MXPA96005635A - Method to reduce the formation of polycolored aromatic compounds during air oxycoloration of hydrocarbons c1 - Google Patents

Abstract

In the present invention an improved process is disclosed for the manufacture of chlorinated hydrocarbons by means of oxychlorination which produces reduced levels of environmental toxins such as chlorobenzenes, polychlorinated biphenyls, polychlorinated dibenzodioxins and polychlorinated dibenzodioxins and polychlorinated dibenzofurans. The process involves the fixed bed oxychlorination or catalyzed fluid bed of a hydrocarbon reagent containing 1 to 3 carbon atoms. The oxychlorination process consists in contacting the hydrocarbon reagent with air, oxygenated air and hydrogen chloride in the presence of the oxychlorination catalyst in a heated reaction zone operated from 150 ° C to 600 ° C and recovering the chlorinated hydrocarbon from the effluents of the reaction zone. The improvement consists of the use of air which is pre-treated before being used in the oxychlorination process operated by means for the removal of aromatic hydrocarbons.

Description

METHOD TO REDUCE THE FORMATION OF POLYCHLORIDE AROMATIC COMPOUNDS DURING OXYCHLOREMENT AIR OF HYDROCARBONS C1 ~ C3 DESCRIPTION The present invention relates to processes involving the oxychlorination of c? ~ C3 hydrocarbons especially methane, ethane, propane, ethylene, propylene, acetylene, and propyne using ambient air as the oxygen source . Some commercial uses of chlorine give rise to small but measurable amounts of polychlorinated aromatics such as chlorobenzenes, polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), the last two being referred to herein as PCDD / F and considered the latter two as environmentally toxic. Polychlorinated aromatics such as PCBs, PCDDs and PCDFs are undesirable compounds, to which they are collectively referred to herein as HUCs, although they have been found in soil and lake sediments and whose reduction or elimination of industrial production is It has become a growing concern. The literature refers to the formation of PCDD / F as inevitable for many of the chlorinated industrial processes, especially for the oxychlorination of ethylene to 1,2-dichloroethane, which is also referred to as ethylene dichloride (EDC), the intermediate principal in the production of vinyl chloride monomer (VCM). Minor amounts of PCDD / F have been monitored in a variety of industries, including solid waste incinerators, EDC / VCM processes and other processes involving the chlorination, oxychlorination, or hydroxychlorination of non-aromatic hydrocarbons, including reversible processes. say dechlorination or dehydrochlorination. A recent report compiled from case studies of emissions from the EDC / VCM processes in Europe estimates annual emissions of what is referred to as toxic equivalents of 2, 3, 7, 8-tetrachloro-dibenzodioxin (TCDD) in 1.8 kg. See De Vorminq van PCDFs, PCDDs in Gerelateerde Verbindinqen Bij de Oxyclorination van Ethen. Evers, E. H. G., Dept. of Environmental Toxicology, University of Amsterdam, Contract No. ZH4005, Nat. Water Service District of So. Holland (hereinafter referred to as the NWS study) 1989. MTC Pub. No. MTC89EE. Additionally, experts disagree on what levels of these toxins are generated from both natural and industrial processes. There are several citations in the research literature concerning the various synthetic routes that give rise to PCDD / F. Chemosphere. Vol. 23, Nos. 8-10, O. Hutzinger, Editor, Pergamon Press, 1991. In summary, important precursors that can lead to the formation of PCDD / F reported in the literature include chlorophenol, benzene, benzene chlorinated, and diphenyl ether. It has been found that these species are converted to PCDD / F by means of condensation, free radical and ionic mechanisms. Chlorinate Dioxins and Related Compounds. O. Hutzinger, et. al, Editors, Pergamon Press, 1982. The de novo synthesis of PCBs and PCDD / F from non-aromatic precursors (including elemental forms) has been reported in the literature of oxychlorination processes. Chemosphere, Eklund, G.; Pederson, J. R.; Stromberg, B., 17, 575, 1988. The de novo term is defined as the formation of PCDD / F directly from acyclic, aliphatic hydrocarbons, such as methane and ethylene in the presence of oxygen and HCl. For example, the NWS study showed that. a number of the PCDD / F were detected in the gas phase and in the catalyst residue of a simulated oxychlorination process. The total amount of PCDD / F observed in the NWS experiments was 546 nanograms per 1.31 grams of EDC formed or 417 ng / g (ppb). The congenial pattern of the PCDD / F formed in the NWS experiments was extremely similar to that found in the residual sludge of the VCM industries along the Rhine River basin and indicates that the laboratory study accurately models the process that occurs in commercial units. The authors of the NWS study concluded that copper catalyst plays a role in the formation of PCDD / F in media in which carbon is present, chlorine, oxygen, and active catalytic surfaces. The data confirm the conclusion that PCDD / F are unavoidable and are formed de novo in the oxychlorination of alkanes and alkenes, for example ethylene. The researchers hypothesized that aromatization of simple carbon structures was occurring to account for apparent de novo synthesis. The de novo formation of chlorinated alkene traces, benzenes, -phenols and biphenyls has also been reported to be formed by the reaction of C02 and HCl in the presence of catalysts. Chemosphere, Stromberg, B. 27, 179, 1993; Chemosphere, 23, 1515, 1990. These catalysts include