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A template-free strategy was designed to prepare hierarchical porous carbons (HPCs) using fluid catalytic cracking oil modified a coal tar pitch (CTP). The resulting HPCs possess large specific surface areas, reasonable pore size distributions, and wrinkled structures, which could improve the overall electrochemical performance. They exhibit a specific capacitance value of 329 F g −1 at 0.5 A g −1 and still maintain 220 F g −1 at 20 A g −1 , manifesting the remarkable rate capability. Additionally, the assembled symmetrical supercapacitor delivers a highest energy density of 23.6 Wh kg −1 at a power density of 500 W kg −1 and outstanding cycle stability of 92.8% capacitance retention after 10000 cycles. This work paves a new way to fabricate advanced carbon materials from low-cost CTP and provides a promising approach for value-added utilization of CTP. Graphical abstract

In this work, pitch-based carbon fibers were utilized to reinforce silicon carbide (SiC) composites via reaction melting infiltration (RMI) method by controlling the reaction temperature and resin carbon content. Thermal conductivities and bending strengths of composites obtained under different preparation conditions were characterized by various analytical methods. Results showed the formation of SiC whiskers (SiC w ) during RMI process according to vapor—solid (VS) mechanism. SiC w played an important role in toughening the C pf /SiC composites due to crack bridging, crack deflection, and SiC w pull-out. Increase in reaction temperature during RMI process led to an initial increase in thermal conductivity along in-plane and thickness directions of composites, followed by a decline. At reaction temperature of 1600 °C, thermal conductivities along the in-plane and thickness directions were estimated to be 203.00 and 39.59 W/(m·K), respectively. Under these conditions, bending strength was recorded as 186.15±3.95 MPa. Increase in resin carbon content before RMI process led to the generation of more SiC matrix. Thermal conductivities along in-plane and thickness directions remained stable with desirable values of 175.79 and 38.86 W/(m·K), respectively. By comparison, optimal bending strength improved to 244.62±3.07 MPa. In sum, these findings look promising for future application of pitch-based carbon fibers for reinforcement of SiC ceramic composites.

Due to their outstanding material properties, carbon fibers are widely used in various industrial applications as functional or structural materials. This paper reviews the material properties and use of carbon fiber in various applications and industries and compares it with other existing fillers and reinforcing fibers. The review also examines the processing of carbon fibers and the main challenges in their fabrication. At present, two main precursors are primarily utilized to produce carbon fibers, i.e., polyacrylonitrile (PAN) and petroleum pitch. Each of these precursors makes carbon fibers with different properties. However, due to the costly and energy-intensive processes of carbon fiber production based on the existing precursors, there is an increasingly growing need to introduce cheaper precursors to compete with other fibers on the market. A special focus will be given to the most recent development of manufacturing more sustainable and cost-effective carbon fibers derived from petroleum asphaltenes. This review paper demonstrates that low-cost asphaltene-based carbon fibers can be a substitute for costly PAN/pitch-based carbon fibers at least for functional applications. The value proposition, performance/cost advantages, potential market, and market size as well as processing challenges and methods for overcoming these will be discussed.

Mesophase pitch is usually prepared by radical polymerization or catalytic polymerization from coal tar, petroleum, and aromatic compounds, and the catalytic synthesis of mesophase pitch from pure aromatic compounds is more controllable in the preparation of high-quality mesophase pitch. However, the corrosive and highly toxic nature of the catalyst has limited the further development of this method. In this study, mesophase pitch was synthetized using ethylene tar and naphthalene as raw materials and boron trifluoride diethyl etherate as a catalyst. The effect of the catalytic reaction on the structure and properties of the mesophase pitch was investigated. The results show that naphthalene plays an important role in the mesophase content and reaction pressure (from above 6 MPa to 2.35 MPa). Mesophase pitch with fine-flow texture can be prepared by introducing more methylene groups, naphthenic structures, and aliphatic hydrocarbons during synthesis. Carbon fibers prepared from mesophase pitch show a split structure, and the thermal conductivity is 730 W/(m·K). This work provides theoretical support for lower toxicity and causticity and for reaction-controlled technology for the synthesis of high-purity mesophase pitch.

