Ethylene commercial production

Mono-alkyl ethers of ethylene glycol, ROCHjCHjOH. The mono methyl, ethyl and n-butyl ethers are inexpensive and are known as methyl cellosolve, cellosolve, and butyl cellosolve respectively. They are completely miscible with water, and are excellent solvents. The commercial products are purified by drying over anhydrous potassium carbonate or anhydrous calcium sulphate, followed by fractionation after... 

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). 

This second reaction leads to the small amount of branching (usually less than 5%) observed in the alcohol product. The alpha olefins produced by the first reaction represent a loss unless recovered (8). Additionally, ethylene polymerisation during chain growth creates significant fouling problems which must be addressed in the design and operation of commercial production faciUties (9). 

In 1937 the first commercial apphcation of the Lefort direct ethylene oxidation to ethylene oxide [73-21-8] followed by hydrolysis of ethylene oxide became, and remains in the 1990s, the main commercial source of ethylene glycol production (1) (see Ethylene oxide). Ethylene oxide hydrolysis proceeds with... 

The principal route for production of isoprene monomer outside of the CIS is recovery from ethylene by-product C streams. This route is most viable where ethylene is produced from naphtha or gas oil and where several ethylene plants are located in relatively close proximity to the isoprene plant. Although the yield of isoprene per mass of ethylene is quite low, there is enough ethylene produced to provide a large portion of demand. Because of the presence of / -pentane in these streams which a2eotropes with isoprene, extractive distillation must be used to recover pure isoprene. Acetonitrile is the most common solvent, but dimethylformamide is also used commercially. 

High density polyethylene (HDPE) is defined by ASTM D1248-84 as a product of ethylene polymerisation with a density of 0.940 g/cm or higher. This range includes both homopolymers of ethylene and its copolymers with small amounts of a-olefins. The first commercial processes for HDPE manufacture were developed in the early 1950s and utilised a variety of transition-metal polymerisation catalysts based on molybdenum (1), chromium (2,3), and titanium (4). Commercial production of HDPE was started in 1956 in the United States by Phillips Petroleum Company and in Europe by Hoechst (5). HDPE is one of the largest volume commodity plastics produced in the world, with a worldwide capacity in 1994 of over 14 x 10 t/yr and a 32% share of the total polyethylene production. 

Commercial production of PE resias with densities of 0.925 and 0.935 g/cm was started ia 1968 ia the United States by Phillips Petroleum Co. Over time, these resias, particularly LLDPE, became large volume commodity products. Their combiaed worldwide productioa ia 1994 reached 13 X 10 metric t/yr, accouatiag for some 30% market share of all PE resias ia the year 2000, LLDPE productioa is expected to iacrease by 50%. A aew type of LLDPE, compositioaaHy uniform ethylene—a-olefin copolymers produced with metallocene catalysts, was first introduced by Exxon Chemical Company in 1990. The initial production volume was 13,500 t/yr but its growth has been rapid indeed, in 1995 its combiaed production by several companies exceeded 800,000 tons. 

Butene. Commercial production of 1-butene, as well as the manufacture of other linear a-olefins with even carbon atom numbers, is based on the ethylene oligomerization reaction. The reaction can be catalyzed by triethyl aluminum at 180—280°C and 15—30 MPa ( 150 300 atm) pressure (6) or by nickel-based catalysts at 80—120°C and 7—15 MPa pressure (7—9). Another commercially developed method includes ethylene dimerization with the Ziegler dimerization catalysts, (OR) —AIR, where R represents small alkyl groups (10). In addition, several processes are used to manufacture 1-butene from mixed butylene streams in refineries (11) (see BuTYLENEs). 

Phthahc anhydride (1) is the commercial form of phthaUc acid (2). The worldwide production capacity for the anhydride was ca 3.5 x 10 metric tons ia 1993, and it was used ia the manufacture of plasticizers (qv), unsaturated polyesters, and alkyd resins (qv) (see Polyesters, unsaturated). Sales of terephthahc acid (3) and its dimethyl ester are by far the largest of any of the benzenepolycarboxyhc acids 14.3 x 10 t were produced in 1993. This is 80% of the total toimage of ah. commercial forms of the benzenepolycarboxyhc acids. Terephthahc acid is used almost exclusively for the manufacture of poly(ethylene terephthalate), which then is formed into textiles, films, containers, and molded articles. Isophthahc acid (4) and trimehitic anhydride (5) are commercial products, but their worldwide production capacities are an order of magnitude smaller than for terephthahc acid and its dimethyl ester. Isophthahc acid is used primarily in the production of unsaturated polyesters and as a comonomer in saturated polyesters. Trimehitic anhydride is used mainly to make esters for high performance poly(vinyl chloride) plasticizers. Trimesic acid (6), pyromehitic dianhydride (7), and hernimehitic acid (8) have specialized commercial apphcations. The rest of the benzenepolycarboxyhc acids are not available commercially. 