many materials used commercially as those used in oxychlorination processes. In addition, it has been shown that fly ash from municipal solid waste incinerators catalyze the formation of PCDD / F. a) Chemosphere, Ross, B. J.; Naik adi, K. P .; Karasek, F.W., 19, 291, 1989; b) Chemosphere, Benfenati, E .; Mariani, G.; Fanelli, R.; Zuccotti, S., 22, 1045, 1992; and Chemosphere. Born, J. G. P .; Louw, R.; Mulder, P., 26, 2087, 1993. One such study has shown that favorable conditions occur at temperatures between 280 ° C and 300 ° C, leading to a consensus among researchers of the incineration methods that PCDD / F are probably formed in post-combustion gas cooling zones of solid waste incinerators. Therefore, studies have shown that de novo synthesis of chlorinated aromatics occurs apparently under a variety of conditions. With the addition of reports of the de novo formation of PCDD / F in the processes that consume industrial chlorine, the reduction or elimination of these collateral products is an intensely sought goal, but apparently elusive. Despite this evidence, some approaches have focused on improving the selectivity in the reaction to achieve the desired product although, with lesser amounts of the undesirable side products. For example, an approach that is considered as the starting point for the reduction in the level of collateral products produced in EDC manufacturing is the improved direct chlorination process described in US Patent 4,410,747 ('747). This liquid phase reaction of ethylene and chlorine taught in '747 is carried out at the boiling point of the EDC liquid in the presence of an added metal chloride and aromatic hydrocarbon catalyst, such as benzene. The side reactions that form the undesirable side products, mainly 1, 1, 2-trichloroethane, are reduced. Following the perspective that the de novo synthesis of PCDD / F is occurring, the reaction selectivity could reduce the level of de novo PCDD / F formed. Other improvements demonstrated in the art have focused on the reduction in the volume of waste effluent discharged from the oxychlorination processes. In the balanced process of ethylene oxychlorination to achieve EDC, the recapture and reuse of hydrogen chloride from the disintegration of 1,2-dichloroethane to form vinyl chloride monomer is contemplated. The amount of the waste effluent is considerably reduced in the HC1 reuse. The recycled HC1 is typically separated from the EDC, VCM and collateral products by distillation. Therefore, reducing the volume of the waste would improve the environmental impact, however, with respect to the HUC, reducing the absolute levels continues to be a matter of vital importance. In recent practice there have been additional reductions in the effluent from the oxychlorination processes incorporating a ventilation recycling system. In this process, the reaction gases of the catalytic processes are cooled under pressure in one or more stages of condensation. The water and the condensed EDC are removed and all the unreacted initial gases and the inert gas are repressurized and recycled to the oxychlorination reactor. The recycling method used in conjunction with an oxygen feed instead of air, reduces the volumes of the exhaust gases to only a small portion of that produced in the one-step, air-base processes. There are many advantages in the use of the ventilation recycling process mainly in terms of efficiency, however, with respect to the PCDD / F, there is no advantage in recycling in the ventilation gases, since the compounds PCDD / F they condense as heavy ends. further, the present invention is directed to the one-step method using air as the main source of oxygen. A laboratory investigation comparing the formation of PCDD / F for the oxychlorination of the air base and the oxygen based method was carried out. This study revealed that PCDD / F are formed with greater intensity with the air base process. This was surprising, since in these experiments the only difference from a practical and theoretical point of view was the source of oxygen. Based on the previously mentioned research studies that show the de novo synthesis of PCDD / F, one would have expected the same levels of PCDD / F formed independently of the oxygen source. The difference was not considered. The practice of air-based oxychlorination is a globally established industrial process. In some parts of the w, pure oxygen is not available or is too expensive, which leaves the air base process as the only available approach. Therefore, an effective cost reduction in the amount of PCDD / F formed in the air base oxychlorination process would be a valuable improvement. In the careful quantitative measurements of the laboratory oxychlorination processes using the copper (II) catalyst using both air and oxygen, measurable levels of PCDD / F were found that are considered surprising not from de novo synthesis, but of the trace levels of the aromatic compounds contained in the ambient air. The finding that de novo synthesis did not occur in a properly controlled oxychlorination process now provides the benefit that by eliminating the trace aromatic compounds present in the ambient air, the incidence of PCDD / F can be reduced or completely eliminated. The novel approach is therefore based on the elimination of sources of precursor compounds that can form PCDD / F in oxychlorination as preferable over an approach that otherwise assumes their inevitable formation and concentrates on isolation in the flow descending and in the disposal of waste after incidental formation. The fact that is revealed here is that these compounds are not inevitable.

