World Ethylene Production by Steam Cracking

In 2008 the ethylene production capacity was still dominated by the developed eeonomies of North Ameriea, the European Union and the Far East. The Ear East is dominated by Japan and Korea but with signifieant contributions from the eountries of South East Asia. Emerging and rapidly growing regions of olefin produetion are China and the Middle East. 

The following is a selected review of the world s major cracking operations produeing olefins and petrochemicals. 

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Ethylene is a constituent of refinery gases, especially those produced from catalytic cracking units. The main source for ethylene is the steam cracking of hydrocarbons (Chapter 3). Table 2-2 shows the world ethylene production by source until the year 2000. U.S. production of ethylene was approximately 51 billion lbs in 1997. ... 

Ethylene is the largest volume organic chemical product, with world production over 50 billion pounds per year. It is normally produced by steam cracking of ethane or heavier hydrocarbons. This process is quite energy and capital intensive. 

Chlorine is one of the most common chemicals in the world. It is produced in huge quantities. Hydrogen is a by-product of catalytic reforming of petrol, made to improve the octane number. It is also a by-product of steam cracking of hydrocarbons for the production of ethylene. This hydrogen is used in other refinery operations. Smaller volumes of hydrogen are by-products in coke ovens and usually are kept for internal use. All by-product hydrogen requires some purification steps before use. 

Monomer. Contrary to butadiene, which is a gas at ambient temperature, 2-methylbuta-1,3-diene is a liquid (r = 34°C). It is a by-product of the production of ethylene obtained from steam-cracking of oil products. It can also be prepared either by catalytic dehydrogenation of pentenes or by dimerization of propylene. The world annual production of isoprene monomCT is in the range of one million tons. 

Ethylene Coproduction. Historically, butadiene was first prepared in pilot plant quantities via an uneconomical electric arc process. However, the primary source of butadiene in the world today is as a by-product of thermal pyrolysis of hydrocarbon feedstocks in ethylene production. In the United States, production of coproduct butadiene exceeded that of on-purpose butadiene for the first time in 1977 and by 1990 high cost on-purpose butadiene production was essentially eliminated in the United States (Fig. 1) (46,47). In 1996, the total US production of butadiene was 1.75 million, 93% of which was co-produced (47). Steam cracking of hydrocarbons yields varying amounts of butadiene, depending on the nature of the feedstock, the volume of ethylene produced, and the severity of the cracking operations (48-50). For example, when feedstocks are switched from atmospheric gas oils and napthas to propane and butane, yields of butadiene drop by as much as 60% (51). 

The world s 140 million metric tons of annual ethylene capacity almost exclusively employs steam cracking of hydrocarbon feedstocks [5]. The majority of the feedstocks come from petroleum refining, such as by cracking of naphtha, but some producers use liquefied natural gas as a feedstock. In Brazil, where sugar cane is plentiful, Braskem has built a 200,000 metric ton per year ethylene plant based upon the dehydration of sugar-derived ethanol [6]. In the United States, natural gas liquids, a mixture of ethane, propane, butane, and other hydrocarbons, are available from shale deposits. The ethane is separated and cracked to make ethylene. Depending on the cost of oil and natural gas, this can be an economic advantage. In 2012, about 70% of United States ethylene production was from ethane [7]. 

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