EA029427B1

EA029427B1 - Process for the hydrohalogenation of an unsaturated hydrocarbon

Info

Publication number: EA029427B1
Application number: EA201591183A
Authority: EA
Inventors: Марко Пиччинини; Армин Т. Либенс; Доминик Бальтазар
Original assignee: Солвей Са
Priority date: 2012-12-19
Filing date: 2013-12-18
Publication date: 2018-03-30
Also published as: EA201591183A1; WO2014095982A1; CN104936933A

Abstract

Described is a process for the hydrohalogenation of an unsaturated hydrocarbon using a catalyst comprising at least one ionic liquid (IL) and at least one metal, according to which said IL and metal are encapsulated inside a porous solid carrier.

Description

The invention relates to a method for the hydrohalogenation of an unsaturated hydrocarbon, preferably the hydrohalogenation of acetylene, in order to obtain vinyl chloride (VC).

Production of VC by reaction between acetylene and hydrogen chloride is usually carried out in the gas phase, in a fixed bed reactor, in the presence of a heterogeneous solid catalyst based on mercury chloride on the carrier. For reasons of toxicity, there is currently a growing interest in low mercury catalytic systems or catalytic systems that do not contain mercury compounds.

Various catalysts have been developed to replace the catalysts currently used in gas phase processes.

For example, Japanese Patent Application No. 52/136104 describes a method for hydrochlorinating acetylene in the gas phase in the presence of a fixed catalytic layer consisting of noble metal halides deposited on activated carbon. However, to date, the service life of such alternative catalysts intended for use in gas-phase processes remains significantly shorter than that of catalysts based on mercury compounds.

In addition, there are some examples in the literature of the hydrochlorination of acetylene in the presence of a liquid catalytic medium.

German patent 709000 describes a method for producing vinyl halides by bringing acetylene into contact at high temperatures with a molten mass of hydrogen halide organic bases containing a standard catalyst. Aliphatic, aromatic or heterocyclic amines and their mixtures are contemplated as organic bases.

In the author's certificate of the USSR 237116 described the use of an aqueous solution of an acid containing 46 wt.% Copper monovalent chloride and from 14 to 16 wt.% Methylamine hydrochloride, dimethylamine or trimethylamine.

European patent application EP-A-0340416 discloses a method for producing VC by reacting acetylene with hydrogen chloride in the presence of a palladium compound as a catalyst in a solvent consisting of an aliphatic or cycloaliphatic amide, at a temperature above room temperature. Although it allows for high yields, this method, however, has some significant drawbacks: it turned out that under the reaction conditions the liquid catalytic system gradually decomposes, forming blackish products that look like coal. In addition, in the presence of hydrogen chloride, the amide is converted to hydrochloride, the melting point of which is usually much higher than room temperature. For example, Ν-methylpyrrolidone hydrochloride is liquid only above 80 ° C. In practice, this can cause serious problems in practical implementation, problems associated with agglomeration of the catalytic medium during reactor shutdowns, or blocking of lines in the coldest points of the installation. Then the temperature of the entire reactor, as well as the lines in which the reaction medium flows, must be constantly maintained above the melting point of the hydrochloride.

These various problems appear to have been resolved by the catalytic hydrochlorination systems described in European patent applications EP-A1-0519548 and EP-A1-0525843, which contain at least one compound of a metal of group VIII and either amine hydrochloride, the melting point of which is less than or equal to 25 ° C, or a fatty amine hydrochloride containing more than 8 carbon atoms, the melting point of which is higher than 25 ° C, and an organic solvent selected from aliphatic, cycloaliphatic and aromatic hydrocarbons and and x mixtures. However, the catalytic systems described in these applications, especially those where the compound of the metal of group VIII is platinum chloride (11) or palladium chloride (P), are not completely satisfactory if we consider the performance achieved using them in terms of production efficiency in VC obtained by acetylene hydrochlorination, and in terms of long-term stability.

Publication No. 2008/77868 discloses a catalytic hydrochlorination system containing at least one amine hydrochloride and at least one compound of a metal of group VIII selected from the group consisting of mixtures of platinum compounds) with chloride 8i (P), mixtures of platinum compounds ( P) with triphenylphosphine oxide and mixtures of a palladium (P) compound with triphenylphosphine. These catalytic systems show improved production efficiency compared to the systems described in European patent applications EP-A-0519548 and EP-A-0525843.

Another example of a disclosure relating to a liquid catalytic medium for the hydrochlorination of acetylene in VC is Chinese patent application 102671701, which discloses catalysts that prevent the release of mercury due to the fact that they are formed by a special carrier loaded with an ionic liquid with fixed mercury, and the ionic liquid is chemically bonded to the surface of the carrier via a silane coupling agent, silicate ether, and mercuric chloride is bonded to the imidazole ring of the ionic liquid by a coordination bond. It is argued that the catalytic hydrochlorination of acetylene is carried out in the layer of ionic liquid fixed on the surface

- 1 029427

carrier, and allows to achieve a high degree of conversion of acetylene.

Finally, Chinese patent application 101716528 (inventor of Ζ1ιίνοη§ Уи) disclosed catalytic systems for obtaining VC by hydrochlorinating acetylene containing an ionic liquid (IL) based on imidazolium (which is an unprotonated cation) with chloride, bromide, hexafluorophosphate or tetrafate. anion and one or more of the chlorides of gold, platinum, palladium, tin, mercury, copper or rhodium.

It turns out that the latter aforementioned catalytic system leads to relatively high selectivity and high degrees of conversion, at least when it is used in a laboratory setup made of a chemically inert material (such as glass or Rugech). In this regard, the publication in Ogep Syt .. 2011, 13, 1495, one of the authors of which is Ζ1ιί \ Όη§ Уи, explicitly describes the glass reactor without mentioning any corrosion problem. In fact, glass was not intentionally chosen to take account of corrosion problems, but it was only a backup material used in a multi-purpose laboratory setup.

However, the applicant noted that, unexpectedly, the materials used in industrial equipment operating with the methods of the above-mentioned patent, which use amine hydrochloride, were subjected to rapid and severe corrosion if they were affected by the above-described hydrochlorination medium containing imidazolium. In addition, based on some of the tests, the applicant noted that this problem seems to be common at least for ILs containing at least one non-protonated cation and HC1.

