Vinyl chloride manufacturing

By-Product Disposal. By-product disposal from vinyl chloride manufacturing plants is compHcated by the need to process a variety of gaseous, organic Hquid, aqueous, and soHd streams, while ensuring that no chlorinated organic compounds are inadvertendy released. Each class of by-product streams poses its own treatment and disposal challenges. 

Process water streams from vinyl chloride manufacture are typically steam-stripped to remove volatile organics, neutralized, and then treated in an activated sludge system to remove any nonvolatile organics. If fluidized-bed oxychlorination is used, the process wastewater may also contain suspended catalyst fines and dissolved metals. The former can easily be removed by sedimentation, and the latter by precipitation. Depending on the specific catalyst formulation and outfall limitations, tertiary treatment may be needed to reduce dissolved metals to acceptable levels. 

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. 

Significant quantities of ethyl chloride are also produced as a by-product of the catalytic hydrochlorination over a copper chloride catalyst, of ethylene and hydrogen chloride to produce 1,2-dichloroethane, which is used as feedstock in the manufacture of vinyl choride (see Vinyl polymers). This ethyl chloride can be recovered for sale or it can be concentrated and catalyticaHy cracked back to ethylene and hydrogen chloride (25). As the market for ethyl chloride declines, recovery as an intermediate by-product of vinyl chloride manufacture may become a predominant method of manufacture of ethyl chloride. 

Vanadium oxide as catalyst, 174 Vinyl chloride, manufacture of, using catalysts, 238... 

Baking chocolate, theobromine and caffeine content, 6 367t Baking enzymes, 10 297 Baking furnaces, 12 734—735 Balanced vinyl chloride processes, in vinyl chloride manufacture, 25 634, 635,... 

Chlorine-hydrogen hazards, 9 646 Chlorine Institute, 21 831 25 343 Chlorine market, in vinyl chloride manufacture, 25 646 Chlorine monofluoride, 13 123-124 Chlorine monoxide, 8 545t Chlorine oxygen acids/salts, 17 389t Chlorine pentafluoride, 13 125 Chlorine peroxide, oxidation state and stability, 8 545t... 

Chloro pink, 9 310-311 Chloroplast transit peptide, 72 489 TV-Chloropolyacrylamides, 7 316 Chloroprene, 6 242, 246. See also 2-Chloro-1,3- butadiene from butadiene, 4 369 chlorocarbon/chlorohydrocarbon of industrial importance, 6 227t copolymerization of, 79 829-830 end use of chlorine, 6 134t removal in vinyl chloride manufacture, 25 642... 

Endothermic EDC cracking, in vinyl chloride manufacture by pyrolysis, 25 643... 

Fixed bed photoreactors, 19 99 Fixed-bed process technology benzene-based, 15 505—506 butane-based, 15 501-502 Fixed-bed reactors, in vinyl chloride manufacture by oxychlorination, 25 640... 

Improvement teams, Six-Sigma, 21 174 Impurities. See also Contaminants Metal ion impurities Purification caustic soda in removing, 22 832 in limestone, 15 33, 34t, 40 in magnesium, 15 342-343 in manganese ore, 15 542—545 in metal, 16 130 in MOCVD growth, 22 157 removal in vinyl chloride manufacture, 25 641, 642... 

Trichloroethane, 25 631—632 preparation of VDC from, 25 692 from vinyl chloride manufacture,... 

Darvic, Elvic, Geon, Koroseal, Marvinol, Mipolam, Opalon, Pliofex, Rucon, Solvic, Trulon, Velon, Vinoflex, Vygen, and Vyram are all trade names for poly(vinyl chloride) manufactured by different companies. Some polymers are better known by their trade name than their generic name. For instance, polytetrafluoroethylene is better known as Teflon, the trade name held by DuPont. 

Kurosaki, M., Taima, S., Hatta, T. Nakamura, A. (1968) Identification of high-boiling materials as by-products in vinyl chloride manufacture. Kogyo Kagaku Zasshi, 71, 488-491 (in Japanese) [Chem. Abstr.. 69, 056857]... 

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