The chemical composition and molecular structure of the pitch-like products obtained by liquid-phase reaction of bituminous coal with heavy hydrocarbon fractions of coal and petroleum origin as solvents at a moderate temperature were comprehensively characterized in terms of a new aromatic feedstock for needle coke and other valuable high-tech carbon materials. The molecular parameters of the products were characterized by using FTIR, 1H NMR, 13C NMR and XPS. Liquid-phase chromatography was used to analyze benzo(a)pyrene (BaP) as a carcinogenicity marker. The chemical composition and the characteristics of the molecular structure of the products were shown to depend greatly on the solvent used. The product obtained using coal tar as a solvent was highly aromatic, its polyaromatic nuclei consisted predominantly of protonated and pericondensed cycles sparsely substituted by CH3 and occasionally CH2 groups. The product obtained using petroleum-derived heavy gas oil as solvent was much less aromatic and prone to autogenous surface oxidation. Its aromatic nuclei contained mainly protonated and highly alkylated catacondensed chains. The intermediate structural parameters were characteristic of the product obtained using binary solvent. A remarkable feature of the pitch-like products obtained was a reduced BaP concentration (up to 40 times compared to typical coal-tar pitch). In terms of the molecular structure, the pitch-like products obtained by low-temperature dissolution of coal can serve as a new polyaromatic feedstock with a reduced carcinogenicity for the production of valuable high-tech carbon materials, needle coke, in particular.

Renewed interest in the reinforced carbon graphite composites has intrigued the community in the advanced materials fields. In this work, we present a simple carbon nanofibers reinforced carbon graphite composites synthetic method by incorporating mixture of coal tar pitch, synthetic graphite, pitch coke and the dispersion liquid of carbon nanofibers via liquid-phase mixing process. The impact of carbon nanofiber utilization on the microstructures and mechanical properties of carbon graphite composites are studied systematically. The covalent surface modification of carbon nanofibers effectively improves its microstructure and thereby promotes the carbon graphite composites’ dispersion behavior. We propose that a small amount of carbon nanofibers could promote the carbonization process of carbon graphite composites, facilitating the densification of carbon graphite composites and reducing the undesired open porosity. The amount of 0.7 wt % of carbon nanofiber concentration allows the enhancement of bend and compressive strength of carbon graphite composites up to 36.50 MPa and 60.46 MPa, increased by 167.9% and 146.9% compared with the pure carbon graphite composite, respectively. Our findings can be rationalized due to the improvement in the mechanical strength of carbon graphite composites could be attributed due to pull-out of carbon nanofibers from the matrix and bridging effect across the crack pores within the matrix.

Coal tar pitch (CTP), a by-product of coking industry, has a unique molecule structure comprising an aromatic nucleus and several side chains bonding on this graphene-like nucleus, which is very similar to the structure of graphene quantum dots (GQDs). Based on this perception, we develop a facile approach to convert CTP to GQDs only by oxidation with hydrogen peroxide under mild conditions. One to three graphene layers, monodisperse GQDs with a narrow size distribution of 1.7 ± 0.4 nm, are obtained at high yield (more than 80 wt. %) from CTP. The as-produced GQDs are highly soluble and strongly fluorescent in aqueous solution. This simple strategy provides a feasible route towards the commercial synthesis of GQDs for its cheap material source, green reagent, mild condition, and high yield.

