Catalytic deacidification optimization of Korean crude oil based on response surface methodology

The presence of naphthenic acids in petroleum crude oil caused serious corrosion problem to the equipment used in the petroleum refinery industry. The acidity level in the petroleum crude oil is determined from the total acid number (TAN) values. In this study, Korean crude oil sample was obtained from PETRONAS Malacca Refinery with an initial TAN of 8.32 mg KOH/g. A catalytic deacidification technique using ammonia–ethylene glycol (NH₃–EG) and KOH solution was applied on this crude oil sample with the aid of an alkaline earth metal oxide catalyst. Parameters investigated in this study were concentration of NH₃–EG, concentration of KOH, catalyst calcination temperature, type of metal oxide catalysts, and percentage of NH₃ in EG. Response surface methodology (RSM) with the central composite design (CCD) was employed to study the optimum condition capable of lowering the TAN in the Korean crude to less than one. The parameters used in the RSM were NH₃–EG concentration, KOH concentration, and percentage of NH₃ in EG. The results showed an 89.9 % reduction of TAN in the Korean crude using 1,000 mg/L of 1 % of 10 M KOH + 4 % NH₃ in EG solution with the aid of Cu/Ca (10:90)/Al₂O₃ catalyst calcined at 1,000 °C. The application of a designed experiment using RSM with CCD confirmed the results obtained experimentally were in good agreement with each other for limited experimental runs.