Anthracene oil

Direct Hydrogenation. Direct hydrogenation of lignitic and other coals has been studied by many investigators. Lignite can be slurried with an anthracene-oil solvent, heated to a temperature of 460—500°C with 1 1 CO H2 synthesis gas at pressures to 28 MPa (280 atm) in a 2 kg/h reactor. The product hquids are separated, and in a commercial process, a suitable hydrogen-donor solvent would be recycled (54). 

In Europe, where an abundant supply of anthracene has usually been available, the preferred method for the manufacture of anthraquinone has been, and stiU is, the catalytic oxidation of anthracene. The main problem has been that of obtaining anthracene, C H q, practically free of such contaminants as carbazole and phenanthrene. Many processes have been developed for the purification of anthracene. Generally these foUow the scheme of taking the cmde anthracene oil, redistilling, and recrystaUizing it from a variety of solvents, such as pyridine (22). The purest anthracene may be obtained by azeotropic distillation with ethylene glycol (23). 

Creosote. In coal-tar refining, the recovery of tar chemicals leaves residual oils, including heavy naphtha, dephenolated carboHc oil, naphthalene drained oil, wash oil, strained anthracene oil, and heavy oil. These are blended to give creosotes conforming to particular specifications. 

Timber-preservation creosotes are mainly blends of wash oil, strained anthracene oil, and heavy oil having minor amounts of oils boiling in the 200—250°C range. Coal-tar creosote is also a feedstock for carbon black manufacture (see Carbon, carbon black). Almost any blend of tar oils is suitable for this purpose, but the heavier oils are preferred. Other smaller markets for creosote were for fluxing coal tar, pitch, and bitumen in the manufacture of road binders and for the production of horticultural winter wash oils and disinfectant emulsions. 

The principal sources of feedstocks in the United States are the decant oils from petroleum refining operations. These are clarified heavy distillates from the catalytic cracking of gas oils. About 95% of U.S. feedstock use is decant oil. Another source of feedstock is ethylene process tars obtained as the heavy byproducts from the production of ethylene by steam cracking of alkanes, naphthas, and gas oils. There is a wide use of these feedstocks in European production. European and Asian operations also use significant quantities of coal tars, creosote oils, and anthracene oils, the distillates from the high temperature coking of coal. European feedstock sources are 50% decant oils and 50% ethylene tars and creosote oils. 

In the SRC work, coal was slurried with a process-derived anthracene oil and heated to 400—455°C at 12.4—13.8 MPa (1800—2000 psi) of hydrogen for 0—1 h. A viscous Hquid was extracted. The product stream contains some hydrocarbon gases, and H2S. The residue is gasified to generate hydrogen for the process. The remaining filtrate is separated into solvent, which is recycled, and SRC, a low ash, tadike boiler fuel. 

A more complex reaction model was proposed from the results of a kinetic study of thermal liquefaction of subbituminous coal. Data were obtained over a temperature range of 673 to 743 K (752 to 878°F) at 13.8 MPa (2000 psia) by using two solvents, hydrogenated anthracene oil (HAO), and hydrogenated phenanthrene oil (HPO), at a coal-solvent ratio of 1 15. Results were correlated with the following model ... 

Anthracen blau, n. aathraceoe blue, -farbstoff, m. anthracene dye. -81, n. anthracene oil. -pech, n. anthracene pitch. 

GrUn-malz, n. green malt, -mist, m. green manure, -ol, n. green oil (anthracene oil), -rost, m. verdigris, griinrostig, a. (a)eruginous. 

About one half of the coal samples used in the above study (61) have been investigated by workers in Gulf Research and Development Company, using a continuous flow reactor (63). The throughput was about 1 kg./h of coal/solvent slurry, the solvent was a partly hydrogenated anthracene oil, temperatures of 440 and 455°C were used, and the system was pressurized with hydrogen to 20.69 MPa. 

The reactor was a 1 liter stainless steel rotating autoclave. In these experiments the ratio of anthracene oil to coal was 3 1. Coal (50 g) impregnated with catalyst (1% Sn as SnC ) was mixed with sand (200 g). The autoclave was pressurized with hydrogen to 10 MPa at room temperature and heated (ca 7°C/minute) to the final reaction temperature (450°C). The pressure at reaction temperature was approximately 25 MPa. 

No data on liquid yields are available for the autoclave experiments because it is not possible to separate the product oil, which results from coal liquefaction, from the anthracene oil and its decomposition products. In the case of the hotrod experiments this complication does not exist. 

Solvent s creosote type creosote oil creosote oil anthracene oil... 

A schematic diagram of the liquid solvent extraction process is illustrated in Figure 1. Where the production of liquid hydrocarbons is the main objective an hydrogenated donor process solvent is used, whereas in the production of needle coke this is not necessary and a coal derived high boiling aromatic solvent may be used (e.g. anthracene oil). An essential economic requirement of the process is that a high extraction yield of the coal is obtained and this will depend upon the coal used and the digestion conditions. 

The coals were crushed 80% less than 75 jjlm. The solvents used were anthracene oil (ex British Steel Corporation), hydrogenated process solvent (produced in a continuous coal extract hydrogenation plant) and several pure organic compounds (ex Koch-light). 

Figure 5. Influence of digestion time and temperature on extraction yield. Coal = Beynon solvent = anthracene oil coal solvent ratio = 1 4.

For example, Beynon and Cwm coals when digested in anthracene oil give extraction yields of 68% and 47% respectively. This variation can be explained by reference to the maceral composition of the coals. Beynon coal contains a lower concentration of inertinite than the Cwm coal (Table V). In experiments where relatively pure samples of petrographic species were digested in anthracene oil, exinite and vitrinite were shown to be highly soluble, whilst in comparison the inertinite was almost completely insoluble. Similar variations in reactivity of macerals have been reported from studies of solubility in pure organic solvents (1(3). 

CRC 502) are the most soluble. In comparison, the extraction yields of exinites were independent of coal rank. The subdivision of inertinites into fusinite and micrinite showed that fusinite was completely insoluble in anthracene oil, whilst the micrinite was slightly soluble. 

A system based upon the reactivity of coals during extraction with anthracene oil and phenanthrene has been developed. A convenient graphical method of expressing the data on Seyler s chart has been adopted. This method has limitations when dealing with prime coking coals, which show wide variations in extraction yield. The differences in extraction yield relate to the concentration of inertinite which is virtually insoluble in anthracene oil. 

Digestion conditions nominally 400 C with 60 min residence time Solvent anthracene oil... 

Digestion conditions 400°C 60 minute residence time Solvent anthracene oil Coal solvent ratio 1 3... 

A system of classifying coals for solvent extraction, based upon the extent of extraction when using anthracene oil and phenanthrene as solvents has been developed. The reactivity of the coals can be conveniently presented by superimposing the results on Seyler s coal chart. The effects of variations in maceral composition are also discussed. 

Solvent additives to the melt (Table 3) fall into two categories extractive and reactive. The extractive solvents (decane, perchloroethane, o-dichlorobenzene, and pyrrolidine) had negligible effect on solubility, possibly due to the preferential wetting of the coal by the solvent and exclusion of the ZnCl2 melt. Reactive solvents (anthracene oil, indoline, cyclohexanol, and tetralin) all incorporated strongly. Donor solvents, tetralin and indoline, increase the "corrected solubility, whereas anthracene oil and cyclohexanol have negligible effect. 

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