Knowledge of the kinetics of petroleum pitch pyrolysis is crucial to improve and optimize the design of pyrolysis reactors, gasification reactors, and circulating fluidized bed combustors (CFBC) to use as feedstock. Thermogravimetric analysis (TGA) was performed to understand the kinetic aspects of the pitch pyrolysis. The isoconversional Friedman, Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), and Starink methods were used to calculate the divergence of activation energy and mechanistic understanding of the complex nature of pitch pyrolysis. The mean activation energies were 176.46, 178.79, 176.79, and 189.90 kJ mol.sup.-1 for the KAS, FWO, Starink, and Friedman methods. The three-dimensional diffusion model, followed by the pyrolysis process, was determined using model-based Coats-Redfern and Criado methods. The linear relationship of the pre-exponential factor and the activation energy was obtained through the kinetic compensation effect (KCE) relationship. The positive values of enthalpy and Gibbs Free energy confirmed the endothermic nature of the pitch pyrolysis. The positive to negative variation of entropy was observed because of the complicated nature of the pitch pyrolysis process. During pyrolysis, the residue's surface morphology detected pores, cracks, and mesophase formation in scanning electron microscope (SEM) analysis, and sulfur, vanadium, and nickel were present in energy-dispersive spectrometer (EDS) analysis of the residue. Fourier transform infrared spectroscopy (FTIR) analysis of the sample and residue showed an intermediate cross-link reaction, which led to the formation of a mesophase coke structure in the pyrolysis process.

The structure and composition of coal tar pitch are critical in the production of superior needle coke. We used high-temperature refined coal tar pitch (HRCTP) to modify medium–low-temperature refined coal tar pitch (MLRCTP) for needle coke preparation. Various characterization techniques were applied to evaluate the effects of the HRCTP addition on the MLRCTP's structure and composition, and to investigate the microstructural and crystallographic differences in needle coke from different feedstocks. We identified the optimal HRCTP addition level and assessed how carbonization reaction conditions influenced needle coke quality. The findings indicated that HRCTP addition increased the aromatic hydrocarbons content while reducing the heterocyclic compounds and excess alkanes, leading to enhanced structure and composition, which supported the structured development of carbon-based structures during the thermal polycondensation process. Notably, higher HRCTP amounts did not equate to better outcomes. With a 25% HRCTP additive level, the needle coke’s microstructure showed a highly ordered fibrous texture with optimal orientation, the greatest degree of graphitization, and a mature graphite crystal content of 24.84%. Further optimization of the carbonization process demonstrated that very high temperatures might cause the formation of numerous mosaic structures due to disordered radical cross-linking. Properly reducing pressure at high temperatures could promote adequate directional airflow and apply shear force during orderly stacking of the mesophase, thus enhancing the carbon lamellae’s streamline and orientation. Following the carbonization process optimization, the mature graphite crystal content in the needle coke increased from 24.84% to 39.87%. Graphical abstract For table of contents only

Carbon-based electrodes have recently been most widely used in P-MFC due to their desirable properties such as biocompatibility, chemical stability, affordable price, corrosion resistance, and ease of regeneration. In general, carbon-based electrodes, particularly graphite, are produced using a complex process based on petroleum derivatives at very high temperatures. This study aims to produce electrodes from bio-pitch and charcoal powder as an alternative to graphite electrodes. The carbons used to manufacture the electrodes were obtained by the carbonisation of Robinia pseudoacacia and Azadirachta indica wood. These carbons were pulverised, sieved to 50 µm, and used as the raw materials for electrode manufacturing. The binder used was bio-pitch derived from coconut shells as the raw materials. The density and coking value of the bio-pitch revealed its potential as a good alternative to coal-tar pitch for electrode manufacturing. The electrodes were made by mixing 66.50% of each carbon powder and 33.50% of bio-pitch. The resulting mixture was moulded into a cylindrical tube 8 mm in diameter and 80 mm in length. The raw electrodes obtained were subjected to heat treatment at 800 °C or 1000 °C in an inert medium. The electrical resistivity obtained by the four-point method showed that N1000 has an electrical resistivity at least five times lower than all the electrodes developed and two times higher than that of G. Fourier-transform infrared spectroscopy (FTIR) was used to determine the compositional features of the samples and their surface roughness was characterised by atomic force microscopy (AFM). Charge transfer was determined by electrical impedance spectroscopy (EIS). The FTIR of the electrodes showed that N1000 has a spectrum that is more similar to that of G compared to the others. The EIS showed the high ionic mobility of the ions and therefore that N1000 has a higher charge transfer compared to G and the others. AFM analysis revealed that N1000 had the highest surface roughness in this study.