Brown Coal Liquefaction Research Articles

ビクトリア褐炭の液化反応に及ぼす溶剤性状と反応条件の影響

The effects of solvent properties on the liquefaction of Victorian brown coal were studied using an autoclave with iron oxide/sulfur catalyst under various reaction conditions (temperature: 430°C or 460°C, initial hydrogen pressure: 3, 6, or 12MPa). The solvents used were a recycling solvent (PR-S) and a further hydrogenated solvent (HD-S), a product of hydrogenation with Ni-Mo/Al2O3 catalyst. Results showed that hydrocarbon gas yield and hydrogen gas consumption were lower, and naphtha (b.p.<180°C) yield was higher using HD-S compared with PR-S. At lower hydrogen pressure, the HD-S provided a higher oil (b.p.<420°C) yield than the PR-S, but with more severe conditions (460°C and 12MPa), the PR-S provided the higher oil yield and more hydrogenated heavy products.The amount of transferred hydrogen to all products was the same in both solvents, and depended only on the reaction conditions, however, the distribution of transferred hydrogen was different. The results suggested that the PR-S worked more effectively as a hydrogen shuttler at severe conditions compared with the HD-S which contained a considerable amount of initial donatable hydrogen. Thus, we can conclude that the overall liquefaction efficiency of such solvents depends on the liquefaction conditions.

ビクトリア褐炭の液化反応に及ぼす含水率の影響

Since Victorian brown coal contains about 60wt.% moisture, it is necessary to remove the water from the coal before liquefaction. The effects of mois-ture content on liquefaction of the coal dewatered in a recycling solvent (DW-coal) were studied using an autoclave with iron oxide/sulfur catalyst under the following conditions: temperature of 430°C, initial hydrogen pressure of 6MPa and hold time of 1h.When moisture content of the coal decreased, distillate (b.p.<420°C) yield and H2 gas consumption increased, and heavy product (b.p.>420°C) and naphtha (b.p.<180°C) yields decreased. Gaseous product yields and reaction pressure also de-pended on the moisture content of the coal. Specifically CO/CO2 ratio was strongly affected by the moisture content, which indicated that CO shift reaction occurred and affected the H2 gas consumption.The coal dried with a tubular dryer (TD-coal) was liquefied under the same con-ditions as the DW-coal to compare the coals in reactivity. The reactivity of the TD-coal was lower than that of the DW-coal. According to these results, it is shown that the dewatering in the solvent is profitable for brown coal liquefaction.

Kinetics of donor-solvent liquefaction of Bulgarian brown coal

This paper presents the results of a kinetic study of the thermal liquefaction of brown coal from the Black Sea mine in Bulgaria. The experiments were carried out in a laboratory ‘tubing bomb’ reactor under isothermal conditions within the 350 to 450 °C temperature range and a reaction time range of 5 to 30 min, in tetralin. A kinetic model is obtained that adequately describes the distributions of preasphaltenes, asphaltenes, oils and gases in the product. The pseudo first-order rate constants for each of the mechanistic steps have been estimated by non-linear regression.

Effects of deashing and low-pressure hydrogen on hydrogen transferring liquefaction at reduced solvent/coal ratio

Hydrogen transfer liquefaction of an Australian brown coal using tetrahydrofluoranthene (THFL) as the donor solvent was examined by varying the THFL/coal ratio from 3 1 to 1 1 . Solvent/coal ratios of 2 1 and 1.5 1 gave yields of 45% oil and 60% oil plus asphaltene at 450 °C for 10 min under 2.0 MPa of nitrogen pressure, while a decrease in oil yield to 33% was observed at a 1 1 ratio under the same conditions. Extending the reaction time to 20 min increased oil, and oil plus asphaltene yields to 60 and 66%, respectively, at the 2 1 ratio. A reaction time of 30 min produced a marked decrease in both oil and oil plus asphaltene yields. Demineralization of the coal greatly reduced the yield of gas, preasphaltene and residue, and significantly increased the oil yield to 65% at ratios of 2 1 and 1.5 1 at 450 °C and reaction time of 10 min. Low pressure (≈2.0 MPa) of hydrogen increased the oil yield from 46% under nitrogen, to 61% at 1.5 1 and 450 °C for 10 min and from 60% to 66% at 2 1 and 450 °C for 20 min, respectively. A combination of demineralization and low pressure hydrogen provided the best yield of oil plus asphaltene, 84% (oil yield, 66%) at 1.5 1 and 450 °C for 10 min. It is suggested that low pressure hydrogen can act as a substitute in some roles for the donor to a minor extent through its dissociation by its reactivity with radicals derived from the donor or coal molecules.

