Upcycling Plastic Waste into a Novel Catalyst for the Adsorption–Oxidation Processes for the Removal of Sulfur Pollutants from Petroleum Refinery

Deep sulfur removal from real refinery kerosene was systematically investigated using a bimetallic Eu–Mn/rGO-700 catalyst prepared on a carbonaceous support derived from discarded advertising-poster plastic waste and exhibiting structural characteristics associated with reduced graphene oxide (rGO). The waste precursor was thermally converted in the presence of bentonite, followed by acid purification and thermal post-treatment at 500, 700, and 900 °C. Among the prepared supports, rGO-700 exhibited the most favorable textural properties, with a BET surface area of 45 m2 g−1 and a total pore volume of 0.33 cm3 g−1, and was therefore selected for catalyst preparation. Manganese and europium were simultaneously incorporated through vacuum-assisted wet impregnation at nominal elemental loadings of approximately 2 wt.% each relative to the initial support mass, followed by thermal treatment under a nitrogen atmosphere. The Eu–Mn/rGO-700 catalyst was assessed for its performance in combined adsorptive–oxidative desulfurization of real kerosene from the Al-Doura Refinery, which contains around 800 ppm sulfur. A 34 full-factorial experimental design consisting of 81 trials was employed to examine reaction time, temperature, catalyst dosage, and H2O2 quantity. Under the best experimentally observed conditions of 35 °C, 10 min, 0.05 g of catalyst, and 3 mL of 35 wt.% H2O2 per 50 mL of kerosene, followed by single-stage acetonitrile extraction, the overall sulfur-removal efficiency reached 98.9%, reducing the residual sulfur concentration to approximately 9 ppm. Additional control experiments demonstrated that the bimetallic Eu–Mn/rGO-700 catalyst achieved a numerically higher mean sulfur-removal efficiency of 82.7 ± 4.0% (n = 3) compared with 78.0 ± 3.6% for Eu/rGO-700 and 70.7 ± 2.1% for Mn/rGO-700 under identical H2O2-assisted treatment conditions without ACN extraction. The complete treatment system, including ACN extraction, achieved a mean sulfur-removal efficiency of 98.2 ± 0.7% (n = 3). XRD, FTIR, Raman spectroscopy, N2 adsorption–desorption analysis, FESEM–EDX, and elemental mapping provided complementary evidence supporting the assignment of the prepared material as an rGO-associated, defect-rich carbon framework and confirming the presence of Mn- and Eu-containing domains within the investigated catalyst regions. Raman analysis of rGO-700 revealed characteristic D and G bands at approximately 1350 and 1598 cm−1, respectively, with an I_D/I_G ratio of 1.18, supporting the presence of a defect-rich sp2 carbon framework. The results demonstrate the potential of plastic-waste-derived carbon materials as supports for bimetallic catalysts for deep desulfurization of real refinery fuel under comparatively mild operating conditions.