It is known that crude oil cannot be used as fuel. It must be processed before a marketable product is obtained, one of the stages of such processing is selective refining.
The general meaning of selective refining is the processing of crude oil or derivatives to improve the quality of oil fractions. Practically, this is done by selective interaction of solvents on the components of “black gold”. Then the solvent is evaporated from the refined and extracted solutions.
This method of processing allows to remove harmful and undesirable substances, such as asphalt and and tar, polycyclic aromatic hydrocarbons with short side chains, heteroatomic compounds etc. The main purpose of selective refining is to obtain a refined oil fraction of monocyclic aromatic hydrocarbons with long side chains, as well as paraffinic and naphthenic hydrocarbons.
The product of selective refining, compared to the initial material, is more viscous and has higher setting point. It also has lighter color. But this product is not yet ready to be sold, so it undergoes deparaffinization to remove solid hydrocarbons. The resulting extract consists of the removed substances of dark color. Ir can be used as heating fuel, rubber softener or plasticizer. The most commonly used solvents are furfural and phenol.