Ethylene, chlorination oxidation

Figure 1. The effect of temperature on the ethcine oxidative chlorination process (silica gel as the support, copper content of 6.0 wt %, potassium content of 4.0 wt %, reactant ratio C2H6 HCl O2 = 1 1 1, t = 3 s). 1 is the conversion of ethane 2 is the yield of oxidation chlorination products 3, 4, and 5 are the yields of ethylene, deep oxidation products, and vinyl chloride, respectively ( x is time- on-stream ).

High purity vinyl chloride is produced in an overall yield of 80 mol% based on ethane. The feed can contain ethane, ethylene, mixed ethylene-chlorination products, and HCl in various mixtures, and can thereby allow recovery of values from such materials. The flow sheet for the simultaneous chlorination, oxidation, and dehydrochlorination for producing vinyl chloride by the Transcat process is shown in Figure 3. 

The chlorhydrin process for making ethylene oxide has been replaced commercially by the direct oxidation of ethylene gas. Oxidation takes place at temperatures of 20o°C to ° (392°F to 572°F) over a silver catalyst. The formula for this reaction is 2CH2=CH2 + 02 —> 2CH2CH20.The yield produced by direct oxidation is slightly less than that produced by the chlohydrin process, but the amount of chlorine wasted by the latter method outweighs the slight difference in efficiency of production. 

Production of Ethylene Chlorohydrin. The preparation of ethylene chlorohydrin as an intermediate in the manufacture of ethylene oxide and ethylene glycol is carried out at the I.G. Farbenindustrie, Wolfen plant, in the following manner. Ethylene, chlorine, and water, as indicated in CjH, + Ch + H,0 - ClC HiOH + HCl (1)... 

Monsanto Kellogg Exclusive Ethylene, chlorine Chlorination, HCl oxidation for C,2... 

The fluidized bed processes operate between 220-235 °C (430-455 F) and from 20-75 psig. The reaction is exothermic and the heat of reaction is removed by generating steam in internal coils in the reactor. Ethylene and HCl react quantitatively to EDC. A small amount of ethylene is oxidized to carbon oxides and some chlorinated hydrocarbon by-products are formed. About l-2< 7o of the ethylene feed to the reactor leaves unreacted in the vent gas from the system. A simplified process flow diagram depicting an air-based fluidized bed oxychlorination system is shown in Figure 14 [22]. 

Ethylene forms explosive mixtures in air the LEE and UEL values are 2.7% and 36% by volume of air, respectively. Its reaction with fluorine is explosively violent (AH = —112 kcal/mol), and violent with chlorine (AH = —36 kcal/mol). In the presence of sunlight or UV light, an ethylene-chlorine mixture will explode spontaneously. The reaction is explosive at room temperature over the oxides of mercury or silver (Mellor 1946, Suppl. 1956). Ethylene reacts vigorously with oxidizing substances. It reacts with ozone to form ethylene ozonide, H2C(03)CH2, which is unstable and explodes on mechanical shock. Acid-catalyzed addition of hydrogen peroxide may produce ethyl hydroperoxide, which is unstable and explodes on heat or shock ... 

Another explanation of the phosphate effect is possible phosphate-Mn(IV) interactions in aqueous phase. When chlorinated ethylenes are oxidized by Mn04, soluble Mn(IV) forms before any colloids. The existence of the soluble Mn(IV) has been reported by many researchers 16, 17). Phosphate ion can react with soluble Mn(IV) species and reduce the formation of die colloid. The process is probably involved with the formation of a phosphate-Mn(IV) conqilex. As the conqilex forms, it keeps the Mn(IV) in the aqueous phase without forming colloids. Eventually, colloids and prec itates will be produced when the capacity of the phosphate effect has reached its limit This mechanism is in agreement widi our observation in the colloid growth experiments. 

Chlorinated hydrocarbons Chlorine oxides Chlorine, water and brine Chlorine, wet or dry Chloroacetic acid Chrome-plating solutions Chromic acid Citric acid Cleaning solutions Copper salts Ethyl sulfate Ethylene dibromide Fatty acids Ferric chloride Ferrous sulfate Foodstuffs Formaldehyde Formic acid Fruit products Flydriodic acid... 

COCH3 - The preparation from acetylhydroquinone required conversion into its ethylene acetal, oxidation to the quinone with silver oxide, addition of chlorine in acetic OH acid and enolisation and cleavage of the acetal with, at... 

Alkali metals Moisture, acetylene, metal halides, ammonium salts, oxygen and oxidizing agents, halogens, carbon tetrachloride, carbon, carbon dioxide, carbon disul-flde, chloroform, chlorinated hydrocarbons, ethylene oxide, boric acid, sulfur, tellurium... 

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... 

Copper Acetylene and alkynes, ammonium nitrate, azides, bromates, chlorates, iodates, chlorine, ethylene oxide, fluorine, peroxides, hydrogen sulflde, hydrazinium nitrate... 

Ethylene Aluminum trichloride, carbon tetrachloride, chlorine, nitrogen oxides, tetrafluo-roethylene... 

Lead(ll) oxide Chlorinated rubber, chlorine, ethylene, fluorine, glycerol, metal acetylides, perchloric acid... 

Mercury Acetylenic compounds, chlorine, fulminic acid, ammonia, ethylene oxide, metals, methyl azide, oxidants, tetracarbonylnickel... 

Once the principal route to vinyl chloride, in all but a few percent of current U.S. capacity this has been replaced by dehydrochlorination of ethylene dichloride. A combined process in which hydrogen chloride cracked from ethylene dichloride was added to acetylene was advantageous but it is rarely used because processes to oxidize hydrogen chloride to chlorine with air or oxygen are cheaper (7) (see Vinyl polymers). 

