Hydroliquefaction of Wyodak coal using bottoms recycle

Wyodak coal has been liquefied using recycle solvents consisting of blends of Wyodak coal-derived distillates and SRC or SRC oils, asphaltenes and oils plus asphaltenes. Whilst the quality of the distillate portion of the bottoms recycle is maintained by hydrogenation and distillation in the Exxon Donor Solvent (EDS) process, no reported efforts have been made to hydrogenate the nondistillable portion of the EDS bottoms recycle solvent nor the bottoms recycle solvent in the SRC-II process. As hydrogenation of the distillate portion of the recycle solvent in the EDS process increased Wyodak coal distillate yields, this study was initiated to determine whether hydrogenation of the nondistillable portions of Wyodak coal-derived bottoms recycle solvent would show similar beneficial effects. Results suggest that distillable liquid yields in the range of 55–60 wt% of dry Wyodak coal can be obtained using mildly hydrogenated SRC or SRC oils plus asphaltenes as a bottoms recycle solvent component. This result can be compared to distillable liquid yields of 40 wt% of dry, Wyodak coal obtained from the EDS process using bottoms recycle. Further, the unhydrogenated, SRC-derived oil and asphaltene portions of the recycle solvent also appear to be effective solvent components. However, the most effective solvents were obtained using hydrogenated SRC or SRC-derived oils plus asphaltenes.     

Coal liquefaction using ore catalysts

Ores and ore concentrates containing minerals of Co, Mo, Ni, Fe, and other potentially active metals have been investigated as slurry catalysts for liquefaction of Blacksville mine, Pittsburgh seam, bituminous coal. The tests were conducted batchwise in a stirred autoclave for 30 min at 425°C and 13.79 MPa (2000 psig) hydrogen pressure according to a two-cycle scheme. In the first cycle, the reaction charge consisted of ground coal, catalyst, hydrogen, and SRC-II heavy distillate. The product of the first cycle was hot-filtered, and the liquid product served as a vehicle for the second cycle, which was otherwise run identically to the first. Reaction products from each cycle were analysed to determine conversion of coal, yield of liquids, liquid product viscosity, and group type (preasphaltene, asphaltene, and oil). Mixtures of ores containing iron pyrites and minerals containing other catalytically active transition metals were compared to pyrites alone and to a pulverized supported Co-Mo-alumina catalyst. An ore catalyst containing both Fe and Ni was superior to another that contained an equivalent mass of iron alone. The best ore catalysts tested, in terms of high liquid yields and low product viscosities, were mixtures of pyrites and molybdenum- and cobalt-containing ores. The latter yielded results that approached those obtained with an equivalent mass of cobalt and molybdenum on an alumina support.     

Hydroliquefaction of Victorian brown coal in a continuous reactor : 2. Comparison of tetralin and a coal-derived oil as hydrogen donor solvents

Slurries of Victorian brown coal in either tetralin (1:3) or a hydrogenated creosote oil (HKC 300) (1:3) were reacted with hydrogen in a continuous reactor system both with and without the addition of iron/tin based catalysts. The product yields and distributions from reactions using HKC 300 oil as a solvent are different from those obtained using tetralin. Under similar operating conditions, conversions are slightly lower and the asphaltene yields are higher for reactions in HKC 300 relative to those in tetralin. These differences are presumably due to the poorer hydrogen donor ability of the HKC 300. The yields of asphaltols, asphaltenes and oils for reactions in both solvent systems under a wide range of conditions are discussed as a function of overall conversion.     

Coal liquefaction using iron complexes as catalysts

Hydroliquefaction of Japanese Miike and Taiheiyo coals was carried out using various iron complexes as catalysts in tetralin at 375–445 °C. Iron pentacarbonyl (Fe(CO)₅) showed the highest catalytic activity, increasing coal conversion by about 10% at 425 °C under an initial hydrogen pressure of 5 MPa. Amounts of hydrogen transferred to coal increased from 1.4–2.3 wt% of daf coal in the absence of the catalyst to 2.5–4.2 wt% of daf coal in the presence of Fe(CO)₅ at 425 °C.     

