Experimental study on the coal tar hydrocracking process over different catalysts

In the paper, the results of the study on a laboratory process of hydrocracking of coal tar are presented. High-temperature coal tar was hydrocracked in an autoclave reactor, at 400–413 °C and 7,3–9,6 MPa over 5 different, hydrocracking catalysts to study the yields and characteristics of the products. Liquid products were obtained with a yield of 88–92 wt.% and gas products with a yield of 12–8 wt.%. After dehydration by azeotropic distillation, liquid products were separated on the oil fraction boiling below 360 °C, and pitch fractions boiling above this temperature. In the balance of distillation, it is clear that only the cracking activity of NiW/Al2O3 and Y zeolite catalysts is so high that the raw material containing 5 vol.% fraction boiling below 200 °C provides a product comprising approx. 12,5 vol.% of this fraction. The influence of five different catalysts on the yield of 18 poly aromatic hydrocarbons (PAHs) in the hydrocracking products have been investigated by GC/MS. The results indicate that NiW/Al2O3 and Y zeolite catalysts have the highest catalytic activity for light aromatic formation (the highest yield of fraction boiling below 200 °C) and aromatic condensed aromatic cracking (PAHs). After the hydrocracking NiW/Al2O3 catalyst, the total yields of PAHs decrease 52.7% as that of raw coal tar.