Ethylene hydration production

Although catalytic hydration of ethylene oxide to maximize ethylene glycol production has been studied by a number of companies with numerous materials patented as catalysts, there has been no reported industrial manufacture of ethylene glycol via catalytic ethylene oxide hydrolysis. Studied catalysts include sulfonic acids, carboxyUc acids and salts, cation-exchange resins, acidic zeoHtes, haUdes, anion-exchange resins, metals, metal oxides, and metal salts (21—26). Carbon dioxide as a cocatalyst with many of the same materials has also received extensive study. 

The photocyclization of appropriate l,2-di(pyridyl)ethylenes provides a route to all the isomeric phenanthrolines, albeit sometimes in very low yield.12 With trans-1 -(2-pyridyl)-2-(3-pyridyl)ethylene (2(5) after irradiation in benzene solution in a stream of air, the hydrated product, 1-(2-pyridyl)-2-(3-pyridyl)ethan-2-ol (27) (20%) predominated, along with 3,7-phenanthroline (8) (6%) and 1,7-phenanthroline (1) (1%). The photocyclization process proceeds from the trans isomer by way of the cis isomer.1798... 

The processes for manufacturing methanol by synthesis gas reduction and ethanol by ethylene hydration and fermentation are very dissimilar and contribute to their cost differentials. The embedded raw-material cost per unit volume of alcohol has been a major cost factor. For example, assuming feedstock costs for the manufacture of methanol, synthetic ethanol, and fermentation ethanol are natural gas at 3.32/GJ ( 3.50/10 Btu), ethylene at 0.485/kg ( 0.22/lb), and corn at 0.098/kg ( 2.50/bu), respectively, the corresponding cost of the feedstock at an overall yield of 60% or 100% of the theoretical alcohol yields can be estimated as shown in Table 11.12. In nominal dollars, these feedstock costs are realistic for the mid-1990s and, with the exception of corn, have held up reasonably well for several years. The selling prices of the alcohols correlate with the embedded feedstock costs. This simple analysis ignores the value of by-products, processing differences, and the economies of scale, but it emphasizes one of the major reasons why the cost of methanol is low relative to the cost of synthetic and fermentation ethanol. The embedded feedstock cost has always been low for methanol because of the low cost of natural gas. The data in Table 11.12 also indicate that fermentation ethanol for fuel applications was quite competitive with synthetic ethanol when the data in this table were tabulated in contrast to the market years ago when synthetic ethanol had lower market prices than fermentation ethanol. Other factors also... 

Ethylene glycol production by hydration of ethylene oxide. Economic data (France conditions, mkt-1986)... 

This is the commercial method for this preparation. Ethanol in various concentrations is produced either by fermenting sugar, starch, or cellulose or by the hydration of ethylene. The products then are concentrated to the 95% azeotrope by regular distillation. In 1982, 816 x 10 L of 190 proof ethanol were produced, 10% by fermentation, and the rest by synthesis. The synthetic method is less expensive ( 0.50/L) in that 1 kg of ethanol requires 2 kg of sugar,... 

Hence, the mole fractions of products will increase with increasing pressure if r > q, a relationship of considerable importance in seeking high conversions in methanol synthesis and ethylene hydration for example. 

Ethanol production by direct ethylene dehydration has recently become less competitive due to the high ethylene price, resulting in many shutdowns of ethylene hydration facilities. With the rising prices of petroleum crude, it is most likely that the bioroute would always be the preferred one for the production of ethanol. 

The photodimerization of fran -cinnamic acid 30 in the presence of CB[8] studied by Ramamurthy et al. was discussed in Section 5.4 [121]. Prior to that report, they specifically examined the templating ability of CB[8] and y-cyclodextrin for this same dimeric photocycloaddition [127]. They also studied the templating action of CB[8] on the dimeric photocycloaddition of trans-1,2-bis(n-pyridyl)-ethylene 33 and other related olefins [128]. In the absence of CB[8], photoreaction of 33 produced only the monomer hydration product 34. However, in the presence of CB[8], 1 2 host guest inclusion complexes were formed, and upon irradiation gave predominantly (90%) the photodimerization product 35. These reactions are illustrated in Fig. 3.17. Thus, in this case,... 

Chemical production routes for ethanol synthesis use mainly ethylene hydratiza-tion [route (c) in Topic 5.3.1]. The direct ethylene hydratization option uses solid acid catalysts (e.g., H3PO4 on kieselguhr, montmorillonite, or bentonite) in a continuous gas-phase reaction at 60-80bar pressure and 250-300 °C. At an adjusted ethylene conversion of 5%, the selectivity to ethanol is 97%, with diethyl ether and acetaldehyde being the major side products. 

In the indirect ethylene hydratization process ethylene is contacted at 10-15 bar and 65-85 °C with concentrated sulfuric acid in a bubble column reactor. Mono and diethyl sulfate form and are hydrolyzed later (70-100 °C) to ethanol. Diethyl ether is the main side-product of the process (up to 10%). In the downstream of the reactor, ethanol and diethyl ether are distilled from the diluted sulfuric add, neutralized, and separated by rectification. The diluted sulfuric add produced in the process (45-60% sulfuric add after water addition) is reenergy intensive and problematic with resped to corrosion issues. Despite its relatively complex process scheme, the total ethanol yield in the indired ethylene hydratization process is only 86%. One advantage of the indired process, however, is that it also works with diluted ethylene feeds (e.g., feeds containing larger amounts of methane and ethane). 

