Coal Tar Research Articles

Coal tar-pitch derived porous carbons with zinc oxide nanoparticles as a dual-functional template and activating agent for high-performance supercapacitors

Coal tar-pitch derived porous carbons with zinc oxide nanoparticles as a dual-functional template and activating agent for high-performance supercapacitors

Degradation and inhibition kinetics of phenanthrene by Alcaligenes ammonioxydans, [VITRPS2] strain isolated from petroleum-contaminated soil

Phenanthrene, a common three-ring polyaromatic hydrocarbon [PAH], originates from sources like grilled meals, tobacco, crude oil, coal tar, and automobile exhaust. Recognized as a hazardous PAH, it is often targeted for bioremediation due to its sustainability and potential for full mineralization. In this study, we focus on biodegrading phenanthrene using the strain Alcaligenes ammonioxydans [VITRPS2], isolated from petroleum-contaminated soil. At 5 mg/ml, degradation occurred at a rate constant of 0.0181/day, with half-life values of 2.7 and 4.49 according to first and second-order kinetics, respectively. Employing a one-factor-at-a-time [OFAT] approach, we optimized biodegradation conditions within Luria–Bertani [LB] media. Under optimal conditions—pH 8.0, 8% inoculum concentration, and 37 °C incubation over seven days—the strain achieved maximal growth with phenanthrene as the sole carbon source. It exhibited a degradation efficiency of up to 72% for phenanthrene under these conditions. Gas chromatography-mass spectrometry [GC–MS] analysis revealed principal metabolites of the breakdown pathway, including salicylic acid, catechol, and various phthalic acid derivatives. This underscores the strain's potential for remediating environments polluted by PAH metabolites, showcasing its remarkable capability for complete phenanthrene degradation.Graphical abstract

Porous carbon nanosheets from coal tar pitch for zinc ion hybrid capacitor

Porous carbon nanosheets from coal tar pitch for zinc ion hybrid capacitor

Hydrogen storage with a naphthenic liquid organic hydrogen carrier (LOHC) obtained from coal tar

A method for producing a liquid organic hydrogen carrier (LOHC) from coal tar is proposed. The carrier, a narrow fraction (T10%/T90% = 199/224 °C) with a naphthenic content of ≈99.9 wt%, was obtained through deep hydrogenation of the corresponding fraction of coal tar recovered by vacuum distillation. As a result of hydrogenation, deep purification from sulfur compounds (<5 ppm) was achieved. The composition of the produced carrier was characterized in detail by GCxGC/MS to identify the main components. Further data processing allowed for the calculation of the theoretic hydrogen capacity (6.3 wt %) and hydrogen mass fraction (13.16 wt %). Dehydrogenation in a batch reactor produced a dehydrogenated form of the carrier with a dehydrogenation degree of about ≈82–85%. The main physical properties (density, boiling range, viscosity, and flash/freezing/pour points) were described. The resulting carrier was dehydrogenated in a flow reactor using a Pt/C catalyst, demonstrating stable operation for 108. Moreover, the LOHC derived from coal tar exhibited stability in its properties across three consecutive hydrogenation-dehydrogenation cycles conducted over a Pt/C catalyst at 360–370 °C.

Multiscale enhancement of carbon/carbon composite performance by self-assembly of sulfonated graphene with silane-treated carbon fibers

The application prospects of carbon/carbon composites are greatly limited by interfacial cracks and pores caused by binder pitch displacement and cracking during high-temperature carbonization. In this study, silane coupling agent was coated on the surface of oxygen plasma-treated carbon fibers (CFs) and subsequently electrostatically self-assembled with sulfonated graphene (SG) to improve the interfacial bonding between filler and CTP. The results indicate that the tensile strength of carbon fiber treated with silane coupling agent increased by 19 % compared to untreated CF. This increase in strength may be related to the layer of silane coupling agent that repaired the grooves and imperfections on the CF surface. The addition of SG not only improves the distribution characteristics of the fibers, allowing the silane-treated CF to play a greater role in the matrix, but also creates a three-dimensional hydrogen-bonded cross-linking between the SG and the coal tar pitch (CTP) on the surface of the fibers. This inhibits CTP displacement and pyrolysis, achieving a tight bonding of the fiber to the matrix. The composites' structural integrity and mechanical properties were significantly improved due to the synergistic effect of silane-treated CF and SG. The compressive strength was 216.98 MPa, with a flexural strength of 54.78 MPa, 250 % higher than the untreated carbon fiber-reinforced composites. Additionally, the porosity decreased by 31.5 %, and the antioxidant properties increased. The study presents a potential solution to improve the performance of carbon/carbon composites by using the silane-treated CF-SG multiscale reinforced phase.

