Tar Distillation Research Articles

Effect of the oxygen content and the functionality of spinnable pitches derived from ethylene tar by distillation on the mechanical properties of carbon fibers

Three basic pitches were prepared by the distillation of ethylene tar at 200, 250, or 300 °C for 3 h. Spinnable pitches were produced from them using air-blowing followed by heat treatment at 330°C for 4 h and are designated P200AT, P250AT and P300AT, respectively. These three pitches, and stabilized fibers and carbon fibers produced from them were characterized by TG-MS, FT-IR, 13C-NMR, XRD, SEM, solubility tests and elemental analysis. The components and oxidation reactivity of the basic pitches, and its influence on the oxygen functionality and microstructures of the spinnable pitches and mechanical properties of the resulting carbon fibers were investigated. Results showed that with increasing distillation temperature the aliphatic carbon content and n-hexane and toluene solubility of the basic pitches decreased, while their aromaticity and planarity increased, and the oxidation reactivity reached a maximum at 250 °C. Of the three spinnable pitches P250AT had the highest softening point, highest carbon yield, oxygen content, and C=O content and the highest toluene insoluble fraction. However, the oxygen uptake of P250AT pitch fibers during stabilization was the lowest among the three. This led to a reduction of gas release during carbonization, and therefore the highest carbon yield, the smallest number of defects, the highest tensile strength and the lowest Young's modulus of all the carbon fibers.

Valuable Products from Coal Tar

Research on the production and properties of coal pitch is conducted in the laboratory at PAO Koks. One topic of interest is the distillation of coal tar to produce a broad tar and pitch fraction, whose quality is analyzed. It is possible to regulate the characteristics of pitch: its ash content and content of components insoluble in toluene (the α fraction) and components insoluble in quinoline (the α1 fraction).

Production of Isotropic Coke from Shale: Characteristics of Coke from Thermally Oxidized Tar-Distillation Residue

The properties of coke produced from residues obtained in the atmospheric distillation of shale tar after low-temperature (250°C) and high-temperature (350°C) thermal oxidation by air injection for different periods are considered. High-temperature thermal oxidation results in the intense formation of α fraction and considerable increase in the softening temperature. By contrast, almost no α fraction is formed in low-temperature thermal oxidation. Nevertheless, low-temperature thermal oxidation ensures more complete removal of anisotropic elements (with a score greater than three according to State Standard GOST 36132) from the microstructure of the coke. The decrease in actual coke density is also less pronounced. In this paper the next denotations are made: isooctane-soluble fraction is denoted as γ fraction, isooctane-insoluble-toluene-soluble is denoted as β fraction, toluene-insoluble-quinoline-soluble is denoted as α fraction, the fraction insoluble in quinoline, pyridine and carbon disulfide is denoted as α1 fraction.

Selective hydrodeoxygenation of p-cresol as a model for coal tar distillate on Ni-M/SiO2 (M = Ce, Co, Sn, Fe) bimetallic catalysts.

Ni–M/SiO2 with different binary metals M (M = Ce, Co, Sn, Fe) prepared by an incipient impregnation method was used in the hydrodeoxygenation (HDO) of low-temperature coal tar distillate, which is rich in phenolic compounds. p-Cresol, as a model compound of the distillate, was used to evaluate the activity and selectivity of BTX products on the series of reduced Ni–M/SiO2 catalysts in a fixed bed reactor. The properties of the catalysts were characterized by N2 adsorption–desorption, ICP-AES, XRD, H2-TPR, and XPS. Benzene and toluene as the direct deoxygenation (DDO) products and cyclohexane and methylcyclohexane as the hydrogenolysis (HYD) products were detected to evaluate the selectivity of the path in the deoxygenation process. In this series of catalysts, the order of reactivity was Ni–Ce > Ni–Sn > Ni–Co > Ni–Fe > monometallic Ni. Meanwhile, the addition of Ce and Co loaded in the Lewis acid sites of the catalyst affected the electron distribution of nickel atom and its atomic arrangement on the surface of the carrier. Compared to monometallic Ni, the DDO path become dominant on Ni–Ce and Ni–Co and the selectivity for BTX products increased from 58.8% to 77.4% and 71.1%, respectively. The binary metal Sn, unlike the former two metals, formed a Ni3Sn crystal form with Ni, which resulted in significant enhancement of the HYD path while obviously increasing the reactivity.