Therefore, the applicant's patent application (AO 2012/113778) aims to protect equipment in the method of hydrohalogenating an unsaturated hydrocarbon (preferably acetylene) using IL as a catalyst, which is also at least partially carried out in an installation made of materials that are resistant to halogenated acids in dissociated form, or coated with such materials.

Now, the applicant has found that, unexpectedly, the catalysts according to the invention significantly reduce the aforementioned problem of corrosion during the hydrohalogenation of an unsaturated hydrocarbon using a catalyst which is an IL.

Therefore, the present invention relates to a method for the halogenation of an unsaturated hydrocarbon using a catalyst containing at least one ionic liquid (IL) and at least one metal, according to which said IL and metal are encapsulated inside a porous solid carrier.

Any unsaturated hydrocarbon can be used in the process of the invention. Preferably it is gaseous at the temperature of the hydrohalogenation reaction.

By unsaturated hydrocarbon is meant a component formed by carbon and hydrogen and having at least one double and / or triple bond between two C atoms; examples are acetylene, ethylene and the like.

In the framework of the invention, acetylene gives good results and is particularly preferred.

In a preferred embodiment of the invention, the hydrohalogenation reaction is hydrochlorination. This embodiment is particularly interesting when the unsaturated hydrocarbon is acetylene.

The method according to the invention, therefore, preferably is a method for the hydrochlorination of acetylene to obtain VC.

In the present description, the term "acetylene" should be understood as a source of acetylene, which can be either "pure" acetylene (commercially available), or mixtures containing acetylene, which can contain other components in addition to acetylene.

Such other components may be by-products of acetylene synthesis, for example, ethylene or other unsaturated hydrocarbons, gases, such as ₂ CO ₂ H ₂ , CO, H ₂ Oh and so on.

Acetylene is produced by partial combustion of methane, by oxidative cracking of a hydrocarbon source, using an arc discharge in a coal furnace, plasma in a coal furnace, or it is present as a by-product in the ethylene stream resulting from the cracking of hydrocarbons.

Another way to produce acetylene is to hydrate calcium carbide.

CAC production ₂ from Cao or CaCO ₃ and C requires extremely high temperatures of approximately 2000 ° C, which necessitates the use of electrical or the like.

When mixtures containing acetylene and ethylene are used, they can be used directly as such, that is, without the need to separate the components, since the higher reactivity of acetylene compared to ethylene should ensure first of all the hydrochlorination of acetylene with separation of the resulting BX and subsequent use of ethylene. This ethylene could be chlorinated to produce 1,2-dichloroethane (DCE) in a combined process.

- 2 029427

with getting BX. The pyrolysis of DCE can produce hydrogen chloride for the first reaction with acetylene.

Alternatively, since such hydrogen chloride resulting from the pyrolysis of DCE usually contains a small amount of acetylene, which is usually hydrogenated before the hydrogen chloride is recycled to the process, such acetylene can be supplied to the process of the present invention.

Therefore, according to one embodiment of the invention, the preferred hydrochlorination method according to the present invention is carried out after the pyrolysis of DCE in a method for producing DCE and VC from ethylene as an alternative to the hydrogenation of acetylene, sometimes used in such a method.

In the first variant, the catalyst of the invention is placed inside or downstream of a cooling device used to rapidly cool the pyrolysis gases.

In the second variant, the catalyst of the invention is placed in a column used to separate HC1 from BX and other components of rapidly cooled gases.

In the third variant, the catalyst of the invention is placed in a side stream withdrawn from a column used to separate HC1 from BX and other components of rapidly cooled gases. Side stream is taken from any position of the column below or above the feed point, preferably above the feed point. Side stream could be removed from the vapor phase or from the liquid phase, or from both phases circulating in the column. Preferably, the side stream is removed from the vapor phase. The reacted gas (i.e., the gas in which acetylene is converted to BX) is recycled downstream of pyrolysis in any suitable location. Suitable recirculation sites are, for example, a rapid cooling section, a column supply section, or a column itself.

In the fourth sub-variant, the catalyst of the invention is placed in the stream separated at the top of the column, preferably after a suitable heat treatment and / or pressure treatment of said stream.

In these embodiments, the catalyst is preferably of the cellular type and preferably has large channels in order to avoid blocking the channels with the resins.

In the context of the present invention, the expression "encapsulated inside a porous solid carrier" should be understood to mean that the ionic liquid and the metal, both, are physically localized mainly in the porous solid carrier; in other words, they are mainly in the cell formed by the porous solid carrier, they are mainly localized / held in the porous solid carrier — the nanopores of the gel are relatively firm, but preferably without any chemical bond.

According to the present invention, the word "mainly" means that essentially all of the ionic liquid and all of the metal are in a porous solid carrier, but this does not exclude that a small part of them can be present on the outer surface of the porous solid carrier, but in any case it is preferable without any chemical bond.

The porous solid support preferably contains silica or alumina. More preferably, the porous solid support contains silica, and more preferably it essentially consists of silica.

The catalyst used in the process of the invention is preferably prepared by mixing the precursor of a porous solid support with alcohol and preparing a mixture thereof; heating such a mixture and then adding IL and metal to it, preferably

mixed;

after obtaining a clear and homogeneous liquid mixture, add acid to the mixture and allow it to coagulate; and

aging the coagulated mixture to form a catalyst, preferably in the form of a powder.

This method can be classified as a sol-gel method, given that it provides the possibility that the ionic liquid and the metal are physically localized / encapsulated in a matrix of a porous solid carrier gel.

In another embodiment, the catalyst may also be obtained by

method of obtaining a catalyst (A) according to the method disclosed in patent application EP2617698 in the name

the applicant, the content of which is incorporated by reference in the present application, moreover, the specified catalyst contains a solid carrier, metal and ionic liquid;

mixing the catalyst (A) with a solution (B) in which the ionic liquid is preferably insoluble, moreover, said solution (B) contains a precursor of a porous solid carrier and alcohol to obtain a suspension (C);

adding acid to this suspension (C) and allowing it to coagulate; and aging the coagulated mixture to form a catalyst, preferably in the form of a powder.

The precursor of the porous solid carrier can be selected among the available precursors.

