RU2330834C1 - Method of selective catalytic methane chlorination to methyl chloride - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention concerns method of obtaining methyl chloride by selective catalytic chlorination of methane, involving throughput of a source reaction gas mix containing at least methane and chlorinating agent in the form of either elementary chlorine or a mix of chlorine hydride with oxygen, through at least one catalyst layer. At that, the catalyst features additionally active centres with increased acidity and deuterium/hydrogen exchange depth not less than 10% at the temperature of 350-355°C in the deuterium and hydrogen mix containing 0.6% of hydrogen, 0.6% of deuterium, 0.05% Ar and 98.75% nitrogen, at the volume deuterium-hydrogen mix feed rate of 20000 hours^-1 in the thermal regulated reaction mode at the heating rate of 10 K/minute. Active catalytic component is either platinum or copper, or silver. Catalyst carrier is microfibre of diametre of 1 to 20 micron, which can be structured in either non-woven or pressed material similar to wad or felt, or fibre of diametre of 0.5-5 mm, or woven material with lattice similar sateen, canvas, or openwork, with weave diametre of 0.5-5 mm.

EFFECT: high activity and selectivity of methane chlorination to methyl chloride at lower temperatures without production of polychlorinated hydrocarbons.

6 cl, 6 ex

Description

The invention relates to the field of chemical industry, and in particular to a method for producing a valuable intermediate product - methyl chloride, which, among other things, is a promising raw material for the production of ethylene and other light olefins.

Light olefins (ethylene, propylene) are valuable monomers used in industry for the production of polymers and also other valuable products of organic synthesis. Currently, the main source of light olefins is petroleum feed. Limited oil reserves and rising oil prices limit the possibilities for increasing the production of light olefins, the market demand for which shows a strong upward trend. In this regard, an urgent problem is the expansion of the raw material base for the production of light olefins, primarily the use of natural gas as a raw material. One of the promising ways to obtain light olefins from methane is based on the intermediate catalytic synthesis of methyl chloride by chlorination of methane. Methyl chloride can also be used in the manufacture of other valuable chemical products. The key factors determining the effectiveness of the method of producing methyl chloride are the high selectivity of methane chlorination with minimal formation of undesirable by-products (especially polychlorinated hydrocarbons) and a high degree of methane and chlorine conversion, determined by the activity of the catalyst.

A known method for the catalytic chlorination of methane using a silicalite catalyst having active centers, which are characterized in the IR spectra of adsorbed ammonia by the presence of an absorption band with wave numbers in the range of ν = 1410-1440 cm ^-1 , containing the active component and a high silica carrier, characterized by the presence in the spectrum NMR of ²⁹ Si lines with chemical shifts of -100 ^± 3 ppm (structural type ³ Q) and -110 ^± 3 ppm (structural type ⁴ Q) with a ratio of integrated intensities of the ³ Q / ⁴ Q lines from 0.7 to 1.2, in the infrared spectrum absorption bands of hydroxyl groups with a wave number ν = 3620-3650 cm ^-1 and a half-width of 65-75 cm ^-1 , having a specific surface measured by the BET method for thermal desorption of argon, S _Ar = 0.5-30 m ² / g, surface area measured by the method of alkaline titration, S _Na = 10-250 m ² / g with the ratio S _Na / S _Ar = 5 -30 (RF Patent No. 2250890, IPC С07С 17/10, B01J 21/08, priority dated 12/26/2003, publ. 12/27/2005, BI No. 12).

The disadvantages of this method are the relatively low activity of the catalyst and the consequent need to increase the reaction temperature (more than 300 ° C), to achieve maximum methane conversion, and, as a result, the formation of undesirable by-products of polychlorinated methanes (methylene chloride, chloroform, carbon tetrachloride).

The authors were tasked with developing a method for the selective catalytic chlorination of methane, which provides high activity and selectivity for the conversion of methane to methyl chloride at sufficiently low temperatures.