Pressure and temperature effects on the hydrogenation of coal-derived asphaltene

Pressure and temperature effects on hydrogenation reactions were examined using coal-derived asphaltene at 390,420 and 450 °C, under 3 and 10 MPa of hydrogen partial pressure. Higher conversion was obtained at higher reaction temperatures. Benzene-insoluble material (Bl) was formed at higher temperatures especially at low hydrogen pressure, this Bl being one-third of the reaction product at 450 °C. From structural analysis of unreacted asphaltenes and product oils, at 390 °C, it was concluded that smaller molecular components convert to oil initially and the larger molecules remain as unreacted asphaltene. Under higher hydrogen pressure for all temperatures carbon aromaticity (f_a) and number of aromatic ring per structural unit (R_aus) in unreacted asphaltenes were lower than those under lower hydrogen pressure suggesting that hydrogenation of the aromatic nucleus was promoted by higher pressure. At lower hydrogen pressure, R_aus for asphaltenes at higher temperature is larger than that at lower temperature. This suggests that at lower hydrogen pressure, dehydrogenation or condensation reactions occur more easily. A large effect at higher hydrogen pressure was a reduction in the extent of condensation reactions. Higher reaction temperatures contribute to splitting of bridged linkages so reducing molecular size and degree of aromatization.     

Hydropyrolysis of a high-sulphur-high-calcite Italian Sulcis coal. 2. Importance of the mineral matter on the sulphur behaviour

The sulphur distribution among the char, oil and gas obtained after hydropyrolysis of a high-sulphur (4.3 wt%) and high-calcite (7.3 wt%) coal has been investigated. The chars were examined by scanning electron microscopy coupled with an energy dispersion analyser and by X-ray diffraction. The proportion of the combustible and non-combustible sulphur in the char has been determined. Hydrogen pressure promotes reaction with sulphur but the sulphur content of the chars increases from 3 to 4.5 wt% when the temperature is increased from 616 to 845 °C. This increase in sulphur is a consequence of the reaction between hydrogen sulphide, produced during hydropyrolysis of coal, with the alkaline-earth mineral matter to produce alkaline-earth sulphide. The SEM and X-ray diffraction images show that in the char formed at 780 °C the sulphur, calcium and magnesium are localized in the same compounds. This is not the case when hydropyrolysis is performed at lower temperature. Combustion of the chars produces only <0.6 S0₂ MJ^?1 compared to 2.2 g S0₂ MJ^?1 for untreated coal. X-ray diffraction has shown that the sulphur in the char is oxidized and fixed in the ashes mainly as CaS0₄ and also some as MgS0₄. Although sulphur remains partly in the chars after hydropyrolysis, 75% of it is non-combustible. The hydropyrolysis of a high-sulphur coal containing calcite, produces a char which may be used as a clean fuel.     

Effect of process conditions on co-liquefaction kinetics of waste tire and coal

Thermal and catalytic liquefactions of waste (recycled) tire and coal were studied both separately and using mixtures with different tire/coal ratios. Runs were made in a batch tubing bomb reactor at 350–425°C. The effect of hydrogen pressure on the product slate was also studied. Mixtures of tire components and coal were used in order to understand the role of the tire as a solvent in co-liquefaction. In the catalytic runs, a ferric-sulfide-based catalyst impregnated in situ in the coal was used. Both the tire components and the entire tire exhibit a synergistic effect on coal conversion. The extent of synergism depends on temperature, H₂ pressure and the tire/coal ratio. Experiments with coal and tire components show that the synergistic effect of tire is due to the rubber portion of the tire and not the carbon black. The synergism mainly leads to an increase in the yields of asphaltenes, which are nearly double those in the coal-only runs at 400°C. The conversion of coal increases dramatically using the catalyst, but the catalytic effect is attenuated somewhat in the presence of tire, especially at high tire/coal ratios. The data were analyzed using a consecutive reaction scheme for the liquefaction of coal to asphaltenes and thence to oil+gas, both reactions being of second order; a second-order conversion of tire to oil+gas; and an additional synergism reaction when both coal and tire are present, first-order in both coal and tire. Parallel schemes were assumed for thermal (uncatalyzed) and catalyzed reactions. The uncatalyzed liquefaction of coal has a low apparent activation energy, 36 kJ/mol, compared to those for the synergism reaction (84 kJ/mol) and the catalytic coal liquefaction (158 kJ/mol). The conversion of asphaltenes to oil+gas is relatively independent of temperature and of the presence of the catalyst. The catalyst appears to play a significant role in the conversion of coal to asphaltenes, but a negligible role in the synergism reaction.     