When the porous solid carrier is silicon dioxide, the precursor is preferably 3 029427

is selected from compounds corresponding to the formula δΐ (Ο-Κ.ι) (Ο-Κ.2) (Ο-Κ. ₃ ) (Ο-Κ4), in which K _one To ₂ To ₃ and K _four are alkyl chains, the same or different, preferably saturated, containing from 1 to 8 carbon atoms, preferably from 1 to 4 carbon atoms and more preferably from 1 to 3 carbon atoms. Preferably, when the porous solid support is silica, the precursor is selected from compounds corresponding to the formula δί (Ο- _one ) (Ο-Κ ₂ ) (ΟΚ ₃ ) (Ο-Κ _four ), in which K _one To ₂ To ₃ and K _four , all represent an ethyl group (tetraethoxyorthosilicate).

When the porous solid support is alumina, the precursor is preferably selected from aluminum alkoxides of the formula Α1 () ₃ and K are three alkyl groups, the same or different, preferably the same.

Any alcohol can be selected to produce the catalysts used in the process of the invention. Preferred alcohols are alcohols containing from 1 to 8 carbon atoms, preferably saturated. More preferably, the alcohols are those containing from 1 to 6 carbon atoms, preferably saturated. The most preferred alcohols are those containing from 1 to 4 carbon atoms, preferably saturated. Ethanol gives very good results.

Heating the precursor mixture of the porous solid support with alcohol can be carried out at any temperature suitable for the components present. Preferably, the heating is carried out at a temperature in the range from 40 to 75 ° C, preferably from 50 to 70 ° C and more preferably at 60 ° C.

The acid to be added may be selected from among any compound considered as Brønsted acid. Examples of acids that can be mentioned are HP, HBg, ΗΙ, HC1, Η ₂ δΟ ₃ Η ₂ δΟ _four ΗΝΟ ₂ ΗΝΟ ₃ Η ₂ ί '.' Ο ₃ . Η ₃ ΡΟ ₃ Η ₃ ΡΟ _four and their corresponding ammonium salts, as well as acetic acid. Preferably, the acid is ΗΟ or ΝΗ _four Ρ.

Aging of the coagulated mixture can be carried out at any temperature required for preparing the catalyst in suitable form. Preferably, this aging is carried out at a temperature in the range from 40 to 80 ° C, preferably from 50 to 70 ° C and more preferably at 60 ° C.

Depending on the content of unsaturated hydrocarbon, preferably acetylene, in the source of unsaturated hydrocarbon, preferably acetylene, the reaction of hydrohalogenation, preferably hydrochlorination, can be carried out preferably at a temperature in the range from -30 to 230 ° C. Higher temperatures are not recommended since the catalytic system tends to decompose.

In the method according to the present invention

when the source of unsaturated hydrocarbon, preferably acetylene, has an unsaturated hydrocarbon content, preferably acetylene, equal to or greater than 10%, the hydrohalogenation reaction, preferably hydrochlorination, is preferably carried out at a temperature of from 40 to 200 ° C;

when the content of unsaturated hydrocarbon, preferably acetylene, in the source of unsaturated hydrocarbon, preferably acetylene, is below 10%, the reaction of hydrohalogenation, preferably hydrochlorination, is carried out preferably at a temperature of from -30 to 200 ° C.

When the source of unsaturated hydrocarbon, preferably acetylene, has an unsaturated hydrocarbon content, preferably acetylene, equal to or greater than 10%, the preferred reaction temperature, i.e., providing the best compromise between performance, yield and stability of the catalytic medium, is more than or equal to 40 ° C. Then the best results are obtained at temperatures greater than or equal to 50 ° C, preferably at temperatures greater than or equal to 80 ° C and most preferably at temperatures greater than or equal to 110 ° C. Preferably, the reaction temperature does not exceed 200 ° C. In certain cases, the preferred reaction temperature was not more than 170 ° C or not even more than 130 ° C. At lower temperatures, lower corrosion rates and reduced coke formation are observed, but at higher temperatures, higher degrees of conversion may occur.

In the method according to the invention

when the source of unsaturated hydrocarbon, preferably acetylene, has an unsaturated hydrocarbon content, preferably acetylene, equal to or greater than 10%, the hydrohalogenation reaction, preferably hydrochlorination, is carried out preferably at a pressure below 10 MPa, preferably below 5 MPa, preferably below 2.5 MPa;

when the content of unsaturated hydrocarbon, preferably acetylene, in the source of unsaturated hydrocarbon, preferably acetylene, is below 10%, the reaction of hydrohalogenation, preferably hydrochlorination, is carried out preferably at a pressure below 5 MPa, preferably below 2.5 MPa and more preferably below 1 MPa.

However, the pressure preferably exceeds 5 Pa, preferably exceeds 8 Pa and more preferably exceeds 10 Pa.

Hydrohalogenation, preferably hydrochlorination, of an unsaturated hydrocarbon, is pre-4 029427

respectfully acetylene, could be carried out in the gas or in the liquid phase, preferably in the gas phase. Hydrohalogenation, preferably hydrochlorination, of an unsaturated hydrocarbon, preferably acetylene, is preferably carried out by bringing the gaseous reactants, preferably acetylene and hydrogen chloride, into contact with the catalyst in any suitable reactor.

The reaction of hydrohalogenation, preferably hydrochlorination, can be carried out in the traditional way in any equipment that promotes the contact of gas or liquid on solid materials. Such equipment is a carried bed, a pneumatic transfer, a cyclone, a fluidized bed, a vibrating bed, a fixed bed, a moving bed, a fluidized bed, a flowing bed, or any combination thereof.

In the first embodiment, the reaction is carried out in a fixed bed and / or in pre-assembled structures in which the ratio of the external surface to the volume (δ / Y) for the catalyst is preferably less than or equal to 6-10 ^four m ^-one preferably less than or equal to 3-10 ^four m ^-one preferably less than or equal to 2-10 ^four m ^-one and preferably more than or equal to 10 m ^-one preferably more than or equal to 20 m ^-one and preferably more than or equal to 25 m ^-one and this method involves continuously feeding the reaction zone containing a catalyst of at least an unsaturated hydrocarbon, preferably acetylene, and a hydrohalogenating reagent, preferably hydrochlorination, both in gaseous form, with a total linear velocity, preferably equal to or more than 0.005 m / s, preferably more than or equal to 0.008 m / s, 0.01 m / s, preferably more than or equal to 0.02 m / s and preferably less than or equal to 20 m / s, preferably less than or equal to 15 m / s, preferably more than less than or equal to 12 m / s, and when the pressure drop in the reaction zone, which is preferably less than or equal to 50 kPa / m, preferably less than or equal to 40 kPa / m and preferably less than or equal to 35 kPa / m.