Physicochemical properties of ionic liquids with indole removal function

Indole exists in coal tar, gasoline, diesel oil and other oil products, in the process of using oil products, will cause serious pollution to the environment, so it is necessary to remove indole from oil products. In this paper, 1-hydroxy-3-methylimidazolserine was synthesized and characterized. Its density, surface tension, and refractive index were measured every 5 K in the range of 293.15–333.15 K using standard addition method. The relationships between temperature and water content were discussed. The mass change with time was measured by thermogravimetric analyzer, and its evaporation enthalpy was discussed. Furthermore, the polarity was predicted using these data. Finally, it was used to separate indole from simulated oil. A simulated oil solution containing 0.2 g/L indole was extracted under conditions of a mass ratio of 1:5 between ionic liquid and simulated oil, temperature of 30 °C, and time of 60 min. The extraction rate reached 88.9 %, indicating that the prepared ionic liquid can be used as an extractant for removing indole from simulated oil. In addition, the extraction mechanism was also investigated, and it was found that the indole was successfully extracted from the simulated oil because of the hydrogen bond between the indole and the ionic liquid.

Theoretical Revelation of HNCO Formation during Coal Pyrolysis: Mechanism, Formation Pathway and DFT Calculation

ABSTRACT Pyridine is one of the main nitrogen-containing compounds that produce NOx precursors (HNCO, HCN, NH3) in coal during pyrolysis, which can be converted into 2-pyridone (2-Py) in the presence of H2O. HNCO is a NOx precursor during coal and coal tar pyrolysis. In this study, the possible paths for the pyrolysis of 2-pyridone to generate HNCO and HCN were studied using density functional theory (DFT). This was the first theoretical revelation of the source of HNCO generation during coal pyrolysis. At the same time, the formation path of HCN was also calculated and compared with the formation of HNCO. Through the transition state theory analysis, the behavior characteristics of NOx precursors produced during the pyrolysis of 2-pyridone were theoretically explained.

Transforming Waste into Wealth: Advanced Carbon-Based Electrodes Derived from Refinery and Coal By-Products for Next-Generation Energy Storage.

This comprehensive review addresses the need for sustainable and efficient energy storage technologies against escalating global energy demand and environmental concerns. It explores the innovative utilization of waste materials from oil refineries and coal processing industries as precursors for carbon-based electrodes in next-generation energy storage systems, including batteries and supercapacitors. These waste-derived carbon materials, such as semi-coke, coal gasification fine ash, coal tar pitch, petroleum coke, and petroleum vacuum residue, offer a promising alternative to conventional electrode materials. They present an optimal balance of high carbon content and enhanced electrochemical properties while promoting environmental sustainability through effectively repurposing waste materials from coal and hydrocarbon industries. This review systematically examines recent advancements in fabricating and applying waste-derived carbon-based electrodes. It delves into the methodologies for converting industrial by-products into high-quality carbon electrodes, with a particular emphasis on carbonization and activation processes tailored to enhance the electrochemical performance of the derived materials. Key findings indicate that while higher carbonization temperatures may impede the development of a porous structure, using KOH as an activating agent has proven effective in developing mesoporous structures conducive to ion transport and storage. Moreover, incorporating heteroatom doping (with elements such as sulfur, potassium, and nitrogen) has shown promise in enhancing surface interactions and facilitating the diffusion process through increased availability of active sites, thereby demonstrating the potential for improved storage capabilities. The electrochemical performance of these waste-derived carbon materials is evaluated across various configurations and electrolytes. Challenges and future directions are identified, highlighting the need for a deeper understanding of the microstructural characteristics that influence electrochemical performance and advocating for interdisciplinary research to achieve precise control over material properties. This review contributes to advancing electrode material technology and promotes environmental sustainability by repurposing industrial waste into valuable resources for energy storage. It underscores the potential of waste-derived carbon materials in sustainably meeting global energy storage demands.

