Organic sulfur compounds of coal tar and coal-tar pitch. 4. Results of experimental studies

Total sulfur content in the coal tars and coal-tar pitches was determined by automatic coolometric method. Conventional schemes of identification used in petroleum chemistry were employed for identification of separate classes of organic sulfur compounds (OSC) in the tar. It is shown that > 90% of all OSC in the tar are represented by complex derivatives of thiophene, which are very stable. During the tar fractional distillation its OSC are distributed among all the fractions of the tar and pitch, moreover, > 50% of the compounds transfer to the pitch. Anthracene and naphthalene fractions feature the highest sulfur content. The method of catalytic hydrorefining permits reduction of the tar sulfur content by a factor of 3.5, and that of the pitch manufactured - by a factor of 2.