Ethylene processing

Acetylene and Ethylene Processes—Conference Report," Chem. Process Eng. (Eondon), 101 (May 1968). 

Table 2. Typical Material Balance for Vinyl Chloride Production by the Air-Based Balanced Ethylene Process...

Alternatives to oxychlorination have also been proposed as part of a balanced VCM plant. In the past, many vinyl chloride manufacturers used a balanced ethylene—acetylene process for a brief period prior to the commercialization of oxychlorination technology. Addition of HCl to acetylene was used instead of ethylene oxychlorination to consume the HCl made in EDC pyrolysis. Since the 1950s, the relative costs of ethylene and acetylene have made this route economically unattractive. Another alternative is HCl oxidation to chlorine, which can subsequently be used in dkect chlorination (131). The SheU-Deacon (132), Kel-Chlor (133), and MT-Chlor (134) processes, as well as a process recently developed at the University of Southern California (135) are among the available commercial HCl oxidation technologies. Each has had very limited industrial appHcation, perhaps because the equiHbrium reaction is incomplete and the mixture of HCl, O2, CI2, and water presents very challenging separation, purification, and handling requkements. HCl oxidation does not compare favorably with oxychlorination because it also requkes twice the dkect chlorination capacity for a balanced vinyl chloride plant. Consequently, it is doubtful that it will ever displace oxychlorination in the production of vinyl chloride by the balanced ethylene process. 

The principal sources of feedstocks in the United States are the decant oils from petroleum refining operations. These are clarified heavy distillates from the catalytic cracking of gas oils. About 95% of U.S. feedstock use is decant oil. Another source of feedstock is ethylene process tars obtained as the heavy byproducts from the production of ethylene by steam cracking of alkanes, naphthas, and gas oils. There is a wide use of these feedstocks in European production. European and Asian operations also use significant quantities of coal tars, creosote oils, and anthracene oils, the distillates from the high temperature coking of coal. European feedstock sources are 50% decant oils and 50% ethylene tars and creosote oils. 

Ethylene oxide (qv) was once produced by the chlorohydrin process, but this process was slowly abandoned starting in 1937 when Union Carbide Corp. developed and commercialized the silver-catalyzed air oxidation of ethylene process patented in 1931 (67). Union Carbide Corp. is stiU. the world s largest ethylene oxide producer, but most other manufacturers Hcense either the Shell or Scientific Design process. Shell has the dominant patent position in ethylene oxide catalysts, which is the result of the development of highly effective methods of silver deposition on alumina (29), and the discovery of the importance of estabUshing precise parts per million levels of the higher alkaU metal elements on the catalyst surface (68). The most recent patents describe the addition of trace amounts of rhenium and various Group (VI) elements (69). 

Most of the vinyl acetate produced in the United States is made by the vapor-phase ethylene process. In this process, a vapor-phase mixture of ethylene, acetic acid, and oxygen is passed at elevated temperature and pressures over a fixed-bed catalyst consisting of supported palladium (85). Less than 70% oxygen, acetic acid, and ethylene conversion is realized per pass. Therefore, these components have to be recovered and returned to the reaction zone. The vinyl acetate yield using this process is typically in the 91—95% range (86). Vinyl acetate can be manufactured also from acetylene, acetaldehyde, and the hquid-phase ethylene process (see Vinyl polymers). 

There are two main processes for the synthesis of ethyl alcohol from ethylene. The eadiest to be developed (in 1930 by Union Carbide Corp.) was the indirect hydration process, variously called the strong sulfuric acid—ethylene process, the ethyl sulfate process, the esterification—hydrolysis process, or the sulfation—hydrolysis process. This process is stiU in use in Russia. The other synthesis process, designed to eliminate the use of sulfuric acid and which, since the early 1970s, has completely supplanted the old sulfuric acid process in the United States, is the direct hydration process. This process, the catalytic vapor-phase hydration of ethylene, is now practiced by only three U.S. companies Union Carbide Corp. (UCC), Quantum Chemical Corp., and Eastman Chemical Co. (a Division of Eastman Kodak Co.). UCC imports cmde industrial ethanol, CIE, from SADAF (the joint venture of SABIC and Pecten [Shell]) in Saudi Arabia, and refines it to industrial grade. 

