Crude tar acids

The Lurgi gasifiers used by Sasol operate at "low" temperatures and consequently phenols, and "tars" are "distilled" from the coal at the top of the gasifier, and carried out with the raw gas. On condensation two liquid phases are formed, "tar" and "gas liquor" (water). The "tar acids" (phenol, cresols etc) are dissolved in the "gas liquor" which is fed to the Phenosolvan unit where the acids are recovered by counter current extraction with butyl acetate or diisopropyl ether. The crude tar acids are fractionated to yield phenol, ortho, meta and para cresol and xylenols. The phenol is further refined to produce a high purity, colourless and stable product. Phenol is used mainly in the production of formaldehyde resins while the cresols are used as flotation frothers and in the manufacture of pesticides etc. 

Crude tar acids (extracted substances from the aqueous phase)... 

Tar, oil, and naphtha, which can be further upgraded by hydrogenation, are mostly salable products to the chemical industry. In some cases, these products are also converted to syngas in a separate oil gasifier or are sold as fuel, for example, for limestone calcination furnaces [40], From the crude tar acid fraction ammonia, phenols or cresyhc acids can be produced [29]. 

Coal-Tar Process. The largest quantities of naphthalene are obtained from the coal tar that is separated from the coke-oven gases. The coal tar first is processed through a tar-distillation step where ca the first 20 wt% of distillate, i.e., chemical oil, is removed. The chemical oil contains practically all the naphthalene present in the tar. It is processed to remove the tar acids by contacting with dilute sodium hydroxide and, in a few cases, is next treated to remove tar bases by washing with sulfunc acid. Principal U.S. producers obtain their crude naphthalene product by fractional distillation of the tar acid-free chemical oiL... 

Coke Manufacture By-products. In United States practice, coking of coal is done almost exclusively by the high-temperature (900-1200c C) process, For many years, the major source of the pyridines was the chemical-recovery coke oven, The volatiles produced in the coke oven are only partially condensed. The noncondensed gases are passed through a scrubber (the ammonia saturator) containing sulfuric acid. After removal of crystals (ammonium sulfate), a solution of ammonium sulfate and pyridinium sulfates is obtained and treated with ammonia to liberate and contained pyridine bases (— 70% is pyndine itself), See also Coal Tar and Derivatives. The balance of the pyndine bases is extracted from the crude coal tar. i.e., the condensed, main portion of the volatilization products from coking. The crude tar contains approximately 0,1 -0.2% pyridine bases, Further separation of the pyridines involves a rather complex series of extractions, distillations, and crystallizations. 

For the same coal, low-temperature liquids contain more tar acids and tar bases than high-temperature liquids. With high-temperature carbonization, the liquid products are water, tar, and crude light oil. The gaseous products are hydrogen, methane, ethylene, carbon monoxide, carbon dioxide, hydrogen sulfide, ammonia, and nitrogen. The products other than coke are collectively known as coal chemicals, or by-products. 

The main impurity in crude 78°C coal-tar naphthalene is sulfur that is present in the form of thionaphthene (1 to 3%). Methyl- and dimethyl-naphthalenes also are present (1 to 2%) with lesser amounts of indene, methylindenes, tar acids, and tar bases. 

Early production of phosphate esters was based on the crude cresylic acid fraction or tar acids from coal tar residue distillation. This feedstock is a complex mixture of cresols, xylenols and other materials. It includes significant quantities of... 

The acid water is very complex, and contains, besides acetic acid, formic, propionic, butyric, valerianic, and oxyphenic acids, acetone, naphthalene, benzene, toluene, cumene, creosote, methyl alcohol, and methyl acetate, etc. Partially freed from tar by decantation, it still contains about 30 per cent, of tarry and oUy material, and about 4 per cent, of acetic acid this is the crude pyroligneous acid of commerce. 

The light oil contains 63.0 benaene, 13.0 toluene, 5,69 xylene, and 5.15 of crude solvent. There are also produced 33.5 tons/day of ammonium sulfate and 00 gallons of tar acids, which are mainly phenols. 

In fact, in the manner of crude petroleum, most high-temperature tars are first fractionated by distillation into (1) light oil, (2) middle (or tar acid) oil, and (3) heavy (or anthracene) oil. This primary separation is carried out by means of batch stills (vertical or horizontal 3000-8000 US gallon [11-30 X 10 L] capacity) or by means of continuous pipe stills in which the tar is heated to a predetermined temperature before injection into a fractionating tower. 

In this context, it should be noted that the tar acids, which are mostly phenol, cresols, and xyle-nols, can be recovered by mixing the crude middle oils with a dilute solution of caustic soda, separating the aqueous layer, and passing steam through it to remove residual hydrocarbons. The acids are then recovered by treatment of the aqueous extract with carbon dioxide or with dilute sulfuric acid and are then fractionated by distillation in vacuo. 

