Coal Liquefaction Products Research Articles

Toxicology of coal liquefaction products: an overview.

Repeated exposure to coal liquefaction products produces a broad range of systemic effects. Among these, growth suppression, anaemia, leucocytosis and other haematological disorders are most prominent. Bone marrow, liver and kidney are the target organs affected by treatment. The effects are more severe with heavy distillates and male rats are more sensitive than females. Other changes included increased serum transaminases, alkaline phosphatase and cholesterol. Depending on the route of administration, the skin or lung may also be affected. Inhalation exposure produces the most severe changes, and oral exposure the least. Distillates containing N-PAHs and sulphur-containing PAHs are also more biologically active. Teratological effects were only observed if animals were exposed to the heavy distillate. Similarly, heavy distillates have mutagenic or carcinogenic properties. Teratological effects, as well as mutagenicity and carcinogenicity, of the coal liquefaction distillates seem to be linked to their PAH content, especially the N-PAHs. From the data presented in this review, it should become evident that the potential effects of coal liquefaction products on human health could be severe, especially with long-term exposure. Limited information exists on the occupational effects to coal liquefaction materials because most of the work to date has been with pilot plants. Careful and good judgement is required in order to extrapolate data from pilot plants to commercial-scale production. Experience in health effects of workers in the petroleum industry and coke-oven operations can serve as a guide for the implementation of industrial hygiene programmes for coal liquefaction operations. These programmes include engineering controls, health education, personal monitoring and hygienic practices, medical surveillance and long-term epidemiology studies, and they should be implemented to make coal liquefaction a healthy and environmentally sustainable industry.

Calcination and graphitization behaviour of cokes from Ql-free coal-derived pitches

Coal tars and coal liquefaction products are possible feedstocks for anisotropic carbon material production. Semi-coke samples were produced from coal tar pitch, CTP 101 and coal hydrogenation pitch, CHP 88, prepared in a laboratory scale from QI-free parent liquids. Changes in the structure and properties of the semi-cokes, during two stage calcination and graphitization treatment up to 2700 °C, were evaluated. Both pitches produced highly anisotropic semi-cokes, slightly differing in the distribution of microconstituents revealed by optical texture. The calcined coke from coal tar pitch CTP 101 was distinguished by higher real density and porosity, lower heteroatom (N + O) content and microstrength and slightly higher graphitizability. The increase of heating rate in the temperature range 500–850 °C from 5 to 100 K min −1 induced negligible alteration in the properties of calcined cokes. The more intensive evolution of nitrogen on heating between 1300 and 1700 °C of the CHP 88 coke was associated with larger development of porosity in the coke grains, corresponding to greater puffing. The lower extent of puffing favours the QI-free coal tar rather than the coal hydrogenation product as a feedstock for electrode coke production.

Comparison of product distributions from the thermal reactions of tetralin in a stirred autoclave and a flowing-solvent reactor

Products from the thermal reactions of tetralin in a stirred micro-autoclave and a flowing-solvent reactor were compared by gas chromatography-mass spectrometry, to study the effect on product composition of residence time in the reaction zone: of the order of seconds in the flowing-solvent reactor and normally 1 h in the stirred micro-autoclave. Significant differences were found between the products obtained in the two reactors; greater quantities of by-products from thermally induced reactions of tetralin — mainly naphthalene, butylbenzene and 1-methylindane — were found in the heated tetralin from the autoclave. A number of compounds, mainly of mass 262 and 258 u (apparently tetralin-tetralin dimers and tetralin-naphthalene adducts), were also identified in the products from both reactors; many of these products have not previously been reported in connection with the thermal reactions of tetralin. The total concentration of this class of compounds did not exceed ~ 1 wt% of the total solvent. Greater concentrations of the relatively stable dimers and adducts were identified in products from the autoclave than in those from the flowing-solvent reactor. These findings have immediate implications for the evaluation by g.c.-m.s. of coal liquefaction products prepared using tetralin as vehicle, since compounds similar to tetralin-derived by-products have also been found in product solutions from actual coal solubilization experiments.