Production of Isotropic Coke from Shale: Microstructure of Coke from the Thermally Oxidized Distillation Residue of Shale Tar

Attention focuses on how the thermal oxidation of hydrocarbon mixtures by air injection at elevated temperatures affects the microstructure of the isotropic coke formed on subsequent carbonization. Specifically, the residue from the atmospheric distillation of shale tar is considered; this hydrocarbon mixture serves as the industrial raw material for the production of isotropic coke. In thermal oxidation at high (350°C) and low (250°C) temperatures, samples are taken for fractionation and coking. In the course of thermal oxidation, the γ fraction of the distillation residue is converted to the α + β fraction. The means size of the structural elements in the coke from the thermally oxidized distillation residue declines. However, for coke produced from the γ and α + β fractions, the opposite changes are observed: decrease in mean size for the α + β fraction, and increase for the γ fraction. For the high-temperature samples, this difference is more pronounced. Thus, the formation of isotropic coke microstructure is due to the conversion of the γ fraction to the α + β fraction and also to the changes in properties of the fractions associated with the thermal-oxidation temperature. In this paper the next denotations are made: isooctane-soluble fraction is denoted as γ fraction, isooctane-insoluble-toluene-soluble is denoted as β fraction, toluene-insoluble-quinoline-soluble is denoted as α fraction, the fraction insoluble in quinoline, pyridine and carbon disulfide is denoted as α-1 fraction. Note that in the domestic literature, the designations of the pitch factions were adopted which differ from the designations used in the English-language literature.

Response of soil phosphatase activities to contamination with two types of tar oil.

Tar oil is a complex mixture of hydrocarbon compounds obtained from high-temperature distillation of coal tar. It has been used for over 100years from now to protect wood and has been applied to wood products, primary utility poles, and railroad ties by pressure methods. Composition of the tar oil depends on the source and typically consists of 85% polycyclic aromatic hydrocarbons (PAHs), 10% phenolic compounds, and 5% heterocyclic compounds. In this research, we performed the laboratory experiment to compare two types of tar oil: C and GX-Plus, and their effects on P-cycling enzymes (phosphatases) in sandy loam and loamy sand. Tar oil was applied to soil samples at the following doses: 2, 10, and 50gkg-1. Soil without tar oil was used as a control sample. The experiment showed that the contamination of soil with tar oil affects the enzyme activities measured and with this most probably the P-cycle in soil. Phosphomonoesterases were the most sensitive to the contamination of soil with both type of tar oil: typeC and type GX-Plus. Greater changes in the enzymatic activity were observed in the loamy sand. Moreover, the type C tar oil demonstrated higher toxicity for phosphatases than type GX-Plus.

STRUCTURAL OPTIMIZATION OF THE NAPHTHALINE DISTILLATION SCHEME BASED ON PHASE EQUILIBRIUM ANALYSIS

The research main aim is to analyze the presence, composition and naphthalene azeotropes type with impurities in the naphthalene fractions obtained by the distillation of coal tar. The presence of mentioned impurities significantly complicates the process of obtaining a pure product – naphthalene. The most difficult problem is the separation of naphthalene-thionaphthene mixture.Based on the simulations of the vapor-liquid equilibrium of the these mixtures components at different pressures, which were carried out in the HYSYS simulation environment using the UNIFAC method and the NRTL activity model, it has been shown that there are positive homogeneous azeotropes of 2,3-xylenol – naphthalene and naphthalene – thionaphthene. Azeotrope of xylenol – naphthalene – thionaphthene existence in the mixture was predicted. At atmospheric pressure, the azeotrope composition is presented: xylenol - 43 mass %, naphthalene - 5 mass % and thionaphthenes - 52 mass %. The boiling point is 201°C.Based on the analysis of phase equilibria, a unified energy efficient naphthalene separation method was proposed. Scheme consist of two columns, which operate under different pressures: the first column at a residual pressure of 100 mm Hg, the second at atmospheric pressure. The required regimes and efficiency of the columns were determined, ensuring the production of a commercial product with a main substance content of more than 99 % from naphthalene fractions with different composition with minimal loss of naphthalene.The conditions for the formation of the power-energy unit were determined in order to use the upper product condensation heat in the second column to heat the column operating under vacuum. This principal reduces the energy costs of obtaining the pure naphthalene (99 mass %) by 35 % in comparison with the design scheme without linking the heat fluxes.