Effect of mesophase formation from quinoline insoluble-containing coal tar pitch on physical properties of carbon blocks

Effect of mesophase formation from quinoline insoluble-containing coal tar pitch on physical properties of carbon blocks

Synthesis of Microscopic 3D Graphene for High-Performance Supercapacitors with Ultra-High Areal Capacitance.

Despite graphene being considered an ideal supercapacitor electrode material, its use in commercial devices is limited because few methods exist to produce high-quality graphene at a large scale and low cost. A simple method is reported to synthesize 3D graphene by graphenization of coal tar pitch with a K2CO3 catalyst. This produces 3D graphenes with high specific surface areas up to 2113 m2 g-1 and exceptional crystallinity (Raman ID/IG as low as ≈0.15). The material has an outstanding specific capacitance of 182.6 F g-1 at a current density of 1.0 A g-1. This occurs at a mass loading of 30mg cm-2 which is 3 times higher than commercial requirements, yielding an ultra-high areal capacitance of 5.48 F cm-2. The K2CO3 is recycled and reused over 10 cycles with material quality and electrocapacitive performance of 3D graphene retained and verified after each cycle. The synthesis method and resulting electrocapacitive performance properties create new opportunities for using 3D graphene more broadly in practical supercapacitor devices.

WASTEWATER TREATMENT OF COAL TAR PROCESSING PROCESS FROM PHENOL

The coal tar processing process provides the chemical industry with valuable products: naphthalene, cresol, xylenols, phenol, technical oils and lubricants. The most significant product of coal tar processing is anthracene, which is a raw material for the production of carbon black. The prospects for the implementation of the coal tar processing process entail a danger to the environment and public health.Wastewater formed during the processing process has a complex chemical composition, mainly represented by organic aromatic compounds. Wastewater pollutants significantly exceed discharge standards permissible for discharge into the Centralized Wastewater Disposal System of Settlements and Urban Districts. Phenol, which has the third hazard class according to the standards of maximum permissible concentrations of harmful substances in the waters of water bodies of fishery importance, is particularly dangerous. The toxic effect of phenol leads to the suppression of biocenoses, a decrease in the number of living organisms, negatively affects human health, and can lead to death. Based on the above, in order to reduce the anthropogenic load on the environment and maintain the quality of water resources, it is necessary to carry out a set of environmental measures aimed at wastewater treatment.The article presents methods of wastewater purification from phenol, describes complex purification methods and formulates proposals for the technology of wastewater treatment of the enterprise. Spectral and quantitative chemical analysis were performed to determine the composition of wastewater. Regenerative cleaning methods are proposed. Methods for wastewater treatment have been formulated and implemented. Methods for wastewater treatment of the coal tar processing process are proposed.The aims of research are to reduce the concentration of phenol in wastewater to the standard values permissible for discharge into the Centralized Wastewater Disposal System of Settlements and Urban Districts, based on experimental data; formulate a proposal for the wastewater treatment of the coal tar processing process from phenol.Objectives of the work are to study the composition of the source wastewater; to consider methods of wastewater treatment from phenols; to carry out wastewater treatment, based on the results of the study, to propose a wastewater treatment scheme.The object of the study is the wastewater of the enterprise after the coal tar processing process.

Fabrication of MnO2@Porous Carbons with High Energy and Power Density and Their Application in Supercapacitors

MnO2@PCs (porous carbons) exhibiting high energy and power density are utilized as supercapacitor electrodes and prepared by impregnating porous carbons (PCs) derived from coal tar pitch (CTP) with KMnO4 as the manganese source. This study systematically investigates the impact of MnO2 loading on the microstructure and electrochemical performance in sample. It is found that the specific surface areas (SSA) of all MnO2@PCs significantly reduced compared to that of the PCs 2789 m2 g−1. The suggested mechanism might be a combination of the energy storage mechanism of dual layer capacitors with pseudo‐capacitance due to redox reactions of MnO2. Notably, MnO2@PCs‐0.0075 exhibits a maximum SSA of 1454.62 m2 g−1. Its specific capacitance reached 561 F g−1 at 0.5 A g−1, while the capacitance of the PCs increased by 81.5% to 309 F g−1. Remarkably, the Coulombic efficiency remained at 100%. The power density and energy density are determined in a two‐electrode test system to be 0.5 kW kg−1 and 58.01 Wh kg−1, respectively, at 0.5 A g−1. Concluding from these results and related literature, the MnO2 content significantly influences the electrochemical performance, suggesting that MnO2@PCs‐0.0075 could be a promising supercapacitor (SC) electrode material, provided its capacitance retention is enhanced.