The problem is solved in that in a method for the selective catalytic chlorination of methane, comprising passing an initial gas reaction mixture containing at least methane and a chlorinating agent, which is either elemental chlorine or a mixture of hydrogen chloride and oxygen through at least one catalyst bed having active sites which are characterized in the IR spectra of adsorbed ammonia by the presence of absorption bands with wave numbers in the range ν = 1410-1440 cm ^-1, containing an active COMPONENT nt vysokokremnezemisty medium and characterized by the presence in the ²⁹ Si NMR spectrum of lines with chemical shifts -100 ^± 3 ppm (structural type ³ Q) and -110 ^± 3 ppm (structural type ⁴ Q) with a ratio of integrated intensities of the ³ Q / ⁴ Q lines from 0.7 to 1.2, in the infrared spectrum absorption bands of hydroxyl groups with a wave number ν = 3620-3650 cm ^-1 and a half-width of 65-75 cm ^-1 , having a specific surface measured by the BET method for thermal desorption of argon, S _Ar = 0.5-30 m ² / g, surface area measured by the method of alkaline titration, S _Na = 10-250 m ² / g with the ratio S _Na / S _Ar = 5 -30, additionally active sites with high acidity are formed on the catalyst, characterized by the depth of deuterium-hydrogen exchange not lower than 10% at a temperature of 350-355 ° C in a mixture of deuterium and hydrogen containing 0.6% hydrogen, 0.6% deuterium, 0.05% Ar and 98.75% nitrogen, with a volumetric flow rate of the specified deuterium-hydrogen mixture of 20,000 hr ^-1 in a thermoprogrammed reaction mode at heating rate 10 K / min. The active component of the catalyst is one of the metals - either platinum, or copper, or silver. The catalyst carrier is made in the form of microfibers with a diameter of 1 to 20 μm, which can be structured as either non-woven or extruded material such as cotton wool or felt, or threads with a diameter of 0.5-5 mm, or woven from threads with a satin-type weave, canvas, lace with a mesh diameter of 0.5-5 mm.

The technical effect of the proposed method is to achieve high activity and selectivity of methane chlorination to methyl chloride at low temperatures without the formation of polychlorinated hydrocarbons.

To implement the method, a reaction mixture containing at least methane and a chlorinating agent — elemental chlorine or a mixture of hydrogen chloride and oxygen — is passed through a catalyst bed having active centers, which are characterized by the presence of an absorption band with wave numbers in the IR spectra of adsorbed ammonia in the range of ν = 1410-1440 cm ^-1 , containing the active component and a high siliceous carrier, characterized by the presence in the NMR spectrum of ²⁹ Si lines with chemical shifts of -100 ^± 3 ppm (structural type ³ Q) and -110 ^± 3 ppm (structural type ⁴ Q) with a ratio of integrated intensities of the ³ Q / ⁴ Q lines from 0.7 to 1.2, in the infrared spectrum absorption bands of hydroxyl groups with a wave number ν = 3620-3650 cm ^-1 and a half-width of 65-75 cm ^-1 , having a specific surface measured by the BET method for thermal desorption of argon, S _Ar = 0.5-30 m ² / g, surface area measured by the method of alkaline titration, S _Na = 10-250 m ² / g with the ratio S _Na / S _Ar = 5 -30, on which active centers with increased acidity are additionally formed, the presence of which is characterized by the depth of deuterohydrogen Nogo sharing at least 10%, carried out under the following conditions: temperature of 350-355 ° C, the mix of deuterium and hydrogen - 0.6% hydrogen, 0.6% of deuterium, 0.05% Ar, and 98.75% nitrogen, a space velocity of 20000 h ^-1 in the mixture thermoprogrammed reaction mode at a heating rate of 10 K / min. The indicated depth of deuterium-hydrogen exchange under the indicated conditions is an unambiguous evidence of the presence of specific super-acid active centers in the catalyst, which provide high activity (including at low temperatures) and selectivity of the catalyst in the reaction of methane chlorination to methyl chloride. The creation of such centers can be carried out by targeted modification of the catalyst by various known methods at the stage of its preparation, in particular by sulfation (X.Song, A.Sayati, Catal. Rev., Sci. Eng., 38 (3), p.329- 412, 1996). The active component of the catalyst may be either one of the platinum group metals, or copper, or silver.