Catalytic hydrogenation of Low temperature coal tar into jet fuel by using two-reactors system

The experiment of the jet fuel fraction through hydrogenation was investigated via hydrogenation in two-stage fixed beds reactor filled with hydrofining catalyst and hydroisomerization catalyst with low-temperature coal tar (LTCT) distillate (<360 °C) as the feedstock. The reaction of coal tar on the catalyst was studied through analyzing the yield of product, the saturation performance, the carbon number distribution and the chemical components of the jet fuel fraction. In current study, the experimental conditions included the temperature at 340∼400 °C, the pressure of 6∼12 MPa and the liquid hourly space velocity (LHSV) of 0.4∼1.0 h−1. The results showed that at a fixed pressure (10 MPa), reaction temperature (380 °C), LHSV (0.8 h−1) and the H2/oil ratio of (1600:1), the yield of the jet fuel fraction and the content of saturated hydrocarbons in the prodcuts were 58.0% and 60.7%, respectively. Finally, by GC–MS analysis, cyclanes and i-alkanes were dominant components in the jet fuel fraction, approximately accounting for 63.08% and 20.25%, respectively.

Characteristics of an improved collector derived from a waste of coal-processing plant for the beneficiation of Indian coking coal fines by froth flotation

ABSTRACTIn the present study, a collector reagent in the form of three distillation fractions from coal tar suitable for froth flotation was developed for the flotation of Indian coking coal fines. The developed tar fractions were compared with known reagent such as diesel, N-dodecane and kerosene oil. Tar fractions were found to be more efficient than the other known collectors. A particular coal tar distillate fraction (B) was found the best, which, in combination with methyl isobutyl carbinol (MIBC) as frother, successfully produced a yield of about 83.4% with low-ash 16.9%. In this way, a higher yield of coal fines was successfully obtained compared with other collectors. To illustrate this point, compared with other known collectors, the yields with diesel, N-dodecane and kerosene as collectors were only 71.4%, 66.7% and 61.1, respectively. The effect of three important variables of coal flotation process, namely collector dosages, frother dosages and pulp density, was also studied. A comparative study was performed of the FTIR (Fourier transform infra red) spectra on a Perking Elmer GX FTIR spectrometer at 2 cm−1 of tar fractions A, B, C and diesel oil to examine the role of various functional groups and structural aspects in their behavior and performance as a collector agent.

Production of Clean Fuels by Catalytic Hydrotreating a Low Temperature Coal Tar Distillate in a Pilot-Scale Reactor

China is one of the largest coal producers in the world and abundant coal tar is produced from coal gasification and carbonization every year. Thus, catalytic hydrotreating coal tar for the production of clean fuel has received substantial attention. In this work, clean liquid fuel was obtained from the catalytic hydrogenation of a low temperature coal tar (LTCT) distillate in a four-stage fixed bed reactor with various catalyst combinations on the pilot scale. Effects of dominant hydrotreating parameters, reaction temperature (290–390 °C), H2 pressure (8–15 MPa), and liquid hourly space velocity (0.2–0.6 h–1), on hydrotreating activity, the intermediate and final products, and chemical components of the hydrogenated oils were evaluated. Meanwhile, a possible reaction scheme for the conversion of alkyl-naphthalenes (AN) and phenols in feedstock was probed. The results showed that the four-stage reacting system was capable of removing sulfur and nitrogen to less than 10 μg/g. Furthermore, after hydrotreati...

Staying in the black

Orion Engineered Carbons has no aspirations to be something it is not. It makes carbon black. Its strategy is simple, too. Whenever possible, it makes and sells the most sophisticated grades of carbon black it can. Orion was founded in 2011 when two private equity firms, Rhone Capital and Triton Partners, bought Evonik Industries’ carbon black business for about $1.2 billion. Three years later, the newly independent firm launched a public offering on the New York Stock Exchange. Along with other players such as Cabot Corp. and Birla Carbon, Orion is among the world’s largest carbon black producers. Carbon black is essential for reinforcing rubber goods, especially tires. It’s also blended into plastics, printing inks, and paints, lending black pigmentation as well as properties such as strength, electrical conductivity, and protection from ultraviolet light. Producers normally make carbon black via the incomplete combustion of coal tar distillates, residual fuel oil,

Coal tar pitch extract could induce chromosomal instability of human bronchial epithelial cells mediated by spindle checkpoint-related proteins.

Coal tar pitch (CTP) is a byproduct of coal tar distillation. The workers working with coal tar or in aluminum smelters, potrooms and carbon plants have the opportunities of exposing to coal tar pitch volatiles. Coal tar pitches from which polycyclic aromatic hydrocarbons (PAHs) originate have been shown to exhibit lung carcinogenicity in humans. Chromosomal instability (CIN) is a mechanism in carcinogenesis, however, whether CIN is involved in coal tar pitch-induced lung cancer remains elusive. In this present study, human bronchial epithelial cells (BEAS-2B) were first exposed to coal tar pitch extracts (CTPE) to induce a malignant transformation model. Then, the occurrence of severe chromosomal changes detected using G band, R band and multiplex fluorescence in situ hybridization (M-FISH) staining were examined. It was shown that more clones of transformed BEAS-2B cells at passage 30 following stimulation with CTPE were formed in the soft agar compared with the vehicle control. Moreover, the expression of the spindle checkpoint-related proteins, mitotic arrest defective 2 (Mad2), budding uninhibited in benzimidazole 1 (Bub1), and anaphase-promoting complex (APC), indicators of abnormal chromosomes and carcinogenesis, reduced in CTPE-treated BEAS-2B cells at Passage 30 compared with the vehicle control using real-time PCR and immunohistochemistry. In summary, exposure of BEAS-2B cells to CTPE may induce chromosomal instability through spindle checkpoint-related proteins.