A new approach for improving the quality of the carbon anode for aluminum electrolysis – An impregnation-baking process

Prebaked carbon anode is the primary consumable material in the aluminum reduction cell, and its quality directly affects the energy consumption of aluminum production. An impregnation-baking process of the anode was proposed to reduce the anode porosity, improve the quality of the anodes, and reduce additional carbon consumption. The theoretical analysis and industrial testing on the impregnation-baking process were carried out. Firstly, the coal tar pitch was immersed into the anode carbon block through the impregnation process. An anode impregnation model was developed and used for theoretical calculations to analyze the effects of pressure and temperature on the impregnation process. The accuracy of the model was verified experimentally. Secondly, the impregnated anodes were placed in an electromagnetic induction heating furnace for baking to carbonize the immersed pitch. The thermogravimetric and pyrolysis kinetics methods were used to analyze the baking process of the impregnated anodes. Finally, the impregnated-baked anodes were compared with common anodes regarding their impact on the technical and economic indicators of the aluminum electrolysis process in industrial tests. The results showed that the physicochemical properties of the impregnated-baked anodes were significantly improved, with the bulk density increase of 0.1 g/cm3, air permeability reduction of 0.54 nPm, compressive strength enhancement of 9.43 MPa, and electrical resistivity decrease of 10 uΩ·m. The anode service life was increased from 31 to 35 days, the current efficiency was increased by 0.44 %, and the operating voltage was reduced by 17 mV, which improved economic benefit significantly.

Determination of the Kinetic Parameters of Thermal Degradation and Hydrodemetallization of a Mixture of the Heavy Fraction of Low-Temperature Coal Tar and Coal Shale

The laws of thermal degradation of the mixture of the heavy fraction of low-temperature coal tar and coal shale were investigated using dynamic thermogravimetry. The kinetic characteristics of the process were determined using various methods, including the Ozawa–Flynn-Wall, Friedman, non-parametric kinetics and Šesták–Berggren methods. It is shown that coal shale initiated changes in the kinetic parameters and decomposition rate of the heavy fraction of coal tar. It was found that a 13% content of coal shale in the mixture led to the maximum rate of weight loss of the heavy fraction of coal tar. A hydrodemetallization kinetic model of the mixture of the heavy fraction of low-temperature coal tar and coal shale is proposed. The kinetic parameters of the hydrodemetallization process were determined; in addition, the rate constants at various temperatures were estimated. The study shows that the distribution of trace elements in the hydrogenate from the initial mixture and in the hydrogenate from the solid residue was characterized by relatively low values of reaction rate constants. The maximum microelement distribution rate was achieved in the hydrogenate solid residue. Energy indicators of activation processes indicated that hydrodemetallization at low temperatures is advantageous from an energy point of view.

Preparation of Mesophase Pitch with Fine-Flow Texture from Ethylene Tar/Naphthalene by Catalytic Synthesis for High-Thermal-Conductivity Carbon Fibers.

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.

Preparation of N and O doped coal tar pitch based porous carbon for supercapacitor electrode

Coal tar pitch (CTP) is mainly composed of a mixture of polycyclic aromatic hydrocarbons, is almost hydrophobic, and has a low heteroatom content, which limits its surface function. During carbonization, it is prone to condensation and difficult to form pore structures, resulting in poor electrochemical performance for carbon electrode materials. Herein, nitrogen (N) and oxygen (O) doped hierarchical porous carbon (C-ANOCTP) was prepared by HNO3 oxidation and KOH activation using CTP as carbon precursor. The oxidation of HNO3 remarkably increases the hydrophilic functional groups containing N and O on the surface of CTP, improves the hydrophilicity of CTP surface, facilitates the activation process of KOH, promotes the development of carbon material pore structure and the generation of active sites, as well as the formation of defect structures. The specific surface area of C-ANOCTP obtained is 1130 m2/g, with O content of 10.29 at% and N content of 2.37 at%. The specific capacitance of C-ANOCTP in a three-electrode system with 6 M KOH electrolyte is as high as 410.51 F/g at 0.5 A/g. A symmetric supercapacitor is assembled in a 6 M KOH electrolyte using C-ANOCTP as electrode. When the power density is 25 W/kg, the energy density is 10.24 Wh/kg. After 10,000 cycles, the capacitance retention rate is still 90.03% and the coulomb efficiency is 100%. The high N and O content of porous carbon is prepared by simple HNO3 oxidation synergistic KOH activation and low temperature carbonization, which shows excellent electrochemical properties in supercapacitors, making CTP an ideal candidate material for high energy density supercapacitors.

