Base Oil It is used in the production of products including base oils, lubricating greases, motor oil, and metalworking fluids. Different products require different compositions and properties in oil. One of the most important factors is the viscosity of the liquid at various temperatures. Whether crude oil is suitable for conversion into base oil is determined by the concentration of base oil molecules and how easily they can be extracted.
Base oil is produced by refining crude oil. This means heating the crude oil so that the various distillates can be separated from each other. During the heating process, light and heavy hydrocarbons are separated; lighter ones can be refined to make petroleum and other fuels, while heavier ones are suitable for bitumen and base oils.
There are many crude oils used in base oil production all over the world. The most common is a type of paraffinic crude oil, but there are also naphthenic crude oils that form products with better solubility and very good properties at low temperatures. By using hydrogenation technology, in which sulfur and aromatics are removed using hydrogen under high pressure, extremely pure base oils can be obtained, suitable for situations where quality requirements are particularly stringent.
Chemical substances – additives – are added to the base oil in order to meet the quality requirements of the final products in terms of friction and cleaning properties. Some types of engine oil contain more than twenty percent additives.
Mineral base oils are primarily distilled from petroleum and consist of 26-40 carbon fractions. Aromatic compounds are initially removed by solvent extraction: The distillation fraction is mixed with an immiscible solvent such as phenol or furfural. This solvent preferably dissolves aromatic compounds well, and the aromatic compounds are separated with the solvent.
Long chain alkanes form waxes that precipitate at relatively high temperature. They are removed by low-temperature crystallization of waxes or can be isomerized to branched alkanes. After this, various levels of hydrogenation are used to remove remaining aromatic compounds and residual heteroatoms (in the form of nitrogen and sulfur compounds).
Very generally, heteroatoms (as nitrogen and sulfur compounds) and aromatic compounds are removed by hydrogenating the base oil from Group I to Group III. Reducing heteroatoms reduces acid formation when engine oils are exposed to the combustion environment, acids are corrosive to the engine. Reducing aromatic compounds increases the oxidative stability of the oil and delays the formation of sludge and varnish. However, both effects cause the oil to become less polar, making it a poorer solvent for both the engine oil’s additive package and accumulated oxidation byproducts.
The least refined type produced by solvent refining, introduced in the 1930s. It usually consists of conventional petroleum-based oils. An improvement in the refining process called hydrotreating in the 1960s made this base oil more stable, less reactive, and longer-lasting than earlier base oils.
The API defines group I as “base stocks contain less than 90 percent saturated matter and/or more than 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120.”
A better quality petroleum-based oil, originating in 1971, that can be produced partially by hydrocracking. All foreign substances in the oil will be removed and a clearer color will be obtained.
The API defines group II as “base stocks that are greater than or equal to 90 percent saturated and contain less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120.”
Originating in 1993, they are the most refined grade of petroleum-based oil as they are produced entirely through hydrocracking, hydroisomerization, and hydroprocessing, making these oils purer.
The API defines group III as “base stocks that are greater than or equal to 90 percent saturated and contain less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 120.”
It consists of synthetic oils made from polyalphaolefins (PAO), originating in 1974. The viscosity index of Group IV base oils is in the range of 125 – 200.
Polyalphaolefin oils have a higher oxidative stability at extreme temperatures and also have extremely low pour points, making them suitable for use in very cold weather (as in Northern Europe) as well as in very hot weather (as in Central Europe). makes it more convenient. East ).
All types of base oils other than those mentioned in the previously defined groups, originating in the 1940s. Group V oils include alkylated naphthalenes (e.g. ExxonMobil Synestic) and esters.