Chlorine cannot be stored economically or moved long distances. International movements of bulk chlorine are more or less limited to movements between Canada and the United States. In 1987, chlorine moved in the form of derivatives was 3.3 million metric tons or approximately 10% of total consumption (3). Exports of ethylene dichloride, vinyl chloride monomer, poly(vinyl chloride), propylene oxide, and chlorinated solvents comprise the majority of world chlorine movement. Countries or areas with a chlorine surplus exported in the form of derivatives include Western Europe, Bra2il, USA, Saudi Arabia, and Canada. Countries with a chlorine deficit are Taiwan, Korea, Indonesia, Vene2uela, South Africa, Thailand and Japan (3). 

This hquid contains 27% chlorine and 12% phosphoms. It is made from ethylene oxide, diethylene glycol, and phosphoms oxychloride (80). It is available ia the United States and Japan from Daihachi. 

Another attractive commercial route to MEK is via direct oxidation of / -butenes (34—39) in a reaction analogous to the Wacker-Hoechst process for acetaldehyde production via ethylene oxidation. In the Wacker-Hoechst process the oxidation of olefins is conducted in an aqueous solution containing palladium and copper chlorides. However, unlike acetaldehyde production, / -butene oxidation has not proved commercially successflil because chlorinated butanones and butyraldehyde by-products form which both reduce yields and compHcate product purification, and also because titanium-lined equipment is required to withstand chloride corrosion. 

Solubility. Poly(ethylene oxide) is completely soluble in water at room temperature. However, at elevated temperatures (>98° C) the solubiUty decreases. It is also soluble in several organic solvents, particularly chlorinated hydrocarbons (see Water-SOLUBLE polymers). Aromatic hydrocarbons are better solvents for poly(ethylene oxide) at elevated temperatures. SolubiUty characteristics are Hsted in Table 1. 

In the chemical industry, titanium is used in heat-exchanger tubing for salt production, in the production of ethylene glycol, ethylene oxide, propylene oxide, and terephthaHc acid, and in industrial wastewater treatment. Titanium is used in environments of aqueous chloride salts, eg, ZnCl2, NH4CI, CaCl2, and MgCl2 chlorine gas chlorinated hydrocarbons and nitric acid. 

In oxychlorination, ethylene reacts with dry HCl and either air or pure oxygen to produce EDC and water. Various commercial oxychlorination processes differ from one another to some extent because they were developed independentiy by several different vinyl chloride producers (78,83), but in each case the reaction is carried out in the vapor phase in either a fixed- or fluidized-bed reactor containing a modified Deacon catalyst. Unlike the Deacon process for chlorine production, oxychlorination of ethylene occurs readily at temperatures weU below those requited for HCl oxidation. 

Other mechanisms, involving initial formation of ethylene oxide [75-21-8] as the possible rate-limiting step, complexation of CuC with HCl (92), and C as the chlorinating agent (93) have been suggested. 

Alternatives to oxychlorination have also been proposed as part of a balanced VCM plant. In the past, many vinyl chloride manufacturers used a balanced ethylene—acetylene process for a brief period prior to the commercialization of oxychlorination technology. Addition of HCl to acetylene was used instead of ethylene oxychlorination to consume the HCl made in EDC pyrolysis. Since the 1950s, the relative costs of ethylene and acetylene have made this route economically unattractive. Another alternative is HCl oxidation to chlorine, which can subsequently be used in dkect chlorination (131). The SheU-Deacon (132), Kel-Chlor (133), and MT-Chlor (134) processes, as well as a process recently developed at the University of Southern California (135) are among the available commercial HCl oxidation technologies. Each has had very limited industrial appHcation, perhaps because the equiHbrium reaction is incomplete and the mixture of HCl, O2, CI2, and water presents very challenging separation, purification, and handling requkements. HCl oxidation does not compare favorably with oxychlorination because it also requkes twice the dkect chlorination capacity for a balanced vinyl chloride plant. Consequently, it is doubtful that it will ever displace oxychlorination in the production of vinyl chloride by the balanced ethylene process. 

The performance of many metal-ion catalysts can be enhanced by doping with cesium compounds. This is a result both of the low ionization potential of cesium and its abiUty to stabilize high oxidation states of transition-metal oxo anions (50). Catalyst doping is one of the principal commercial uses of cesium. Cesium is a more powerflil oxidant than potassium, which it can replace. The amount of replacement is often a matter of economic benefit. Cesium-doped catalysts are used for the production of styrene monomer from ethyl benzene at metal oxide contacts or from toluene and methanol as Cs-exchanged zeofltes ethylene oxide ammonoxidation, acrolein (methacrolein) acryflc acid (methacrylic acid) methyl methacrylate monomer methanol phthahc anhydride anthraquinone various olefins chlorinations in low pressure ammonia synthesis and in the conversion of SO2 to SO in sulfuric acid production. 

Chlorine dioxide gas generated from chlorite has been used as a chemosterilizing agent substitute for ethylene oxide in medical appHcations (174,175). Aqueous foam compositions containing chlorine dioxide have also been developed for the sanitization of hard surfaces (176). 

Elastomer ECH, % Chlorine, % Ethylene oxide, % CAS Registry Number Specific gravity ml T,°C... 

The reaction is carried out over a supported metallic silver catalyst at 250—300°C and 1—2 MPa (10—20 bar). A few parts per million (ppm) of 1,2-dichloroethane are added to the ethylene to inhibit further oxidation to carbon dioxide and water. This results ia chlorine generation, which deactivates the surface of the catalyst. Chem Systems of the United States has developed a process that produces ethylene glycol monoacetate as an iatermediate, which on thermal decomposition yields ethylene oxide [75-21-8]. 

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