Ethylene or ethene - a colorless, flammable gas with a mild muscatel and sweet smell.Its chemical formula C2H4.Ethene is the simplest alkenyl (unsaturated hydrocarbons having one double bond between adjacent carbon atoms).Molar mass - 28,05 g / mol.Melting point - -169.2 ° C, boiling temperature - -103.7 ° C.Flashpoint - -136 ° C, the self-ignition - +542,8 ° C.In 1680, J. Berger (German physician and chemist) of ethyl alcohol when exposed to oil of vitriol (since then called sulfuric acid) was first carried out the production of ethylene from ethanol.The structural formula of ethylene in 1860 established a Russian chemist AM Butlerov by the reaction of methyl iodide with copper.This gas is slightly lighter than air, it is poorly soluble in water, in organic solvents - good.
producing ethylene and study of its properties, the beginning of which dates to the mid 19th century, today has led to the fact that ethylene is the most popular organic compound.Of world production in 2006 reached more than 109 million tons.Today, the production of ethylene continues to evolve.By 2010, it produced no less than 117 companies in 55 countries.Ethylene is used as raw material in the production of polyethylenes of high and low pressure sevilene and other polymeric materials obtained in the process of copolymerization with various comonomers.Also it is used for the production of ethylbenzene and styrene, ethylene oxide, vinyl chloride, vinyl acetate, acetic acid, ethyl alcohol and ethylene glycol.
What caused the growth of production capacity, aimed at producing ethylene?Mainly market expansion of polymeric materials.Polythene different types consume more than half the world's production of ethylene.The polymeric material is most widely used plastic in the world.Because he made the film for various purposes.Linear alpha-olefins obtained by oligomerization (formation of short chain polymers) are used as precursors, detergents, plasticizers, synthetic lubricants, additives, and as comonomers in the production of polyethylenes.Another important area to use ethylene - it is its oxidation to produce ethylene oxide, the main raw material in the production of surface-active agents and detergents.Ethylene oxide is subjected to hydration to yield ethylene.It is widely used as automotive antifreeze.
Today, the production of ethylene is carried out mostly in the pyrolysis of straight-run gasoline or natural gas liquids.In Russia and the former Soviet republics of the installation of various capacities, built both on domestic (Giprokauchuk, VNIPINeft, Bashgiproneftekhim), and on foreign technologies (Linde AG).Current production can be divided into three groups: low-power (30 and 60 thousand. Tonnes of ethylene per year), medium (100 and 200 thousand. Tons per year) and high (300 and 450 thousand. Tons of ethylene per year).Now in the world operate at a much higher installation capacity: 400 to 500 or even up to 800 million tons per year of ethylene.This allows you to reduce the growth of specific material, energy and capital costs.
Production of ethylene is carried out in the chemical industries, including the installation of a pyrolysis gas separation plant, chemical water treatment plant.Raw material - gas or other light oil or a refinery fraction in admixture with water vapor (a process for reducing the formation of coke in the furnace tubes).The raw material enters the pyrolysis furnace, where a temperature of 750 to 900 ° C formed pyrogas consisting of hydrogen and hydrocarbons whose molecules contain one (methane) to twenty carbon atoms.The heat is utilized in the pyrolysis of special machines, where treated water is produced from high-pressure steam, and chilled pyrogas comes to separating unit resin pyrolysis (heavy) and pyrocondensate.Thereafter pyrogas containing mainly hydrocarbons from C1 to C4, is supplied to the turbocharger (the turbine are driven by high pressure steam), which under pressure is fed to distillation column gas separation installation.There is an allocation of key products such as ethylene and propylene (yield it, as compared with ethylene, always in two times less), and the byproducts of hydrogen, methane, ethane, propane, butylene, butadiene fraction, tar pyrolysis light or componentsavtmobilnyh gasoline.
It is also possible to obtain ethylene catalytic pyrolysis.In industrial scale this method is not implemented, although the test in our country at the time spent not only on laboratory apparatus, but also in industrial conditions.Its advantage is the possibility of reducing the temperature of pyrolysis due to the use of catalysts.By increasing the selectivity (selectivity) of the process is increased, as compared with the thermal pyrolysis, yield of ethylene and propylene, reduced formation of by-products and coke.Currently, researchers in different countries are working to find an efficient catalyst and hardware design process.