The equipment for such a first embodiment may be a static fixed layer, a structured fixed layer, a catalytic structured packing, a cellular structure, and the like, or any combination of this equipment.

In the second embodiment, the reaction is carried out in a fluidized bed, in which the ratio of the external surface to the volume (δ / Y) for the catalyst is preferably less than or equal to 10 ^five m ^-one preferably less than or equal to 8-10 ^four m ^-one preferably less than or equal to 5-10 ^four m ^-one and more than or equal to 100 m ^-one preferably more than or equal to 200 m ^-one and preferably more than or equal to 250 m ^-one the method involves continuously feeding the reaction zone containing the catalyst of at least an unsaturated hydrocarbon, preferably acetylene, and a hydrohalogenating reagent, preferably hydrochlorination, both in gaseous form, with a total linear rate, preferably equal to or more than 0.15 m / s, preferably more than or equal to 0.25 m / s, preferably more than or equal to 0.4 m / s and preferably less than or equal to 6 m / s, preferably less than or equal to 4 m / s, preferably less than or equal to 3 m / s and at a pressure differential in the reaction zone, which preferably is less than or equal to 100 kPa / m, preferably less than or equal to 60 kPa / m.

Equipment capable of realizing a fluidized bed may be a fluidized bed, a moving bed, a vibrating bed, a flowing bed, a fluidized bed, and the like, or any combination of this equipment.

In the third embodiment, the reaction is carried out in a entrained flow, in which the ratio of the external surface to the volume (δ / Y) for the catalyst is preferably less than or equal to 2-10 ⁶ m ^-one preferably less than or equal to 1.2-10 ⁶ m ^-one preferably less than or equal to 6-10 ^five m ^-one and preferably more than or equal to 100 m ^-one preferably more than or equal to 200 m ^-one and preferably more than or equal to 250 m ^-one and this method involves continuously feeding the reaction zone containing a catalyst of at least an unsaturated hydrocarbon, preferably acetylene, and a hydrohalogenating reagent, preferably hydrochlorination, both in gaseous form, with a total linear rate, preferably equal to or more than 0.25 m / s, preferably more than or equal to 0.4 m / s, preferably more than or equal to 0.5 m / s and preferably less than or equal to 20 m / s, preferably less than or equal to 15 m / s, preferably e less than or equal to 12 m / s, where the pressure drop in the reaction zone is preferably less than or equal to 50 kPa / m, preferably less than or equal to 20 kPa / m and preferably less than or equal to 5 kPa / m.

The equipment that enables the realization of the entrained flow may be pneumatic transfer, entrained layer, circulating layer, cyclone and the like or any combination of this equipment.

In the present invention, a fixed bed and a fluidized bed are preferred, with a fixed bed being most preferred.

Catalyst particles are meant to mean a solid catalyst element, such as powders, extrusion products, granules, etc., cellular structures, catalytic microreactors and

- 5 029427

structured nozzles, such as Ka1arask®, Me1arask®, and so on. The catalyst may be a bulk catalyst or supported catalyst.

The catalyst particles could be assembled into substructures, such as cellular structures, catalytic microreactors, structured packing elements, and the like; individual particles could also be assembled in an orderly manner, such as in the form of a layer; or individual particles could be considered as an aggregate in a fluidized bed, entrained bed, vibrating bed, moving bed, spouting bed, fluidized bed, or the like.

When catalyst particles are assembled into substructures, the external catalyst volume can be calculated from the geometric average external dimensions of the catalyst substructures, using classical formulas to calculate the surface and volume. The catalyst surface can be calculated from the geometric average of the external and internal dimensions of the macroscopic element. If the shape of the catalyst particles cannot be determined, they are considered as spheres, and the geometric external dimension is the diameter of an equivalent sphere.

When catalyst particles are assembled in an orderly manner, such as in a fixed bed of various geometric shapes, the external volume can be calculated from the average geometric external dimensions of the catalyst layer using classical formulas to calculate the surface and volume. The catalyst surface can be calculated from the average geometric external and internal particle sizes. If the shape of the catalyst particles cannot be determined, they are considered as spheres, and the geometric external dimension is the diameter of an equivalent sphere.

When catalyst particles are considered as aggregates, such as in a fluidized bed, entrained layer, vibrating layer, moving bed, spouting layer, fluidized bed, or the like, the outer volume can be calculated from the geometric average outer dimensions of the catalyst bed at rest, using classical formulas for surface and volume calculations. The catalyst surface can be calculated from the geometric geometric external and internal dimensions of the individual catalyst particles in the bed. If the shape of the catalyst particles cannot be determined, they are considered as spheres, and the geometric external dimension is the diameter of an equivalent sphere.

In the method according to the invention, the catalyst particles can detect any shape. The catalyst particle is usually present in a form selected from the group consisting of rings, beads, pellets, tablets, extrusion products, granules, crushed, saddle, scaly, cellular structures, impregnated structured nozzles, and any mixture thereof.

When the catalyst is in the form of beads, the beads are considered as spheres, and the geometric external dimension is the diameter of an equivalent sphere.

When the catalyst is in the form of cylindrical particles (for example, pellets, extrusion products), the catalyst particles are considered as cylinders, and the geometric external dimensions are the average particle diameter and average particle length. The mean value can be geometric, arithmetic or logarithmic. Especially convenient is, for example, the arithmetic mean.

When the catalyst particles do not have a simple geometric shape, such as crushed particles, flakes, saddle particles, extrusion products of various shapes (stars, etc.), they are considered as spheres, and the geometric external dimensions are the diameter of an equivalent sphere.

When the catalyst particles are in the form of cylindrical rings, the catalyst particles are considered as hollow cylinders, and the geometrical dimensions are the average diameters (inner and outer) of the cylinders and the average length of the cylinders.

When the catalyst is in the form of a cellular structure with cylindrical channels, the geometric dimensions are the average values of the length and diameter of the channels.

The above are just a few examples of how to determine the geometric external dimensions of the catalyst particles needed to calculate the ratio of the external surface to the volume for the catalyst. A person of ordinary skill in the art will readily understand how to obtain these dimensions for any form of catalyst, including forms not disclosed above.

The value of the characteristic external dimensions of the catalyst particles can be obtained by any method, for example, by visual or microscopic measurements of individual catalyst particles, followed by averaging the measurement results over a sufficiently large number of particles (for example, more than 100) to be statistically significant, or, for example, from the distribution particles in size obtained by sieving, sedimentation (natural or forced) or by light scattering.

