زهرا كاييد

In this research, the extractive oxidative desulfurization process from model fuel over magnetic heterogenous nanocomposites in a magnetically fluidized bed reactor was investigated. The research was conducted in two main parts, that in the first part, the synthesis of efficient nanocatalyst in the oxidative desulfurization process was carried out. In the second part, the EODS process was investigated in the fluidized bed reactor with and without a magnetic field. In the first part, xMoO3-Fe3O4 catalysts (where x = 3–15 wt%) with various MoO3 content were successfully synthesized using the impregnation method, and their activity was eva‎luated in the extractive oxidative desulfurization process in a batch reactor system. The obtained results demonstrated that the MoO3-Fe3O4 catalyst with a MoO3 content of 9 wt% calcined at 400 ℃ displayed the highest efficiency in the extractive oxidative desulfurization process (EODS). Response surface methodology (BBD) was employed to investigation the influence of various parameters, including O/S molar ratio, reaction temperature, and catalyst dosage, on the desulfurization performance from a model oil containing DBT. Based on the model fitness factors, the experimental data were highly close to the predicted data. The highest sulfur removal efficiency from the model oil (500 ppm sulfur content, DBT) using 9 wt.%MoO3-Fe3O4 catalyst obtained above 98 % at optimum conditions of 30 min, 58 ℃, O/S molar ratio: 5.9, 0.116 g catalyst dosage, and 1500 rpm mixing rate. In the second part of the research, 9wt.% MoO3-Fe3O4 nanocomposite was considered as the support of the catalyst. The effect of adding cobalt, manganese, iron, and nickel oxides on the activity of the MoO3–Fe3O4 catalyst was examined. The obtained results demonstrated that, the MnO2–9MoO3–Fe3O4 catalyst exhibited high activity due to its effective dispersion of active sites and remarkable performance in the oxidative process. Then, the activity of the MnO2 (x)–9MoO3–Fe3O4 catalysts with different weight percentages of manganese oxide (x=1, 2, 3, 4, 5 wt.%) in the EODS process was investigated. To study the effect of magnetic field on the performance of extractive oxidative desulfurization process, the EODS process was investigated using 4MnO2-9MoO3-Fe3O4 catalyst in both magnetic fluidized bed (MOFB) and conventional fluidized bed (CFB) reactors. The effect of different variables such as magnetic field strengths, reaction temperature, reactant flow rate, oxidant to sulfur (O/S) molar ratio, and catalyst dosage on the efficiency of the EODS process in conventional fluidized bed reactor (CFB) and magnetically oscillatory fluidized bed (MOFB) was investigated. The desulfurization efficiency from the fuel oil using a 4MnO2–9MoO3–Fe3O4 nanocomposites in the CFB and MOFB reactors was achieved 80.2% and 92.8%, respectively under the operating reaction conditions: magnetic field strength = 25mT, magnetic field frequency = 50 Hz, reaction temperature = 50 ℃, O/S molar ratio = 4, catalyst dosage = 0.225 g, reaction time= 30 min, and reactant flow rate= 280 ml/min. In the MOFB reactor, the use of a magnetic field causes magnetic nanoparticles to act as microscopic stirrers, increasing contact surface area and enhancing mass transfer between nanocomposites and liquid phases. On the other hand, the presence of the magnetic field causes the proper dispersion of nanocomposites inside the reactor, which reduces the empty space of the reactor and, as a result, increases the effective contact between the phases. Additionally, the obtained results demonstrated that, in the same operating reaction conditions, the presence of the magnetic field increased the desulfurization efficiency.

نانوكامپوزيت مغناطيسي , اكسيد فلزات واسطه , باكس بنكن , فرآيند گوگردزدايي اكسيداسيوني استخراجي , راكتور بستر سيال مغناطيسي متناوب , جداسازي كارآمد

Magnetic nanocatalysts , Metal oxide , Box-Bennken , Extractive oxidative desulfurization process (EODS) , Magnetically oscillatory fluidized bed (MOFB) reactor , Efficient separation

zahra kaeed

Dr. Shahrokh Shahhosseini