To implement the method using a catalyst prepared using a carrier in the form of microfibers with a diameter of from 1 to 20 microns. The carrier may be formed in the form of flexible, permeable to the flow of the reaction mixture, fiberglass structures made in the form of threads, woven or pressed materials. This structuring simplifies the placement and fixing of the catalyst layer in the catalytic reactor and prevents the entrainment of microfibers of the catalyst with the reaction stream.

Chlorination of methane according to the described method provides a high yield of methyl chloride at low temperatures, and polychlorinated hydrocarbons are practically not formed. The catalyst used in the method is characterized by increased selectivity, activity, stability and a high service life without the need for regeneration and reactivation procedures.

Example 1

The methane chlorination process is carried out at atmospheric pressure, a temperature of 240 ° C, a volumetric feed rate of the mixture of 500-800 h ^-1 , the volumetric ratio of methane and chlorine in the initial mixture is 2: 1. A catalyst containing platinum on a fiberglass support is used, characterized by the presence of ²⁹ Si lines with chemical shifts of -100 ^± 3 ppm in the NMR spectrum. (structural type ³ Q) and -110 ^± 3 ppm (structural type ⁴ Q) with a ratio of integrated intensities of ³ Q / ⁴ Q lines from 0.7 to 1.2, in the infrared spectrum by absorption bands of hydroxyl groups with a wave number of ν = 3620-3650 cm ^-1 and a half-width of 65-75 cm ^-1 , having a specific surface measured by the BET method for thermal desorption of argon, S _Ar = 0.5-30 m ² / g, surface area measured by the method of alkaline titration, S _Na = 10-250 m ² / g with the ratio S _Na / S _Ar = 5 -30, and in the process of preparation, the catalyst is subjected to gas-phase sulfation with a mixture of SO ₂ (5-15%) and air at a temperature of 200-500 ° C after blowing calcination for the formation of acidic active sites characterized by a deuterium-hydrogen exchange depth of at least 10% at a temperature of 350-355 ° C in a mixture of deuterium and hydrogen containing 0.6% hydrogen, 0.6% deuterium, 0.05% Ar and 98.75% nitrogen, at a volumetric feed rate the specified deuterium-hydrogen mixture of 20,000 h ^-1 in a thermoprogrammed reaction mode at a heating rate of 10 K / min.

The catalytic activity increases sharply so that when chlorine is converted, 100% methane conversion is achieved, close to stoichiometric, methyl chloride formation selectivity reaches 96%, while the only by-product of chlorination is methylene chloride. Chloroform and carbon tetrachloride are absent in the reaction products.

In the method adopted for the prototype, where a catalyst is used in which the depth of deuterium-hydrogen exchange under the above conditions is less than 2%, under similar conditions, an equal level of methane conversion is observed at temperatures not lower than 300 ° C, while the methyl chloride selectivity is reduced to 85%, Among the by-products along with methylene chloride, polychlorinated hydrocarbons (chloroform) appear.