In the above embodiments, the implementation of the total linear velocity is understood as meaning the linear velocity of the total flow of gaseous material into the reaction zone containing the catalyst.

The total linear velocity is obtained by dividing the flow of the total supply of gaseous material into the reaction zone containing the catalyst into the cross section of this zone.

- 6 029427

The total supply of gaseous material can be measured by any method, such as, for example, through holes, venturi tubes, nozzles, nozzles, rotameters, pitot tubes, calorimetric, turbine, vortex, electromagnetic, Doppler, ultrasonic, thermal or coriolis flow meters.

The cross section of the specified reaction zone is understood as meaning the average cross section along the length of the specified reaction zone. The reaction zone may be horizontal or vertical.

The pressure drop over the reaction zone containing the catalyst is understood to mean a dynamic pressure drop, including the pressure drop corresponding to the hydraulic devices connected to the zone.

The pressure drop can be measured by any means, such as, for example, cells for measuring the pressure drop (Br), pressure gauges such as an E-tube pressure gauge, a cup pressure gauge, a Bourdon pressure gauge, a Piranni pressure gauge, an ionization pressure gauge, a diaphragm pressure gauge, a piezoelectric pressure gauge and any combination of them. Preferred means are selected from the group consisting of cells for measuring Br, manometer with I-tube, Bourdon manometer, membrane manometer, piezoelectric manometer, and any combination thereof. More preferred means are selected from the group consisting of cells for measuring Br, membrane pressure gauge, piezoelectric pressure gauge, and any combination thereof.

The embodiments described above, which can be combined, usually allow such a residence time to be obtained that a high conversion can be obtained, as well as to ensure a good dispersion of the reactants within the catalyst.

In the method according to the invention

when the source of unsaturated hydrocarbon, preferably acetylene, has an unsaturated hydrocarbon content, preferably acetylene, equal to or greater than 10%, the molar ratio of the hydrohalogenation reagent, preferably hydrogen chloride, to the unsaturated hydrocarbon, preferably acetylene, is preferably greater than or equal to 0.5, preferably more equal to 0.8 and preferably less than or equal to 3, preferably less than or equal to 1.5;

when the content of unsaturated hydrocarbon, preferably acetylene, in the source of unsaturated hydrocarbon, preferably acetylene, is below 10%, the molar ratio of the hydrohalogenation reagent, preferably hydrogen chloride, to the unsaturated hydrocarbon, preferably acetylene, is preferably more than or equal to 1000, preferably more than or equal to 5000 and less than or equal to 100,000, preferably less than or equal to 50,000, and preferably less than or equal to 20,000.

The unsaturated hydrocarbon, preferably acetylene, and the hydrohalogenation reagent, preferably hydrogen chloride, can be brought into contact in the reactor or preferably mixed before being introduced into the reactor.

The catalyst used in the present invention contains at least one ionic liquid (a liquid that exhibits ionic properties at least during the implementation of the method of the invention, that is, during the hydrohalogenation of the unsaturated hydrocarbon), therefore, containing at least one cation and at least one anion, and in one embodiment, containing at least one non-protonated cation and at least one anion.

In principle, ionic liquids are salts in a liquid state, while ordinary liquids, such as, for example, water and gasoline, are predominantly formed by electrically neutral molecules. Ionic liquids are preferably formed by ions. It should be noted that in the framework of this invention, the imidazoles themselves are not ionic liquids, but in the method of the invention involving the hydrohalogenation of an unsaturated hydrocarbon, they can become ionic liquids by reaction with a hydrohalogenating reagent (for example, HC1).

In general, it can be said that any salt that melts without decomposition will usually produce an ionic liquid. However, many salts melt at high temperatures, much higher than the temperatures used in catalytic processes. In the context of the present invention, the term "ionic liquid" will refer to a system that is liquid at the temperature used in the process in which the catalytic system is used.

Preferred ionic liquids in the context of the present invention are those that are liquid at temperatures of 150 ° C or less, more preferably at temperatures of 100 ° C or less, and more preferably at temperatures of 80 ° C or less. Moreover, preferred ionic liquids are those that have a very low vapor pressure and a very low flammability and which exhibit good electrical conductivity.

The ionic liquid, which preferably functions as a reaction medium, preferably has a solubility with respect to reagents (unsaturated hydrocarbon and hydrohalogenating reagent, such as, for example, acetylene and HC1), but preferably products (and, ultimately, intermediates) formed in the reaction (such as BX) are insoluble in the ionic liquid.

- 7 029427

In the present description, the expression "at least one ionic liquid" should be understood as meaning one or more than one ionic liquid.

Preferably, the catalyst contains only one ionic liquid, as defined above.

In the rest of the text, the expression "ionic liquid", used in the singular or plural, should be understood as denoting one or more than one ionic liquid, unless otherwise indicated.

In the present description, the expression "at least one non-protonated cation" is understood to mean one or more non-protonated cations.

Preferably, the ionic liquid contains one unprotonated cation.

In the rest of the text, the expression "unprotonated cation" used in a singular or plural number should be understood to mean one or more unprotonated cations, unless otherwise indicated.

The term “non-protonated cations” as used herein in the context of the present invention means cations that do not carry free hydrogen atom (s) at the atom (s) on which the positive charge of the cation is localized.

Preferably, the non-protonated cation is selected from

quaternary ammonium cations, which can be represented by the general formula [ ^one Κ ² Κ ³ Κ] +,

phosphonium cations, which can be represented by the general formula [RK ^one TO ² TO ³ K] +, and cations containing five- or six-membered heterocycles, which have at least

one nitrogen atom, preferably one or two nitrogen atoms.

Preferred cations containing five- or six-membered heterocycles are

imidazolium cations of the general formula (I)

pyridinium cations of general formula (II)

and

pyrrolidinium cations of general formula (III)

in which the radicals K and K ^one by K ⁹ , independently of each other, provided that the radical that carries (ut) atom (s) on which the positive charge of the cation is localized is not hydrogen, each can be hydrogen, optionally substituted saturated or unsaturated C _R WITH ₁₈ -alkyl group (preferably optionally substituted saturated or unsaturated With _one -WITH _sixteen is an alkyl group and, preferably, optionally substituted saturated or unsaturated With _one -WITH ₁₄ -alkyl group) optionally substituted saturated or unsaturated C ₂ WITH ₁₈ -alkyl group with a carbon chain interrupted by a single oxygen atom, or optionally substituted With ₆ -WITH ₁₂ -aryl group.

