Low temperature desulfurization of crude oil using ferric oxide nano catalysts: experimental optimization, performance evaluation, and techno-economic assessment

Abstract

The present study investigates the desulfurization of heavy and light crude oils using ferric-oxide (Fe₂O₃) nano-catalysts under mild operating conditions, with the goal of developing an energy-efficient, hydrogen-free alternative to conventional hydrodesulfurization (HDS). Laboratory experiments were conducted in a fixed-bed catalytic reactor, evaluating the effects of temperature (35–75 °C), pressure (1.0–1.9 bar), catalyst particle diameter (54–91 nm), and catalytic-bed diameter (1–2.5 cm) on sulfur-removal efficiency. Optimal desulfurization occurred at 55 °C, 1.6 bar, and a bed diameter of 2.5 cm, with 58 nm and 77 nm nanoparticles showing the best performance for heavy and light crudes, respectively. A quadratic regression model developed through analysis of variance (ANOVA) yielded an excellent fit (R² = 0.9997, Adj-R² = 0.9899), validating the model’s predictive capability. Compared with conventional HDS, the Fe₂O₃ nano-catalyst achieved 70–90 % sulfur removal without hydrogen consumption and at less than one-tenth of the energy intensity. A preliminary techno-economic analysis indicated that the heating energy accounts for ~45 k USD yr⁻¹ (≈0.1 kWh kg⁻¹ S removed) for a 1,000 bbl day⁻¹ pilot system. Benchmarking against HDS, oxidative desulfurization (ODS), and bio-desulfurization (BDS) demonstrated the potential of the nano-catalyst process for decentralized or small-scale refinery units. The findings provide a foundation for scaling up low-pressure, low-temperature catalytic desulfurization systems and integrating them with sustainable refining operations.