RU2333192C1 - Method of obtaining light olefins from methylchloride - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention concerns a method of obtaining low olefins from methylchloride involving passing of source gas reaction mix containing at least methylchloride over at least one catalyst layer with active centres characterised by the presence of absorption band with wave numbers within ν=1410-1440 cm^-1 in the infrared spectres of adsorbed ammonium, the catalyst containing active component and high-silica carrier characterised by the presence of Si bands with chemical shifts of -100^±3 ppm (band Q³) and -110^±3 ppm (band Q⁴) in the NMR²⁹ spectres with integrated intensity ratio of Q³/Q⁴ bands within 0.7 to 1.2, and by hydroxyl groups absorption bands with wave number ν=3620-3650 cm^-1 and half-width 65-75 cm^-1 in the infrared spectre, and specific surface area measured by BET method by argon heat desorption S_Ar=0.5-30 m²/g, surface area measured by alkali titration method S_Na=10-250 m²/g at the S_Na/S_Ar ratio of 5-30. The method also involves formation of active centres with higher acidity in the catalyst characterised by deuterium-hydrogen exchange depth of not less than 10% at 350-355°C in a deuterium and hydrogen mix containing 0.6% of hydrogen, 0.6% of deuterium, 0.05% of Ar and 98.75% of nitrogen, at volume feed rate of the said deuterium-hydrogen mix of 20000 h^-1 in thermoprogrammed reaction mode at heating rate of 10 K/min and/or by additional introduction of either copper, or zinc, or silver to the active component content.

EFFECT: high selectivity of methylchloride transformation to light olefins together with high ethylene yield and improved deactivation resistance of catalyst.

3 cl, 8 ex

Description

The invention relates to the field of chemical industry, and in particular to methods for producing valuable lower olefins, primarily ethylene, from methyl chloride.

Light olefins (ethylene, propylene) are valuable intermediates and are used in industry for the production of polymers and other valuable organic synthesis products. Currently, the main source of light olefins is petroleum feed. Limited oil reserves limit the ability to increase 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.

A promising direction for the development of methods for producing ethylene from methane is the preliminary chlorination of methane to methyl chloride:

followed by dehydrochlorination of methyl chloride in ethylene and other light olefins:

Theoretically, this way allows one to achieve a high yield of ethylene with reduced energy consumption and minimal formation of by-products, while ensuring high selectivity and high degrees of conversion of the reactants in reactions (1) and (2).

There is a method of achieving high selectivity in methane chlorination reactions, therefore, the key task is to ensure high selectivity and high degrees of conversion of the reactants in the dehydrochlorination reaction (2) (RF patent No. 2250890, IPC С07С 17/10, priority dated 12/26/2003, publ. 27.04. 2005).

There is also known a method of dehydrochlorination of methyl chloride to obtain light olefins based on the use of aluminosilicate and zeolite catalysts (US patent 2004186334, "Methane to olefins", IPC C07C 1/00, publ. 2004.09.23).

A disadvantage of the known methods is the low yield of olefins, as well as the rapid deactivation of the catalyst.

Closest to the proposed invention is a method for the catalytic dehydrochlorination of methyl chloride using silica glass fiber catalyst (RF patent No. 2250890, IPC С07С 17/10, priority dated 12/26/2003, publ. 04/27/2005). The catalyst is characterized in the IR spectra of adsorbed ammonia by the presence of an absorption band with wave numbers in the range ν = 1410-1440 cm ^-1 , contains an active component and a high siliceous carrier, characterized by the presence of ²⁹ Si lines with chemical shifts of -100 ^± 3 ppm in the NMR spectrum. (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 , has 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- thirty. The use of this catalyst allows one to achieve high selectivity for the formation of ethylene in reaction (2), as well as high resistance of the catalyst to deactivation.

The disadvantage of this method is the low conversion of methyl chloride to ethylene according to reaction (2) (not higher than 5%).

The authors were tasked with developing a method for producing light olefins, primarily ethylene, from methyl chloride, which provides high selectivity for the conversion of methyl chloride to light olefins in combination with an increased yield of ethylene and an increased resistance to deactivation of the catalyst.

The problem is solved in that in a method for producing lower olefins from methyl chloride, comprising passing an initial gas reaction mixture containing at least methyl chloride through at least one catalyst layer having active centers that are characterized in the IR spectra of adsorbed ammonia by an absorption band with wave numbers in the range 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 (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, additionally active sites with increased acidity are formed on the catalyst, characterized by a deuterium-hydrogen exchange depth of 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-hydrogen mixture of 20,000 h ^-1 in a thermoprogrammed reaction mode at a heating rate of 10 K / min, or / and additionally enter into the composition of the active component either copper, or zinc, or silver. The catalyst carrier can be made in the form of microfibers with a diameter of 1 to 20 μm, and the catalyst carrier fibers can be 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 with weaving type satin, canvas, lace with a mesh diameter of 0.5-5 mm.

