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What is the difference between aromatic oils?
01. What is aromatics?
Aromatics, also known as aromatic hydrocarbon or aromatic oil, refers to hydrocarbons with benzene ring structure in molecules. It is one of the basic products and raw materials of petrochemical industry, mainly including benzene, toluene, xylene, ethylbenzene, etc. It is a general term for a series of solvents composed of isomers of C9 and C10 heavy aromatics.
02. Where does aromatics come from?
1. Extraction from coal
The light tar produced in coal coking process contains a lot of benzene. This is the first way to produce benzene. The coal tar and the gas are washed and absorbed together, and the coal tar with high boiling point is used as washing and absorbent to recover the coal tar in the gas. After distillation, the crude benzene and other high boiling point fractions are obtained. Industrial grade benzene can be obtained by refining crude benzene. The purity of benzene obtained by this method is relatively low, and the environmental pollution is serious, and the process is relatively backward.
2. Extraction from crude oil
This method is a common method for aromatics extraction. Crude oil refining and reforming refers to the process of cyclization and dehydrogenation of aliphatic hydrocarbons to aromatics. This is a craft developed during the Second World War. At 500-525 ° C and 8-50 atmospheres, various aliphatic hydrocarbons with boiling point between 60-200 ° C are converted to benzene and other aromatics through dehydrogenation and cyclization over platinum rhenium catalyst. Benzene is separated by distillation after aromatics are extracted from the mixture. These fractions can also be used as high octane gasoline. At present, more than 90% of the world's total production comes from oil.
Therefore, aromatics are products of petrochemical industry, which also means that the market trend of aromatics fluctuates with petroleum.
03. Why light and heavy aromatics?
Light aromatics and heavy aromatics are alkanes or alkenes containing benzene ring. Heavy and light aromatics are distinguished by the length of carbon chain of benzene ring linked alkanes or olefins. Of course, heavy aromatics are connected with long carbon chain, and light aromatics are connected with short carbon chain.
Generally, C6-C9 can be called aromatics; heavy aromatics refer to the mixed aromatics with molecular weight greater than xylene, in which C 9 and C 10 aromatics are the majority, mainly from reforming aromatics, cracking aromatics and coal tar. It can be used as a blending component to reduce the freezing point and cold filter point of diesel oil, but because its main component is aromatics and its cetane number is very low, cetane number improver should be added to meet the quality requirements.
04. What is high boiling aromatic solvent oil?
With the continuous improvement of performance, a new solvent high boiling point aromatic solvent oil emerges as the times require in order to adapt to the green direction. Compared with the corresponding alkane solvent, high boiling point aromatic solvent oil has the characteristics of strong solvent, small odor, stable chemical and physical properties, good emulsification, moderate volatilization speed, no water, olefins, chlorine and heavy metals, good leveling and so on. It can be widely used as paint solvent and diluent; special agent and diluent for ink; pesticide emulsifier, special solvent for pesticide; special solvent for hydrogen peroxide and banana water production; brightener for leather and plastic production; cleaning solvent for precision machine tool; paper polish and moisture-proof agent.
In addition, high boiling point aromatic solvent oil can adjust the composition of various isomers in the solvent to form different distillation range and different solubility to meet the needs of different coatings. For example:
1. Aromatic solvents with high boiling point can be miscible with most organic solvents, so it is easy to adjust the formula;
2. Suitable volatilization rate can help to adjust the volatilization rate of the whole solvent system;
3. It has good leveling property to increase the flexibility and adhesion of the paint film, especially in the baking coating, it can give full play to the high solubility in the later stage of film formation, so as to make the film flat and reduce the surface defects such as orange peel, pinhole, fish eye, crater, etc;
4. The characteristics of high boiling point and suitable process can avoid the defects caused by the film explosion due to the too fast volatilization speed, and can give the film a smooth appearance, which is conducive to the adhesion and toughness of the film and the convenience of post-processing. It can be widely used in epoxy coatings and polyurethane coatings. It is also widely used in epoxy zinc rich and thick film heavy-duty coatings.