Acetic direct ethylene oxidation

Fig. 10.15. Acetic acid via direct ethylene oxidation. [Chem Systems Report No. 99/0055. Copyright Nexant Chem Systems, Inc. and used by permission of the copyright owner.)...

A direct ethylene oxidation process for the acetic acid production was commercialized by Denko in 1997. This process is only competitive for small- or medium-scale plants. The raw material ethylene is more expensive than methanol and carbon monoxide, but the investment costs of these plants are much lower. Table 6.15.1 gives an overview of the catalysts, reaction conditions, yield, and byproducts for the major acetic add processes. The different processes are discussed in more detail in Sections 6.15.1-6.15.4. 

Other Technologies for the Commercial Production of Acetic Acid 6.15.4.1 Direct Ethylene Oxidation... 

For many years the development of a direct ethylene oxidation process to manufacture acetic acid (without acetaldehyde isolation) has attracted scientific and commercial interest ... 

Owing to the high price of ethylene, direct ethylene oxidation is only attractive today for local small-scale acetic add production. 

To exemplify the second relationship, process competition, there are the two alternate routes from ethylene to ethylene oxide-direct oxidation and chlorohydrination. Even more involved is the acetic acid picture, in which, as has been described, at least ten processes have been in use at the same time in commercial competition with one another. 

When media other than water are used, related processes operate. Thus in acetic acid ethylene gives vinyl acetate, whereas vinyl ethers may be formed in alcohols. Both homogeneous and heterogeneous syntheses of vinyl acetate have been commercialized. The latter process (Hoechst) involves direct oxidation over a palladium-gold catalyst containing alkali acetate on a support ... 

The formation of tertiary azetidines from the secondary imines can bo accomplished by hydride reduction of the amidee or by reductive tdkylation the imine with lithium aluminum hydride in tlw T ethyl acetate. Tertiary azetidines can also be obtained by direct alkylation. Azetidine and methyl iodide in ether solution furnish y-m ylasetidiDe hydriodide a oontraiy report by Gibeon et of is clearly ii> error. Resetion of (he secondary baeee with ethylene oxide (Eq. 25) gives the A -hydrmcyethylazetidines which con... 

A single-bath method can be used if desired. The dyes are dissolved separately and added to the dyebath which already contains an ethylene oxide condensate which acts as an anti-precipitant. The dyebath is adjusted to pH 5 to 5-5 with acetic acid and sodium acetate and the goods are entered at 40 to 45°C (104 to 113°F). A period of 45 minutes is taken to raise the temperature to the boil, at which it is maintained for one hour. Alternatively, the acrylic fibre may be dyed first and then the same liquor is neutralized and the cellulosic fibre is dyed. Application of a cationic fixing agent improves wet fastness of direct dyes but copper after-treatment should be avoided because this can have an adverse effect on the light fastness of the cationic dye. Very good fastness is obtained if, after the acrylic component has been dyed, the cellulosic fibre is brought to shade with vat dyes. 

Ethylene from cracking of the alkane gas mixtures or the naphtha fraction can be directly polymerized or converted into useful monomers. (Alternatively, the ethane fraction in natural gas can also be converted to ethylene for that purpose). These include ethylene oxide (which in turn can be used to make ethylene glycol), vinyl acetate, and vinyl chloride. The same is true of the propylene fi action, which can be converted into vinyl chloride and to ethyl benzene (used to make styrene). The catalytic reformate has a high aromatic fi action, usually referred to as BTX because it is rich in benzene, toluene, and xylene, that provides key raw materials for the synthesis of aromatic polymers. These include p-xylene for polyesters, o-xylene for phthalic anhydride, and benzene for the manufacture of styrene and polystyrene. When coal is used as the feedstock, it can be converted into water gas (carbon monoxide and hydrogen), which can in turn be used as a raw material in monomer synthesis. Alternatively, acetylene derived from the coal via the carbide route can also be used to synthesize the monomers. Commonly used feedstock and a simplified diagram of the possible conversion routes to the common plastics are shown in Figure 2.1. 

Since sucrose might seem to be an ideal monomer in polymerization reactions, a very large variety of reactions of this type have been investigated in Sugar Research Foundation supported projects. In the 1940 s, ethylene oxide was combined with sucrose, but the products obtained did not lend themselves directly to commercial development. The first intensive efforts to produce polymers occurred concurrently with the sugar ester detergent activities in the 1950 s. These efforts included studies of the polymerization of sucrose with urea, vinyl acetate,phenol and formaldehyde, ammonia cuid hydrogen, melamine and formaldehyde and meuiy other variations. 

Ethylene is an important feedstock for the polymer industry, in general. About half of all ethylene produced goes directly into a polymerization process to make all types of polyethylene resins. This includes about 25% to make high-density PE, 12% to make low-density PE, and 14% to make linear low-density PE. In addition, about 20% of ethylene production goes to produce ethylene dichloride (for PVC). Another 12% of ethylene production is used to make ethylene oxide while about 10% is used to synthesize alpfia-oleRns (some of which are the second monomer in LLDPE production). Only 6% of ethylene goes into ethylbenzene production (mainly to make SBR for the rubber industry). Lastly, 2% of ethylene goes to produce vinyl acetate and linear alcohols. 

