Ethylene producer

Ethylene is the cornerstone of the world s mam moth petrochemical industry and is produced in vast quantities In a typical year the amount of ethylene produced in the United States (5 x 10 ° lb) exceeds the combined weight of all of its people In one process ethane from natural gas is heated to bring about its dissociation into ethylene and hydrogen... 

Proceedings of the 4th Ethylene Producers Conference, Vol. 1, American Institute of Chemical Engineers, New York, 1992, pp. 177—211. 

The principal route for production of isoprene monomer outside of the CIS is recovery from ethylene by-product C streams. This route is most viable where ethylene is produced from naphtha or gas oil and where several ethylene plants are located in relatively close proximity to the isoprene plant. Although the yield of isoprene per mass of ethylene is quite low, there is enough ethylene produced to provide a large portion of demand. Because of the presence of / -pentane in these streams which a2eotropes with isoprene, extractive distillation must be used to recover pure isoprene. Acetonitrile is the most common solvent, but dimethylformamide is also used commercially. 

Polyethylene. Low pressure polymerization of ethylene produced in the Phillips process utilizes a catalyst comprised of 0.5—1.0 wt % chromium (VI) on siUca or siUca-alumina with pore diameter in the range 5—20 nanometers. In a typical catalyst preparation, the support in powder form is impregnated with an aqueous solution of a chromium salt and dried, after which it is heated at 500—600°C in fluid-bed-type operation driven with dry air. The activated catalyst is moisture sensitive and usually is stored under dry nitrogen (85). 

The quantity of ethylene transported by international tankers accounts for only 1% of production. The majority of ethylene produced in the United States and Western Europe is moved by integrated pipeline systems. 

Almost all ethylene produced is consumed as feedstock for manufacturing other petrochemicals. Only a very small amount has been used in the agricultural industry for ripening fmits. Table 9 Hsts the principal ethylene derivatives and capacities. 

Table 12. U.S. Ethylene Produced from Various Feedstocks,...

Although polyethylene is virtually defined by its very name as a polymer of ethylene produced by addition polymerisation, linear polymers with the formula (CH2), have also been prepared by condensation reactions. For example in 1898 von Pechmann produced a white substance from an ethereal solution of... 

This banner opens the excited states output for ethylene produced by Gaussian ... 

Catalytic oxidation of ethylene produces ethylene oxide, which is hydrolyzed to ethylene glycol. Ethylene glycol is a monomer for the production of synthetic fibers. Chapter 7 discusses chemicals based on ethylene, and Chapter 12 covers polymers and copolymers of ethylene. 

The direct addition of chlorine to ethylene produces ethylene dichloride (1,2-dichloroethane). Ethylene dichloride is the main precursor for vinyl chloride, which is an important monomer for polyvinyl chloride plastics and resins. 

A typical Ziegler-Natta catalyst is the complex prepared from titanium tetrachloride and triethylaluminium. It is fed into the reaction vessel first, after which ethylene is added. Reaction is carried out at low pressures and low temperatures, typically no more than 70 °C, with rigorous exclusion of air and moisture, which would destroy the catalyst. The poly(ethylenes) produced by such processes are of intermediate density, giving values of about 0.945 g cm. A range of relative molar masses may be obtained for such... 

The quantity of these materials is relatively small compared with the amount of waste high-density poly(ethylene) produced each year. Containers made from HDPE are widely used for detergents, oil, and antifreeze, and enormous amounts of material are used in disposable applications aimually. In principle recycled poly(ethylene) could be used for drain pipes, flower pots, dustbins, and plastic crates. The problem remains, however, that economics do not favour recycling of these polymers and in the absence of Government intervention little or nothing can be done to alter commercial attitudes towards recycling. 

About 50% of all the ethylene produced is used to make polyethylene. There are two main types high density or HDPE and low density or LDPE. HDPE melts higher and is stiffer and harder than LDPE. It is also opaque, while LDPE is flexible and transparent. HDPE is used for molding bottles, housewares, toys, and for extruding pipe and conduit. LDPE is used mainly for packaging film. HDPE is made by a catalytic polymerization at relatively low pressure while LDPE is made by polymerization at very high pressure using a different catalyst. 

About 10% of the ethylene produced in the U.S. is used to make vinyl chloride, which in the chemical trade is usually referred to as vinyl chloride monomer or VCM. The largest use of VCM is for polymerization to poly(vinyl chloride) (PVC), a thermoplastic, which in terms of volume is second only to polyethylene. PVC is used in such diverse areas as containers, floor coverings (linoleum), plastic pipes, raincoats, and many, many others. PVC has an evironmental disadvantage over non-chlorine containing plastics in that when it is disposed of by incineration it produces hydrogen chloride, which dissolves in atmospheric water to give hydrochloric acid. Polyethylene does not have this undesirable feature. 

Hydration of ethylene produces ethanol, C2H4 + H20 C2Hs0H. 

If the ethylene produced with sulphuric acid is analysed (method ) it is found that very much carbon monoxide is present. The phosphoric acid method is better suited for the production of the pure gas, but the best way is to remove with zinc dust and glacial acetic acid the bromine from the ethylene dibromide already prepared. The dibromide is dropped into a suspension of an excess (not too great) of zinc dust in alcohol and glacial acetic acid (2-5 moles) and the ethylene is collected over water in a gas-holder. 

Methane to Ethylene One target is to achieve an ethylene selectively of 90% at a methane conversion level of 50% in a single pass. Additionally, design of novel recycle reactors or membrane systems (to remove the ethylene produced) remain part of the active research. 

Polyethylene in its various forms account for about 57% of the ethylene produced in the world, with the following distribution, more or less ... 

Alkylation of benzene and ethylene produces ethyl benzene, which is dehydrogenated to styrene for polystyrene. 

Only a few of the major developments can be traced here, yet these should give a fair idea of the magnitude and importance of the aliphatic petrochemical growth. It is well to remember that some of the chemistry involved in this industry is old. Four Dutch chemists, otherwise unrecalled today, prepared ethylene dichloride by addition of chlorine to ethylene in 1795, and the synthesis of ethyl alcohol from ethylene via sulfuric acid absorption was studied by Berthelot in 1855 (8). Of course, this was coal-gas ethylene, and the commercial application of this synthesis did not occur until 75 years later, in 1929, when ethylene produced from natural gas was first converted into ethyl alcohol on a practical scale (84). 

From the isotopic analysis of ethylene produced from the photolysis of CH4 + CD4 mixtures, they conclude (VIII-123) is a dominant process for the ethylene production. 

The outlook for ethylene demand in the next decade is one of continued strong growth. Based on our discussions with several ethylene producing and consuming companies, we feel that the projections shown in Table I, which presents estimated annual ethylene demands for the 1970-80 period, are realistic and if anything, somewhat conservative. 

Table X shows the effect of capacity on ethylene production costs for a European naphtha plant. Note that investment-based items such as return on investment and depreciation and others included in operating cost decrease, per unit of ethylene produced, as plant size gets larger.

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