Non-aqueous enzymatic solubilization of coal-derived materials

The utilization of enzymes in non-aqueous solvents was explored for the conversion of coal-derived materials to oil-soluble derivatives for use as fuels. A novel three-step process was developed: 1. (1) an initial low-severity conversion to a form that is soluble or dispersible in a polar solvent; 2. (2) formation of an alcohol substrate with a high activity for subsequent enzymatic processing; 3. (3) lipase-catalysed transesterification to a product that is soluble in hydrocarbon solvents. The process was successful for the conversion of a first-stage liquefaction product from Wyodak subbituminous coal to an acylated product, about half of which is soluble in hexane and the remainder in toluene. Coals, humic acids and several other higher-molecular-weight coal liquefaction products, such as Chemcoal, and their derivatives inhibited the lipases, and thus the alcohol intermediates from these precursors were converted in 0–5% yields to acylated products.

Comparison of hydrogen transfer from cyclic olefins and hydroaromatic donors under thermal and catalytic liquefaction conditions

A new class of compounds is being investigated for their ability to donate hydrogen during coal liquefaction. The compounds, known as cyclic olefins, are hydroaromatic species without an aromatic ring. These compounds are extremely reactive at coal liquefaction conditions, readily forming other partially saturated compounds and aromatics. This investigation demonstrates the effectiveness of these compounds for coal conversion and liquefaction products. 1,4,5,8-Tetrahydronaphthalene, also known as isotetralin, and 1,4,5,8,9,10-hexahydroanthracene are the two cyclic olefins employed in this study. Their hydrogen-donating ability, as reflected by the amount of coal converted to tetrahydrofuran solubles, is compared to that of their conventional hydroaromatic analogues, tetralin, dihydroanthracene, and octahydroanthracene, at equivalent donable hydrogen levels

Systemic toxicity of the heavy fraction of a coal coprocessing product in male rats following subchronic dermal exposure

The systemic toxicity of a coal coprocessing product [heavy gas oil II (HGOII)] following subchronic, dermal exposure in male Sprague-Dawley rats was investigated. HGOII was applied to the dorsal skin daily at doses of 8.7, 20.8, 50.0, or 120.0 mg/kg body weight (bw) for 13 weeks. Another group of rats treated with a medium boiling coal liquefaction product (CLP) served as positive controls. Growth suppression and decreased food consumption were noted in the groups exposed to HGOII at 20.8 mg/kg and higher, and to CLP starting at the third week of treatment. Relative liver, kidney, and brain weights in the 20.8 mg/kg HGOII group and up were higher than those of the control. Increased spleen weight was observed in all HGOII-treated groups. CLP treatment also caused increased relative kidney and brain weights. Serum cholesterol was elevated in the HGOII-treated groups starting at 8.7 mg/kg while increased uric acid and lactate dehydrogenase were observed at 20.8 mg/kg and up. Decreased erythrocyte, hemoglobin, and platelet counts were observed at 20.8 mg/kg and higher. All HGOII-treated groups had elevated reticulocytes. These biochemical and hematological changes were not observed in the CLP-treated group. Mild to marked histological changes were observed in the thyroid, thymus, liver, spleen, and bone marrow of HGOII groups. In contrast, morphological changes were relatively mild in CLP-treated animals. Data from the present study demonstrated that the hematological endpoints were sensitive to the liquid fuels and that HGOII was more toxic than CLP. Based on the growth rate and biochemical, hematological, and morphological changes, the no observable adverse effect level for HGOII is judged to be below 8.7 mg/kg bw in the rat.

Systemic Toxicity of the Heavy Fraction of a Coal Coprocessing Product in Male Rats Following Subchronic Dermal Exposure

