Abstract
This study examined the effect of a molybdenum-containing catalyst precursor and elemental sulfur on the hydroprocessing of coal tar. The experiments were conducted in a stirred high-pressure batch reactor at a temperature of 350 °C and a pressure of 5.0 MPa, using ammonium paramolybdate as the catalyst precursor. The catalyst concentration ranged from 0.025 to 0.05 wt.%, while the elemental sulfur content varied from 0.015 to 0.10 wt.%. The quantitative composition of the products was determined after separating the resulting hydrogenated materials into fractions, and the catalyst phase obtained during the process was examined using scanning electron microscopy (SEM). The data obtained showed that elemental sulfur is a key factor in the formation of the catalytically active molybdenum disulfide (MoS2) phase and significantly affects the yield of liquid products. In the absence of sulfur, the yield of the liquid fraction did not exceed 33.9 wt.%. The addition of 0.015 wt.% sulfur at a catalyst concentration of 0.025 wt.% increased the yield of liquid products to 76.85 wt.%, which is more than three times higher than in the experiments conducted without sulfur. However, a further increase in the sulfur content to 0.10 wt.% led to a decrease in the liquid yield to 57.18 wt.%. Scanning electron microscopy confirmed the formation of layered MoS2 particles directly during the hydroprocessing reaction. The obtained results demonstrate that optimization of catalyst and sulfur concentrations is essential for maximizing liquid product yield and improving the efficiency of coal tar hydroprocessing.