More than 100 polymers, both synthetic and natural, have been successfully electrospun into nanofibers, mostly from polyma solutions, as any polymer may be electrospun into nanofibers, provided that the polymer molecular weight is sufficiently high and the solvent can be evaporated in the time during the jet transit period, over a distance between the spinneret and the collector. Standard polymers successfully electrospun into nanofibers include polyacrylonitrile (PAN), poly(ethylene oxide) (PEO), poly(ethylene terephthalate) (PET), polystyrene (PS), poly(vinyl chloride) (PVC), Nylon 6, PVA, poly(8-caprolactone), Kevlar (poly[p-phenylene terephthalamide]), poly(vinylidene fluoride) (PVDF), polybenzimidazole, polyurethanes (PUs), polycarbonates, polysulfones, poly(vinyl phenol) (PVP), and many others [36,37]. Electrospinning has also been used to produce nanofibers from natural biomacromolecules, including cellulose [either electrospun from cellulose acetate (CA) with subsequent hydrolysis or directly electrospun from cellulose solutions in Af,Af-dimethylacetamide with lithium chloride], collagen and gelatin, modified chitin, chitosan, and DNA. 

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. 

Bromoacetic acid can be prepared by the bromination of acetic acid in the presence of acetic anhydride and a trace of pyridine (55), by the HeU-VoUiard-Zelinsky bromination cataly2ed by phosphoms, and by direct bromination of acetic acid at high temperatures or with hydrogen chloride as catalyst. Other methods of preparation include treatment of chloroacetic acid with hydrobromic acid at elevated temperatures (56), oxidation of ethylene bromide with Aiming nitric acid, hydrolysis of dibromovinyl ether, and air oxidation of bromoacetylene in ethanol. 

Whereas this reaction was used to oxidize ethylene (qv) to acetaldehyde (qv), which in turn was oxidized to acetic acid, the direct carbonylation of methanol (qv) to acetic acid has largely replaced the Wacker process industrially (see Acetic acid and derivatives). A large number of other oxidation reactions of hydrocarbons by oxygen involve coordination compounds as detailed elsewhere (25). 

Other large-volume esters are vinyl acetate [108-05-4] (VAM, 1.15 x 10 t/yr), methyl methacrylate [80-62-6] (MMA, 0.54 x 10 t/yr), and dioctyl phthalate [117-81-7] (DOP, 0.14 x 10 t/yr). VAM (see Vinyl polymers) is produced for the most part by the vapor-phase oxidative acetoxylation of ethylene. MMA (see Methacrylic polymers) and DOP (see Phthalic acids) are produced by direct esterification techniques involving methacryHc acid and phthaHc anhydride, respectively. 

Heteropolyacids are also beginning to emerge from academic laboratories and find commercial applications. Showa Denko, for example, claim to have a process [14] for the direct oxidation of ethylene to acetic acid employing a bifunctional Pt/heteropolyacid catalyst system. 

Bromoacetic acid has been prepared by direct bromination of acetic acid at elevated temperatures and pressures,2-3-4 or with dry hydrogen chloride as a catalyst 6 and with red phosphorus as a catalyst with the formation of bromoacetyl bromide.6-7-8-9-19 Bromoacetic acid has also been prepared from chloroacetic acid and hydrogen bromide at elevated temperatures 6 by oxidation of ethylene bromide with fuming nitric acid 7 by oxidation of an alcoholic solution of bromoacetylene by air 8 and from ethyl a,/3-dibromovinyl ether by hydrolysis.9 Acetic acid has been converted into bromoacetyl bromide by action of bromine in the presence of red phosphorus, and ethyl bromoacetate has been... 

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. 

Table 8.1 shows the stochastic model solution for the petrochemical system. The solution indicated the selection of 22 processes with a slightly different configuration and production capacities from the deterministic case, Table 4.2 in Chapter 4. For example, acetic acid was produced by direct oxidation of n-butylenes instead of the air oxidation of acetaldehyde. Furthermore, ethylene was produced by pyrolysis of ethane instead of steam cracking of ethane-propane (50-50 wt%). These changes, as well as the different production capacities obtained, illustrate the effect of the uncertainty in process yield, raw material and product prices, and lower product... 

The Carbide and Carbon Co began large scale manuf of EtnO thru ethylene chloro-hydrin in 1925 and by the direct oxidation of ethylene in 1937. Dow entered the field in 1939 Si 1941 Jefferson and Wyandotte in 1941 and Mathieson Chem Corp in 1951. These four Co s used the chlorohydrin method. US consumption, which was in 1939 108 million pounds, increased in 1949 to 354 million Several laboratory methods of prepn are described in Ref 17, pp 75—7. In one of them hydroxide is added gradually to a soln of 2-chloroethyI acetate heated to a temp betwn 40 150°C. An excess of unreacted base is avoided. The reaction proceeds as follows ... 

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