Passing a stream of nitrogen at 95—100°C through a reaction mixture of ethyl ether and 30 wt % oleum prepared at 15°C results in the entrainment of diethyl sulfate. Continuous operation provides a >50% yield (96). The most economical process for the manufacture of diethyl sulfate starts with ethylene and 96 wt % sulfuric acid heated at 60°C. The resulting mixture of 43 wt % diethyl sulfate, 45 wt % ethyl hydrogen sulfate, and 12 wt % sulfuric acid is heated with anhydrous sodium sulfate under vacuum, and diethyl sulfate is obtained in 86% yield the commercial product is >99% pure (97). 

At room temperature, ca 60 wt % ethylene oxide is needed to solubilize the fatty acids. Surface activity of the ethoxylates is moderate and less than that of alcohol or alkylphenol ethoxylates (84). The ethoxylates are low foamers, a useful property in certain appHcations. Emulsification is the most important function. Its importance is reflected in the wide range of lipophilic solubiHties available in the commercial products. Like all organic esters, fatty acid ethoxylates are susceptible to acid and alkaline hydrolysis. 

Suspension Polymerization. At very low levels of stabilizer, eg, 0.1 wt %, the polymer does not form a creamy dispersion that stays indefinitely suspended in the aqueous phase but forms small beads that setde and may be easily separated by filtration (qv) (69). This suspension or pearl polymerization process has been used to prepare polymers for adhesive and coating appHcations and for conversion to poly(vinyl alcohol). Products in bead form are available from several commercial suppHers of PVAc resins. Suspension polymerizations are carried out with monomer-soluble initiators predominantly, with low levels of stabilizers. Suspension copolymerization processes for the production of vinyl acetate—ethylene bead products have been described and the properties of the copolymers determined (70). Continuous tubular polymerization of vinyl acetate in suspension (71,72) yields stable dispersions of beads with narrow particle size distributions at high yields. 

The pattern of commercial production of 1,3-butadiene parallels the overall development of the petrochemical industry. Since its discovery via pyrolysis of various organic materials, butadiene has been manufactured from acetylene as weU as ethanol, both via butanediols (1,3- and 1,4-) as intermediates (see Acetylene-DERIVED chemicals). On a global basis, the importance of these processes has decreased substantially because of the increasing production of butadiene from petroleum sources. China and India stiU convert ethanol to butadiene using the two-step process while Poland and the former USSR use a one-step process (229,230). In the past butadiene also was produced by the dehydrogenation of / -butane and oxydehydrogenation of / -butenes. However, butadiene is now primarily produced as a by-product in the steam cracking of hydrocarbon streams to produce ethylene. Except under market dislocation situations, butadiene is almost exclusively manufactured by this process in the United States, Western Europe, and Japan. 

MethylceUulose is made by reaction of alkaU ceUulose with methyl chloride until the DS reaches 1.1—2.2. HydroxypropyhnethylceUulose [9004-65-3], the most common of this family of products, is made by using propylene oxide in addition to methyl chloride in the reaction MS values of the hydroxypropyl group in commercial products are 0.02—0.3. Use of 1,2-butylene oxide in the alkylation reaction mixture gives hydroxybutyhnethylceUulose [9041-56-9, 37228-15-2] (MS 0.04—0.11). HydroxyethyhnethylceUulose [903242-2] is made with ethylene oxide in the reaction mixture. 

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). 

Although the mbbery properties of ethylene—propylene copolymers are exhibited over a broad range of compositions, weight percentages of commercial products generally range from 50 50 to 75 25 ethylene propylene. 

Ethylene oxide has been produced commercially by two basic routes the ethylene chlorohydrin and direct oxidation processes. The chlorohydrin process was first iatroduced dufing World War I ia Germany by Badische Anilin-und Soda-Eabfik (BASE) and others (95). The process iavolves the reaction of ethylene with hypochlorous acid followed by dehydrochlofination of the resulting chlorohydrin with lime to produce ethylene oxide and calcium chloride. Union Carbide Corp. was the first to commercialize this process ia the United States ia 1925. The chlorohydrin process is not economically competitive, and was quickly replaced by the direct oxidation process as the dominant technology. At the present time, all the ethylene oxide production ia the world is achieved by the direct oxidation process. 