Example 2

The methane chlorination process is carried out at atmospheric pressure, a temperature of 180 ° C, a volumetric feed rate of the mixture of 300-500 h ^-1 , the volumetric ratio of methane and chlorine in the initial mixture is 4: 1. A catalyst containing platinum on a fiberglass support is used, characterized by the presence of ²⁹ Si lines with chemical shifts of -100 ^± 3 ppm in the NMR spectrum. (structural type ³ Q) and -110 ^± 3 ppm (structural type ⁴ Q) with a ratio of integrated intensities of ³ Q / ⁴ Q lines from 0.7 to 1.2, in the infrared spectrum by absorption bands of hydroxyl groups with a wave number of ν = 3620-3650 cm ^-1 and a half-width of 65-75 cm ^-1 , having a specific surface measured by the BET method for thermal desorption of argon, S _Ar = 0.5-30 m ² / g, surface area measured by the method of alkaline titration, S _Na = 10-250 m ² / g with the ratio S _Na / S _Ar = 5 -30, and in the process of preparation, the catalyst is subjected to gas-phase sulfation with a mixture of SO ₂ (5-15%) and air at a temperature of 200-500 ° C after blowing calcination for the formation of acidic active sites characterized by a deuterium-hydrogen exchange depth of at least 10% at a temperature of 350-355 ° C in a mixture of deuterium and hydrogen containing 0.6% hydrogen, 0.6% deuterium, 0.05% Ar and 98.75% nitrogen, at a volumetric feed rate the specified deuterium-hydrogen mixture of 20,000 h ^-1 in a thermoprogrammed reaction mode at a heating rate of 10 K / min.

Under these conditions, the catalyst exhibits high catalytic activity so that upon chlorine conversion, 100% stoichiometric methane conversion and almost 100% methyl chloride selectivity are achieved. In the method adopted for the prototype, under these conditions, the methane conversion at the same selectivity for the formation of methyl chloride does not exceed 10%, so that unreacted chlorine is observed among the reaction products.

Example 3

The methane chlorination process is carried out at atmospheric pressure, a temperature of 260 ° C, a volumetric feed rate of the mixture of 500-800 h ^-1 , the volumetric ratio of methane and chlorine in the initial mixture is 3: 1. A catalyst containing platinum on a fiberglass support is used, characterized by the presence of ²⁹ Si lines with chemical shifts of -100 ^± 3 ppm in the NMR spectrum. (structural type ³ Q) and -110 ^± 3 ppm (structural type ⁴ Q) with a ratio of integrated intensities of ³ Q / ⁴ Q lines from 0.7 to 1.2, in the infrared spectrum by absorption bands of hydroxyl groups with a wave number of ν = 3620-3650 cm ^-1 and a half-width of 65-75 cm ^-1 , having a specific surface measured by the BET method for thermal desorption of argon, S _Ar = 0.5-30 m ² / g, surface area measured by the method of alkaline titration, S _Na = 10-250 m ² / g with the ratio S _Na / S _Ar = 5 -30, and in the process of preparation, the catalyst is subjected to gas-phase sulfation with a mixture of SO ₂ (5-15%) and air at a temperature of 200-500 ° C after by calcining at 400–650 ° С to form acidic active sites characterized by a depth of deuterium-hydrogen exchange of at least 10% at a temperature of 350–355 ° С in a mixture of deuterium and hydrogen containing 0.6% hydrogen, 0.6% deuterium, 0.05% Ar, and 98.75% nitrogen, with a volumetric feed rate of the specified deuterium-hydrogen mixture 20,000 h ^-1 in a thermally programmed reaction mode at a heating rate of 10 K / min

The catalyst is highly active, so that with a complete conversion of chlorine, an almost stoichiometric conversion of methane is achieved. The selectivity of the formation of methyl chloride is 97% and the only by-product of the reaction is methylene chloride. Chloroform and carbon tetrachloride are absent in the reaction products.

In the method adopted for the prototype, where a catalyst is used in which the depth of the deuterium-hydrogen exchange is less than 2%, complete conversion of chlorine is not achieved under similar conditions, and the selectivity for methyl chloride is 96%.

