Catalytic upgrading of polyethylene-derived pyrolysis distillate over Pd/C catalyst under mild hydrogenation conditions

Pyrolysis distillate generated as a by-product of polyethylene production represents a promising secondary carbon resource for the production of cleaner transportation fuels. However, its direct utilization as a fuel component is limited by the high contents of sulfur, nitrogen, and unsaturated hydrocarbons. In the present study, the catalytic hydrogenation of pyrolysis distillate obtained from the Uz-Kor Gas Chemical plant was investigated in a laboratory-scale autoclave reactor using a Pd/C catalyst. The effects of key process parameters, including reaction temperature, hydrogen pressure, hydrogen-containing gas circulation ratio, and feed volumetric hourly space velocity, on the hydrogenation performance were systematically evaluated in order to establish the optimal operating conditions. The maximum hydrogenation efficiency of 97% was achieved at a reaction temperature of 150°C, a hydrogen pressure of 3.0 MPa, a hydrogen concentration of 75 vol% in the gas phase, a hydrogen-containing gas circulation ratio of 200 Nm 3 /m 3 of feedstock, and a feed volumetric hourly space velocity of 2.0 h −1 . The resulting hydrogenate was characterized by elemental analysis, gas chromatography–mass spectrometry (GC–MS), and infrared (IR) spectroscopy. The sulfur content decreased from 9.24 wt% to 0.05 wt%, while the nitrogen content decreased from 7.4 wt% to 0.05 wt%, demonstrating the high efficiency of the hydrodesulfurization and hydrodenitrogenation processes. Furthermore, GC–MS and IR analyses confirmed the saturation of unsaturated hydrocarbons and a significant reduction in aromatic compounds. The hydrogenated product contained 36.75 wt% alkanes, indicating a substantial improvement in fuel quality. In addition, an industrial-scale material balance for the processing of 105000 t/year of pyrolysis distillate was developed, confirming the technical feasibility of converting pyrolysis by-products into valuable low-sulfur fuel fractions. The proposed process provides a viable technological route for the valorization of petrochemical pyrolysis residues and contributes to the development of sustainable and environmentally responsible fuel production technologies.