Basic information of Naphthenic acid

Naphthenic acid is the name for an unspecific mixture of several cyclopentyl and cyclohexyl carboxylic acids with molecular weight of 120 to well over 700 atomic mass units. The main fraction are carboxylic acids with a carbon backbone of 9 to 20 carbons. The naphtha fraction of the crude oil refining is oxidized and yields naphthenic acid. The composition differs with the crude oil composition and the conditions during refining and oxidation. Naphthenic acids are present in crude oil and leads to corrosion problems within the oil refineries, therefore "naphthenic acid corrosion" phenomena are well researched. Crude oils with a high content of naphthenic acids are often referred to as high TAN (Total Acid Number) crude oils or high acid crude oil (HAC).