Example 4

The methane chlorination process is carried out with a mixture of HCl and air at atmospheric pressure, a temperature of 350 ° C, a volumetric feed rate of the mixture of 500-800 h ^-1 , the volumetric ratio of methane, HCl and air in the initial mixture 2: 1: 3. A catalyst containing platinum on a fiberglass support is used, characterized by the presence of ²⁹ Si lines with chemical shifts of -100 ^± 3 ppm in the NMR spectrum. (structural type ³ Q) and -110 ^± 3 ppm (structural type ⁴ Q) with a ratio of the integrated intensities of the Q ³ / Q ⁴ lines from 0.7 to 1.2, in the infrared spectrum by the absorption bands of hydroxyl groups with a wave number of ν = 3620-3650 cm ^-1 and a half-width of 65-75 cm ^-1 , having a specific surface measured by the BET method for thermal desorption of argon, S _Ar = 0.5-30 m ² / g, surface area measured by the method of alkaline titration, S _Na = 10-250 m ² / g with the ratio S _Na / S _Ar = 5 -30, and in the process of preparation, the catalyst is subjected to gas-phase sulfation with a mixture of SO ₂ (5-15%) and air at a temperature of 200-500 ° C after by calcining at 400–650 ° С to form acidic active sites characterized by a depth of deuterium-hydrogen exchange of at least 10% at a temperature of 350–355 ° С in a mixture of deuterium and hydrogen containing 0.6% hydrogen, 0.6% deuterium, 0.05% Ar, and 98.75% nitrogen, with a volumetric feed rate of the specified deuterium-hydrogen mixture 20,000 h ^-1 in a thermally programmed reaction mode at a heating rate of 10 K / min

The catalyst is highly active so that the methane conversion reaches 54%, hydrogen chloride is close to 100%, and the selectivity for methyl chloride is 92%. In products, in addition to methyl chloride and 0.5% methylene chloride, 0.3% CO and CO _{2 are} detected. In the method adopted for the prototype, the methane conversion does not exceed 20%, and the methyl chloride selectivity is reduced to 80%.

Example 5

The same as in example 3. Use a catalyst containing copper on a glass fiber carrier, characterized by the presence in the NMR spectrum of ²⁹ Si lines with chemical shifts of -100 ^± 3 ppm (line Q ³ ) and -110 ^± 3 ppm. (line Q ⁴ ) with a ratio of the integrated intensities of the lines Q ³ / Q ⁴ from 0.7 to 1.2, in the infrared spectrum absorption bands of hydroxyl groups with a wave number of ν = 3620-3650 cm ^-1 and a half-width of 65-75 cm ^-1 having a specific surface measured by the BET method for thermal desorption of argon, S _Ar = 0.5-30 m ² / g, surface area measured by the method of alkaline titration, S _Na = 10-250 m ² / g with the ratio S _Na / S _Ar = 5- 30, wherein during preparation, the catalyst mixture is subjected to gas phase sulphation SO ₂ (5-15%) and air at a temperature of 200-500 ° C followed by direct tracing for the formation of acidic active sites characterized by a deuterium-hydrogen exchange depth of at least 10% at a temperature of 350-355 ° C in a mixture of deuterium and hydrogen containing 0.6% hydrogen, 0.6% deuterium, 0.05% Ar and 98.75% nitrogen, with a volumetric feed rate of deuterohydrogen mixture 20,000 h ^-1 in a thermoprogrammed reaction mode at a heating rate of 10 K / min.

Under these conditions, the catalytic activity increases sharply so that a complete conversion of chlorine results in a stoichiometric conversion of methane, and the selectivity of the formation of methyl chloride is 96%, while the only by-product of chlorination is methylene chloride. Chloroform and carbon tetrachloride are absent in the reaction products.

In the method adopted for the prototype, where a catalyst is used in which the depth of deuterium-hydrogen exchange under the above conditions is less than 2%, under similar conditions an equal level of methane and chlorine conversion is observed at temperatures above 300 ° C, while the methyl chloride selectivity is less than 90% , and the main by-products are polychlorinated hydrocarbons (mainly methylene chloride, chloroform).

