Ethylene is produced commercially by the steam cracking of a wide range of hydrocarbon feedstocks. In Europe and Asia, ethylene is obtained mainly from cracking naphtha, gasoil and condensates with the coproduction of propylene, C4 olefins and aromatics (pyrolysis gasoline). The cracking of ethane and propane, primarily carried out in the US, Canada and the Middle East, has the advantage that it only produces ethylene and propylene, making the plants cheaper to construct and less complicated to operate.
No major advances are seen in steam cracking technology in the near term with efforts being directed at improving plant performance through process optimisation, computer control and furnace design. However, ceramic-based furnaces could be developed in the future offering much higher conversion rates and efficiency achieved by very high temperature cracking with no coke formation.
An advanced catalytic olefins (ACO) process that produces ethylene, propylene and other olefins from naphtha at a lower temperature of 700C has been developed by SK Corp and the Korea Research Institute of Chemical Technology. The process is claimed to reduce energy needs by 20%, initial investment costs by 30% as well as reducing carbon dioxide emissions. SK has concluded a strategic alliance with US contractor Kellogg Brown & Root for the ACO process. Plans are to install the ACO process in an existing olefins plant at SK's Ulsan site.
Olefin cracking and interconversion processes are being developed to boost light olefins output. Typically, they can convert C4-C8 olefins and light pyrolysis gasoline into ethylene and propylene. Newer catalytic processes are under development that provide enhanced control of the cracking process or permit catalytic dehydrogenation of ethane.
Small quantities of dilute ethylene can be obtained from refinery streams. In South Africa, ethylene is produced by the Fisher-Tropsch process from gases obtained by coal gasification. Efforts have been made to develop processes which can crack crude or residual oil but they suffer from high operating costs.
Processes are available that use lower alcohols as feedstocks. Norsk Hydro and UOP have developed a MTO (methanol-to-olefins) technology that converts methanol to ethylene and propylene. There is considerable interest in using this technology in China with methanol produced via the gasification of coal.
Working with UOP, Total has developed a technology which takes the heavier olefins from the MTO unit and converts them into lighter olefins, more specifically into propylene. A pilot plant has been built at Feluy, Belgium, to assess this olefin cracking process (OCP) in conjunction with the MTO process.
Lurgi has also developed a methanol-to-propylene (MTP) process.
Much research is being conducted into the direct conversion of methane to ethylene. However, the problem with this technology, called oxidative coupling of methane (OCM), is the low per-pass yield of ethylene and the high yield of unwanted carbon oxide by-products such as carbon monoxide and carbon dioxide. Most attempts to increase product yield have been through new catalyst formulations. Research is also focussing on making further use of the carbon oxides by producing methanol or methane.
Ethylene Margin Reports
ICIS pricing’s weekly ethylene margin reports (Europe, Asia and US) are designed to complement ICIS's highly regarded pricing data. They assess producer cash costs and cash margins for ethylene by modelling raw material and key variable manufacturing costs, co-product credits and product yields across the business from feedstock naphtha, ethane or liquefied petroleum gas.
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Combining ICIS pricing’s benchmark price assessments with feedstock yield models from Linde Engineering the reports provide a clear indication of the direction of business cash costs and cash margins, forming a basis for informed market positioning by sellers, buyers and traders.
Find out more by visiting www.icis.com/margins