Corrosivity and Interactions of Different Acidic Species in Petroleum Fractions

Corrosivity and Interactions of Different Acidic Species in Petroleum Fractions

Petroleum industry

Gasoline

Corrosion rate

Corrosion protection

Corrosion prevention

Scanning electron microscopy

Aromatization

Steel corrosion

Dispersions

Aromatic hydrocarbons

Iron compounds

Naphthas

Fatty acids

Benzoic acid

Corrosivity of petroleum fractions with the same total acid value (TAN) can be much different due to chemical structure differences of acidic species. To investigate corrosivity difference and interactions between different acidic species, acids with similar relative molecular mass, i.e., n-octylic acid, cyclohexylacetic acid, and benzoic acid, were chosen to prepare different simulation oils with the same TAN of 2.3 mgKOH/g. Vacuum scanning electron microscopy, X-ray energy dispersion spectroscopy, and laser micro Raman spectroscopy were used to characterize the steel surfaces and the corroded products. Static corrosion test results at 190 show that, for different acidic species, the descend order of corrosion rates is naphthenic acid, aromatic acid, paraffinic acid. However, it was found that corrosion rate of paraffinic acid can be higher if other two acids are present simultaneously. It can be observed that corrosion products from paraffinic acids and naphthenic acids can't be steadily attached on the steel surfaces. If benzoic acid is present in the simulation oil, the corrosion products on the steel surfaces contain oxidation products from iron and also organic compounds with aromatic ring structures. The above two components can form a protection layer, and thus prevent further corrosion. Corrosion products from both benzoic acid and n-octanoic acid can form anchored interfacial layers. These layers have a micellar structure, in which polar aromatics are the core, paraffinic acid salts as dispersion medium, and outside are non-polar hydrocarbons. 2021, Editorial Office of Acta Petrolei Sinica(Petroleum Processing Section). All right reserved.

653-661

3

37

Shiyou Xuebao, Shiyou Jiagong/Acta Petrolei Sinica (Petroleum Processing Section)

2021

Ge, Lin

Lu, Ya

Jia, Lingyan

journalArticle

10018719

10.3969/j.issn.1001-8719.2021.03.021