Primary distillation of crude tar produces pitch (residue) and several distillate fractions, the amounts and boiling ranges of which are influenced by the nature of the crude tar (which depends upon the coal feedstock) and the processing conditions. For example, in the case of the tar from continuous vertical retorts, the objective is to concentrate the tar acids, (phenol, cresols, and xylenols) into carbolic oil fractions. On the other hand, the objective with coke oven tar is to concentrate the naphthalene and anthracene components into naphthalene oil and anthracene oil, respectively. 

Tar acids are produced by the extraction of the oils with aqueous caustic soda at a temperature sufficient to prevent naphthalene from crystallizing. The phenols react with the sodium hydroxide to give the corresponding sodium salts as an aqueous extract known variously as crude sodium phenate, sodium phenolate, sodium carbolate, or sodium cresylate. The extract is separated from the phenol-free oils, which are then taken for naphthalene recovery. 

Cresol kre- s61 [ISV, irreg. fi. cresote] (ca. 1869) (hydroxytoluene, methylphenol) n. H3CC6H4OH. An important family of coal-tar derivatives, occurring in ortho, meta, and para isomers, and used in the production of phenol-formaldehyde resins and tricresyl phosphate, an important plasticizer for PVC. Three cresols are possible, namely (a) o-cresol, mp 30°C bp, 19rC (b) m-cresol, mp 4°C bp, 205°C (c) p-cresol, mp 36°C bp, 201°C, and these are found together in the crude cresylic acid from coal tar. The main use of the cresols is in the manufacture of cresol-formaldehyde resins, and cresylic acid, rich in the meta isomer, is usually chosen for this purpose. 

Crude tar oils are the cmde products of the sulfate soaps which are separated from the black liquor of paper pulping. The contents of fatty acids and resin acids are increased through the cmde processing. For instance, the components of domestic cmde tar oil are listed as follows ... 

The components of several foreign crude tar oils are found in Tables 2.4 and 2.5. The flowchart of crude tar oils is shown in Fig. 2.2. The content of active ingredient of crude tar oils is twice as much as that of paper pulp products. And the component of crude tar oils is relatively steady. Therefore, the flotation performance of crade tar oils is relatively better. It should be pointed out that however, the contents of unsaturated fatty acids and resin acids are relatively higher. Therefore, the frothing capacity of crude tar oils is so high that cmde tar oils are hard to be applied in industry. 

Crude tar oils Fatty acid and resin acid Oleic acid 28-43 % Linoleic acid 38-65 % Linolenic acid 0.5-2.0 % Stearic acid 4-10 % Palm acid 4-10 % Class A organic acid 95 % Class B organic acid 90 % Fatty acid 35-55 % Resin acid 30-55 % Neutral 4-20 % Acid value 115-175 Soap value 140-180 Making up aqueous solution mixed with hydrocarbon oil emulsified by emulsifier saponified with caustic soda emulsified by sodium alkyl benzene sulfonate and alkylsodiumsulfate... 

These are found in crude petroleum including bitumen in the Athabasca tar sands of Northern Alberta. They contain a complex mixture of saturated polycyclic live- and six-membered cycloalkanes with alkane and alkanoic acid substituents. Attention has been directed to the degradation of both commercially available products, and those that are produced during bitumen extraction. Although the former were degradable (Clemente et al. 2004), the higher molecular mass components of the latter were much more recalcitrant (Scott et al. 2005). 

The residue of a sample of olein chloride (crude oleoyl chloride) was tipped into a waste container containing acid tars (70-80% waste sulfuric acid). There was a vigorous reaction, with gas evolution, which sprayed the analytical technician involved with the liquid contents of the container, causing bums. 

Azeotropic and extractive distillation Distillation processes Extractive distillation(s) argon, 13 460 for aroma isolation, 11 519 atmospheric, 13 646 batch versus continuous, 3 780 of coal-tar naphthalene, 17 78-79 corrosion, 3 779-780 of crude oil, 12 401-402 13 593 debottlenecking, 13 521 in fatty acid neutralization, 22 740 favorable vapor-liquid equilibria, 3 778 feed composition, 3 778 general separation heuristics for, 22 316-317... 

To a solution of 27.6 gm (0.2 mole) of m-nitroaniline in 240 ml of glacial acetic acid maintained at 40°C is added, with shaking, 23.3 gm (0.22 mole) of nitrosobenzene. The reaction mixture is allowed to stand in the dark for 2 days. Then the crude product is removed by filtration (31 gm, m.p. 94°C). To the mother liquor is added 80 ml of water, and another 5 gm of crude product precipitates. Greater dilution must be avoided to prevent tar formation. Yield 80%. The product may be recrystallized from ethanol, m.p. of pure m-nitro-phenylazobenzene 96°C. 

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