Ethyl Ether. Most ethyl ether is obtained as a by-product of ethanol synthesis via the direct hydration of ethylene. The procedure used for production of diethyl ether [60-29-7] from ethanol and sulfuric acid is essentially the same as that first described in 1809 (340). The chemical reactions involved in the production of ethyl ether by the indirect ethanol-from-ethylene process are like those for the production of ether from ethanol using sulfuric acid. 

The demethanizer distillation column of an ethylene process works at extremely low temperatures. The feed is cooled with extremely small temperature differences of the order of 1°C to minimize the refrigeration costs associated with the cooling. What type of heat exchanger would you expect to be used for this duty ... 

UNIPOL [Union Carbide Polymerization] A process for polymerizing ethylene to polyethylene, and propylene to polypropylene. It is a low-pressure, gas-phase, fluidized-bed process, in contrast to the Ziegler-Natta process, which is conducted in the liquid phase. The catalyst powder is continuously added to the bed and the granular product is continuously withdrawn. A co-monomer such as 1-butene is normally used. The polyethylene process was developed by F. J. Karol and his colleagues at Union Carbide Corporation the polypropylene process was developed jointly with the Shell Chemical Company. The development of the ethylene process started in the mid 1960s, the propylene process was first commercialized in 1983. It is currently used under license by 75 producers in 26 countries, in a total of 96 reactors with a combined capacity of over 12 million tonnes/y. It is now available through Univation, the joint licensing subsidiary of Union Carbide and Exxon Chemical. A supported metallocene catalyst is used today. 

Ethanol to ethylene process, 70 621 Ethanol transportation fuel, 70 60 Ethanol trifluoroborane, 4 144t Ethanol vapor concentration, effects in humans, 70 552t... 

Most of the vinyl acetate produced in the United States is made by the vapor-phase ethylene process. 

Carbocyclic brighteners gained new impetus after 1959, when the trialkylphos-phite-activated ethylenation process developed by Homer became available [27], This process, which features a high yield and high selectivity for the E isomers needed for optical brighteners, is extremely interesting from an industrial point of view. The principal products are distyrylarenes and divinylstilbenes, which have retained their importance to the present day. 

Fig. 10.18. Vapor phase vinyl acetate from ethylene process. (Chem Systems Report No. 98/99-S3. Copyright Nexant Chem Systems, Inc. and used by permission of the copyright owner.)... 

Gather all the available information on one of the ethylene processes for which a flow sheet was prepared in the preceding problem and make a preliminary material balance for the production of 50 million lb/yr of ethylene. Assume an operating factor of 90 percent. 

The Mobil-Badger process has also been modified to use dilute ethylene from FCC off-gas streams as a feedstock. The dilute ethylene process was first commercialized at Shell s Stanlow U.K. refinery in 1991 and has been in continuous use ever since. 

Steam pyrolysis is performed at temperatures higher than most other ethylene processes creating more coking potential. Process requires two separate water quench exchangers. 

For the propylene oxide process, the economics of ethylbenzene production are the same as above. Propylene is a co-product of the ethylene process described in detail in cluqiter 3, and is economically frivorable as shown there. The propylene oxide process itself is economically promising as shown in Problem 4-3. 

This process looks economically fevorable, though not nearly as favorable as the ethylene process. Moreover, the processing is more con lex. Several byproducts, including animal feed are produced. There is a currently a U.S. government subsidy > ch he s the operation be profitable. The fermentation step of the process is usually batch, but the rest can continuous. 

Acetylene hydro- chlori- nation Ethylene dicliinrido Itula need acetylene/ ethylene process ( rude oil pyrolysis und in ethylene Fluidized I red dichloridc, > Fixed bed set Hydro- chloric aeitl cotes... 

Bedell, K. R- Rain bird. H. A " Make AM from ethylene, Hydrocarbon Processing, 51 (11) 141-143 (1972). Ohmae, T, Development of ethylene process, vinyl acetate and process comparison . Chon. Econ. and Engng. Rev. 4(11, 55)46-57 <1972). 

Table 9.30 Composition of Fractions of Chlorotrifluoroethylene Polymer Obtained by Supercritical Ethylene Processing...

PP/PB and a poly(/-butene-co-ethylene) processability, impact strength, Hwo, 1994... 

The same principal products were detected in the photolysis of an alcohol and its corresponding ether. For example, ethanol and ethyl ether gave ethylene (process a), acetaldehyde (process b), and formaldehyde (process b). In an attempt to find out whether the formaldehyde and... 

Fiq. 7-8. Flow diagram continuous ethanol-from-ethylene process. 

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