Kinetics and isotope effect of brown coal liquefaction in ethanol

Liquefaction kinetics are described by a first-order equation. Deuterium introduction into the α-position of ethyl alcohol produces a considerable kinetic isotope effect. This effect is suggested to be due to the hydrogen donor capacity of the initial ethyl alcohol α-CH2-groups or of ethyl substituents inserted into the aromatic fragments of coal after alkylation.

The structure and reactivity of brown coal: 13. Residence time study of the liquefaction of brown coal

The liquefaction behaviour of brown coal has been investigated using a reactor system that can be used to rapidly charge a coal slurry into a preheated autoclave and then sample its contents throughout the course of reaction. A comparison of the conversion activity for two brown coals of different atomic H C ratio has been performed. Differences are observed in the amount of oil liberated upon hot-charging, and in oil formed during the total reaction period. The results correlate well with a binary, guest-host structural model developed for low rank coals. A limited comparison with a bituminous coal has also been carried out.

Combined process of brown coal liquefaction

Combined process of brown coal liquefaction

Interactions of iron and tin-based promoters during brown coal liquefaction

Mössbauer spectroscopy was used to investigate the reported synergism of iron and tin when used together to promote the hydroliquefaction of Victorian brown coal. Several differences from the behaviour of the individual iron or tin promoted systems are documented, including an enhanced rate of reduction of the initial compounds of both elements, the prevention of the carbiding of α-Fe to Fe 3C and the formation of an iron-tin alloy, FeSn 2. Possible mechanisms of iron-tin synergism are suggested.

Viscosity of coal-derived liquids in the brown coal liquefaction (BCL) process

The viscosity of the liquids derived from Victorian brown coal in the two-stage Brown Coal Liquefaction (BCL) process was measured by using a rotational viscometer. The effects of temperature and liquid properties on the viscosity were determined for a wide variety of the samples which were prepared at different liquefaction and/or distillation conditions. The equations for estimating their viscosities were obtained by using these results. These equations are similar to Andrade's and involve two parameters of temperature and the liquid properties. The latter is represented by the 50 vol.%-off boiling point for the distillate fractions and the ratio of benzene insolubles-pyridine solubles content to benzene solubles content for the heavy fractions (vacuum residue).

褐炭液化プロセスの開発

The Brown Coal Liquefaction Process (BCL Process) has been developed by Nippon Brown Coal Liquefaction Co., Ltd.(NBCL), and a 50-ton-per-day Pilot Plant was con-structed and has been operated by Brown Coal Liquefaction (Victoria) Pty., Ltd.(BCLV) at Morwell, Victoria, Australia.This project has been sponsored by the New Energy Development Organization (NEDO) and has been promoted as a National Project with funding by the Japanese Government.The BCL Process is a two-stage form of liquefaction technology developed to convert brown coal into crude naphtha and middle distillate and consists of the four sections: 1. New slurry-dewatering section, 2. Primary hydrogenation section, 3. Solvent deashing section, and 4. Secondary hydrogenation section.

Influence of donor amount in the hydrogen-transfer liquefaction of Australian brown coal

Effects of tetrahydrofluoranthene (4HFL) concentration on the product composition in the liquefaction of an Australian brown coal at 450 °C were studied, using a coal-solvent weight ratio of 1:3 under low nitrogen pressure to optimize the conditions. Pure 4HFL solvent liquefied the coal very rapidly, a longer reaction time markedly increasing the yield of gaseous product as well as the total yield of oil and asphaltenes. Although a reduction in the 4HFL content of the solvent reduced the rates of liquefaction for both gas and liquid products, 4HFL contents of 75 and 50 mol% provided more favourable product compositions (high yield, > 80% of oil plus asphaltenes and low yields of preasphaltenes and gaseous products). In liquefaction of the deashed coal with 75 % 4HFL, the product composition was further improved by using a shorter reaction time. Several roles of donors in the liquefaction process are proposed to explain the product composition and rate of liquefaction.

