Ethylene oxychlorination process

Nevertheless these special crackers proved expensive, and many gave serious operational problems. The final solution came with the development of the ethylene oxychlorination process. The reaction... 

For the conditions of Figure 6 the temperature levels of the washcoat are acceptable, while the O2 conversion after a reactor length of 3.5 m (over 90%) is comparable with that reported for a conventional packed-bed first stage reactor in an oxygen-based ethylene oxychlorination process. However, the calculated pressure drop in the monolithic reactor is below 0.1 atm, which is about five times less than in the packed bed reactor. 

Ethylene Dichlonde and Vinyl Chloride. In the United States, all ethylene dichloride [107-60-2] (EDC) is produced from ethylene, either by chlorination or oxychlorination (oxyhydrochlorination). The oxychlorination process is particularly attractive to manufacturers having a supply of by-product HCl, such as from pyrolysis of EDC to vinyl chloride [75-01-4] monomer (VCM), because this by-product HCl can be fed back to the oxychlorination reactor. EDC consumption follows demand for VCM which consumed about 87% of EDC production in 1989. VCM is, in turn, used in the manufacture of PVC resins. Essentially all HCl generated during VCM production is recycled to produce precursor EDC (see Chlorocarbons and Cm OROHYDROCARBONS ViNYLPOLYAffiRS). 

Oxychlorination of Ethylene. When compared with direct chlorination, the oxychlorination process is characterized by higher capital investment, higher operating costs, and slightly less pure EDC product. However, use of the oxychlorination process is dictated by the need to consume the HCl generated in EDC pyrolysis. 

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. 

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. 

Oxychlorination. This is an important process for the production of 1,2-dichloroethane which is mainly produced as an intermediate for the production of vinyl chloride. The reaction consists of combining hydrogen chloride, ethylene, and oxygen (air) in the presence of a cupric chloride catalyst to produce 1,2-dichloroethane (eq. 24). The hydrogen chloride produced from thermal dehydrochlorination of 1,2-dichloroethane to produce vinyl chloride (eq. 25) is usually recycled back to the oxychlorination reactor. The oxychlorination process has been reviewed (31). 

The first large-scale commercial oxychlorination process for vinyl chloride was put on-stream in 1958 by The Dow Chemical Company. This plant, employing a fixed-tube reactor containing a catalyst of cupric chloride on an active carrier, produced 1,2-dichloroethane from ethylene. The high temperatures involved in the reaction were moderated by a suitable diluent. The average heat output from the reaction is 116 kJ/mol (50,000 Btu/lb mol). 

Removal of metal chlorides from the bottoms of the Hquid-phase ethylene chlorination process has been studied (43). A detailed summary of production methods, emissions, emission controls, costs, and impacts of the control measures has been made (44). Residues from this process can also be recovered by evaporation, decomposition at high temperatures, and distillation (45). A review of the by-products produced in the different manufacturing processes has also been performed (46). Several processes have been developed to limit ethylene losses in the inerts purge from an oxychlorination reactor (47,48). 

Ethylene glycol could also be obtained directly from ethylene by two methods, the Oxirane acetoxylation and the Teijin oxychlorination processes. The production of ethylene glycol from formaldehyde and carbon monoxide is noted in Chapter 5. 

Originally, vinyl chloride polymers were based on acetylene. The switch to ethylene,chemistry came after the development of the oxychlorination process for vinyl chloride described in Chapter 9. Today very little acetylene-, based vinyl chloride monomer (VCM) processing remains. 

What probably happens in the oxychlorination process is that chlorine is formed in situ. The reaction of hydrogen chloride and oxygen to give chlorine and water was discovered by Deacon in 1858. Once the chlorine is formed, it then adds to ethylene as in the direct chlorination mechanism. Cu ... 

Vinyl chloride, formerly obtained from acetylene, is now produced by the transcatalytic process where chlorination of ethylene, oxychlorination of the by-product hydrogen chloride, and dehydrochlorination occur in a single reactor. 

