Modification Of Coal Tar Pitch Research Articles

Modification of coal tar pitch by solvent extraction for high density C/C composites

C/C composites have excellent mechanical and thermal properties even in extreme environments. Thus, they are used in various fields such as aircraft, automobiles, rockets and etc. The characteristics of the raw materials are very important to reduce the swelling or pores that occur during the carbonization. In this study, the properties of coal tar pitch were controlled, one of the raw materials for C/C composites, using three solvents (acetone, toluene, and tetrahydrofuran (THF)). Using the solvent extraction method, the insoluble (CTP-AceI, CTP-TI, CTP-THFI) and soluble (CTP-AceS, CTP-TS, CTP-THFS) are separated and used as a binder and impregnation pitch, respectively. As a result, when CTP-TI is used as a binder, density is 1.75 g/cm3, which is the highest. And the highest density appeared in the order of CTP-TI, CTP-THFI, CTP-AceI, and CTP-Raw. This coincided with the order in which β-resin, which is an important parameter for binders. Additionally, the volatile matter that causes swelling could be reduced from 22.33 wt% to 9.30 wt%. Thus, the swelling was suppressed efficiently. When CTP-AceS was used as the impregnation pitch, the density was 1.89 g/cm3, the impregnation rate was 60 %, and the porosity was 2.5 %. The impregnation rates were higher in the order of CTP-AceS, CTP-TS and CTP-THFS. This is because QI reduces fluidity and interrupt penetration into pores.

Modification of coal-tar pitch with 10-Undecenal to reduce the content of environmental pollutants of polycyclic aromatic hydrocarbons

Although there were approximate 10 million potential yields of coal-tar pitch (CTP) annually in China since 2011, plenty of environmental pollutants of polycyclic aromatic hydrocarbons (PAHs) existing in CTP limit its many applications. Reducing the content of PAHs hazardous to environment in CTP becomes an imminent problem. In the paper, CTP was modified with 10-Undecenal (UNL) over the catalysis of potassium bisulfate (KHSO4) in cyclohexane solvent to reduce the content of U.S. Environment Protection Agency (EPA) priority PAHs in CTP. The effects of modifier and catalyst quantities, reaction temperature and reaction time on the reduction efficiency of 16 EPA priority PAHs were investigated. The optimum reaction conditions were obtained as follows: UNL additive quantity 8 wt% of CTP, KHSO4 additive quantity 5 wt% of CTP, reaction temperature 50 °C and reaction time 4 h. Under these conditions, the reduction efficiency of the 16 priority PAHs in CTP reached 91.10%, Benzo[a]pyrene, a typical toxicant to environment, decreased by 93.14%. Simultaneously, the softening point of modified CTP (MCTP) dropped from 87 °C to 59 °C. The changes of structure of CTP before and after modification were investigated via thermogravimetry analysis (TGA), differential thermal analysis (DTA), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and 13C nuclear magnetic resonance (NMR) Spectrum. It was proved that the alkylation reaction generated between PAHs and UNL might reduce markedly the content of the 16 priority PAHs in CTP.

Electrochemical Characteristics of Coal Tar Pitch Prepared By Chemical Activation for Lithium Ion Battery

In recent years, carbon-based materials have been extensively investigated as an anode material for Li-ion battery (LIB). Because of their low material cost, abundance, nontoxicity and good capacity, carbon materials have been considered promising materials for LIB anodes in portable electronic devices and electric/hybrid vehicles. Despite these advantages, the practical application of carbon-based materials in many electronic device and electric/hybrid vehicles is still limited by its poor electrochemical performances . To enhance these electrochemical performances, we have performed the surface modification of coal tar pitch (CTP) by the chemical activation with KOH and K2CO3 . Coa l tar pitch (CTP) as an industrial by-product, composed of cyclical hydrocarbons of various molecular weights and configurations. The preparation method has been optimized through the analysis of diverse experimental variables. The results obtained confirm the importance of the activating chemical agents to CTP ratio and the flow rate of gas during carbonization on the development of porosity. In addition, it shows that chemical activation with KOH and K2CO3 can be successfully used to develop CTP with high surface area and mean pore size. In this study, the effect of activating chemical agent /CTP weight ratio, CTP particle size and vinylene carbonate (VC) as an electrolyte additive on electrochemical performances was investigated. The prepared modified CTP was analyzed by BET, XRD, FE-SEM and XPS. Also the electrochemical performances of modified CTP as the anode were investigated by constant current charge/discharge, cyclic voltammetry and electrochemical impedance tests in the electrolyte of LiPF6 dissolved in organic solvents(EC:DMC=1:1 vol%). The coin cell using modified CTP( KOH /CTP = 1 : 5 in weight) has better initial capacity (421 mAh/g) than that of other composition coin cells. Also, modified CTP anode appeared a high capacity of 4 11 mAh/g on the second cycle and the retention rate capability of 2C/0.1C was 83 % after 30 cycle. It is found that prepared CTP anode showed improved cycling and rate capacity performance.

