extracts and to investigate the role and action mechanism of centrosome in the lung cancer induced by coal tar pitch. Medium-temperature coal tar pitch smoke extracts were used to treat immortalized human bronchial epithelial cells (BEAS-2B) and establish a malignant transformation model. The treated BEAS-2B cells were used as exposure group, and solvent control group and normal control group were also set for passage culture. The changes of centrosome in BEAS-2B cells seeded on coverslips were evaluated by indirect immunofluorescence assay. The mRNA expression of p53, p21, and cyclin E in BEAS-2B cells was measured by real-time quantitative RT-PCR, and their protein levels in BEAS-2B cells seeded on coverslips were measured by semiquantitative immunohistochemical analysis. The overall rate of centrosome abnormalities in BEAS-2B cells at passage 20 was 6.56±1.01% in the exposure group, significantly higher than those in the normal control group (3.40±0.86%) and solvent control group (3.14±0.59%) (P < 0.05). In addition, the exposure group had a significantly higher overall rate of centrosome abnormalities in BEAS-2B cells at passage 30 compared with the normal control group and solvent control group (22.39±9.5% vs 4.34±1.04%, P < 0.05; 22.39±9.5% vs 4.33±1.20%, P < 0.05). Compared with the normal control group and solvent control group, the exposure group had significantly decreased mRNA and protein expression of p53 and significantly increased mRNA and protein expression of cyclin E in BEAS-2B cells at passages 20 and 30 (P < 0.05). Centrosome abnormalities occur before the malignant transformation in BEAS-2B cells treated with coal tar pitch smoke extracts, and they may be mediated by the p53/p21/cyclin E signaling pathway.

Study on Preparation of Activated Carbon Precursor from Medium Temperature Coal Tar Pitch

In order to explore the optimal method to prepare high performance activated carbon precursors from medium temperature coal tar pitch, orthogonal tests are adopted to study the effects of oxygen-blowing time in the pretreatment process as well as carbonization temperature and carbonization time in activation and carbonization processes on the adsorption capacities of activated carbon. Moreover, the effects of additives (coke powder and anionic surfactant) on the adsorption capacities of activated carbon are examined. The results show that the factors affecting the adsorption capacities of pitch-based activated carbon, in order of importance, are carbonization temperature, oxygen-blowing time, carbonization time and additives. The optimal conditions for preparation of activated carbon precursor from medium temperature pitch are: 4h for oxygen-blowing time, 400°C for carbonization temperature, 60 minutes for carbonization time and no additives. The iodine absorption capacity of the prepared activated carbon precursor which is activated for 100 min at 800°C is 1739mg/g.

In situ preparation and mechanical properties of CNTs/MCMBs composites

By adding carbon nanotubes (CNTs) into medium temperature coal tar pitch, mesocarbon microbeads (MCMBs) were obtained via thermal condensation, then CNTs/MCMBs composites were in situ prepared using compression molding. The morphology, structure and mechanical properties of CNTs/MCMBs composites were characterized by optical microscope, digital camera, scanning electron microscope (SEM) and mechanical test machine. Results showed that CNTs were used as the nucleating agent and could inhibit the growth and coalescence of MCMBs. The optical textures of CNTs/MCMBs composites showed similar characteristics to the thermal condensation products from coal tar pitch with CNTs. The mass ratio of CNTs to coal tar pitch played an important role in the mechanical properties of CNTs/MCMBs composites. The density and bending strength of CNTs/MCMBs composite first increased and then decreased with the increase of the proportion of CNTs. When the proportion of CNTs was 5wt%, the density of the composite reached the maximum (1.76g/cm3). In addition, the bending strength of the composite reached the maximum (79.6MPa) as adding 2wt% CNTs into coal tar pitch.

Factors of large graphite crucible life

Production methods used to prepare graphite crucibles with high operating properties are considered: use as a filler of good graphitizing acicular coke, vibration molding of the original coke mix, use of production cycles for impregnation with medium temperature coal-tar pitch - firing, firing of compacted billets in metal containers, graphitization of fired billets in graphite cylinders. The last two production methods make it possible to reduce the temperature drop throughout the volume of a billet during heat treatment, and as a consequence to reduce crack development to a minimum as a result of reducing thermal stresses. All of the production methods recommended may be entirely accomplished in existing electrode plants and may be used to increase markedly the quality crucible graphite. It is possible to achieve a quality for these materials at the best world level.

Production of high-quality graphite crucibles for metallurgy

Processes for the manufacture of crucible graphite with high performance characteristics are considered. Among these processes are the use of highly graphitized needle coke as a filling agent, the vibromolding of a starting coke-pitch mixture, the use of medium-temperature coal-tar pitch impregnation-burning cycles, the burning of molding compounds in metal containers, and the graphitization of burnt materials in graphite cylinders. The latter two techniques decrease a temperature drop across the bulk raw material in the course of thermal treatments and, consequently, minimize the appearance of cracks due to a decrease in thermal stresses. All of the recommended techniques can be implemented at current electrode plants, and they can considerably improve the quality of the manufactured crucible graphite. In this case, the quality of the resulting materials can correspond to world standards.

The effect of composition of tar bond on the properties of tarred magnesite refractories

The most effective agents for the production of tarred magnesite articles are the bonds prepared from 70% medium-temperature coal-tar pitch and 30% anthracene oil (permissible limits, 20–40%).