褐炭液化油中質留分混合燃料によりディーゼル乗用車を運転した時の排出物質特性

In order to evaluate the feasibility of coal derived middle distillates as diesel-powered automobile fuels, mass emissions of several substances (CO, HC, NOx, and particulate matter) in exhaust gas from two kinds of test automobiles were measured by operating the automobiles under 10 mode driving cycle, idling condition and constant speed conditions at 20, 40 and 60km/h. Also, compositions of soluble organic fraction, hydrocarbon type and polycyclic aromatic hydrocarbons in particulate matter were analyzed. The middle distillates were obtained from the liquefaction of Australian brown coal in a continuously operating bench unit and treated with catalytic hydrogenation in a batch autoclave. Two kinds of test fuels were prepared by mixing the middle distillates and a commercial gas oil., Mass emissions of CO, HC and particulate matter were exponentially increased with mixing percent of the middle distillates in the gas oil. Therefore, as far as mixing percent of the middle distillates was low, the extent of increase in mass emissions was small. The content of polycyclic aromatic hydrocarbon in particulate matter increased with the increase of the middle distillates, but the contents of total soluble organic, aliphatic, aromatic and polar fractions were not correlated with the middle distillates.Aromatic hydrocarbon in the fuels significantly affected the emissions, which was the same tendency as petroleum derived fuels. Accordingly, it is desirable that the techniques for decreasing aromatic hydrocarbon content in coal derived middle distillates at catalytic hydrogenation are developed.

Mössbauer study of iron catalysis in Victorian brown coal liquefaction

Mössbauer spectroscopy was used to investigate the means by which iron promotes the hydroliquefaction of Victorian brown coal. Microparticulate ferric oxyhydroxide incorporated in the initial coal is reduced during hydrogenation through magnetite and troilite to α-iron, which transforms to cementite at 380 °C. It is proposed that a transient divalent iron species slows the initial thermal degradation of coal and that α-Fe is responsible for enhancing the ultimate liquefaction yield.

褐炭液化溶剤成分の二次水素化処理 Ｉ

A coal derived middle distillate produced from the liquefaction of Australian brown coal using a bench unit, was subjected to hydrotreatment on NiMo/Al2O3 and NiW/Al2O3 in a fixed bed reactor of 20 ml in volume at 350-390°Cunder hydrogen pressure of 100 kg/cm2 G with LHSV of 1 h-1. Further, catalytic hydrogenation of model mixture was carried out at 370°C on NiMo/Al2O3 with the same equipment to clarify the influence of phenols and quinolines, which occupied the significant amount of the feed oil, on the hydrogenation reactivi-ty.Most of phenols were reduced to hydrocarbons at 390°C over NiMo/Al2O3, but at lower reaction temperatures, ortho-substituted alkylphenols gave lower conversions than those of meta-and para-isomers. Sterically hindered 2, 6-dimethylphenol also showed the poorest conver-sion (21‰) at 370°C compared to ortho-dimethylphenols;3, 4-(96‰) >2, 3-(87‰) >2, 4-(76‰) >2, 5-(58‰) >2, 6-dimethylphenol.Basic constituents in the crude oil were reduced almost completely at 390°C over NiMo/ Al2O3 except carbazole (HDN 98.6‰).Hydrotreatment of the mixture comparising of p-cresol, quinoline, biphenyl and 1-methylnaphthalene showed that the increasing p-cresol content (0-14.2 mol‰) gave no noticiable effect on the hydrogenation degree of each component. On the other hand, addition of quinoline (0-6.2 mol‰) causes a considerable decrease of methyldecalin yield and biphenyl con-version, indicating the deactivation of catalyst by the adsorption of bases. Nitrogen content rather than that of phenolics in the recycle solvent should be one of the critical factors to affect the catalytic hydrogenation reactivity at the upgrading stage.