Hydrocracking of Athabasca asphaltene over ZnCl2-KCl-NaCl melts with or without an additive of some transition metal chlorides

Hydrocracking of Athabasca asphaltene over molten salts has been studied at 400 °C for 1 h at an initial hydrogen pressure of 9.8 M Pa. The hydrocracking over ZnCl₂-KCl-NaCl produced 57.0 wt% of pentanesolubles (PS), 4.7 wt% of benzene-solubles (BS) and 22.7 wt% of gases together with 15.6 wt% of coke. These melts containing NiCl₂ and CuCl, respectively, were examined, the former exerting a little better influence on reducing the coke yield. A small amount of coke (3.7%) and a higher conversion attained with ZnCl₂-KCl-NaCl-MoCl₅ suggested excellent properties of MoCl₅ for the hydrocracking of asphaltene. The sulphur contents of the PS and BS were lowest with melt catalysts containing MoCl₅. A compound-type separation of each pentane-soluble showed that in the presence of melt catalyst, monoaromatic and diaromatic contents increased greatly at the expense of polyaromatics and polar materials. The trend of catalytic activity of each melt for hydrocracking of asphaltene was found to be quite different from that for the decomposition reaction of tetrahydrothiophene in a continuous flow system.     

反应时间对加氢沥青质结构变化的影响

在高压反应釜中对煤焦油进行催化加氢反应,利用XPS和元素分析对不同加氢反应时间下提取的煤焦油沥青质进行表征,系统分析加氢油品四组分变化、沥青质转化率、化学组成和杂原子赋存形态的变化。结果表明,随着反应时间的延长,加氢油品中饱和分和芳香分收率增大,胶质和沥青质收率减小。加氢后沥青质转化率逐渐增大,分子量先减小后增大,沥青质中氧原子主要以羰基氧和碳氧单键形式存在,氮原子主要以吡咯氮、吡啶氮和质子化吡啶形式存在。     

Influence of temperature on the hydrogenation of Australian Loy-Yang brown coal. 1. Oxygen removal from coal and product distribution

A study is made of the composition of the solid, liquid and gaseous fractions produced by hydrogenation of Australian Loy-Yang brown coal at temperatures ranging from 300 to 500 °C. The high oxygen content of the coal (25.5 wt%) is not found to result in a proportionally higher hydrogen consumption when compared to previously published results for a coal with approximately half the oxygen content. Oxygen is found to be removed from the coal mainly as carbon dioxide and water, most probably by decarboxylation and dehydration reactions. At temperatures up to ≈400 °C hydrogen is consumed almost solely by transference from the solvent tetralin to the coal. By this temperature both the maximum degree of conversion and the maximum oil yield are reached. The heavy oil fraction at 400 °C is composed mainly of asphaltenes and preasphaltenes. Above 400 °C hydrogen is consumed from both solvent and gas. A major part of this appears to be involved in the stabilization of decomposition products from the tetralin. The yield of pentane-soluble material is relatively constant up to 450 °C, however, at higher temperatures conversion of asphaltenes and preasphaltenes to pentane-solubles occurs in conjunction with gasification to C₁–C₃ hydrocarbons. Despite the fact hydrogen consumption and oxygen removal both increase with rising hydrogenation temperature, the H/C atomic ratio for the three heavy oil fractions decreases over the same range.     

Co-pyrolysis as a method of upgrading some products of coal processing

Co-pyrolysis was investigated as a method of upgrading various products resulting from coal processing. Co-pyrolysis of vacuum residue (VR) with coal extraction products as well as with primary tars from flash pyrolysis leads to a considerably enhanced yield of liquid products. It has been established that superheated steam and increased outgassing rate, favour the yield of liquid products. The proportion of the ingredients in the mixture as well as the quality of the VR also have a definite effect. The excess yield of liquid products in co-pyrolysis of coal extraction products was 8–23 wt%, depending on operating conditions and the composition of the mixture. The flash co-pyrolysis of primary tars yielded a 1.5–15.9 wt% surplus of liquid products depending on the mixture composition. Products originating from co-pyrolysis of these raw materials with VR are characterized by relatively high atomic hydrogen to carbon ratio, usually not less than 1.5 and the total abscence of asphaltenes. Generally, co-pyrolysis of VR with various products of coal processing is comparable with hydrogenation in the light of good yields of liquid products.     