Effect of isopropyl chloride addition in AlCl3 catalytic system on the formation of coal tar pitch-based mesophases

Mesophase pitch is a high-quality precursor for the synthesis of high-performance pitch-based carbon fibers. The mesophase content, texture and softening point are the most important factors for the structure, properties and spinnability of mesophase pitch (MP). Herein, we report a novel approach for the preparation of mesophase pitch with high anisotropic content and low softening point by AlCl3 catalytic pyrolysis in the presence of isopropyl chloride (PrCl). The variation of anisotropic content and mesophase texture under different PrCl additions and the effect of the introduction of isopropyl on the molecular stacking of aromatic lamellar molecules were investigated. The results confirmed that, except for their role in improving catalytic activity, carbocation co-catalysts can improve the structure and molecular assembly of aromatic molecules through the introduction of alkyl groups. The reaction of isopropyl chloride (PrCl) as a co-catalyst catalyzed pyrolysis of medium-temperature coal pitch at 370 ℃ for 8h produced a bulk mesophase with a content close to 100%. Compared to the AlCl3 system (without PrCl), the AlCl3-PrCl system can catalyze the preparation of mesophases at lower temperatures. In addition, it is logical that the introduction of isopropyl group significantly increases the stacking spacing of the mesophase pitch layer molecules, which can effectively improve the mobility of the aromatic layer molecules resulting in the growth of mesophase. The fusion texture and anisotropic content of mesophase pitch were significantly improved by replacing the nucleophilic reagent of the AlCl3-catalyzed system. This work provides feasible ideas for the preparation of high-performance coal tar based mesophase pitch.

Nitrogen heteroatom anchored on porous carbon cathode for zinc ion hybrid capacitor

Heteroatom doped porous carbons have been widely used in aqueous zinc ion hybrid capacitors (AZICs) due to their merits of simple preparation process, excellent electric conductivity and abundant expose active sites. However, toxic and corrosive processes hinder their further applications. Herein, we report a template-free strategy to prepare nitrogen doped porous carbons from coal tar pitch for AZICs. Due to the structural characteristics of hierarchical pores and N, O heteroatoms, the AZIC fabricated by cathode presents the highest discharge capacity (133.1mAhg−1), the maximum energy density (112.3Wh kg−1), an excellent rate performance (65.9Wh kg−1at 15.26 kW kg−1) and a superior cycle stability over 15,000 cycles. This study points to an environmentally-friendly strategy to construct heteroatom-doped porous carbons for high-performance AZICs.

A preliminary study on the co-hydrogenation process of coal tar and bio-oil

A preliminary study on the co-hydrogenation process of coal tar and bio-oil

Dealkylation of alkylphenols in phenol oil on acid zeolites

The majority of the phenolic compounds in coal tar are alkyl-substituted phenols. To overcome the difficulty of separation, zeolites catalyzed dealkylation of alkylphenols was studied in a slurry-bed reactor. ZSM-5 displayed higher catalytic performance than other zeolites within a group of acidic zeolites with various topologies (including SAPO-34, ZSM-23, MCM-22, USY, and Mordenite). The yield of phenol gradually increased together with the zeolite acidity, but the types and yields of byproducts also increased in step with it. The pore size of the zeolites was a significant influence at similar acidity. The micropore of ZSM-5 inhibited some bimolecular processes, decreasing disproportionation/transalkylation as a result of transition state shape selection. In this study, the reaction paths of alkylphenols were investigated, based on the composition of products catalyzed by different zeolites, the distribution of products under different conditions, and the reaction process of various alkylphenols. Reaction process of alkylphenols included dealkylation, isomerization, disproportionation, transalkylation, and C-C cracking. Dealkylation took the place of isomerization as the primary reaction when the reaction temperature exceeded 350 °C. Disproportionation, transalkylation, and C-C cracking were exacerbated by excessive temperature. In addition, excessive reaction time and pressure can exacerbate side reactions, alkylphenols yields and coke deposition.