Utilization of coal tar

Gas, Tar. See Coal Tar and Coal Tar Pitch in Vol 3 of Encycl, pp C379-R to C38Q-R Davis (1941), pp 129—32 gives a detailed description of "Utilization of Coal Tar ... 

Utilization of coal and oil shale to produce liquid and gaseous synfuels results in the generation of many hazardous sub-tances. Workers in these synfuel plants are likely to be exposed to potentially carcinogenic materials present in coal tars and oils. Among the various pathways of exposure, skin contamination by direct contact transfer or by adsorption of vapors and particulates into the skin presents a serious occupational health hazard. The skin irritant and potential carcinogenic properties of raw syncrudes and their distillate fractions have been reported (1. 2, 3). 

The characterization of benzofuran and its derivatives in the various fractions of coal tar and petroleum mentioned above utilizes molecular... 

This is the residue from the processing of coal tar. Since pitch constitutes over 50% of the crude tar, its utilization has a major effect on the economics of tar processing. Coal tar contains an estimated 5,000-10,000 compounds ... 

Today, petroleum is the chief source of the enormous quantities of benzene, toluene, and the xylenes required for chemicals and fuels. Half of the toluene and xylenes are utilized in high-test gasoline where, in a sense, they replace the aliphatic compounds—inferior as fuels—from which they were made. (A considerable fraction even of naphthalene, the major component of coal tar distillate, is now being produced from petroleum hydrocarbons.)... 

Creosote is obtained from high temperature distillation of coal tar (itself a mixture of hundreds of organic substances). Over 100 components in creosote have been identified. It is used as a fungicide, insecticide, miticide, and sporicide to protect wood and is applied by pressure methods to wood products, primarily utility poles and railroad ties. This treated wood is intended for exterior/outdoor uses only. Its commercial uses include railroad ties (70%), utility poles (15-20%), and other miscellaneous commercial uses (10-15%). 

Benefits of the Plant. The shortage of dumping space has led to a drastic increase in dumping costs, so that production of pure naphthalene by chemical refining is no longer economically possible. Development of this residue-free environmentally friendly process has made a decisive contribution to the stabilization of coal tar utilization in Germany. 

In addition to the significant consumption of coal and lignite, petroleum, and natural gas, several countries utilize modest quantities of alternative fossil fuels. Canada obtains some of its energy from the Athabasca tar sands development (the Great Canadian Oil Sands Project). Oil shale is burned at... 

Phenol (C5H5OH) or carboUc acid is an aromatic hydrocarbon derived originally from coal tar, but prepared synthetically in a process that utilizes monochlorobenzene as a starting point. Ninety-eight percent phenol appears as transparent crystals, while liquefied phenol consists of 88% USP solution of phenol in water. 

SPI Division Level 3 and 4 LTTD systems have been designed and manufactured for thermal treatment of soils contaminated with polycychc aromatic hydrocarbons (PAHs), including coal tars from former manufactured gas plant (MGP) sites. When equipped with acid-scrubbing systems, these LTTD systems have been utilized in treatment of soils contaminated with a wide range of chlorinated hydrocarbons including industrial solvents and degreasers, pesticides, herbicides, and polychlorinated biphenyls (E CBs). 

Co-burning is a commercially available, ex situ technology for the treatment of nonhazardous tar and tar-contaminated soils from former manufactured gas plant (MGP) sites. The process burns MGP waste with coal in existing utility boilers at coal-fired power plants. 

Benzene, naphthalene, toluene, and the xylenes are naturally occurring compounds obtained from coal tar. Industrial synthetic methods, called catalytic reforming, utilize alkanes and cycloalkanes isolated from petroleum. Thus, cyclohexane is dehydrogenated (aromatization), and n-hexane(cycli> zation) and methylcyclopentane(isomerization) are converted to benzene. Aromatization is the reverse of catalytic hydrogenation and, in the laboratory, the same catalysts—Pt, Pd, and Ni—can be used. The stability of the aromatic ring favors dehydrogenation. 

The production of domestic sulfur values (elemental recovered sulfur and the sulfur content of acid) will total about 18 million long tons per year by the year 2000. By region (Petroleum Administration for Defense districts), except for the east coast (PAD I), there will be no deficit areas in the U. S. Major contributors are sour natural gas and the refining of heavier, sour, crude oil. Proximate, scenario dependent sources, are electric utilities and coal-based synfuels. Shale oil, domestic tar sands and heavy oil, and unconventional sources of natural gas will be small suppliers. 

Following the cessation of hostilities of World War II, there was a short period of abundant supply of aromatics, particularly toluene, caused by the sudden decline in consumption of aromatics for nitration and for use in aviation gasoline. Soon, however, the peacetime uses for aromatics created a demand which could be satisfied only by the combined production of aromatics from petroleum and coal-tar sources. Consequently, many of the toluene plants were purchased from the Government by the petroleum refiners and utilized for manufacture of the many aromatic products available on the market today. 

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