One-step green synthesis of nitrogen and phosphorus co-doped pitch-based porous graphene-like carbon for supercapacitors

Using coal tar pitch (CTP), a byproduct from coal tar distillation, as precursor, with the assistance of a common polymer (ammonium polyphosphate), we develop a one-step green synthesis route to prepare nitrogen and phosphorus co-doped porous graphene-like carbon (designated as N,P-PGC). The obtained products possess a high surface area and micropore attributing to the activation of the generated H3PO4. We have also demonstrated the potential applications of the resultant N,P-PGC as high-performance electrode material for supercapacitors. The materials possess a high capacitance of 219 F/g in 6 M KOH electrolyte at the current density of 0.5 A/g and excellent cycle stability with 95.6% capacitance retention after 10000 cycles, which can be attributed to the synergetic effect of (1) the electric double layer capacitance that came from the uniform porosities developed by in situ activation; and (2) pseudo-capacitance that originated from rich and tunable surface group by co-doping. Thus this work provides a low-cost and simple synthetic strategy to complete the transformation of byproduct to high value-added products.

Ozonolysis of isoquinoline in a polystyrene-based sulfonate cation exchanger

Nanoreactor ozonolysis of aromatic heterocycles is studied. It is found that cinchomeronic acid (which is used in the production of medical preparations) may be obtained by the nanoreactor ozonolysis of isoquinoline, which is a component of the heavy pyridine bases obtained in the distillation of coal tar.

Novel corrosion inhibitors for acidizing oil wells

Acidizing is a common job in both new and old oil and gas wells. In new wells, acids are forced into the pore spaces of the rock formation, dissolving them, enlarging the existing flow channels, and open new ones to the wellbore. In old wells, it is used for the removal of scale deposits which cause plugging the porosity of the formation containing oil and/or gas, and decreasing the production of the wells. Formation of deposits on production equipments is also a major problem, causes corrosion, flow restriction, and production decline. The majority of acidizing treatments utilize HCl at high concentrations and high temperatures. To avoid the acid attack on the metallic surface, highly effective corrosion inhibitors are needed for this process. In this paper, tow inhibitor formulations have been investigated for the inhibition of mild steel in 15 and 20% HCl solutions at 65 and 90 °C. One of these formulations is composed mainly of coal–tar distillation products [CTDP] and the second from the aqueous extract of ginger. The corrosion inhibition effectiveness was measured by the weight loss of the steel coupons after immersing in the acid solution for 6 h. The results showed decrease of corrosion rate [CR] and increase of inhibition efficiency [Inh. Eff.] with increasing the concentration of the two inhibitors. In 15% HCl, the lowest CR values given by CTDP are 1.867 and 22.75 g/m2h, respectively, at 65 and 90 °C. The corresponding blank CR values are 136.03 and 233.667 g/m2h, and the maximum Inh. Eff. values are 98.6 and 90.3%. Ginger extract formulation achieved 99.3 and 96%, respectively at 65 and 95 °C. No significant change in the efficiency of the two formulations has been obtained with increasing the HCl concentration to 20%. The results have been compared with those obtained with currently used commercial inhibitors and it is found that the two formulations are more effective.

Effect of Dephenolization on Low-Temperature Coal Tar Hydrogenation To Produce Fuel Oil

The experiment of fuel oil production through hydrogenation has been conducted on a hydrorefining–hydrocracking two-stage serial fixed-bed reactor with coal tar distillate [CTD; initial boiling point (IBP)–360 °C] and phenol extraction coal tar distillate (PE-CTD) as the feedstocks. By comparison of the changes in chemical composition and carbon number distribution as well as product distribution and properties before and after hydrogenation in the two feedstocks, the influences of phenol extraction treatment on fuel oil production with coal tar hydrogenation were studied. The experimental conditions of this study include the reaction pressure of 13 MPa, liquid hourly space velocity of 0.5 h–1, hydrorefining reaction temperature at 360 °C, hydrocracking reaction temperature at 380 °C, and filling proportion of hydrorefining catalyst/hydrocracking catalyst of 1:1. The experimental result shows that phenol extraction reduces the naphtha yield by 8.69 wt % but produces 13.58% of mixed phenols. Furthermore, the phenol extraction treatment is favorable for converting a heavy distillate of coal tar to a light fraction.