Modification of coal tar pitch with P-phthalaldehyde to reduce toxic PAH content

ABSTRACTCoal tar pitch (CTP) was modified with p-phthalaldehyde as a cross-linking agent, p-toluenesulfonic acid as a catalyst, and cyclohexane as solvent, to reduce the toxic PAH content. The optimum reaction conditions were obtained as follows: 8% of p-phthalaldehyde, 5% of p-toluenesulfonic acid, reaction temperature 60°C, and reaction time 4 h. Under the optimum conditions, the reduction rate of the 16 toxic PAHs in CTP achieved 82.75%. The physical properties of modified CTP were improved simultaneously. The detoxification mechanism was investigated via TG-DTG and FT-IR. It was proved that the electrophilic substitution cross-linking reaction took place between PAHs and p-phthalaldehyde, which might significantly contribute to the high reduction rate of the 16 toxic PAHs in CTP.

Autocatalytic modification of coal tar pitch using benzoyl chloride and its effect on the structure of char

Benzoyl chloride (BC) is used as both a modifier and a catalyst to successfully modify coal tar pitch (CTP). The char structure formed by the modified coal tar pitch (MCTP) was investigated in this study, and the results showed that the softening point, coking value, and β-resin content of MCTP increased in comparison with those of CTP. Effects of modification conditions, such as temperature, ratio of BC to CTP, and time on the char structure, were studied by polarized light microscopy, XRD, FT-IR, and 1H NMR. Ordered, fibrous structures were produced at optimal conditions in char as a result of the carbonization of MCTP. The optimal conditions were as follows: modification reaction time of 15h, reaction temperature of 150°C, and BC to CTP ratio of 5wt.%. Data from the XRD spectra indicated that the interplanar crystal spacing of the char, which was obtained after MCTP carbonization, was 0.339nm, which is close to the crystal structure of graphite. The crystallite height of the MCTP char was higher than that of the CTP char. A possible reaction mechanism is therefore proposed in this paper.

Effect of oxidised mesoporous carbon containing silver nanoparticle on selectivity of adsorption desulphurisation

This paper presents the experimental investigation of the effects of nitric acid oxidation and silver loaded modification of coal tar pitch based mesoporous carbons (MCs) on adsorption capacity of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The structural and textural properties of the samples were characterised by means of X-ray diffraction, scanning electron microscopy, Boehm titration and nitrogen adsorption–desorption techniques. The results show that after oxidative modification, the average pore sizes of MCs were not changed. It is also found that the specific surface area decreased, while the mesopore ratio, the density of the surface oxygen containing groups increased remarkably. Furthermore, silver loaded modification improved the mesopore ratio obviously. The oxidative modification considerably enhanced the adsorption capacity and silver loaded modification improved the selectivity against benzene. After three regeneration cycles, the regenerated adsorption afforded 96 and 93% of the initial adsorption capacities of DBT and 4,6-DMDBT respectively. The results suggest excellent reuse ability of the MCs.

Comparative Study of the Modification of Coal Tar Pitch for Higher Carbonization Yield and Better Properties

Parent coal tar pitch (CTP) was modified with boric acid (BA), cinnamaldehyde (CMA) and the mixture of BA and CMA, respectively. The parent CTP and three modified CTPs were characterized by elemental analysis, thermogravimetric analysis, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy. The four samples were carbonized at different temperatures and resultant carbonized products were characterized by FT-IR spectroscopy, X-ray diffraction and polarized-light microscopy. The results show that the morphologies and carbonization behaviors of the parent CTP and modified CTPs are quite different. The carbonization yield of the CTP modified with the mixture of BA and CMA is higher than that of CTP modified with BA or CMA only. In addition, the modification of CTP with 7 g of BA and 10 ml of CMA results in an increase in carbonization yield by 5.64%. During the pyrolysis of modified CTPs, the dehydration of BA or the distillation of CMA occurs at the temperature lower than 300 °C, and methyl and methylene groups of the modified CTPs disappear gradually as temperature rises. Furthermore, the modification of CTP by the mixture of BA and CMA results in more intensive mesophase spheres than other modified CTPs, and the modified CTP is easier to be carbonized to form graphitic carbon.

Modification of Coal Tar Pitch to Reduce the Carcinogenic Polycyclic Aromatic Hydrocarbons

This research investigated on reducing carcinogenic polycyclic aromatic hydrocarbons(PAHs),especially benzo[a]pyrene (BaP) in coal tar pitch by modifying with the two selected modifiers: Paraformaldehyde and Epoxy Resin. The reaction emphasis on the change of temperature, reaction time and the quantity of the modifiers. The results indicated that Paraformaldehyde and Epoxy Resin could decrease the PAHs content greatly. The BaP decreasing rate reached 75.86% and 53.45% respectively. And the BaP equivalency content of the pitch decreased from 2.94% to 1.41% and 1.47% respectively. The properties of the modified coal tar pitch, including soft point (SP), toluene insolubles (TI), quinoline insolubles (QI) have changed a lot.