連続液化装置によるビクトリア褐炭の液化 Ｉ 循環溶剤の性状変化と液化反応

連続液化装置によるビクトリア褐炭の液化 Ｉ 循環溶剤の性状変化と液化反応

Chemistry of solvents in brown coal liquefaction: Estimation of steady state recycle solvent quality

A convenient method to evaluate equilibrated recycle solvent qualities and liquefaction yields at steady state for the Morwell brown coal liquefaction process with solvent recycle has been studied. At first, three principal solvent quality factors have effects on yield patterns; these are: amount of transferable hydrogen, heavy phenolic compounds and polar nitrogen-containing compounds. These were specified using various coal-derived solvents. The changes of these factors were studied in the initial cycle of liquefaction, using two kinds of start-up solvents to estimate the quality of the equilibrated solvent.

Promoters for the liquefaction of wet Victorian brown coal in carbon monoxide

Sodium aluminate and sodium silicate have been found to be useful as promoters for the reaction of brown coal with carbon monoxide and water. Promoters such as sodium aluminate have been shown to behave effectively as a two-component system. The first component involves the sodium aluminate behaving as a mild base interacting with acidic groups in the coal. This role can be adopted by other basic salts (acetate, hydroxide, carbonate, etc.) of other alkali metals which have been found to be effective in the order Cs > K > Na > Li. The second component of the sodium aluminate system is an alkali metal ion doped alumina, whose role in the liquefaction is unclear but may involve the generation of strong Lewis base sites on the alumina which can facilitate one electron transfer reactions leading to radical stabilisation. These systems also catalyse the production of hydrogen by the water gas shift reaction but this has been shown not to be an essential feature of their action as magnesium acetate, which does not promote the water gas shift reaction, shows similar promoter activity. When these catalyst systems are combined with those traditionally active in promoting the reaction of coal with hydrogen (e.g. Cu, Ni, Co) new multi-element promoter systems are obtained which are particularly effective for promoting the reaction of brown coal with synthesis gas (CO + H 2) and water.

Brown coal: Victoria's vital resource

In relation to the rest of the developed world, Australia is particularly well endowed with energy resources. In the state of Victoria, these resources are principally in the form of 200,000 million tonnes (Mt) of brown coal—located mainly in the Latrobe Valley region of Central Gippsland. This resource is among the largest and most accessible in the world and represents 95% of Victoria's non-renewable energy reserves. Brown coal-fired thermal power stations provide the bulk of Victoria's electrical energy requirements, and dried brown coal compressed into “briquettes” is used as domestic and industrial fuel and for the manufacture of high-purity char. A major pilot project for liquefaction of brown coal has commenced operation in the Latrobe Valley, and potential exists for the development of industries to manufacture a range of high-value carbon products. Brown coal could also provide the feedstock for substitute natural gas production when Victoria's present reserves of natural gas are depleted.

Studies related to the structure and reactivity of coals: 11. The hydrogenation of lignin

Hardwood ( Eucalyptus regnans) and softwood ( Pinus radiata) lignins were hydrogenated at temperatures between 200–405 °C to determine whether lignin is a good model for brown coal liquefaction. Both lignins decompose at temperatures below that observed for brown coal suggesting that ether linkages in brown coal are probably decomposing at temperatures below that at which observable liquefaction of the coal occurs. The effects of water and an added copper(II) acetate catalyst on the hydrogenation of lignins were also studied and the effect of copper(II) acetate on the reaction of P. radiata lignin was compared with its effect on the hydrogenation of brown coal.

Hydrogenation of brown coal: 10. Multi-element promoters for the liquefaction of wet Victorian brown coal in synthesis gas

A series of multi-element promoters based on copper, nickel or cobalt in association with sodium aluminate, sodium silicate, or magnesium acetate have been shown to be excellent promoters of the reaction of only partially dried (40 wt% moisture) Victorian brown coal with synthesis gas in the presence of tetralin. The best of these promoters, based on copper (0.30 mole kg −1 dry coal) and sodium aluminate (1.10 mole kg −1 dry coal) features a high conversion (94 wt%) for liquefaction at 405 °C with a high yield of useful liquid products (46 wt%) soluble in light petroleum. The process also yields a net production of hydrogen through in-situ promotion of the water gas shift reaction.