Acetaldehyde ethylene oxidation

Technically, acetaldehyde is mainly made by the oxidation of ethylene using a CuCl2/PdCl2 catalyst system.. Although some acetic acid is still prepared by the catalytic oxidation of acetaldehyde, the main process is the catalytic oxidation of paraffins, usually -butane. 

At one time acetaldehyde was prepared on an industrial scale by this method Modern methods involve direct oxidation of ethylene and are more economical... 

Ammonia, anhydrous Mercury, halogens, hypochlorites, chlorites, chlorine(I) oxide, hydrofluoric acid (anhydrous), hydrogen peroxide, chromium(VI) oxide, nitrogen dioxide, chromyl(VI) chloride, sulflnyl chloride, magnesium perchlorate, peroxodisul-fates, phosphorus pentoxide, acetaldehyde, ethylene oxide, acrolein, gold(III) chloride... 

Acetaldehyde, first used extensively during World War I as a starting material for making acetone [67-64-1] from acetic acid [64-19-7] is currendy an important intermediate in the production of acetic acid, acetic anhydride [108-24-7] ethyl acetate [141-78-6] peracetic acid [79-21 -0] pentaerythritol [115-77-5] chloral [302-17-0], glyoxal [107-22-2], aLkylamines, and pyridines. Commercial processes for acetaldehyde production include the oxidation or dehydrogenation of ethanol, the addition of water to acetylene, the partial oxidation of hydrocarbons, and the direct oxidation of ethylene [74-85-1]. In 1989, it was estimated that 28 companies having more than 98% of the wodd s 2.5 megaton per year plant capacity used the Wacker-Hoechst processes for the direct oxidation of ethylene. 

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). 

Oxidation of Ethylene. In 1894 F. C. Phillips observed the reaction of ethylene [74-85-17 in an aqueous paHadium(II) chloride solution to form acetaldehyde. 

From Acetylene. Although acetaldehyde has been produced commercially by the hydration of acetylene since 1916, this procedure has been almost completely replaced by the direct oxidation of ethylene. In the hydration process, high purity acetylene under a pressure of 103.4 kPa (15 psi) is passed into a vertical reactor containing a mercury catalyst dissolved in 18—25% sulfuric acid at 70—90°C (see Acetylene-DERIVED chemicals). 

The direct oxidation of ethylene is used to produce acetaldehyde (qv) ia the Wacker-Hoechst process. The catalyst system is an aqueous solution of palladium chloride and cupric chloride. Under appropriate conditions an olefin can be oxidized to form an unsaturated aldehyde such as the production of acroleia [107-02-8] from propjiene (see Acrolein and derivatives). 

Ca.ta.lysis, The most important iadustrial use of a palladium catalyst is the Wacker process. The overall reaction, shown ia equations 7—9, iavolves oxidation of ethylene to acetaldehyde by Pd(II) followed by Cu(II)-cataly2ed reoxidation of the Pd(0) by oxygen (204). Regeneration of the catalyst can be carried out in situ or ia a separate reactor after removing acetaldehyde. The acetaldehyde must be distilled to remove chloriaated by-products. 

Equation 1 is referred to as the selective reaction, equation 2 is called the nonselective reaction, and equation 3 is termed the consecutive reaction and is considered to proceed via isomerization of ethylene oxide to acetaldehyde, which undergoes rapid total combustion under the conditions present in the reactor. Only silver has been found to effect the selective partial oxidation of ethylene to ethylene oxide. The maximum selectivity for this reaction is considered to be 85.7%, based on mechanistic considerations. The best catalysts used in ethylene oxide production achieve 80—84% selectivity at commercially useful ethylene—oxygen conversion levels (68,69). 

Viayl acetate [108-05-4] is obtained by vapor-phase oxidation of ethylene with acetic acid. Acetic acid is obtained by oxidation of acetaldehyde. 

In addition to ethylene oxide, carbon dioxide, and water, small quantities of acetaldehyde and traces of formaldehyde are also produced in the process. They generally total less than 0.2% of the ethylene oxide formed. Acetaldehyde is most likely formed by isomerization of ethylene oxide, whereas formaldehyde is most likely formed by direct oxidation of ethylene (108). 

Because the epoxidation with Tl(III) is stoichiometric to produce Tl(I), reoxidation is needed. Halcon has patented processes based on such epoxidation to yield ethylene oxide (200—203). The primary benefits of such a process are claimed to be high yields of ethylene oxide, fiexibihty to produce either propylene oxide or ethylene oxide, and the potential of a useful by-product (acetaldehyde). Advances usiag organic hydroperoxides ia place of oxygen for reoxidation offer considerable promise, siace reaction rates are rapid and low pressures can be used. 

The Wacker process for the oxidation of ethylene to acetaldehyde with PdCb/CuCb at 100°C (212°F) with 95 percent yield and 95 to 99 percent conversion per pass. 

Oxidation catalysts are either metals that chemisorb oxygen readily, such as platinum or silver, or transition metal oxides that are able to give and take oxygen by reason of their having several possible oxidation states. Ethylene oxide is formed with silver, ammonia is oxidized with platinum, and silver or copper in the form of metal screens catalyze the oxidation of methanol to formaldehyde. Cobalt catalysis is used in the following oxidations butane to acetic acid and to butyl-hydroperoxide, cyclohexane to cyclohexylperoxide, acetaldehyde to acetic acid and toluene to benzoic acid. PdCh-CuCb is used for many liquid-phase oxidations and V9O5 combinations for many vapor-phase oxidations. 

