Ethylene oxide, manufacture

C HioOj, (H0CH2CH2)20. A colourless and almost odourless liquid b.p. 244 C. Readily absorbs moisture from the atmosphere. It is obtained as a by-product in the manufacture of ethylene glycol by the hydra-lion of ethylene oxide. Manufactured by heat-... 

The atom utilization or atom efficiency concept is a useful tool for rapid evaluation of the amount of waste that will be generated by alternative routes to a particular product. It is calculated by dividing the molecular weight of the desired product by the sum total of the molecular weights of all the substances produced in the stoichiometric equation of the reaction(s) in question. The comparison is made on a theoretical (i.e. 100% chemical yield) basis. Fig. 2.8 shows a simple illu.stration of the concept for ethylene oxide manufacture. 

Direct oxidation, of H2S, 23 616—617 Direct oxidation catalyst, 23 616—617 Direct oxidation ethylene oxide manufacture, 10 641—648 Direct oxidation tail gas process, 23 619 Direct oxide reduction (DOR) process, 19 676-677... 

Another 1% is recovered as a by-product of ethylene oxide manufacture from ethylene and oxygen. When the oxidation goes too far some carbon dioxide is formed. 

Another example of a famous organic chemical reaction being replaced by a catalytic process is furnished by the manufacture of ethylene oxide. For many years it was made by chlorohydrin formation followed by dehydrochlorination to the epoxide. Although the chlorohydrin route is still used to convert propylene to propylene oxide, a more efficient air epoxidation of ethylene is used and the chlorohydrin process for ethylene oxide manufacture has not been used since 1972. 

Epoxides (oxiranes) are three-membered cyclic ethers. The simplest and commercially most important example is ethylene oxide, manufactured from ethylene, air, and a silver catalyst. In the laboratory, epoxides are most commonly prepared from alkenes and organic peroxy acids. 

Fig. 10.8. Air-based direct oxidation process for ethylene oxide. (Encyclopedia of ChemicalTechnology, Kirk and Othmer, Web site ed., ethylene oxide, manufacture, 2002. Copyright by John Wiley Sons, Inc. and reproduced by permission of the copyright owner.)...

Vaughan, W. E., and Goepp, R. M., Proposed Ethylene Oxide Manufacture via Oxidation... 

While simple, the reduction of fugitive emissions is not inexpensive. In a case study involving ethylene oxide manufacturing, 1.5 million was spent over 2 years, with 55% spent on materials, 30% spent on labor, and 15% spent on a study of equipment leak rates. Just the labor involved in regular monitoring of the status of the thousands to tens of thousands of... 

Explain the atom efficiency concept by comparing the classical chlorohydrin route and the newer petrochemical ethylene oxide manufacture. 

P. Bernardo, G. Clarizia, Potential of membrane operations in redesigning industrial processes. The ethylene oxide manufacture, Chemical Engineering Transactions 25 (2011) 617-622. 

Celcon n. Poly(formaldehyde) (from trioxane with some ethylene oxide). Manufactured by Celanese, USA. 

By linking the ethylene oxide manufacturing and purification directly to the consumer plant, the ethylene oxide inventory is reduced from 50 tons to 6 tons for a 300,000-tpa ethoxylate surfactant manufacturing plant. 

Ethylene oxide is prepared commercially by two basic methods direct oxidation processes and the process via ethylene chlorohydrin. The most commonly used process today involves the direct catalytic oxidation of ethylene with air or oxygen over a silver-based catalyst to yield ethylene oxide. The major by-products of this process are carbon dioxide and water. The reaction product is purified by distillation. In 1979, this method accounted for over 96 percent of the nameplate capacity of ethylene oxide manufacture in the United States and Puerto Rico [7]. 

In 1931 the basis for another, more economical ethylene oxide manufacturing process was laid by the French chemist Lefort. He discovered the formation of ethylene oxide from ethylene and oxygen over a metallic silver catalyst. Only six years later, in 1937, the first process based on this reaction was commercialized by UCC (Union Carbide Corporation). 

Direct oxidation of propylene with air or pure oxygen (equivalent to ethylene oxide manufacturing) is not efficient, since the silver catalysts used in the direct ethylene oxidation are not suitable for the reaction of alkenes with allylic hydrogen atoms (like propylene). Direct oxidation of propylene results mainly in acrolein formation and total oxidation. Some 3% of the world capacity of PO is produced by very recently developed processes, for example, hydroperoxidation of cumene and propylene and catalytic epoxidation of propylene using H2O2. 

Polyox n Eligh-molecular-weight poly(ethylene oxide, manufactured by Union Carbide, US. 

---