Preparation and carbonization behavior of cinnamaldehyde modified coal tar pitch

In this paper, coal tar pitch (CTP) was modified with cinnamaldehyde (CMA) in the presence of p-toluene sulfonic acid. The parent CTP and CMA modified CTP were characterized by 1H nuclear magnetic resonance spectroscopy, elemental analysis and scanning electron microscopy. Carbonization behaviors of CMA modified CTPs were studied by thermogravimetric analysis, Fourier transform infrared spectroscopy and X-ray diffraction techniques. The results show that the carbonization behaviors of parent CTP and CMA modified CTPs are much different. The modification of CTP with CMA results in an increase in carbonization yield by 3.46–5.08% when 100g CTP was modified with 5–15ml of CMA. During the carbonization process, methyl and methylene groups of the CMA modified CTP gradually disappear while increasing temperature and its chemical structures change greatly when the temperature is higher than 400°C. In addition, the modification with CMA is beneficial for increasing graphitizability of CTP.

Modification of coal tar pitch in hydropercussion-cavitation field

A new process for modification of coal tar pitch is proposed. The time of modification is reduced to 1 hour as compared to 8 hours in the conventional process. The consideration of mechanism of the modifications in structure and properties of pitch under hydropercussion-cavitation treatment is focused on expanding its application scope with a view of manufacture of electrodes.

Modification of coal tar pitch by high-temperature treatment with polyvinyl chloride

Properties of residues from joint pyrolysis of poly(vinyl chloride) and coal tar pitch at 300 and 400°C were studied.

05/02009 Study of the modification of coal-tar pitch with p-methyl benzaldehyde

05/02009 Study of the modification of coal-tar pitch with p-methyl benzaldehyde

A role of charge-transfer complex with iodine in the modification of coal tar pitch

Iodine introduced into coal tar pitch (CTP) can drastically alter its reology and carbonization behavior. Here, the mechanism of interaction between iodine and CTP has been investigated by using various spectroscopic methods such as 127I-NMR, EPR and FT–IR. It is shown that some iodine molecules infiltrated into the CTP and form charge transfer complexes with the relative large aromatic components of the CTP. Hyperfine sublevel correlation spectroscopy (HYSCORE) revealed the molecular size of cation radicals, which contain more than ten benzene rings, and the location of iodine anion that is incorporated at ca. 0.3 nm from the aromatic cation radicals. The elemental H/C ratio decreased and the viscosity of CTP increased with the density of the charge-transfer complexes, which was also increased by the iodine treatment. These results strongly suggest that dehydrogenative polymerization of CTP occurs during the iodine treatment. The cation radicals in the charge-transfer complexes accelerate the dehydrogenative polymerization and result in a high carbon yield.

96/01456 Chemical modification of coal tar pitch

96/01456 Chemical modification of coal tar pitch

96/01491 Modification of coal-tar pitch by air-blowing. II. Influence on coke structure and properties

96/01491 Modification of coal-tar pitch by air-blowing. II. Influence on coke structure and properties

95/05976 Modification of coal-tar pitch by air-blowing - I. Variation of pitch composition and properties

95/05976 Modification of coal-tar pitch by air-blowing - I. Variation of pitch composition and properties

Modification of coal-tar pitch by air-blowing — I. Variation of pitch composition and properties

Pitch oxidation by air-blowing has been studied as a possible method to modify pitch properties for composite preparation. Two commercial coal-tar pitches, an impregnating pitch and a binder pitch, were air-blown at temperatures between 250–300 °C, for 18 and 14 h, respectively, to produce pitches of similar softening point ranging from 148 to 223 °C. Parent and treated pitches were characterized by elemental analysis, FTIR, thermal analysis (TMA, TGA, and DTA), solubility in toluene and quinoline, XPS, X-ray diffraction, and optical microscopy. Additionally, parent pitches were also characterized by extrography. Pyrolysis products of parent and treated pitches, obtained at 450 °C, were characterized by optical microscopy to monitor the influence of air-blowing on mesophase formation. Results show that pitch modification by air-blowing produces a significant increase in carbon yield, without restricting the fluidity necessary to pitch for impregnation. During air-blowing, the reactions of dehydrogenative polymerization and crossing-linking of oligomers occur.

Modification of coal-tar pitch by air-blowing II. Influence on coke structure and properties

This study is concerned with the use of air-blowing to improve pitch properties as matrix precursor of carbon-carbon composites. Two commercial coal-tar pitches, an impregnating pitch and a binder pitch, and their air-blown products obtained at temperatures between 250 and 300 °C, were pyrolyzed in a horizontal tube furnace at 1000 °C. Cokes were characterized by light microscopy to monitor the influence of air-blowing on their optical texture. Density and porosity of cokes were determined by helium densimetry and mercury porosimetry, and their strength and reactivity by a microstrength test and thermogravimetric analysis, respectively. Results show that air-blowing of the impregnating pitch produces a decrease of the optical texture of coke, while in the case of the binder pitch there is an improvement of the microcrystalline structure. Moreover, air-blowing brings about a substantial increase in the density and strength of cokes, and a decrease in their porosity and reactivity.