The systemic toxicity of a coal coprocessing product [heavy gas oil II (HGOII)] following subchronic, dermal exposure in male Sprague-Dawley rats was investigated. HGOII was applied to the dorsal skin daily at doses of 8.7, 20.8, 50.0, or 120.0 mg/ kg body weight (bw) for 13 weeks. Another group of rats treated with a medium boiling coal liquefaction product (CLP) served as positive controls. Growth suppression and decreased food consumption were noted in the groups exposed to HGOII at 20.8 mg/kg and higher, and to CLP starting at the third week of treatment. Relative liver, kidney, and brain weights in the 20.8 mg/kg HGOII group and up were higher than those of the control. Increased spleen weight was observed in all HGOII-treated groups. CLP treatment also caused increased relative kidney and brain weights. Serum cholesterol was elevated in the HGOII-treated groups starting at 8.7 mg/kg while increased uric acid and lactate dehydrogenase were observed at 20.8 mg/kg and up. Decreased erythrocyte, hemoglobin, and platelet counts were observed at 20.8 mg/kg and higher. All HGOII-treated groups had elevated reticulocytes. These biochemical and hematological changes were not observed in the CLP-treated group. Mild to marked histological changes were observed in the thyroid, thymus, liver, spleen, and bone marrow of HGOII groups. In contrast, morphological changes were relatively mild in CLP-treated animals. Data from the present study demonstrated that the hematological endpoints were sensitive to the liquid fuels and that HGOII was more toxic than CLP. Based on the growth rate and biochemical, hematological, and morphological changes, the no observable adverse effect level for HGOII is judged to be below 8.7 mg/kg bw in the rat.

Brown coal conversion to liquid products at the ST-5 pilot plant

The results of brown coal hydrogenation from the Borodinsky deposit of the Kansk-Achinsk basin ( W r 0.9 wt%, A d 5.7 wt%, V daf 39.0 wt%, C daf 73.18 wt%, H daf 5.48 wt%, S t d 0.26 wt%, N daf 0.79 wt%) under field conditions of the ST-5 pilot plant are given. The characteristics of gasoline and diesel fuel samples obtained from distillate fractions of coal liquefaction products are analogous to the characteristics of the same samples obtained from petroleum. According to data obtained in the presence of coal paste-forming agent the specific thermal effect of hydrogenation is 760 kJ/kg of feedstock. Summary material balances of coal hydrogenation at the ST-5 pilot plant were obtained.

VARIATION OF TEMPERATURE EFFECT WITH HYDROGEN SUPPLY IN NON-CATALYTIC COAL LIQUEFACTION

ABSTRACT A Spanish subbituminous coal was subjected to non-catalytic liquefaction with tetralin in a 250 ml stirred autoclave. The operating conditions used were: one hour reaction time, 17 MPa operating pressure and 400 r.p.m, stirring speed. The liquefaction products were fractionated into oils, asphaltenes, preasphaltenes and solid residue by a solvent extraction technique using pentane, toluene and THF as extractive solvents. It was found that the influence of temperature on coal liquefaction yields and product distributions varies with the amount of donatable hydrogen. Total coal conversion increases with temperature, when very high tetralin/coal ratios are used On the contrary, when 1/1 ratio is used, conversion does not seem to depend on temperature, and appears to be limited by the amount of liquid medium available as physical solvent. At intermediate tetralin/coal ratios,conversion generally increases with both factors: temperature and amount of solvent. However, retrogressive reactions are observed at 475°C which indicates that these reactions are produced at high temperatures when there is not enough hydrogen in the system As far as product distribution are concerned, it is observed that asphaltenes and preasphaltenes decrease, while oils + gases increase with temperature.

Short‐term dermal toxicity and mutagenicity of coal coprocessing products in the rat

The present study was conducted to determine the dermal toxicity of coal coprocessing products and to assess their potential health hazards. Groups of 10 male and 10 female Sprague-Dawley rats were administered dermally coal coprocessing products (light gas oil, LGO; heavy gas oil I, HGOI; heavy gas oil II, HGOII) at 1 g/kg body weight/d for 14 d. The control and positive control groups received normal saline and a coal liquefaction product (CLP) at the same dose level, respectively. Treatment with either the three fractions of coprocessing products or CLP caused decreased growth rate and food consumption in animals of both sexes. Liver enlargement occurred in groups treated with HGOI, HGOII, and CLP. Decreased serum glucose was observed in animals of both sexes treated with the three fractions and CLP. Treatment with HGOI and CLP caused an elevation of hepatic microsomal ethoxyresorufin deethylase activity in the rat of both sexes. The three fractions and CLP caused mild anemia. Mild treatment-related histological changes were observed in the liver, spleen, thyroid, bone marrow, and kidney. All three fractions of coprocessing products were tested for their mutagenicity in five strains of Salmonella typhimurium: TA98, TA100, TA1535, TA1537, and TA1538. HGOI, after metabolic activation, was found to be mutagenic in the strains of TA98, TA100, and TA1538. In contrast, HGOII was mutagenic in the five strains with or without metabolic activation. These data indicate that HGOI and HGOII are more toxic than LGO, and should be subjected to further studies to determine their long-term effects.