Dehydrogenation processes in particular have been studied, with conversions in most cases well beyond thermodynamic equihbrium Ethane to ethylene, propane to propylene, water-gas shirt reaction CO -I- H9O CO9 + H9, ethylbenzene to styrene, cyclohexane to benzene, and others. Some hydrogenations and oxidations also show improvement in yields in the presence of catalytic membranes, although it is not obvious why the yields should be better since no separation is involved hydrogenation of nitrobenzene to aniline, of cyclopentadiene to cyclopentene, of furfural to furfuryl alcohol, and so on oxidation of ethylene to acetaldehyde, of methanol to formaldehyde, and so on. 

In recent years vinyl acetate has been prepared in large quantities by oxidation of ethylene. If ethylene is passed into a solution of palladium chloride in acetic acid containing sodium acetate, then vinyl acetate, ethylene diacetate and acetaldehyde are produced, the vinyl acetate being obtained in good yields by the reaction shown in Figure 14.3... 

The process is similar to the catalytic liquid-phase oxidation of ethylene to acetaldehyde. The difference hetween the two processes is the presence of acetic acid. In practice, acetaldehyde is a major coproduct. The mole ratio of acetaldehyde to vinyl acetate can he varied from 0.3 1 to 2.5 1. The liquid-phase process is not used extensively due to corrosion problems and the formation of a fairly wide variety of by-products. 

Figure 8.42. Effect of Ag/YSZ catalyst potential and work function on the rates of formation of ethylene oxide, acetaldehyde, and C02 at low Po/Pc2h4 ratios. T=260°C P=500 kPa 3.5% 02 9.8% C2H4 , C2H40 , CH3CHO , C02. Reprinted with permission from Academic Press.

In degree 2 only reactivity degrees are treated vis- i-vis exothermic polymerization in particular and addition reactions on the double bond (ethylene, butadiene, styrene, propylene), easy peroxidation (isopropyl oxide, acetaldehyde), hydrolysis (acetic anhydride). Possibly only propionitrile and substances with code 0 have an actual NFPA stability code. Every time one has to deal with the NFPA code one has to interpret it after carefully reading the paragraphs in Part Two. 

The oxidation of ethylene to acetaldehyde by palladium chloride in water has been known since the nineteenth century.80 However, the reaction requires the use of a stoichiometric amount of PdCl2, resulting in Pd(0) deposit. Anderson, in 1934, observed a similar reaction (but... 

The oxidation of ethylene to acetaldehyde by dioxygen catalyzed by palladium and cupric salts found important technological application. The systematic study of this process was started by Smidt [245] and Moiseev [246]. The process includes the following stoichiometric stages [247,248] ... 

Palladium-catalyzed oxidation of hydrocarbons has been a matter of intense research for about four decades. The field was initiated by the development of the aerobic oxidation of ethylene to acetaldehyde catalyzed by palladium chloride and co-catalyzed by cupric chloride (the Wacker process, equation l)1. 

DIIOOOETHANE ACETALDEHYDE ETHYLENE OXIDE THIOACETIC-ACID ACETIC ACID METHYL FORMATE THIACYCLOPROPANE BROMOETHANE ETHYL CHLORIDE... 

Double bonds characterize the basic building blocks of the petrochemical business. Ethylene, for example, is the chemical compound used to make vinyl chloride, ethylene oxide, acetaldehyde, ethyl alcohol, styrene, alpha olefins, and polyethylene, to name only a few. Propylene and benzene, the other big-volume building blocks, also have the characteristic double bonds. 

Oxidation of ethyl alcohol was one of the two important commercial routes to acetaldehyde until the 1950s, The other, much older route was the hydration of acetylene. The chemical industry was always after a replacement of acetylene chemistry, not just for acetaldehyde production, but all its many applications. Acetylene was expensive to produce, and with its reactive, explosive nature, it was difficult to handle. In the 1950s, acetylene chemistry and the ethyl alcohol oxidation route were largely phased out by the introduction of the liquid phase direct oxidation of ethylene. Almost all the acetaldehyde produced uses the newer process. 

Acetaldehyde is made by the direct oxidation of ethylene, C2H4. It is a liquid at room temperature and is an intermediate in the production of acetic acid, acetic anhydride, butyl, and 2-ethyl hexyl alcohol. 

Chemical/Physical. Reacts violently with acetaldehyde, ethylene oxide, ethylene dichloride (Patnaik, 1992). 

Unstable chemicals are subject to spontaneous reactions. Situations where unstable chemicals may be present include the catalytic effect of containers, materials stored in the same area with the chemical that could initiate a dangerous reaction, presence of inhibitors, and effects of sunlight or temperature change. Examples include acetaldehyde, ethylene oxide, hydrogen cyanide, nitromethane, organic peroxides, styrene, and vinyl chloride. 

Acetaldehyde may be made (1) from ethylene by direct oxidation, with the Wacker-catalyst containing copper(II) and palladium(II) salts (2) from ethanol by vapor-phase oxidation or dehydrogenation or (3) from butane by vapor-phase oxidation. The direct oxidation of ethylene is the most commonly used process, accounting for 80% of acetaldehyde production. 

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