LaMn_xCo_1-xO₃ (x=0, 0.25) Perovskites: Novel Nano Catalysts for Removal of Thiophene compounds in Fuels by Catalytic and Ultrasound-assisted Oxidative Desulfurization

LaMnxCo1-xO3 (x=0, 0.25) perovskites were developed as novel nanocatalysts for the desulfurization of thiophenes compounds by catalytic oxidative desulfurization (CODS) and ultrasound-assisted oxidative desulfurization (UAOD). The perovskites were synthesized by the sol-gel auto-combustion method and characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), Scanning electron microscopy (SEM) and BET surface area. The experiments were designed by the Box-Behnken method of response surface methodology. The catalytic experiments were designed by response surface methodology (RSM). LaMn0(.25)Co(0.75)O(3) despite having a lower surface area rather than LaCoO3 exhibited superior activity due to easy reducibility and high surface electron density approved by TPR. Pareto analysis indicated that the DBT concentration had the most effect on the CODS process. Ultrasound waves enhanced the activity of the catalysts via the formation of hot spots as an accelerating and de-agglomerating agent in the UAOD process, leading the LaMn0.25Co0.75O3 to be reusable at least for 5 cycles. A mechanism for DBT oxidation was proposed by the formation of DBT sulfone. Due to steric hindrance and the electron density of the sulfur atoms in thiophene derivatives, the following order resulted in their desulfurization rate: DBT>4-MDBT>BT. The study indicated that perovskites could be novel and promising nanocatalysts for the desulfurization of fuels.