摂動型状態方程式による超臨界流体に対する高沸点化合物の溶解度の相関

A perturbed-hard-sphere equation of state (PHS-EOS) was applied to correlate the solubilities of high boiling compounds such as coal liquefaction products in supercritical fluids. A suitable mixing rule for the constants contained in the PHS-EOS is needed to apply the equation of state to a mixture composed of high boiling compound and supercritical fluid. In this study, mixing rules for the constants were examined and discussed. It was found that a local composition mixing rule with three characteristic parameters introduced into both molecular attraction and molecular size terms gives a good result because the solubility is quite small near infinite dilution.

Correlation of solubilities of coal liquefaction products in supercritical ethylene and ethane using an equation of state.

Correlation of solubilities of coal liquefaction products in supercritical ethylene and ethane using an equation of state.

A teratological assessment of coal liquefaction products in the rat

Teratogenicity of coal liquefaction products (CLP) was assessed in the pregnant rat. Three product streams of CLP (medium, hydrotreated medium and heavy fractions) were each administered dermally on Sprague-Dawley rats at doses of 125, 250 or 500 mg kg-1 day-1 from Day 6 through to Day 15 of gestation. Depressed maternal weight gain and reduced number of fetuses resulting from an increased resorption rate, decreased fetal weight and retarded ossification were observed in the group treated with the heavy fraction at a dose of 500 mg kg-1 day-1. The heavy fraction at 500 mg kg-1 day-1 also caused anaemia and increased liver and spleen weights in dams. The dams exposed to the highest dose of three CLP fractions had mild and adaptative hepatic changes consisting of increased cytoplasmic eosinophilia and nuclear anisokaryosis. No treatment-related histological changes were observed in fetuses. None of the fractions demonstrated any teratological effects.

Reactions of coal liquids with cross-linked smectite catalysts: 1. Effects of pillaring materials and recycling

To determine their potential for upgrading coal liquefaction products, a range of clays pillared with aluminium, aluminofluoride, titanium, cerium, vanadium, tin, chromium and zirconium species have been synthesized and reacted with Australian brown coal (Yallourn) liquefaction products in the presence of a conventional sulphided nickel molybdenum catalyst. Typically, 13% of the recycle solvent comprising an oil-vacuum bottom mixture was cracked to gas by these catalysts, so that the conversion to liquid products was lower than those obtained from initial liquefaction. However, the liquid products are comparatively more volatile. A synergistic effect between pillared clay and nickel molybdenum catalyst has been identified. Although yields of oil were similar, the product oil contained less aromatic carbon when prepared in the presence of aluminium pillared clay and nickel molybdenum catalyst than when prepared using nickel molybdenum and pillared clay catalyst in sequence. Catalysts pillared with vanadium, titanium, cerium, fluorine or phosphorus based materials improve the hydrogen content and decrease the aromaticity of the product compared with uncatalysed experiments. However, in experiments in which the catalyst was recycled, there was a marked deterioration in yields and volatility of the product.

Hydrogenation of distillate products from coal liquefaction

The catalytic activities of two commercial nickel-molybdenum-alumina catalysts were tested for hydroprocessing of coal liquefaction distillate products with b.p. up to 425 °C. One of the catalysts was effective for the hydroprocessing of coal liquefaction products at 400 °C, 8 MPa, LHSV = 0.5 h −1. Hydrogenation reactions of heteroatomic compounds, unsaturated compounds and aromatic hydrocarbons in the presence of this catalyst can be described by first order rate equations with respect to these compounds.

Comparison of primary and two-stage coal liquefaction products

Coal-derived liquids obtained from direct, non-catalytic hydrogenation of Polish subbituminous coal were fractionated into four main distillation fractions: light, middle, vacuum and carbonization oils. The light and middle fractions were upgraded in a two-stage hydrogenation process under various conditions using Ni-Mo hydrotreating catalysts. Recycle solvent and hydroproducts were characterized by routine i.r., 1H 13C n.m.r. and g.c.-m.s. techniques. The results revealed complex changes occurring in physicochemical properties, structural parameters and chemical composition of hydroproducts with distillation range and hydrorefining conditions. The n.m.r. and g.c.-m.s. data on donatable hydrogen showed a good correlation.