Preferably, the unprotonated cation is selected from quaternary ammonium cations, phosphonium cations, imidazole cations, pyridinium cations, and pyrrolidinium cations.

More preferably, the unprotonated cation is selected from phosphonium cations, imidazolium cations, pyridinium cations, and pyrrolidinium cations.

Most preferably, the non-protonated cation is selected from phosphonium cations and imidazolium cations. Particularly preferred are the latter, and more specifically: dialkyl imidazolium cations, and more preferably 1,3-dialkyl imidazole cations.

Examples of quaternary ammonium cations are tributylmethylammonium, butyltrimethylammonium, octyltrimethylammonium, tetramethylammonium, tetraethylammonium, tetrabutylammonium, methyl- 8 029427

trioctylammonium, 2-hydroxyethyltrimethylammonium and diethylmethyl (2-methoxyethyl) ammonium.

Examples of phosphonium cations are triisobutylmethylphosphonium, tributylmethylphosphonium, ethyltributylphosphonium, tetrabutylphosphonium, tetraoctylphosphonium, tributyltetradecylphosphonium, trihexyltetradecylphosphone, and xipherophone, and in the form of asphione) and also aspheres, and in the form of asparate, and also asparate, and in the form of asparate, and in the form of asparate, and in the form of asparate, and in the form of asparate, and in the form of asparate and in the way in the I and I and I, and I, and

Examples of imidazolium cations are 1,3-dimethylimidazolium, 1-ethyl-3-methyl-imidazolium, 1-butyl-3-methyl-imidazolium, 1-pentyl-3-methyl-imidazolium, 1-hexyl-3-methyl-imidazolium, 1-decyl-3-methyl-imidaz, 3metilimidazoly, 1-tetradecyl-3metilimidazoly, 1-hexadecyl-3metilimidazoly, 1- (2-hydroxyethyl) -3-methylimidazolium, 1-allyl-3metilimidazoly, 1-benzyl-3metilimidazoly, 1-phenylpropyl, 3- methylimidazolium, 1,3-diethylimidazolium, 1-butyl-3-ethylimidazolium, 1-methyl-3-propylimidazolium, 1-methyl-3-octylimidazolium, 1-methyl-3-octadecylimidazolium, 1,3-butyl-2-methylim idazolium, 1,3-didecyl-2-methylimidazolium, 1- (2-hydroxyethyl) -3-methylimidazolium, 1-ethyl-2,3-dimethylimidazolium, 1-propyl-2,3-dimethylimidazolium, 1-butyl-2, 3-dimethylimidazolium, 1-butyl-3,4-dimethyl-imidazolium, 1-hexyl-2,3-dimethyl-imidazolium, 1-hexadecyl-2,3-dimethyl-imidazolium, 1,2,3-trimethyl-imidazolium, 1,3,4-trimethyl-imidazolium, 1- butyl-3-ethylimidazolium, 1,3-dibutylimidazolium, 1-methyl-3-octylimidazolium, 1-butyl-3,4,5-trimethylimidazolium and 1,3,4,5-tetramethylimidazolium.

Examples of the pyridinium cations include 1-methylpyridinium, 1-ethylpyridinium, 1-propylpyridine, 1-butylpyridinium, 1-hexylpyridinium, 1-oktilpiridiny, 1,2-dimethylpyridine, 2-etil1-methylpyridinium, 1-butyl-2-methylpyridinium, 1- butyl-3-methylpyridinium, 1-butyl-4-methylpyridinium, 1-hexyl-3-methylpyridinium, 1-hexyl-4-methylpyridinium, 1-butyl-2-ethylpyridinium, 1-butyl-3ethylpyridinium, 4-methyl-1- Octylpyridinium, 1-butyl-2-ethyl-6-methylpyridinium, 2-ethyl-1,6-dimethylpyridinium, 1-butyl-3,4-dimethylpyridinium and 1-butyl-3,5-dimethylpyridinium.

Examples of the pyrrolidinium cation are 1,1-dimethylpyrrolidine, 1-ethyl-1-methylpyrrolidinium, 1-ethyl-3-methylpyrrolidinium, 1-butyl-1-methylpyrrolidinium, 1-hexyl-1-methylpyrrolidinium, 1-octyl-1-methylpyrrolidinium, 1-butyl-1-ethylpyrrolidinium and 1-methyl-1-propylpyrrolidinium.

In another embodiment, the cation may be a protonated cation, such as an imidazole cation, preferably a c-alkylated imidazole cation.

Preferably, the Ν-alkylated imidazole is defined by formula (IV)

in which the radicals K ^one To ² To ³ TO ^four can independently of each other, each represent hydrogen or an optionally substituted saturated or unsaturated CpC ^ -alkyl group.

Preferably Ν-alkylated imidazole is selected from 1-methylimidazole, 1-ethylimidazole, 1-butylimidazole, 1-geksilimidazola, 1-oktilimidazola, 1-detsilimidazola, 1-methyl-2-oktilimidazola, 1-ethyl-2-methylimidazole, 1-butyl -2-methylimidazole, 1-hexyl-2-methylimidazole and 1-decyl-2-methylimidazole. Even more preferred are α-alkylated imidazoles selected from 1 methyl imidazole, 1-ethyl imidazole and 1-butyl imidazole.

In the present description, the expression "at least one anion" is understood to mean one or more than one anion.

Preferably, the ionic liquid contains one anion.

In the rest of the text, the expression "anion", used in the singular or plural, should be understood as denoting one or more than one anion, unless otherwise indicated.

As anions, in principle, you can use any anions. The anion is preferably selected from

a group consisting of halides and halogen-containing anions and the so-called pseudohalides,

a group consisting of sulfates, sulfites and sulfonates,

a group consisting of phosphates,

a group consisting of phosphonates and phosphinates,

group consisting of phosphites,

a group consisting of phosphonites and phosphinites,

a group consisting of carboxylic acids,

group consisting of borates,

group consisting of boronaty,

a group consisting of carbonates and esters of carbonic acid, a group consisting of silicates and esters of silicic acid, a group consisting of salts of alkylsilanes and arylsilanes,

- 9 029427

a group consisting of carboximides, bis- (sulfonyl) imides, and sulfonylimides; a group consisting of alkoxides and aryloxides.

