Ethylene oxide catalyst used

Salts of neodecanoic acid have been used in the preparation of supported catalysts, such as silver neodecanoate for the preparation of ethylene oxide catalysts (119), and the nickel soap in the preparation of a hydrogenation catalyst (120). Metal neodecanoates, such as magnesium, lead, calcium, and zinc, are used to improve the adherence of plasticized poly(vinyl butyral) sheet to safety glass in car windshields (121). Platinum complexes using neodecanoic acid have been studied for antitumor activity (122). Neodecanoic acid and its esters are used in cosmetics as emoUients, emulsifiers, and solubilizers (77,123,124). Zinc or copper salts of neoacids are used as preservatives for wood (125). 

Promoters. Many industrial catalysts contain promoters, commonly chemical promoters. A chemical promoter is used in a small amount and influences the surface chemistry. Alkali metals are often used as chemical promoters, for example, in ammonia synthesis catalysts, ethylene oxide catalysts, and Fischer-Tropsch catalysts (55). They may be used in as Httie as parts per million quantities. The mechanisms of their action are usually not well understood. In contrast, seldom-used textural promoters, also called stmctural promoters, are used in massive amounts and affect the physical properties of the catalyst. These are used in ammonia synthesis catalysts. 

Ethylene oxide catalyst research is expensive and time-consuming because of the need to break in and stabilize the catalyst before rehable data can be collected. Computer controlled tubular microreactors containing as Httle as 5 g of catalyst can be used for assessment of a catalyst s initial performance and for long-term life studies, but moving basket reactors of the Berty (77) or Carberry (78) type are much better suited to kinetic studies. 

Ethylene Oxide Catalysts. Of all the factors that influence the utihty of the direct oxidation process for ethylene oxide, the catalyst used is of the greatest importance. It is for this reason that catalyst preparation and research have been considerable since the reaction was discovered. There are four basic components in commercial ethylene oxide catalysts the active catalyst metal the bulk support catalyst promoters that increase selectivity and/or activity and improve catalyst life and inhibitors or anticatalysts that suppress the formation of carbon dioxide and water without appreciably reducing the rate of formation of ethylene oxide (105). 

The operational characteristics of the older Berty reactors are described in Berty (1974), and their use in catalyst testing in Berty (1979). Typical uses for ethylene oxide catalyst testing are described in Bhasin (1980). Internal recycle reactors are easy to run with minimum control or automation. 

The most important example of this reaction is the formation of ethylene oxide (Eqn. 1), over Ag-catalysts which displaced the two-step chlorohydrine route (Eqn. 2). Ethylene oxide is used in the production of ethylene glycol, antifreeze, polyesters and surfactants, and accounts for 18% of U.S. ethylene consumption (Figure 3). ... 

Commercial copolymers of ethylene and 1-butene generally contain small amounts of 1-butene (typically about 5 mole %). Polymerization is usually effected with metal oxide catalysts using the procedures employed for the preparation of the homopolymer, which have been described previously. The presence of random 1-butene units results in a polymer which is less regular than the homopolymer. The copolymers thus have lower density, softening point and stiffness however, they do have better impact strength and resistance to environmental stress cracking and have found use in applications such as detergent bottles. 

In 1929, workers at the Indigo Laboratory of I. G. Farbenindustrie in Ludwigshafen reported (7) that Dr. Staudinger had pointed out to them that ethylene oxide in the presence of small amounts of catalysts such as potassium, tin tetrachloride, and trimethylamine can occasionally polymerize completely in a few seconds at ordinary temperatures. Since the large heats of reaction caused explosive destruction of the reaction tubes, and because ethylene oxide was used in large amounts at I. G. Farbenindustrie, an investigation of ethylene oxide in the presence of different materials, and particularly iron and iron compounds, was undertaken. The researchers found that explosions could result from a number of materials when they were added to ethylene oxide. Other products were more mild in their reaction characteristics. Table 2 contains qualitative results and heats of reaction from a number of experiments. 

Control of the reaction sequence in making flexible, open-cell, polyurethane foam using the one-shot process is accomplished by choosing the polyol, the surfactant, and the combination of tertiary-amine and organometallic, usually tin, catalysts. As in the previously described procedures for making urethane elastomers and microcellular products, for foams, polyols— poly(propylene oxide) polyols often containing minor amounts of ethylene oxide—are used. These polyols are selected by functionality, molecular weight, and reactivity (see Table 3). 