According to the invention, an oxychlorination process operated for the manufacture of chlorinated hydrocarbon is provided. The process involves a catalyzed fixed bed or fluidized bed oxychlorination of a hydrocarbon reagent containing 1 to 3 carbon atoms. The oxychlorination process comprises contacting a hydrocarbon reagent of c? _c3 with air and HC1. The feeds are reacted in the presence of an oxychlorination catalyst in a heated reaction zone operated from 150 ° C to 600 ° C where the chlorinated hydrocarbon product is recovered from the effluents of the reaction zone. The process is characterized by the fact that the air is treated before being used in the oxychlorination process operated as a means to remove aromatic hydrocarbons. The present invention arises from the unexpected discovery that the de novo synthesis of PCDD / F is not a necessary result in the oxychlorination of non-aromatic hydrocarbons under industrially practiced conditions. It has been shown that a significant amount of the PCDD / F found in the effluent of the air-base oxychlorination process is due not only to the de novo synthesis during the oxychlorination of aliphatic hydrocarbons but also to a low level of aromatic compounds discovered in the air supply current. These aromatics are removed from the air by conventional means prior to their use in the oxychlorination process of the present invention, thus preventing their conversion to PCBs and PCDD / F during oxychlorination. The removal of the aromatic compounds by distillation of the air includes the steps of condensing the air in a container equipped with a condenser, followed by the separation of the condensed vapors from the non-condensable gases. The vaporization and condensate steps preferably include a means for providing a countercurrent, multistage fractionation, as widely used in the distillation of a variety of liquids. Other processes for treating air for the removal of trace aromatic compounds are known in the art such as passing air through a vessel containing a solid or liquid adsorbent. Solid adsorbents known in the art include, but are not limited to, activated carbon, zeolite, alumina, diatomaceous earth, various forms of silica such as silica gel and adsorbent polymer resin or selective and supported absorbent. Liquid absorbers include, but are not limited to, paraffins, ie, aliphatic hydrocarbons such as pentanes, hexanes, 5-CQ distilled fractions, the like, and water.