The anion (s) are preferably selected from the following anions: chloride, bromide, iodide, triflate (trifluoromethanesulfonate), tosylate, tetrafluoroethylsulfonate, bis-trifluoromethylsulfonylimide, tetrachloroferrate, tetrafluoroborate, tetrafluorophosphate and hexa-fluorophosphate, and tetrafluorophosphate;

The most preferred ILs are the imidazolium halide salts, and more specifically the chlorides. Chloride 1-butyl-3-methylimidazolium (BM1MC1) is particularly preferred since it is readily commercially available.

Methods for obtaining suitable ionic liquids are known to the person skilled in the art, and thus there is no need for their detailed description here, especially since some of them, in particular BM1MC1, are commercially available.

The catalyst used in the invention also contains at least one metal.

In the present description, the expression "at least one metal" is understood to mean one or more than one metal. Preferably, the catalyst contains only one metal.

The metal may be any metal. The metal is preferably selected from Ρά, Ρΐ, Au, Hg, Ki, δ, Ki, PH and 1g. Preferably, the metal is selected from Ρά, Ρΐ, Au, Nd Ki and Θδ.

Although good results are obtained when the metal is chosen among the metals listed above, very good results are obtained when the metal is chosen from Ρά, Ki, Au and Οδ, especially good results are obtained when the metal is chosen from, Ki and Au, and, more specifically, very good results are obtained when the metal is chosen from Ρά and ki. The most interesting results are obtained when the metal is Ρά.

The metal content in the catalyst according to the invention is preferably equal to or greater than 0.25 wt.% (Calculated on the total weight of the catalyst), preferably greater than 0.5 wt.%. In general, it is equal to or less than 10% by weight, preferably less than 5% by weight.

The term "metal" as used herein includes a metal compound, that is, a single compound of the same metal, as well as mixtures of different compounds of the same metal or a mixture of compounds of different metals or compounds containing two metals, which are defined above in the present description.

Preferably, the catalyst is prepared from a single compound of at least one metal, and more preferably from a single compound of a single metal.

The metal compound can be of any nature; however, it is usually a salt, more preferably a halide and more preferably a chloride.

Among the chloride-based compounds containing palladium (11), mention may be made of palladium chloride (11) and chloropalladates of alkali metals or alkaline earth metals, such as, for example, No. ₂ ( _four ) Κ ₂ ( _four ) Ρί ₂ ( _four ) and (ΝΗ _four ) ₂ ( _four ). Palladium (II) chloride gives good results.

All the embodiments described above provide very low degrees of corrosion of materials that can be used in an industrial installation during a normal industrial life (several years, typically at least 10 years) at design pressure, either in massive form or as a protective layer. , allowing the unit to withstand the corrosive effects of the reaction medium.

The protective layer could be made of the same material that provides the mechanical strength of the installation, or of another material.

Examples of materials that are resistant to halogenated acids, preferably HC1, in dissociated form, which can be used either in solid form or as a protective layer, are metals, fluorinated polymers, ceramics, graphite (impregnated), enamel and silicon carbide.

Examples of materials that can be used as a protective layer (made of a material that differs from that providing mechanical strength) are metals, such as, Ta, metal alloys, such as ΗαδΙοΙΙον® C276, No.Ms11ou® HB2, Mope1®, 1psoppe1 ®, 1по1о®, enamels, such as ΡΓα and ά1е ^ ®eta ^ 1 ννθ, ΡΓαιιάΚι®Αιηαί1 4300, ΡΓaaiά1e ^ ®eta ^ 1 A8C, fluorinated polymers, such as ΡΤΡΕ, ΡΡA, MPA, ΡΥΟΡ and so on.

For metals, the corrosion tolerance (or the degree of corrosion allowed before replacing the part affected by corrosion) is usually less than 5 mm, with a corrosion tolerance of less than 3 mm being preferable, a corrosion tolerance of less than 2 mm is preferable and a corrosion tolerance of less than 1.8 is particularly preferable mm The corrosion tolerance for metals is usually more than 0.01 mm, preferably more than 0.03 mm, and more preferably more than 0.05 mm.

For non-metallic protective layers, the layer thickness is usually more than 0.1 mm, preferably more than 0.3 mm, more preferably more than 0.5 mm. Typically, the thickness of the protective layer is less than 20 mm, preferably less than 15 mm and more preferably less than 10 mm.

The installation could be made from a single material or two materials. When usa- 10 029427

The machine is made of two materials, usually the carrier material is not in contact with the reaction medium and provides mechanical strength. The carrier material could be metal or plastic. Examples of carrier materials are carbon steel, glass-fiber reinforced polyester, polyethylene, polypropylene, PVC (polyvinyl chloride), and so on. Carbon steel is preferred. Bearing material that provides mechanical strength, usually exposed to corrosive external atmosphere. Preferably, the carrier material also has a protective layer against external corrosion. The outer protective layers could be a thickening of the same material or a layer of paint. When the protective layer is a thickening, it is usually more than 0.1 mm, preferably more than 0.3 mm and more preferably more than 0.5 mm, and moreover it is usually less than 5 mm, preferably less than 3 mm, and more preferably less than 2, 5 mm.

The following examples are intended to illustrate the invention without, however, limiting its scope.

Example 1 (Invention)

BM1MS1 (1.4 g) was melted for 5 minutes at 100 ° C. Then with stirring for 45 min was added RyS1 ₂ (0.097 g).

A mixture of tetraethoxyorthosilicate (ΤΕΟδ, 10 ml) and ethanol (7 ml) was heated to 60 ° C, and then a mixture containing BM1MS1 and RyuS1 ₂ , immediately transferred to a solution containing ΤΕΘδ.

After a clear and homogeneous liquid mixture was formed, hydrochloric acid (5 M, 5 ml) was added and the mixture gradually coagulated.

After aging at 60 ° C for 12 hours, the resulting solid material was dried in vacuum at 150 ° C for 3 hours, and then ground to obtain a fine powder.

The hydrochlorination reaction was carried out in a glass reactor having a diameter of 10 mm, equipped with a sintered glass disk at the bottom in order to obtain good dispersion of gaseous reactants, which are acetylene and hydrochloric acid.

The catalyst particles were placed as a fixed bed lying on the bottom of the reactor.

Temperature control in the system was carried out using a double-walled reactor with heat-transfer oil to maintain the desired temperature, controlled by a thermocouple socket located in the reactor itself.

