Reaction oxychlorination

Consider vinyl chloride production (see Example 2.1). In the oxychlorination reaction step of the process, ethylene, hydrogen chloride, and oxygen are reacted to form dichloroethane ... 

The oxychlorination reaction is very exothermic and the catalyst is very active, which makes it necessary to mix the catalyst with an inert diluent to avoid overheating in a fixed-bed reactor. A low surface area, spherically- or ring-shaped alumina or chemical porcelain body can be used as a diluent with the ring-shaped catalyst. The density of the inert material should be similar to the catalyst to avoid segregation during loading, and the size should be slightly different to allow separation of the inert material from the spent catalyst. 

In a typical oxychlorination reaction, preheated gas streams at temperatures of 180—200°C are fed onto a fixed- or fiuidized-catalyst bed containing 2—10% copper impregnated on an activated alumina. The reaction occurs during a 15—22 s residence time on the catalyst bed at a temperature of 230—315°C. Typical yields to 1,2-dichloroethane range from 92—97%. 

Chloroethanol generated due to oxychlorination reaction = Chloroethanol in off-gas 4- Chloroethanol in wastewater V/f,... 

The HCl produced in this reaction is used in an oxychlorination reaction to chlorinate additional ethylene ... 

In oxychlorination. ethylene reacts with dry HC1 and either air or pure oxygen to produce EDC and water. While commercial oxychlorination processes may differ from one another to some extent because they were developed independently by many different vinyl chloride producers, 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. Cupnc chloride is usually the primary active ingredient of the catalyst, supported on a porous substrate such as alumina, silica-alumina, or diatomaceous earth. The oxychlorination reaction is highly exothermic (AH = —239 kJ/mol for eq. 3) and requires heat removal for temperature control. 

The hydrogen chloride is recovered as a dry gas and can be used for certain oxychlorination reactions or other industrial purposes for which elemental chlorine is now used. The potassium bisulfate is used, with more sulfuric acid, to... 

An oxychlorination unit, in which recycled hydrogen chloride is reacted with further ethylene feedstock in the presence of catalyst and oxygen, is also employed to generate further quantities of EDC, while excess hydrogen is oxidised to form water. Figure 2 is a schematic representation of the process. The oxychlorination reaction is shown in Figure 3. 

Direct chlorination of vinyl chloride generates 1,1,2-tnchloroethane [79-00-5] from which vinylidene chloride required for vinylidene polymers is produced. Hydrochlorination of vinylidene chloride produces 1,1,1-trichloroethane [71-55-6], which is a commercially important solvent. Trichloroethylene and perchloroethylene are manufactured by chlorination, hydrochlorination, or oxychlorination reactions involving ethylene. Aromatic solvents or pesticides such as monochlorobenzene, dichlorobenzene, and hexachlorobenzene are produced by reaction of chlorine with benzene. Monochlorobenzene is an intermediate in the manufacture of phenol, insecticide DDT, aniline, and dyes (see Chlorocarbons a>td Chlorohydrocarbons.)... 

Reactor effluent gases are quenched with water in a prestressed brick-lined, packed tower. The liquid leaving the tower is cooled further and separated into aqueous and DCE phases. The aqueous phase is split, part being recycled to the tower as quench liquid and the remainder recycled to the reactor, except for a purge equal to the water produced in the oxychlorination reaction. The water recycled to the reactor is first used to absorb part of the HCl feed and enters the reactor as an aqueous HCl solution. DCE product is cooled further and flashed to separate out more water (purged) and dissolved ethylene (recycled). 

Oxychlorination of hydrocarbons refers to a chemical reaction in which oxygen and hydrogen chloride react with a hydrocarbon in the vapor phase over a supported copper chloride catalyst to produce a chlorinated hydrocarbon and water. The oxychlorination of ethylene to produce 1, 2-dichloroethane (commonly, ethylene dichloride (EDC)) is of the greatest commercial importance. EDC is the precurser for vinyl chloride monomer, which when polymerized to polyvinyl chloride (PVC), becomes one of the most conunonly used commercial plastics. The overall oxychlorination reaction of ethane is given by... 

The process operates with a melt consisting of CuCl2 and KC1, which act simultaneously as a chlorine source and catalyst. The melt first produces the chlorinated methanes and is fed into an oxidation reactor, where it is rechlorinated in an oxychlorination reaction with hydrogen chloride or hydrochloric acid and air. The chlorinated methanes then are recovered in a similar manner to the methane chlorination method [158,159],... 

