Hydrocarbons with benzene ring structure are important raw materials for organic chemical industry, including monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons and condensed aromatic hydrocarbons. Monocyclic aromatic hydrocarbons contain only one benzene ring, such as benzene, toluene, ethylbenzene, xylene, cumene and dodecylbenzene.

Polycyclic aromatic hydrocarbons (PAHs) are composed of two or more benzene rings (there are no carbon atoms shared by two rings on the benzene rings), and they are connected by single bonds or carbon atoms, such as biphenyl and triphenylmethane. Polycyclic aromatic hydrocarbons are formed by condensation of two or more benzene rings (so that the two benzene rings share a pair of carbon atoms), and at least one of them is a benzene ring, such as naphthalene and anthracene.

The most important products in aromatic hydrocarbons are benzene and xylene, followed by toluene, ethylbenzene, styrene and cumene. Benzene and its homologues with smaller molecular weight are flammable liquids, insoluble in water and less dense than water. Polycyclic aromatic hydrocarbons and polycyclic aromatic hydrocarbons are mostly crystalline solids. Aromatic hydrocarbons are toxic, among which benzene has the strongest influence on the central nervous system and blood. Polycyclic aromatic hydrocarbons cause cancer.

Source:

Aromatic hydrocarbons come from coal and petroleum, and many kinds of aromatic hydrocarbons can be generated during the dry distillation of coal. Aromatic hydrocarbons such as benzene, toluene, naphthalene and anthracene were separated from coal tar obtained by dry distillation in the early and middle period of the 0/Kloc-9th century.

Since then, industrial aromatics mainly come from coke oven gas and coal tar, a by-product of coal coking. Oil contains many kinds of aromatic hydrocarbons, but the content is not much, and the composition and content vary with the place of origin.

After 1940s, catalytic reforming of naphtha was realized, and non-aromatic hydrocarbons in naphtha were converted into aromatic hydrocarbons. Aromatic hydrocarbons can also be separated from cracked gasoline obtained by hydrocarbon cracking. The main source of aromatic hydrocarbons has changed from coal to oil. Now, more than 90% of the world's total output comes from oil.

Bibliography:

Hancock, translated by Mu et al. Benzene and its industrial derivatives, Chemical Industry Press, Beijing, 1982. (such as Hancock, benzene and its industrial derivatives, Ernest Ben, London, 1975. )

In 20 12-20 14, the supply capacity of various products in the global PX-PTA-PET industrial chain maintained rapid growth. Among them, the production capacity of PX (p-xylene) increased by 810.3 million tons/year, reaching 46.33 million tons/year; PTA (purified terephthalic acid) production capacity increased by18.66 million tons/year, reaching 75.38 million tons/year; The production capacity of PET (polyethylene terephthalate) increased by13.47 million tons/year, reaching 89.57 million tons/year.

Time analysis of production capacity shows that the increase of PTA and PET production capacity is concentrated at 20 13, and then the growth rate slows down slightly, while the increase of PX production capacity is mainly concentrated at 20 14, and the growth rate of production capacity is accelerated year by year. It is predicted that in 20 14 years, the global PTA and PET production capacity growth will be reduced to 10% and 4.3% respectively, while the PX production capacity growth will be accelerated to about 1 1%.