Nature of hydrogen bonding in coal-derived asphaltenes

Near-infrared (n.i.r.) and proton magnetic resonance (p.m.r.) studies are reported of hydrogen bonding between the hydroxyl group of o-phenylphenol (OPP) and two coal-derived asphaltenes, and their acid and base components. The asphaltenes were isolated from two centrifuged liquid product (CLP) samples prepared from West Virginia, Ireland Mine bituminous coal under the same reaction conditions, except that CLP FB44–56 was prepared with the reactor charged with a CoMo catalyst, while CLP FB50-17 was prepared with glass pellets in place of the catalyst. The base asphaltene components from both FB44–56 and FB50-17 cause a decrease in the OPPOH absorbance at 1.44 μm in CS₂ and a downfield shift of the OPPOH p.m.r. resonance in CS₂, while these changes are not observed for the original asphaltenes or their acid components. Furthermore, the base asphaltene component from CLP 44–56 is more effective in decreasing the OPPOH absorbance when compared with the base asphaltene component from CLP FB50-17. Also, the absorbance of a pentane-soluble fraction of the acid asphaltene component at 1.42 μm in CS₂ from CLP FB50-17 is decreased upon addition of the corresponding base asphaltene component. Our results lead to the conclusion that the use of a CoMo catalyst leads to a base asphaltene component of lower molecular weight and higher hydrogen-bond acceptor strength.     

中低温煤焦油加氢过程中沥青质组成与性质

以中低温煤焦油为原料,采用小型固定床连续加氢反应装置进行2 500 h全馏分加氢实验,研究煤焦油加氢沥青质组成与性质随加氢反应器运行时间延长的变化规律。结果表明:随反应时间的延长,催化剂活性逐渐降低,煤焦油沥青质脱除率降低,加氢沥青质S和N杂原子含量以及Fe和Ca金属含量均增加,脱除率均降低,在一定温度范围内,提高反应温度可以提高煤焦油沥青质加氢转化性能,但也促进大分子量的沥青质生成;此外,随反应时间的延长,加氢沥青质芳香度(f_A)增大,H和C原子比降低,说明加氢沥青质缩合度提高,另外,加氢沥青质分子量逐渐增大,甚至超过原生沥青质,说明部分沥青质发生缩聚反应;反应后期,沥青质缩聚反应加剧,金属Fe和Ca易沉积在催化剂上,催化剂失活严重。     

The effect of coal rank on flash hydropyrolysis of Chinese coal

Fourteen kinds of Chinese coal were flash hydropyrolysed in a small entrained reactor at 750°C and hydrogen atmosphere. The results indicated that carbon content and yields of liquid hydrocarbon, H/C and yields of gaseous hydrocarbon, oxygen content and yields of CO, CO₂ and H₂O show better corresponding relations. The correlations between yields of CH₄, C₂ and C₂H₆ and H/C can be expressed as Y_CH4=−42.2+100(H/C)(0.51<0.59), Y_CH4=15.8+1.67(H/C)(0.59<1.11), Y_C2=0.347+4.78(H/C), Y_C2H6=0.352+4.74(H/C); The correlations between yields of CO₂ and water and oxygen content can be expressed as: Y_CO2=−0.0437+0.0355(O); Y_H2O=0.726+0.467(O). The cutoff points of flash hydropyrolysis for coal are that H/C is 0.6 and carbon content is 85%. The coal which H/C is lower than 0.6 and carbon content is higher than 85% is usually not good for flash hydropyrolysis. It is found that influence of coal rank on yields of liquid, gas product and total yields of product in flash hydropyrolysis can be expressed as of H/C in coal.     

Reaction mechanism of coal hydrogenation. 3. Effect of coal type

Seven coals have been hydrogenated in naphthalene and phenanthrene under 10 MPa (initial pressure) of hydrogen with a stabilized niekel catalyst at 400°C for 15 min. Preasphaltene, asphaltene and oil conversions and solvent conversion were measured. The amounts of hydrogen absorbed by coal and by solvent were calculated. Coal conversion and the amount of hydrogen absorbed by coal decreased, while the amount of hydrogen absorbed by solvent increased, with increase in coal rank. The ratio of the amounts of hydrogen absorbed by coal and by solvent showed a good correlation with conversion to benzene- and n-hexanesoluble materials. Naphthalene and phenanthrene gave similar results, suggesting that the coal was hydrogenated directly by gaseous hydrogen.     