Hydrochlorination carried out at 150 ° C using 1.543 g of catalyst and at a flow rate of 5 nl / h of gas for C ₂ H ₂ and 6 nl / h for HC1, gave conversion C ₂ H ₂ 24.6% and a selectivity of more than 99.8%, resulting in productivity (expressed in g VC / g catalyst / h) equal to 2.036 after 22 hours.

Example 2 (Invention)

The example was reproduced using 2.0 g BM1MS1 and 0.024 g RyC1 ₂ to obtain a catalyst.

The hydrochlorination was carried out in the same conditions, except that the amount of catalyst was 2.7 g

Conversion With ₂ H ₂ was 17.10%, and the selectivity of more than 99.8%, leading to productivity (expressed in g I / g catalyst / h), equal to 0.809 after 167 h.

Example 3 (Invention)

BM1MS1 (5.7 g) was melted for 5 minutes at 100 ° C. Then with stirring for 45 min was added RyS1 ₂ (0.39 g).

A mixture of tetraethoxyorthosilicate (ΤΕΟδ, 40 ml) and ethanol (28 ml) was heated to 60 ° C, and then a mixture containing BM1MS1 and RyuS1 ₂ , immediately transferred to a solution containing ΤΕΟδ.

After forming a clear and homogeneous liquid mixture, hydrochloric acid (5 M, 20 ml) was added and the mixture gradually coagulated.

An experiment to determine corrosion was performed as described here, after using a quantity of fresh catalyst. First, a plate of zirconium with a thickness of 1.5 +/- 0.2 mm was placed inside the reactor. Then the catalyst was added in such a way as to ensure that it covers at least 75% of the entire surface of the plate. Then the reaction was started under the conditions: flow rate 5 nl / h for C ₂ H ₂ and 6

- 11 029427

nl / h for HC1 at 150 ° C and stopped after 2 h. The plate was removed and then sent for analysis. These results were obtained according to ΆδΤΜ C1, version 1999. The measured corrosion was 330 μm / year.

If the disclosure of any patents, patent applications and publications that are incorporated into this application by reference, leads to a discrepancy with the description of this application to such an extent that it may make any term unclear, this description should be preferred.

Claims

CLAIM

1. A method of hydrohalogenating an unsaturated hydrocarbon using a catalyst containing at least one ionic liquid (IL) and at least one metal, according to which said IL and metal are encapsulated inside a porous solid carrier, with essentially all ionic liquid and all metal localized / held in a porous solid carrier relatively firmly, but without any chemical bond, i.e. essentially ionic liquid and all metal are in a porous solid carrier and only small I may part of them on the outer surface of the porous solid carrier, but without any chemical bond.

2. The method according to the preceding paragraph, in which the porous solid carrier contains silica or alumina.

3. The method according to any of the preceding paragraphs, wherein the porous solid support comprises silica.

4. A method according to any one of the preceding claims, wherein the catalyst is obtained by mixing the precursor of a porous solid support with alcohol and preparing a mixture thereof; heating such a mixture and then adding IL and metal to it;

after obtaining a clear and homogeneous liquid mixture, add acid to the mixture and allow it to coagulate and

aging the coagulated mixture to form the catalyst, preferably in the form of a powder.

5. The method according to claim 4, in which the alcohol is ethanol.

6. The method according to any of the preceding paragraphs, wherein

the hydrohalogenation reaction is carried out at a temperature of from 40 to 200 ° C, when the source of unsaturated hydrocarbon has an unsaturated hydrocarbon content equal to or greater than 10%;

when the content of unsaturated hydrocarbon in the source of unsaturated hydrocarbon is below 10%, the hydrohalogenation reaction is carried out at a temperature of from -30 to 200 ° C.

7. The method according to any of the preceding paragraphs, wherein

when the source of unsaturated hydrocarbon has an unsaturated hydrocarbon content equal to or greater than 10%, the hydrohalogenation reaction is carried out at a pressure below 10 MPa;

when the content of unsaturated hydrocarbon in the source of unsaturated hydrocarbon is below 10%, the reaction of hydrohalogenation is carried out at a pressure below 5 MPa.

8. The method according to any of the preceding paragraphs, in which the reaction is carried out in a fixed bed and / or in a pre-assembled structure in which the ratio of the outer surface to the volume (δ / ν) for the catalyst is from 6-10 ⁴ m ^-1 to 10 m ^-1 , moreover, this method includes a continuous flow into the reaction zone containing the catalyst, at least an unsaturated hydrocarbon and a hydrohalogenation reagent, both in gaseous form, at a total linear velocity of from 0.005 to 20 m / s, and when the difference pressure in the reaction th band less than or equal to 50 kPa / m.

9. The method according to any one of claims 1 to 7, in which the reaction is carried out in a fluidized bed, in which the ratio of the outer surface to the volume (δ / ν) for the catalyst is from 10 ⁵ to 100 m ^-1 , and this method includes continuous flow into the reaction zone containing the catalyst of at least an unsaturated hydrocarbon and hydrohalogenation reagent, both in gaseous form, with a total linear velocity of 0.15 to 6 m / s and with a pressure drop in the reaction zone less than or equal to 100 kPa / m

10. The method according to any one of claims 1 to 7, in which the reaction is carried out in entrained flow, in which the ratio of the external surface to the volume (δ / ν) for the catalyst ranges from 2-10 ⁶ to 100 m ^-1 , and this method includes continuous flow into the reaction zone containing the catalyst of at least an unsaturated hydrocarbon and a hydrohalogenation reagent, both in gaseous form, at a total linear velocity of between 0.25 and 20 m / s, and at a pressure drop in the reaction zone less than or equal to 50 kPa / m.

11. A method according to any one of the preceding claims, wherein

when the source of the unsaturated hydrocarbon has an unsaturated hydrocarbon content equal to or greater than 10%, the molar ratio of the hydrohalogenation reagent to the unsaturated hydrocarbon is from 0.5 to 3;

when the content of unsaturated hydrocarbon in the source of unsaturated hydrocarbon is 12 029427

less than 10%, the molar ratio of the halogen reactant to the unsaturated hydrocarbon is from 1000 to 100000.

12. A method according to any one of the preceding claims, wherein the IL is 1-butyl-3-methyl-imidazolium chloride (BM1MC1).

13. The method according to any one of the preceding claims, wherein the metal is py.

14. The method according to any of the preceding paragraphs, wherein said method is a method for hydrochlorinating acetylene to produce vinyl chloride.