CH3CH1CH2CH2OCH2CH2OH. Colourless liquid with a pleasant odour b.p. 17rC. Manufactured by heating ethylene oxide with 1-butanol in the presence of nickel sulphate as a catalyst. Used as a solvent in brushing lacquers. 

Processes rendered obsolete by the propylene ammoxidation process (51) include the ethylene cyanohydrin process (52—54) practiced commercially by American Cyanamid and Union Carbide in the United States and by I. G. Farben in Germany. The process involved the production of ethylene cyanohydrin by the base-cataly2ed addition of HCN to ethylene oxide in the liquid phase at about 60°C. A typical base catalyst used in this step was diethylamine. This was followed by liquid-phase or vapor-phase dehydration of the cyanohydrin. The Hquid-phase dehydration was performed at about 200°C using alkah metal or alkaline earth metal salts of organic acids, primarily formates and magnesium carbonate. Vapor-phase dehydration was accomphshed over alumina at about 250°C. 

Poly(ethylene oxide)s [25372-68-3] are made by condensation of ethylene oxide with a basic catalyst. In order to achieve a very high molecular weight, water and other compounds that can act as chain terminators must be rigorously excluded. Polymers up to a molecular weight of 8 million are available commercially in the form of dry powders (27). These must be dissolved carefliUy using similar techniques to those used for dry polyacrylamides. Poly(ethylene oxide)s precipitate from water solutions just below the boiling point (see Polyethers, ethylene oxide polymers). 

The process can be operated in two modes co-fed and redox. The co-fed mode employs addition of O2 to the methane/natural gas feed and subsequent conversion over a metal oxide catalyst. The redox mode requires the oxidant to be from the lattice oxygen of a reducible metal oxide in the reactor bed. After methane oxidation has consumed nearly all the lattice oxygen, the reduced metal oxide is reoxidized using an air stream. Both methods have processing advantages and disadvantages. In all cases, however, the process is mn to maximize production of the more desired ethylene product. 

Ethylene glycol esterification of BHET is driven to completion by heating and removal of the water formed. PET is also formed using the same chemistry starting with dimethyl terephthalate [120-61-6] and ethylene glycol to form BHET also using an antimony oxide catalyst. 

Lead sesquioxide is used as an oxidation catalyst for carbon monoxide ia exhaust gases (44,45) (see Exhaust control), as a catalyst for the preparation of lactams (46) (see Antibiotics, P-lactams), ia the manufacture of high purity diamonds (47) (see Carbon, diamond-natural), ia fireproofing compositions for poly(ethylene terephthalate) plastics (48), ia radiation detectors for x-rays and nuclear particles (49), and ia vulcanization accelerators for neoprene mbber (50). 

In addition to these principal commercial uses of molybdenum catalysts, there is great research interest in molybdenum oxides, often supported on siHca, ie, MoO —Si02, as partial oxidation catalysts for such processes as methane-to-methanol or methane-to-formaldehyde (80). Both O2 and N2O have been used as oxidants, and photochemical activation of the MoO catalyst has been reported (81). The research is driven by the increased use of natural gas as a feedstock for Hquid fuels and chemicals (82). Various heteropolymolybdates (83), MoO.-containing ultrastable Y-zeoHtes (84), and certain mixed metal molybdates, eg, MnMoO Ee2(MoO)2, photoactivated CuMoO, and ZnMoO, have also been studied as partial oxidation catalysts for methane conversion to methanol or formaldehyde (80) and for the oxidation of C-4-hydrocarbons to maleic anhydride (85). Heteropolymolybdates have also been shown to effect ethylene (qv) conversion to acetaldehyde (qv) in a possible replacement for the Wacker process. 

Chromium Oxide-Based Catalysts. Chromium oxide-based catalysts were originally developed by Phillips Petroleum Company for the manufacture of HDPE resins subsequendy, they have been modified for ethylene—a-olefin copolymerisation reactions (10). These catalysts use a mixed sihca—titania support containing from 2 to 20 wt % of Ti. After the deposition of chromium species onto the support, the catalyst is first oxidised by an oxygen—air mixture and then reduced at increased temperatures with carbon monoxide. The catalyst systems used for ethylene copolymerisation consist of sohd catalysts and co-catalysts, ie, triaLkylboron or trialkyl aluminum compounds. Ethylene—a-olefin copolymers produced with these catalysts have very broad molecular weight distributions, characterised by M.Jin the 12—35 and MER in the 80—200 range. 