The removal of the aromatic compounds from the air can also be achieved by conversion to a non-aromatic species by hydrogenation reactions which include the treatment of the air with metal hydrogenation catalysts such as nickel, platinum or palladium in the presence of a source of hydrogen to convert the aromatic compounds to saturated cyclic aliphatic compounds. Catalytic oxidation on an oxidation catalyst in the presence of oxygen to convert the aromatic compounds to carbon dioxide and water is another suitable means for removing aromatics from the air. The particular method for the removal of aromatic compounds from the air is not critical as long as the selected method effectively reduces the level of aromatic compounds in the air to less than 0.1 parts per trillion (or 0.1 ng / g), and can be selected by the technician merely on the basis of the available equipment and the preferred economy that are beyond the scope of this description. In addition, the selected method can be performed on the basis of the level of aromatic compounds present in the ambient air at a particular location. For example, the Houston Regional Monitoring Network measured a mean annual benzene concentration in the air in the range of a volume basis of 1 to 3.5 parts per billion in 1990. Other areas may contain higher or lower levels. Between the pretreatment stages available, preferred methods include treatment with an oxidation catalyst, passing the air through an adsorbent column containing activated carbon, and extraction with paraffin liquids. In another aspect of the invention, an improved oxychlorination process effluent is provided, which portion of the waste contains reduced polychlorinated aromatics and preferably less than 0.1 parts per billion, the process effluent is produced in an oxychlorination process by contacting it with an oxychlorination catalyst and in a heated reaction zone operated from 150 ° C to 600 ° C, a hydrocarbon reagent of C- ^ to C3, such as methane, ethane, ethylene, propane, propylene, acetylene, propyne, chloroethane, chloropropane , dichloromethane, dichloroethane and the like, in the presence of air, and hydrogen chloride. Suitable catalysts used in oxychlorination processes are known and conventionally known. Examples are described in U.S. Pat. Nos. 3,624,170, 4,446,249, 4,740,642, and 5,011,808 and in European Patent Publication No. 0255156. The process conditions required in catalytic oxychlorination are also known and established in the art. Examples are described in U.S. Pat. No. 3,488,398 to Harpring et al.