Silver-containing catalysts are used exclusively in all commercial ethylene oxide units, although the catalyst composition may vary considerably (129). Nonsdver-based catalysts such as platinum, palladium, chromium, nickel, cobalt, copper ketenide, gold, thorium, and antimony have been investigated, but are only of academic interest (98,130—135). Catalysts using any of the above metals either have very poor selectivities for ethylene oxide production at the conversion levels required for commercial operation, or combust ethylene completely at useful operating temperatures. 

Biological. Several recent patents have claimed the production of ethylene oxide from a wide variety of raw materials using enzymatic catalysts (221—224). However, no commercial production routes based on biological mechanisms have been proposed. 

In 1960 the author was charged with the review and improvement of the ethylene oxide technology of Union Carbide Corporation (UCC). A historic overv iew revealed some interesting facts. The basic French patent of Lefort (1931,1935) for ethylene oxide production was purchased by UCC in 1936. In 1937, a pilot-plant was operated and commercial production started in 1938. By 1960, UCC s production experience was several hundred reactor-years. This was expressed as the sum of the number of production reactors, each multiplied by the number of years it had been in operation. Research and development had continued since the purchase of the original patent and the total number of people involved in ethylene oxide related research at one time reached one hundred. 

Many monomers have been copolymerised with ethylene using a variety of polymerisation systems, in some cases leading to commercial products. Copolymerisation of ethylene with other olefins leads to hydrocarbon polymers with reduced regularity and hence lower density, inferior mechanical properties, lower softening point and lower brittle point. 

There are three general methods of interest for the preparation of vinyl chloride, one for laboratory synthesis and the other two for commercial production. Vinyl chloride (a gas boiling at -14°C) is most conveniently prepared in the laboratory by the addition of ethylene dichloride (1,2-dichloroethane) in drops on to a warm 10% solution of sodium hydroxide or potassium hydroxide in a 1 1 ethyl alcohol-water mixture Figure 12.1). At one time this method was of commercial interest. It does, however, suffer from the disadvantage that half the chlorine of the ethylene dichloride is consumed in the manufacture of common salt. 

Consider the application of chemical reactor technology to a commercial reactor. Figure 5-40 illustrates a simplified flow diagram of ethylene glycol production. Consider the reactions in the formation of glycol ... 

Many commercial products are derived from ethylene oxide by reacting with different reagents. The following reviews the production and the utility of these chemicals. 

The preparation and properties of a novel, commercially viable Li-ion battery based on a gel electrolyte has recently been disclosed by Bellcore (USA) [124]. The technology has, to date, been licensed to six companies and full commercial production is imminent. The polymer membrane is a copolymer based on PVdF copolymerized with hexafluoropropylene (HFP). HFP helps to decrease the crystallinity of the PVdF component, enhancing its ability to absorb liquid. Optimizing the liquid absorption ability, mechanical strength, and processability requires optimized amorphous/crystalline-phase distribution. The PVdF-HFP membrane can absorb plasticizer up to 200 percent of its original volume, especially when a pore former (fumed silica) is added. The liquid electrolyte is typically a solution of LiPF6 in 2 1 ethylene carbonate dimethyl car-... 

Monoester salts of phosphoric acid derived from fatty alcohol ethylene oxide adduct or alkylphenol ethylene oxide adduct useful as surfactants are prepared by addition of R(OCH2CH2) OH, alkali fluoride and (C12P0)20 in a molar ratio of 0.9-1.5 0.05-1 1.0 at -50 to + 10°C and hydrolysis of the Cl-containing intermediates with a base. The monoester phosphates showed comparable or better washing and foaming efficiency than commercial products [12]. 

Ethylene oxide treatment can also be considered as an alternative to radiation sterilizahon in the commercial production of disposable medical devices (Chapter 21). These techniques do not, however, offer the same degree of sterility assuranee as heat methods and are generally reserved for temperature-sensihve items. 

Mixtures of aqueous sodium hypochlorite (presumably the 15% available chlorine commercial product) and ethylene glycol were observed to erupt violently after an induction period of 4 to 8 minutes. Caution is advised in view of the use of glycol as a cooling fluid in industrial reactors. 

The Zr-FI catalyst selectively forms PE even in the presence of ethylene and 1-octene, while the Hf complex affords amorphous copolymers, resulting in the catalytic generation of PE- and poly(ethylene-c6>-l-octene)-based multiblock copolymers through a reversible chain transfer reaction mediated by R2Zn. The development of an FI catalyst with extremely high ethylene selectivity as well as a reversible chain transfer nature has made it possible to produce these unique polymers. Therefore, both Ti- and Zr-FI catalysts are at the forefront of the commercial production of polyolefinic block copolymers. 

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