Heterogeneous Catalytic Polymerization. The preparation of polymers of ethylene oxide with molecular weights greater than 100,000 was first reported in 1933. The polymer was produced by placing ethylene oxide in contact with an alkaline-earth oxide for extended periods (61). In the 1950s, the low yield and low polymerization rates of the eady work were improved upon by the use of alkaline-earth carbonates as the catalysts (62). 

Molecular Weight. Measurement of intrinsic viscosity in water is the most commonly used method to determine the molecular weight of poly(ethylene oxide) resins. However, there are several problems associated with these measurements (86,87). The dissolved polymer is susceptible to oxidative and shear degradation, which is accelerated by filtration or dialysis. If the solution is purified by centrifiigation, precipitation of the highest molecular weight polymers can occur and the presence of residual catalyst by-products, which remain as dispersed, insoluble soHds, further compHcates purification. 

High purity 4-dodecylphenol is used to produce specialty surfactants by its reaction with ethylene oxide. The low color of high purity 4-dodecylphenol is important in this appHcation from a standpoint of aesthetics. 4-Dodecylphenol is also used to produce phenoHc resins which are used in adhesive appHcations and printing inks. 4-Dodecylphenol is also used as an epoxy curing catalyst where the addition of 4-dodecylphenol accelerates curing of the epoxy resin to a hard, nontacky soHd. 

Allyl Glycidyl Ether. This ether is used mainly as a raw material for silane coupling agents and epichlorohydrin mbber. Epichlorohydrin mbber is synthesized by polymerizing the epoxy group of epichlorohydrin, ethylene oxide, propylene oxide, and aHyl glycidyl ether, AGE, with an aluminum alkyl catalyst (36). This mbber has high cold-resistance. 

Ethoxylation and Propoxylation. Ethylene oxide [75-21-8] or propylene oxide [75-56-9] add readily to primary fatty amines to form bis(2-hydroxyethyl) or bis(2-hydroxypropyl) tertiary amines secondary amines also react with ethylene or propylene oxide to form 2-hydroxyalkyl tertiary amines (1,3,7,33—36). The initial addition is completed at approximately 170°C. Additional ethylene or propylene oxide can be added by using a basic catalyst, usually sodium or potassium hydroxide. 

Catalysts. Silver and silver compounds are widely used in research and industry as catalysts for oxidation, reduction, and polymerization reactions. Silver nitrate has been reported as a catalyst for the preparation of propylene oxide (qv) from propylene (qv) (58), and silver acetate has been reported as being a suitable catalyst for the production of ethylene oxide (qv) from ethylene (qv) (59). The solubiUty of silver perchlorate in organic solvents makes it a possible catalyst for polymerization reactions, such as the production of butyl acrylate polymers in dimethylformamide (60) or the polymerization of methacrylamide (61). Similarly, the solubiUty of silver tetrafiuoroborate in organic solvents has enhanced its use in the synthesis of 3-pyrrolines by the cyclization of aHenic amines (62). 

Reaction and Heat-Transfer Solvents. Many industrial production processes use solvents as reaction media. Ethylene and propylene are polymerized in hydrocarbon solvents, which dissolves the gaseous reactant and also removes the heat of reaction. Because the polymer is not soluble in the hydrocarbon solvent, polymer recovery is a simple physical operation. Ethylene oxide production is exothermic and the catalyst-filled reaction tubes are surrounded by hydrocarbon heat-transfer duid. 

Reaction of olefin oxides (epoxides) to produce poly(oxyalkylene) ether derivatives is the etherification of polyols of greatest commercial importance. Epoxides used include ethylene oxide, propylene oxide, and epichl orohydrin. The products of oxyalkylation have the same number of hydroxyl groups per mole as the starting polyol. Examples include the poly(oxypropylene) ethers of sorbitol (130) and lactitol (131), usually formed in the presence of an alkaline catalyst such as potassium hydroxide. Reaction of epichl orohydrin and isosorbide leads to the bisglycidyl ether (132). A polysubstituted carboxyethyl ether of mannitol has been obtained by the interaction of mannitol with acrylonitrile followed by hydrolysis of the intermediate cyanoethyl ether (133). 

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