Removal of naphthenic acids from crude oils by catalytic decomposition using Mg–Al hydrotalcite/γ-Al2O3 as a catalyst

Abstract

High total acid number (TAN) crude oils contain large amounts of naphthenic acids that could create serious corrosion problems in the oil refining process. This paper studied the catalysts that can make the naphthenic acids in crude oil to be decomposed to decrease the TAN of the crude oil effectively. Therefore, less corrosion of the facilities would occur. The results indicated that Mg–Al hydrotalcite/γ-Al2O3 effectively removed the naphthenic acids in high TAN crude oils, and the catalyst prepared with the ball-rolling method possessed a high mechanical strength and good pore structures. The TANs of the crude oils decreased from 2.7mg KOH/g to below 0.5mg KOH/g at 320°C after 60min with a pressure of 1.013×105Pa and a catalyst/oil ratio of 0.17–0.20, which meet the requirements of high TAN crude oil processing in refineries without material upgrades. FT-IR of processed crude oil and the gas product analysis certificated the occurrence of the decomposition of carboxyl group.