Characterization of coal liquefaction products by gas chromatography—fourier transform infrared spectroscopy—mass spectrometry

An integrated gas chromatography—Fourier transform infrared spectroscopy—mass spectrometry system was utilized in the analysis of a neutral and acidic fraction obtained from the aqueous portion of the low-severity coal liquefaction products. Reconstructed selected-ion chromatograms along with reconstructed absorbance chromatograms over elected ranges were useful in discriminating between the types of organic compounds in the complex mixtures. A series of γ-lactones and a series of ketones were characterized, the ring size and unsaturation being determined by the absorbance frequency of the carbonyl stretching band.

シェールオイルの化学構造特性および水素化処理によるその変化

Shale oil is characterized by high nitrogen content, coal liquefaction product by high oxygen content and tar sand bitumen by high sulfur content. Shale oil contains a low content of hydrogens bound to aromatic carbons (Ha) and a high content of hydrogens bound to aliphatic carbons β or further from aromatic rings (Ho). The aromaticity is low, and the size of aromatic rings in the structural unit is small (1ring).The hydrogen content of hydrotreated shale oil increases, and the atomic ratio H/C reaches 2.1. On the other hand, the nitrogen content decreases up to 22-56% of raw shale oil, and the oxygen content up to 25-88% of raw shale oil. During hydrotreatment, Ha and hydrogens bound to aliphatic carbons α from aromatic rings (Hα) decreases, and Ho increases. The resin component decreases remarkably, the aromatic component increases initially and then decreases, and the saturate component increases remarkably. Consequently, the hydroconversion of shale oil is considered to proceed as follows;Resins→Aromatics→SaturatesThe middle fraction (200-325°C) decreases and the naphtha fraction (IBP-200°C) increases. The yield of naphtha fraction is ca.40wt% independent of reaction conditions.

Identification of heteroaromatic compounds in coal liquefaction and gasification products by deuterated reagent chemical ionization mass spectrometry

Deuterated reagent chemical ionization (CI) mass spectrometry was used to identify isomeric oxygen-, nitrogen- and sulphur-containing species in a phenolic fraction from the liquefaction of lignite, a base fraction from the gasification of lignite and the headspace of the liquefaction of pine sawdust. The exchange of active hydrogens (OH, NHR and SH) for deuterium from the CI reagent aids in the identification of isomeric species. Standard CH 3OD CI spectra for 76 oxygen-, nitrogen- and sulphur-containing compounds are presented. The complementary use of both CH 3OD CI and EI mass spectra enables one to assign the compound class of many heteroatom-containing aromatics.

Dermal toxicity of a high-boiling (bp 250-450 degrees C) coal liquefaction product in the rat--II.

Coal liquefaction products have been considered as an alternate source of energy to replace conventional crude oil. The present study was designed to investigate the dermal toxicity of a heavy fraction of coal liquefaction product (CLP, bp 250-450 degrees C) in the rat. Groups of 10 male and 10 female Sprague-Dawley rats (180-200 g) were treated dermally with CLP at dose levels of 100, 200, 400, or 800 mg/kg body weight.d for 6 wk. The controls were treated with 0.4 ml/kg of normal saline, while the positive control group received 400 mg/kg diesel fuel. Growth suppression was observed in all CLP-treated groups of males; in the females this effect occurred in the two highest dose groups. Diesel fuel at 400 mg/kg also caused growth suppression of a similar magnitude to that of CLP in male rats. Male animals treated with high doses of CLP or diesel fuel had severe skin lesions. Increased liver weights were observed in the diesel fuel-treated as well as all CLP-treated groups of females. The kidney weights of females treated with 400 mg/kg and 800 mg/kg CLP were also higher than control values. Decreased red cell count, hemoglobin, and hematocrit volume occurred in some CLP and diesel fuel groups of both sexes. There was mild bone marrow hyperplasia in rats of both sexes treated with CLP or diesel fuel. Mild histological changes were observed in the thyroid, liver, bone marrow, and skin of rats of both sexes treated with CLP and diesel fuel. Based on the data presented, dermal application of CLP produced systemic toxicity at the dose levels studied, and CLP and diesel fuel possess toxic effects of similar nature and magnitude.