3种类型石油酸的腐蚀性以及相互影响

以相对分子质量相近的正辛酸、环己基乙酸和苯甲酸为模型石油酸，采用SEM、X射线能谱和拉曼光谱等手段，分析了相同酸值(2.3 mgKOH/g)下各种石油酸模拟油全浸静态腐蚀实验后的试片和模拟油的形貌和组成，探究了不同类型石油酸的腐蚀特性和相互影响。结果表明:在190℃静态腐蚀实验中，腐蚀速率由大到小的顺序依次为环烷酸、芳香酸、脂肪酸；脂肪酸能增大环烷酸、芳香酸的腐蚀速率，脂肪酸和芳香酸对环烷酸的腐蚀性能和产物产生复杂影响；脂肪酸和环烷酸的腐蚀产物不能附着在试片表面，芳香酸的腐蚀产物有含铁氧化物和芳环结构有机物，附着在试片表面，有一定的钝化缓蚀作用；苯甲酸和正辛酸同时存在的腐蚀产物有极性芳香核、脂肪酸盐分散媒介和非极性烃类的胶团结构。

Corrosivity and Interactions of Different Acidic Species in Petroleum Fractions

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.