Coal hydroliquefaction using iron pentacarbonyl as a catalyst precursor

Hydroliquefaction of several coals, Taiheiyo (Japanese), Mi-ike (Japanese), Wandoan (Australian), and Illinois No.6 (American), was carried out using iron pentacarbonyl(Fe(CO)₅) at 425–460°C under a hydrogen pressure of 4.9MPa in a non-hydrogen donating solvent, 1-methylnaphthalene. With the addition of iron pentacarbonyl coal conversion increased substantially for all of the coals used. Lighter fraction (oil) also increased, by ≈ 10–17 wt%, in the presence of the catalyst. The addition of Fe(CO)₅ suppressed coking, resulting in high values of coal conversion and oil fraction even at 460°C. The amounts of hydrogen transferred from the gas phase increased by 2–4 times with Fe(CO)₅. A process involving direct hydrogen transfer to coal fragment radicals is proposed.     

Process effects on the nature of coal liquefaction products

The products obtained by liquefaction of the same coal using four different processes are compared. The processes were dry hydrogenation (hydropyrolysis) in a short residence time semi-continuous reactor and in a rotating autoclave, and supercritical gas extraction using toluene with and without hydrogen assistance using an autoclave and a short residence time reactor. The temperature and pressure were the same for all the experiments and runs were carried out with and without catalysts. The liquid product from the rotating autoclave was more aromatic and contained less polar compounds than the product from the semi-continuous reactor. The asphaltenes from supercritical gas extraction were more aliphatic and of higher molecular weight than those obtained on dry hydrogenation. Solvent breakdown products had a considerable effect on the composition of the oil from supercritical gas extraction, and this breakdown was affected by the time that the solvent was maintained at temperature.     

煤热解制焦油的工艺研究进展

煤热解是一种重要的煤炭分质利用技术,中低温热解焦油是制取液体燃料和化学品的重要原料。本文从对煤进行预处理、改变热解气氛、催化热解与催化加氢热解、煤与其它物质共热解、新型耦合热解工艺等方面综述了煤热解制焦油的工艺研究进展,探讨了影响煤热解过程焦油产率的因素及机理,并对各工艺进行了评价。     

Fixed-bed pyrolysis of coal under hydrogen pressure at low heating rates

Fixed-bed hydropyrolysis has been investigated by treating 100 g coal up to 900°C and 10 MPa. The devolatilization rate of Beringen coal (32.8 wt% volatile matter) treated on a fixed bed approximates to that obtained by flash hydropyrolysis. However, the oil yield is smaller because of the slower heating of the coal and the rather longer residence time of the primary volatile matter in the reaction space. The product gas is mainly methane. The oil composition depends on the temperature of pyrolysis. The benzene content of the oil rises with temperature. At constant temperature, the influence of hydrogen partial pressure is important between 0–1 MPa. At higher pressure, the yields and compositions vary only slightly with pressure. It has also been shown that from 580°C pyrolysis under hydrogen yields an additional quantity of water, when compared with pyrolysis under inert atmospheres or under atmospheric pressure. This additional water comes from the hydrogenation reactions of the hydroxyl functions of heavy phenols and xylenols. This implies a hydrogen consumption (from 0.2–0.3 wt% of the coal), varying with the pyrolysis temperature.     

神华煤液化残渣的加氢反应动力学

在微型反应管中,以神华煤液化残渣为原料,四氢萘为溶剂,在氢初压6 MPa、反应温度425～485℃、反应时间为0～30 min条件下,进行了煤液化残渣加氢实验,研究了煤液化残渣的加氢动力学特性。将氢化产物分为油气、沥青质和四氢呋喃不溶有机质,根据集总概念建立了煤液化残渣的加氢动力学模型,所建模型与实验值吻合程度高。在实验条件下,四氢呋喃不溶有机质向沥青质转化的活化能为147.41 kJ·mol^-1,沥青质向油气转化的活化能为34.81 kJ·mol^-1,沥青质缩合为四氢呋喃不溶有机质的活化能为173.48 kJ·mol^-1。