Optimization study on deep extractive oxidative desulfurization with tetrabutylammonium bromide/polyethylene glycol...

Area of Science:

• Petroleum Chemistry
• Green Chemistry
• Catalysis

Background:

• Petroleum desulfurization is crucial for environmental protection and fuel quality.
• Developing efficient, inexpensive, and environmentally friendly desulfurizing agents remains a significant research challenge.

Purpose of the Study:

• To synthesize and characterize novel deep eutectic solvents (DESs) for petroleum desulfurization.
• To investigate the efficiency of a tetrabutylammonium bromide (TBAB)/polyethylene glycol 200 (PEG-200) based DES system in removing sulfur compounds.
• To optimize reaction conditions and evaluate the reusability of the DES.

Main Methods:

• Synthesis and characterization of TBAB/PEG-200 DESs using Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance spectroscopy.
• Extractive oxidative desulfurization of model oil and crude oil using the synthesized DES and H2O2.
• Optimization of reaction parameters including oxidant-to-sulfur ratio, DES-to-oil ratio, temperature, and time.
• Evaluation of DES reusability and sulfur compound removal efficiency.

Main Results:

• The TBAB/PEG-200 DES system demonstrated high efficiency in removing dibenzothiophene (DBT) and other organic sulfides.
• Optimized conditions (O/S = 8, DES/oil = 1:5, 40 °C, 75 min) achieved high removal rates: 99.65% for DBT, 96.71% for 4,6-dimethyldibenzothiophene, and 93.52% for benzothiophene.
• The DES maintained over 98.14% desulfurization efficiency for DBT after 7 reuse cycles.
• A mechanism for the synergistic effect of hydrogen bonds and the oxidant was proposed.

Conclusions:

• The TBAB/PEG-200 DES is a promising green, efficient, and reusable solvent for petroleum desulfurization.
• The developed system effectively utilizes H2O2 for extractive oxidative desulfurization.
• The study provides insights into the mechanism of synergistic action in the DES-based desulfurization process.