Example 6

The same as in example 5. Use a catalyst containing silver on a glass fiber carrier, characterized by the presence in the NMR spectrum of ²⁹ Si lines with chemical shifts of -100 ^± 3 ppm (line Q ³ ) and -110 ^± 3 ppm. (line Q ⁴ ) with a ratio of the integrated intensities of the lines Q ³ / Q ⁴ from 0.7 to 1.2, in the infrared spectrum absorption bands of hydroxyl groups with a wave number of ν = 3620-3650 cm ^-1 and a half-width of 65-75 cm ^-1 having a specific surface measured by the BET method for thermal desorption of argon, S _Ar = 0.5-30 m ² / g, surface area measured by the method of alkaline titration, S _Na = 10-250 m ² / g with the ratio S _Na / S _Ar = 5- 30, wherein during preparation, the catalyst mixture is subjected to gas phase sulphation SO ₂ (5-15%) and air at a temperature of 200-500 ° C followed by direct tracing for the formation of acidic active sites characterized by a deuterium-hydrogen exchange depth of at least 10% at a temperature of 350-355 ° C in a mixture of deuterium and hydrogen containing 0.6% hydrogen, 0.6% deuterium, 0.05% Ar and 98.75% nitrogen, with a volumetric feed rate of deuterohydrogen mixture 20,000 h ^-1 in a thermoprogrammed reaction mode at a heating rate of 10 K / min.

The catalyst is highly active so that a complete conversion of chlorine results in a stoichiometric conversion of methane and a selectivity of methyl chloride formation of 95%, with methylene chloride being the only by-product of chlorination. Chloroform and carbon tetrachloride are absent in the reaction products.

In the method adopted for the prototype, where a catalyst is used in which the depth of deuterium-hydrogen exchange under the above conditions is less than 2%, under similar conditions, an equal level of methane conversion is observed at temperatures above 300 ° C, while the methyl chloride selectivity is less than 90%, and The main by-products are polychlorinated hydrocarbons (mainly methylene chloride, chloroform).

Claims (6)

1. A method for the selective catalytic chlorination of methane to methyl chloride, comprising passing an initial gas reaction mixture containing at least methane and a chlorinating agent, which is either elemental chlorine or a mixture of hydrogen chloride and oxygen through at least one catalyst bed, having active centers, which are characterized in the IR spectra of adsorbed ammonia by the presence of absorption bands with wave numbers in the range ν = 1410-1440 cm ^-1, containing the active ingredient and vysokokremnezemist second carrier, characterized by the presence in the ²⁹ Si NMR spectrum of lines with chemical shifts -300 ^± 3 ppm (structural type ³ Q) and -110 ^± 3 ppm (structural type ⁴ Q) with a ratio of integrated intensities of the ³ Q / ⁴ Q lines from 0.7 to 1.2, in the infrared spectrum absorption bands of hydroxyl groups with a wave number of ν = 3620-3650 cm ^-1 and a half-width of 65-75 cm ^{- 1} having a specific surface area measured by the BET method for thermal desorption of argon, S _Ar = 0.5-30 m ² / g, surface area measured by the method of alkaline titration, S _Na = 10-250 m ² / g with the ratio S _Na / S _Ar = 5-30, characterized in that it further formed on the catalyst active sites with high acidity, characterized depth Deit hydrogen exchange not less than 10% at a temperature of 350-355 ° C in a mixture of deuterium and hydrogen containing 0.6% hydrogen, 0.6% deuterium 0.05% Ar and 98.75% nitrogen, with a volumetric feed rate of the specified deuterium mixture 20,000 h ^-1 in a thermoprogrammed reaction mode at a heating rate of 10 K / min. 2. The method according to claim 1, characterized in that the active component of the catalyst is one of the metals of the platinum group. 3. The method according to claim 2, characterized in that the active component of the catalyst is platinum. 4. The method according to claim 1, characterized in that the active component of the catalyst is copper. 5. The method according to claim 1, characterized in that the active component of the catalyst is silver. 6. The method according to any one of claims 1 to 5, characterized in that the catalyst carrier is in the form of microfibers with a diameter of 1 to 20 microns, structured as either non-woven or pressed material such as cotton wool or felt, or threads with a diameter of 0.5-5 mm, or woven from threads of material with weaving such as satin, canvas, lace with a mesh diameter of 0.5-5 mm.