The Treatment of Acidic Petroleum Crude Oil Assisted by Ca/Al2O3 Catalyst

Abstract

Crude oil processing in a petroleum refinery is important due to the increasing demand for petroleum by-products. The presence of Naphthenic Acids (NAs) in crude oil is of great concern to the petroleum industry as they can cause corrosion problems in the oil refinery process. In this study, the NA extraction reaction was conducted using 2-methylimidazole in ethanol assisted by a heterogeneous catalyst to speed up the reaction. Calcium nitrate Ca(NO3)2 loaded at a concentration of 10% on an aluminium oxide (Al2O3) support was prepared by the Incipient Wetness Impregnation (IWI) method. The feedstock, obtained from Petronas Penapisan Melaka, had an original Total Acid Number (TAN) value of 4.38 mg KOH/g. The operating conditions used in this catalytic extraction reaction included a reagent to oil ratio of 0.5:0.5, catalyst loading at 5, 10, 15 and 20 wt%, a reaction temperature of 35 °C, reaction time of 15 minutes and catalyst calcination temperatures of 700, 900 and 1000 °C. The TAN value of crude oil was successfully lowered to 0.48 mg KOH/g using a Ca/Al2O3 catalyst at a calcination temperature of 1000 °C. The catalyst was extensively investigated using TGA-DTA. Results revealed that a calcination temperature above 700 °C was suitable as all impurities in the metal precursor had been removed. SEM micrographs showed an inhomogeneous distribution of various particle sizes, confirming Ca was present on the prepared catalyst. EDX results confirmed the presence of 6.69 % Ca. It can be concluded that the catalytic extraction reaction method with the aid of Ca/Al2O3 was efficient in removing the NAs from acidic crude oil and lowering the TAN value to less than 0.5 mg KOH/g.