The formation of dichlorobenzenes in the oxychlorination reaction and that of polyphenols during hydrolysis reduce the total yield... 

From Ethylene. This process utilizes an oxychlorination reaction with ethylene and chlorine as feedstocks. In the process, three distinct reactions can be considered to be taking place ... 

An extensive literature exists on the characterization and structure—activity correlation of industrial copper-alumina oxychlorination catalysts [95-120]. At least two different major copper species have been identified. At low concentrations of copper (below ca 5 %), a well-dispersed copper species in intimate interaction with the alumina surface is formed. This species has a very low oxychlorination activity. At higher concentrations, a second species, probably formed by the de-position/precipitation of the copper chloro complexes, is observed. The latter gives rise to the active sites during the oxychlorination reaction. On the basis of an FTIR study of the oxychlorination reaction Finocchio et al. [42] postulated the formation of surface copper chloride-ethylene r-complex intermediates (which lead eventually to EDC) and weakly adsorbed HCl during oxychlorination. Formate species associated with copper and probable precursors for formation of the oxides of carbon by combustion were also identified. 

In the balanced process, all of the hydrochloric acid produced in the ethylene dichloride pyrolysis is used as feed to the oxychlorination step so that there is no net production or consumption of hydrochloric acid. The ethylene feedstock is split with about half used in the chlorination reaction and the other half in the oxychlorination reaction. A block flow diagram illustrating the major steps in the process is shown in Figure 13 [20]. 

The following calculation based on the stoichiometry and catalyst selectivity for the oxychlorination reaction gives the oxygen required per pound of VCM produced. For simplification, it is assumed that the balance of the ethylene feedstock which does not form ethylene dichloride forms carbon dioxide and water vapor. 

Neutralization of oxychlorination reaction water, wastewater of ElXi acidic wash, surficial wastewater, or acidic wastewater from flue gas scrubber of heavy ends-tar incineration. 

This reaction path combines paths 3 and 4. It has the advantage of converting both atoms of the chlorine molecule to vinyl chloride. All of the HCl produced in the pyrolysis reaction is consumed in the oxychlorination reaction. Indeed, it is a fine candidate for the solution of design alternative 2. 

The model described in the previous paragraphs representing heat transfer in monolith structures has been extended by including material balances for the key reacting species (O2) in the gas phase and at the gas-solid interface, and by modifying the energy balance to incorporate the generation term associated with the oxychlorination reaction. 

PVC), which is one of the most widely used commercial plastics. The overall oxychlorination reaction of ethane is given as follows ... 

The Catoxid catalyst is robust and is compatible with the oxychlorination reaction. Catalyst makeup is required only for attrition losses. The catoxid catalyst dust moves through the oxychlorination fluid bed reactor and leaves the system with the oxy catalyst fines. 

European Patent 1110605B and US Patent 7,678,342 toEVC (now Ineos)" describe the use of catalysts with various metallic honeycomb supports in gas-phase reactions, specifically cUorination/oxychlorination reactions, claiming greater yields and selectivities, avoidance of hot spots, prolonged catalyst lifetime and flexibility in use as compared to conventional catalysts in pellet form. 

The dehydrohalogenation of EDC to VCM is an endothermic reaction. It is sometimes referred to as a thermal cracking reaction. The heat can be supplied by the reactions that produce EDC. Both the direct chlorination and the oxychlorination reactions are exothermic. 

D) Technology invented in the early 1990s may render obsolete processes that use the oxychlorination reaction (rxn 6) in part (C) (see Chemical Engineering Progress, April 1993, p. 16). The new technology converts HCl into CI2 as follows ... 

Publications on bromination are very limited. Olah (1985) used antimony and tantalum oxyfluorides on alumina as catalysts and reported a 77% conversion at 260 C. Although no "oxybromination" was mentioned in the literature, its reactions can be defined, as similar to the oxychlorination reactions, by combining Reactions (19) to (22) with Reaction (23). 

Chemical equilibria of the oxychlorination reaction were calculated using 250 C(150-400 C), 10 atm(2-50 atm), and 100/100/50 molar CH4/HCI/O2 feed. Essentially complete conversions of both HCl and O2 were found and the CH4 conversions and the distributions of various chlorides were the same as those of the chlorination cases (Tables 2 and 3). 

Equilibrium calculations were also repeated for the oxybromination reactions using the same conditions as those for the bromination reactions. As similar to the oxychlorination reactions, essentially complete conversions of either HBr or O2 were found and CH4 conversions and bromides distributions were the same as those of the bromination cases (Table 7). 

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