The oxychlorination catalysts are suitable either in the form of the fixed bed or fluid bed types. In the case of oxychlorination of saturated hydrocarbons containing 1, 2, or 3 carbon atoms, the heated reaction zone is generally operated at 300 ° C to 600 ° C. In the case of oxychlorination of unsaturated hydrocarbons containing 2 or 3 carbon atoms, the heated reaction zone is operated from 150 ° C to 300 ° C. The halogenated derivatives may be advantageously chlorinated using the present process and include chloromethane, dichloromethane, chloroethane, dichloroethane, trichloroethane, fluoromethane, fluoroethane, fluoropropane, chlorofluoromethane, chlorofluoroethane, chlorofluoropropane, and substituted B ^ -3-hydrocarbons. The process is operated at atmospheric pressure or above atmospheric pressure. The molar ratios of reactive HCl / C2H4 / 02 feed gases are generally maintained at 2 / 1-1.5 / 0.5-1.0. Further treatment of the chlorinated product using conventional thermal disintegration and / or purification means established in the art is possible. Experiments Several experiments have been conducted to demonstrate that the careful removal of the aromatic compounds from the air streams used as oxygen sources for oxychlorination processes leads to a significant reduction in the amount of PCBs and PCDD / F. The reactions were carried out in laboratory scale fluid bed oxychlorination reactors operated between 210 ° C and 245 ° C, the contact time of 15 and 40 seconds, and otherwise, within the range of operation of the commercial units. The contact time is defined as the volume of the fluidized bed of the catalyst bed divided by the volumetric flow rate of the sum of all the feed gases at the reactor control temperature and the maximum reactor pressure. In some experiments, the previously measured levels of the aromatic compounds were allowed to enter the reactor with the feed gases. Other experiments involved the artificial addition of benzene, dichlorobenzene, or toluene as model compounds. Baseline experiments were conducted where no aromatic compounds were present in the feed or in the catalyst. It is reported in the scientific literature dealing with the quantitative analysis of PCBs and PCDD / F that PCBs and particularly PCDD / F formed in oxychlorination and other processes accumulate and concentrate in the catalyst and are found in extractable residues. of the solid particles of the catalyst. De Vorminq go PCDFs, PCDDs in Gerelateerde Verbindinqen Bii of Oxychlorination van Etheen, Evers, E. H. G., Doctoral Thesis, University of Amsterdam, 1989. MTC Pub. No. MTC89EE. In the experimental work that is synthesized below, analyzes were carried out both in the effluent of the reactor (product and gases) and in the solid particles of the catalyst. For consistency and analytical simplicity, only the results of the analyzes on the residues of the catalyst samples are reported below. Oxychlorination test conditions. A fluid-bed reactor was used at the laboratory scale of local construction. Approximately 300g of catalyst was charged and controlled at a temperature between 210 ° C and 245 ° C by means of resistance heating. The system was operated at atmospheric pressure. The feed gases C2H4, HCl and air or N2 and 02 were introduced into the reactor just below the catalyst bed. Feeding rates were maintained using commercial mass flow controllers so that the contact time of the fluid bed was about 25 seconds and the molar ratio of HCl / C2H4 / 02 was about 1.96 / 1.0 / 1, respectively. The reactants and products pass through the fluidized bed at the top to a decoupling zone that separates the particles of catalyst of the gases of the product. The product gases are then transported through a closed system to the gas sampling stations. When the analyzes were to be performed it was essential that the reactor and all the downstream sampling lines remain above the dew point of the gases. Samples of the catalyst were removed from the reactor during the reaction conditions. A sampling port located near the base of the reactor but above the point where the feed gases are introduced was opened and the catalyst sample was taken in a clear glass vessel and sealed. The catalyst samples were extracted with toluene according to the following procedure: Five grams of catalyst were placed in a 50cc pleated vessel. "Toluene (25ml) was added and the sample was mechanically stirred for 7 hours and then allowed to settle for about 15 hours The catalyst and the solvent were filtered through Whatman # 2 paper into a 6 dram amber container., 4,8-trichlorodibenzodioxina as a standard of internal recovery. The sample was then evaporated to dryness. The residue was reconstituted in 2-3 ml. of isooctane was transferred to a 4 ml amber container. , and evaporated to dry without heating. The residue was then extracted in 0.1 ml. of isooctane for analysis by GC.

Two methods of CG analysis were employed. The qualitative selection was made in a CG II of the series HP5890 equipped with an electron capture detector (ECD) and an RTX-5 column. The quantitative analysis was performed on an HP5870 CG equipped with an HP5790 mass selective detector and a 30m XTI-5 capillary column. (movie 0. 25μm). The sample size was 2μl, and the conditions of the column were 70 ° C for two minutes, ° C / minute ramp at 300 ° C, and a wetting time of 17.7 minutes. The detection limits were at 0. In PCBs or PCDD / F per gram of catalyst removed from the reactor.

