Microwave-Assisted Nickel and Vanadium Removal from Crude Petroleum Oil Using Bis(2-ethylhexyl)phosphoric Acid: A Kinetic Study

Amongthe various metals in crude oils, nickel (Ni) and vanadium(V) exist as oil-soluble organic compounds, making them extremelydifficult to remove. The presence of these metals has been provento have deleterious effects, such as catalyst poisoning and corrosionin crude refinery processes. This study aimed for Ni/V removal fromIranian crude oil using bis-(2-ethylhexyl)-phosphoric acid (D2EHPA)under microwave heating. The impact of primary process parameters,such as temperature, residence time, and D2EHPA dosage, on Ni andV removal efficiencies was studied. The demetallization reaction kineticsand mechanism were investigated at 230-250 degrees C and optimizedconditions. The findings demonstrated that at low microwave powersof 40-50 W, Ni and V removal efficiencies could reach up to63% and 72%, respectively, after a reaction time of 1 h at 250 degrees C.The kinetics of demetallization reactions was found to be of first-order,and the activation energies and pre-exponential factors for Ni andV were estimated to be 29.8 and 34.7 kJ/mol and 16.5 and 66.2 min(-1), respectively. A well-fitted kinetic model was proposedbased on the coefficients of determination. The reaction between themetalloporphyrins in crude oil and D2EHPA resulted in the substitutionof Ni and V with protons provided by D2EHPA, leading to the formationof metal salts that are soluble in water. The formation of N-Hbonds in the treated oil, as confirmed by the FTIR analysis results,indicated the occurrence of the demetallization reaction.

Automated summary

This study investigated the removal of nickel (Ni) and vanadium (V) from Iranian crude oil using bis-(2-ethylhexyl)-phosphoric acid (D2EHPA) under microwave heating. The results showed that with low microwave powers and a reaction temperature of 250℃, the removal efficiencies of Ni and V could reach up to 63% and 72% respectively after 1 hour of reaction. The demetallization reactions followed a first-order model, with activation energies of 29.8 and 34.7 kJ/mol for Ni and V.