The same study reveals ethanol production via methanol homologation to be less economic than ethylene hydration. 

Concentrated 70-98% snlfuric acid was used as the catalyst at a low pressure and temperature. The reaction mechanism involved the sulfate monoester intermediate, which was then hydrolyzed to isopropanol. The proeess is similar to the production of ethanol from ethylene, although the hydration step beeomes easier as the carbon number of the olefin inereases. The acid strength reqnired for effective operation deereases from more than 90% for ethylene hydration to abont 70% for propylene hydration. 

HOCHj CHjOH. Colourless, odourless, rather viscous hygroscopic liquid having a sweet taste, b.p. 197 C. Manufactured from ethylene chlorohydrin and NaHC03 solution, or by the hydration of ethylene oxide with dilute sulphuric acid or water under pressure at 195°C. Used in anti-freezes and coolants for engines (50 %) and in manufacture of polyester fibres (e.g. Terylene) and in the manufacture of various esters used as plasticizers. U.S. production 1979 1 900 000 tonnes. 

Since 1960, the Hquid-phase oxidation of ethylene has been the process of choice for the manufacture of acetaldehyde. There is, however, stiU some commercial production by the partial oxidation of ethyl alcohol and hydration of acetylene. The economics of the various processes are strongly dependent on the prices of the feedstocks. Acetaldehyde is also formed as a coproduct in the high temperature oxidation of butane. A more recently developed rhodium catalyzed process produces acetaldehyde from synthesis gas as a coproduct with ethyl alcohol and acetic acid (83—94). 

Denture Adhesives. Fast hydration and gel-forming properties are ideally mated to produce a thick, cushioning fluid between the dentures and gums (100). The biologically inert nature of poly(ethylene oxide) helps reduce unpleasant odors and taste in this type of personal-care product (see... 

Propanol has been manufactured by hydroformylation of ethylene (qv) (see Oxo process) followed by hydrogenation of propionaldehyde or propanal and as a by-product of vapor-phase oxidation of propane (see Hydrocarbon oxidation). Celanese operated the only commercial vapor-phase oxidation faciUty at Bishop, Texas. Since this faciUty was shut down ia 1973 (5,6), hydroformylation or 0x0 technology has been the principal process for commercial manufacture of 1-propanol ia the United States and Europe. Sasol ia South Africa makes 1-propanol by Fischer-Tropsch chemistry (7). Some attempts have been made to hydrate propylene ia an anti-Markovnikoff fashion to produce 1-propanol (8—10). However, these attempts have not been commercially successful. 

Ethyl chloride can be dehydrochlorinated to ethylene using alcohoHc potash. Condensation of alcohol with ethyl chloride in this reaction also produces some diethyl ether. Heating to 625°C and subsequent contact with calcium oxide and water at 400—450°C gives ethyl alcohol as the chief product of decomposition. Ethyl chloride yields butane, ethylene, water, and a soHd of unknown composition when heated with metallic magnesium for about six hours in a sealed tube. Ethyl chloride forms regular crystals of a hydrate with water at 0°C (5). Dry ethyl chloride can be used in contact with most common metals in the absence of air up to 200°C. Its oxidation and hydrolysis are slow at ordinary temperatures. Ethyl chloride yields ethyl alcohol, acetaldehyde, and some ethylene in the presence of steam with various catalysts, eg, titanium dioxide and barium chloride. 

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. 

Manufacture. Much of the diethyl ether manufactured is obtained as a by-product when ethanol (qv) is produced by the vapor-phase hydration of ethylene (qv) over a supported phosphoric acid catalyst. Such a process has the flexibiHty to adjust to some extent the relative amounts of ethanol and diethyl ether produced in order to meet existing market demands. Diethyl ether can be prepared directly to greater than 95% yield by the vapor-phase dehydration of ethanol in a fixed-bed reactor using an alumina catalyst (21). 

Addition. Addition reactions of ethylene have considerable importance and lead to the production of ethylene dichloride, ethylene dibromide, and ethyl chloride by halogenation—hydrohalogenation ethylbenzene, ethyltoluene, and aluminum alkyls by alkylation a-olefms by oligomerization ethanol by hydration and propionaldehyde by hydroformylation. 

Hydration. Ethanol [64-17-5] is manufactured from ethylene by direct catalytic hydration over a H PO —Si02 catalyst at process conditions of 300°C and 7.0 MPa (1015 psi). Diethyl ether is also formed as a by-product. 

With Water. Wurtz was the first to obtain ethylene glycol by heating ethylene oxide and water in a sealed tube (1). Later, it was noted that by-products, namely diethjlene and triethylene glycol, were also formed in this reaction (50). This was the first synthesis of polymeric compounds of well-defined stmcture. Hydration is slow at ambient temperatures and neutral conditions, but is much faster with either acid or base catalysis (Table 8). The type of anion in the catalyzing acid is relatively unimportant (58) (see Glycols). 

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