Perchloroethylene and trichloroethylene are produced in a single-stage oxychlorination process from ethylene dichloride and chlorine. 

Oxychlorination Process to produce vinyl chloride monomer from ethylene, hydrogen chloride, and oxygen over a copper chloride on alumina catalyst. 

If desired, the hydrochloric acid can be obtained via cracking of ethylene dichloride. The oxychlorination process freed vinyl chloride production from the economics of a more costly raw material, acetylene. Deliberate acetylene manufacture is energy intensive and relatively expensive. By-product acetylene from gas cracking is less expensive, but it has not been available in sufficient supply for the large, approximately billion-pound-per-year plus, vinyl chloride production units. 

Figure 10.11 shows an integrated plant for producing EDC and vinyl chloride from ethylene, chlorine, and air. In this process, vinyl chloride (VCM) is produced by the thermal cracking of EDC. The feed EDC may be supplied from two sources. In the first source, ethylene and chlorine are reacted in essentially stoichiometric proportions to produce EDC by direct addition. In the second source, ethylene is reacted with air and HC1 by the oxychlorination process. Ideally, both processes are carried out in balance, and the oxychlorination process is used to consume the HC1 produced in the cracking and direct chlorination steps. The chemical reactions are... 

Application The modern Vinnolit oxychlorination process produces ethylene dichloride (EDC) by an exothermic reaction from feedstocks including ethylene, anhydrous hydrogen chloride (HCI) and oxygen. Anhydrous HCI can be used from the VCM process as well as from other processes such as isocyanates (MDI, TDI), chlorinated methanes, chlorinated ethanes, epichlorohydrin, etc. 

Oxygen can be supplied from an air separation plant, as well as from the cost-effective pressure swing adsorption (PSA) process. The Vinnolit oxychlorination process is also able to handle ethylene and/or anhydrous HCI containing vent streams from direct chlorination, acetaldehyde, monochloroacetic acid and other processes. 

Application A process to produce vinyl chloride monomer (VCM) and ethylene dichloride (EDC) from ethylene, chlorine and oxygen using a high efficiency fixed-bed oxychlorination process. 

Vin Tec Ethylene dichloride (EDC) via lean oxychlorination Ethylene, chlorine Oxychlorination process producess EDC cost-effectively with an exothermic, cooper catalyst-based process NA NA... 

Mitsui Chemicals, Inc. Vinyl chloride monomer Chlorine, ethylene, oxygen Oxygen-based balanced oxychlorination process, high temp, direct chlorination process 23 1998... 

Ethylene dichloride (EDC) is used to manufacture vinyl chloride monomer (VCM), which is one of the largest commodity chemicals produced in the world. EDC may be produced by the direct chlorination of ethylene or oxychlorination of ethylene in the presence of oxygen and hydrogen chloride. Pyrolysis of EDC produces VCM and an equal amount of hydrogen chloride as a co-product. This hydrogen chloride produced in the pyrolysis reactor is utilized by the oxychlorination process as one of the reactants. Therefore, the component processes of direct chlorination, EDC pyrolysis and oxychlorination are combined to develop a balanced process for the production of VCM with no net consumption or production of hydrogen chloride ... 

Formation of the mixed cement-containing systems within the range of low copper concentrations with addition of alkali metal dopants as well as catalytical properties of these systems in the ethane oxidative chlorination process have been investigated. Based on the obtained data the efficient and stable copper-cement catalyst has been worked out. This catalyst will assist in the development of a new technology of the vinyl chloride production from ethane. The basic peirameters of the ethane oxychlorination process have been determined at 623-673K, time-on-stream 3-5s and reactant ratio of C2H6 HCI 02 = 1 2 1 the conversion of ethane is more than 90% and the total selectivity to ethylene and vinyl chloride is 85-90%. 

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