The quantitative data reported below are listed in units of ng / g in the catalyst. Values for PCBs with 8, 9 and 10 chlorine atoms are added together and reported as "PCB". Under the heading "OCDD" and "OCDF" are the octachlorinated dibenzodioxins and the octachlorinated dibenzofurans respectively. It is well known in the art that the oxychlorination process favors the formation of the more highly chlorinated PCDF derivatives on those of lower chlorination and of the more suspicious environmental congeners. Experiments were carried out with fresh catalyst, with catalyst previously used in the oxychlorination reactor of the laboratory, and with catalyst previously used in the oxychlorination reactor of the laboratory in the presence of aromatic hydrocarbons and chlorinated aromatic hydrocarbons aggregates. The experiments were also conducted to determine if the chlorinated ethene derivatives would lead to aromatic compounds or their known precursors (butadiene derivatives). In all cases, no evidence was found of the aromatization of the C2 hydrocarbons or the production of PCBs or PCDD / F when the feed to the reactor contained only C2H4, HCl, 02 and N2. Example 1 Fresh catalyst (baseline). A sample of a fresh oxychlorination catalyst of the type described in US 5,292,703 was extracted as described above. Qualitative and quantitative CG analyzes indicated that 'the fresh catalyst contained only minor levels of PCBs and PCDD / F. Pollution levels were consistent with those reported in the literature. These are similar to the background levels found in a wide variety of commercial and non-commercial materials. This analysis was repeated on 5 additional samples of fresh catalyst to establish a baseline. The results are summarized in table 1 below. The units are listed in nanograms per gram of produced EDC (ng / g).

TABLE 1 PCB catalyst nq / q OCDD (nq / q) OCDF (nq / q) 1-A < 0. 1 not detected ~ 0.8 1-B < 5 not detected < 5 1-C 3. 0 not detected 2.3 1-D < 1 not detected < 1 1-E < 1 not detected < 1 1-F < 1 not detected < 1 Example 2 (comparative) A sample of fresh catalyst is used in the oxychlorination reactor of the laboratory operating at 225 ° C, with molar ratios of HCl / C2H4 / 02 controlled at 1.97 / 1.0 / 1.1, and with approximately 25 seconds of time contact. He HCl, ethylene, and air were quantitatively pretreated to remove the aromatics. The catalyst was shown and extracted as described above.

Surprisingly, no evidence of elevated levels (compared to baseline experiments) of PCBs or PCDD / F was found in the quantitative analysis of the catalyst particles. If unavoidable, de novo synthesis of the polychlorinated aromatics was occurring, detectable increases in the PCB and / or PCDD / F in the catalyst particles. Therefore, without aromatic compounds present in the air after treatment using a suitable medium to remove aromatic compounds, the oxychlorination effluent will contain reduced levels of PCBs and PCDD / F. Example 3 (comparative) The fresh catalyst was placed in the oxychlorination reactor of the laboratory under the above conditions. A mixture of aromatic hydrocarbons consisting mainly of xylenes and benzenes from C-j was introduced at a combined level of approximately 100 ppb based on the air feed rate. The reaction was carried out for approximately 24 hours to allow a steady state to be established, and the catalyst was shown and analyzed as described above. GC-MSD results indicated elevated levels of PCBs and PCDD / F: PCB = 21.2 ng / g; OCDD = not detected; OCDF = 94.2 ng / g. In a similar experiment we found: PCB = 23.9 ng / g; OCDD = not detected; OCDF = 14.6 ng / g. These observations illustrate that the aromatic compounds present in the air stream do not contribute to the amount of polychlorinated aromatics found in the oxychlorination effluent. Example 4 (Comparative) Following the same procedure of Example 3, benzene was introduced at a rate of about 7% of the air feed rate for 6 hours. The catalyst was shown and analyzed as described above, and elevated levels of PCBs and PCDD / F were found: PCB = 5.3 ng / g; OCDD = not analyzed; OCDF = 1137 ng / g. Example 5 (Comparative) Following the procedures of Example 4 above, toluene was introduced at a rate of about 2% based on the air feed. Analysis of the catalyst after approximately 6 hours of exposure gave the following results: PCB = 46.4 ng / g; OCDD = 42.3 ng / g; OCDF = 315.6 ng / g. Example 6 (aromatization test) In an effort to determine if the hydrocarbons can bind to form butadiene and butadiene derivatives known to react with the olefins to produce the aromatics, perchlorethylene was introduced to the oxychlorination reactor of the laboratory operating under similar to those of example 5. The qualitative analysis of the product of the reaction by GC-MSD indicated the presence of all the chlorinated derivatives of ethane and ethene. However, no evidence of Co, C¿ or major hydrocarbons or their derivatives was found. This indicates that there is no aromatization occurring under typical oxychlorination conditions. The type of catalyst used in the above experiments is not unique in relation to the observed behavior and is merely illustrative of a typical oxyclozid catalyst in commercial use.