Product compositions from catalytic hydroprocessing of low temperature coal tar distillate over three commercial catalysts

Catalytic hydroprocessing of low temperature coal tar (LTCT) <360 °C distillate was performed over commercial Ni–W/γ-Al2O3, Ni–Mo/γ-Al2O3 and Co–Mo/γ-Al2O3 catalysts in a fixed-bed reactor to produce clean liquid fuel. Experimental feedstock and liquid products were divided into twelve groups based on converted material with the molecules and saturation levels to investigate the effect of catalysts on reaction network of the main compounds in feedstock by GC/MS analysis. Meanwhile, the influence of catalyst component on the product composition like group composition, distribution of carbon number, heteroatom removal, gaseous and oil properties was also investigated. The experimental results showed that phenols were mainly transformed into cycloalkanes and alkylbenzene, while alkyl-naphthalenes were converted to phenyl cycloalkanes and phenyl olefins. In addition, total carbon number in a slightly decreasing tendency. The Ni–W/γ-Al2O3 catalysts showed a higher hydrogenation activity and intermediate carbon number (C9–C16) selectivity, whereas the higher HDN and ring open activity was observed using Ni-Mo/γ-Al2O3 catalyst. The highest percentage of sulfur removal (about 97.8 %) was reached over the Co-Mo/γ-Al2O3 catalyst. Besides, methane was the predominant constituent in the light hydrocarbon gaseous product. And the properties of raw LTCT could be considerably upgraded after hydrotreatment.

Fossil rootlet biopores as conduits for contaminant transport through clay horizons: a case study of DNAPL behaviour in Severn alluvium, UK

This paper presents a case study of several DNAPL contaminated sites around the Severn Estuary (UK) where a combination of detailed observations, core dissections and physicochemical characterisation of alluvial clay–silt horizons have revealed the presence of fossil rootlet biopores which act and have the potential to act as conduits for contaminant migration through up to 13 m of clay–silt. The biopores are shown to penetrate the low-permeability (K ~ 10−10 m/s) clay–silt matrix throughout its entire depth (up to 13 m) and provide a preferential transport pathway for DNAPLs from near surface to the underlying aquifer, with particularly high concentrations measured in the biopores themselves. Capillary rise experiments with coal tar distillate demonstrate that DNAPLs are drawn into biopores, with values of surface interfacial tension for the system calculated as 8 × 10−2 J/m2. Wicking by residual plant fibres was demonstrated qualitatively and is thought to be an important additional transport mechanism. The DNAPL contamination below and throughout the Severn alluvial clay–silt horizons demonstrates that the assumption that these horizons act as an effective seal protecting underlying aquifers from severe pollution from the legacy sites around the Severn is flawed and highlights the failure of current protocols for sampling of clay horizons for hydraulic conductivity assessments, since current methods can destroy delicate in situ biopore structures. The study demonstrates that the interplay between ecological and the geological depositional environment can, at a regional scale, result in a network of biopores that can potentially act as conduits for contaminant transport.

The aceramic production of Betula pubescens (downy birch) bark tar using simple raised structures. A viable Neanderthal technique?

Following on from our previous research into the prehistoric aceramic distillation and production of birch bark tar, this series of exploratory experiments investigated the use of raised structures within a fire. These field-based experiments were conducted using sand, gravel, wood fuel, and bark from Betula pubescens (downy birch). The structures that were created were simple raised sand mounds, which reflected known Neanderthal combustion surfaces from the Middle Palaeolithic. The bulk of the experiments were recorded throughout using a thermocouple to provide temperature readings from the base of the bark pyrolysis chamber. The experiments proved successful at producing birch bark tar and several containers were used to catch the tar for later analysis. Based on the results, the authors contend that not only could Neanderthals control fire but that regular birch bark tar production by Neanderthals was most likely a result of specific chaines operatoires in order to provide the necessary control and outcomes.

Production of coal tar/petroleum pitch by the combined distillation of coal tar and heavy cycle oil at JSC Gubakhinskii Koks

Coal tar/petroleum pitch has been produced by the combined distillation of coal tar and heavy cycle oil from catalytic cracking, in industrial trials. In processing a 60: 40 mixture of those components, 306 t of pitch that meets the requirements for anode binder is produced. The benzo[a]pyrene content is lower in the petroleum–coal pitch than in regular coal pitch used in electrode production.