DISCUSSION Example 1 illustrated that before being used in the oxychlorination reaction, it is observed that the fresh catalyst contains only trace amounts of the PCBs and the PCDD / F. Example 2 illustrated the surprising result that when all the feed components used in the process are free of aromatics and fresh catalyst is used there is no de novo synthesis of PCBs and PCDD / F under the conditions that are suitable for the operation on an industrial scale. There are advantages in preventing the occurrence of the formation of PCBs and PCDD / F in the effluent of the oxychlorination process since the heavy end collateral products contained in the crude EDC and the accumulated wastewater sludge from the process can now be approximate or reach zero levels of PCBs and PCDD / F. There are considerable economic advantages when eliminating the decontamination stages of the residual effluents. The environmental contamination is finally reduced. In view of the above understanding, one can appreciate the application of the invention in other similar processes such as chlorination, hydrochlorination, and reversible processes. The ability to prevent the formation of PCBs and PCDD / F can be achieved for any industrial process involving chlorine, hydrogen chloride and aliphatic hydrocarbons, under conditions that prevent the conversion of aliphatic hydrocarbons into aromatic hydrocarbons. The present invention is not applicable to those processes where the de novo synthesis of aromatic compounds and polychlorinated aromatics occurs intrinsically or where the aromatic compounds are an integral part of the process.

Claims (6)

1. CLAIMS 1. An improved process for the manufacture of hydrocarbons with a reduced formation of chlorobenzenes, polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), initiating the process with a hydrocarbon reagent of C- C3 selected from the group consisting of methane, ethane, ethylene, acetylene, propane, propylene, methylacetylene, and substituted halogen versions thereof, the process comprising: contacting the reagent with oxygen or oxygenated gas and hydrogen chloride at that a portion of the hydrogen chloride to be consumed is obtained from an external source other than the recovery of the thermal disintegration of the product produced in the oxychlorination process, such contact being carried out in the presence of an oxychlorination catalyst in a heated reaction zone operated from 150 ° C to 600 ° C where the chlorinated hydrocarbon is recovered from the effluents of the reactive area The process is characterized by the fact that the air is pretreated with a means to remove the aromatic hydrocarbons.
2. 2. The process according to claim 1, characterized in that the means for removing the aromatic compounds from hydrogen chloride are selected from the group consisting of distillation, adsorption, absorption, hydrogenation and oxidation.
3. 3. The process according to claim 1 characterized in that the means for the removal of the The aromatic compounds are selected from the group consisting of (a) passing air through a container containing activated carbon, (b) treating the air with activated carbon, (c) treating the air with silica, (d) treat the air with an aromatic compound-absorbent resin, (e) subject the air to a hydrogenation process, (f) extraction with an aliphatic liquid hydrocarbon and, (g) subject the air to an oxidation process. .
4. The process according to claim 1, characterized in that the hydrocarbon is selected from the group consisting of methane, ethane, and prophane and in which? ~ \ the heated reaction zone is operated from 300 ° C to 600 ° C.
5. 5. The process according to claim 1, characterized in that the hydrocarbon is selected from the group consisting of ethylene, acetylene, propylene, and methylacetylene and wherein the heated reaction zone is 2'? operates from 150 ° C to 300 ° C.
6. 6. The process according to claim characterized in that the hydrocarbon is ethylene.