The technical effect of the proposed method is to increase the yield of ethylene and other light olefins in the reactions of dehydrochlorination of methyl chloride.

To implement the method, the reaction mixture containing at least methyl chloride is passed through a catalyst bed 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 ν = 1410-1440 cm ^-1 , containing the active component and highly siliceous 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- thirty. Active sites with increased acidity are additionally formed on the catalyst, the presence of which is characterized by a depth of deuterium-hydrogen exchange of at least 10%, carried out under the following conditions: temperature 350-355 ° C, the composition of the mixture of deuterium and hydrogen is 0.6% hydrogen, 0.6% deuterium, 0.05% Ar and 98.75% nitrogen, the volumetric feed rate of the mixture is 20,000 h ^-1 in a thermoprogrammed reaction mode at a heating rate of 10 K / min, or / or zinc, copper, or silver are introduced into the active component. 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 ensure high activity and selectivity of the catalyst in the dehydrochlorination reaction of methyl chloride (2). 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.

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 can 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.

Obtaining light olefins from methane according to the described method provides a high yield of target products (mainly ethylene) at reduced temperatures. 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

Methyl chloride in a mixture with argon (1: 1) is supplied with a space velocity of 400 h ⁻¹ at a temperature of 450 ° C to a catalyst bed 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 ν = 1410- 1440 cm ^-1 containing the active component and high siliceous 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 450-550 ° C followed by direct tracing for the formation of acid catalytically active centers characterized by a depth of deuterium-hydrogen exchange 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% argon and 98.75% nitrogen, with a volumetric feed rate the specified deuterium-hydrogen mixture of 20,000 h ^-1 in a thermally programmed reaction mode at a heating rate of 10 K / min.

A conversion of 10% methyl chloride is achieved with a 95% ethylene selectivity (3% propylene selectivity, ethane, propane by-products). In the method adopted for the prototype, under similar conditions, there is a 1.5% conversion of methane chloride at 90% selectivity for ethylene.

Example 2

The same as in example 1, but the volumetric feed rate of the mixture 300 h ^-1 . The conversion of methyl chloride increases to 17.5% with a selectivity of conversion to ethylene of 94%.

Example 3

Methyl chloride in a mixture with argon (1: 1) is supplied with a bulk velocity of 300 h ⁻¹ at a temperature of 450 ° C to a catalyst bed 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 ν = 1410- 1440 cm ^-1 , containing the active component, into which zinc and a high-siliceous support are introduced, which are glass fibers, characterized by the presence of ²⁹ Si lines with chemical shifts of -100 ± 3 ppm in the NMR spectrum. (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 of the absorption band 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- thirty.

A conversion of methyl chloride of 20% is achieved with a 94% selectivity for ethylene (selectivity for propylene - 4%, the rest is ethane, propane).

Example 4

The same as in example 3, but copper is introduced into the active component of the catalyst.

The conversion of methyl chloride is 15% with a 96% ethylene selectivity (propylene selectivity 3%, the rest is ethane, propane).

Example 5

The same as in example 3, but silver was introduced into the active component of the catalyst.

The conversion of methyl chloride increases to 22% with a 97% selectivity for ethylene (selectivity for propylene - 2%, the rest is ethane, propane).

Example 6

The same as in example 1, but copper is introduced into the active component of the catalyst.

The conversion of methyl chloride is 17% with 96% ethylene selectivity (propylene selectivity - 2%, the rest is ethane, propane).

Example 7

The same as in example 1, but zinc is introduced into the active component of the catalyst.

The methyl chloride conversion is 24% at 94% ethylene selectivity (4% propylene selectivity, the rest is ethane, propane).

Example 8

The same as in example 1, but silver was introduced into the active component of the catalyst.

The conversion of methyl chloride is 25% at 94% ethylene selectivity (4% propylene selectivity, the rest is ethane, propane).

Claims (3)

1. A method of producing lower olefins from methyl chloride, comprising passing an initial gas reaction mixture containing at least methyl chloride through at least one catalyst layer 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 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 (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 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 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 at a ratio of S _Na / S _Ar = 5-30, characterized in that it further formed on the catalyst active sites with high acidity, characterized depth deyterovodoro exchange of 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 hydrogen a mixture of 20,000 h ^-1 in a thermoprogrammed reaction mode at a heating rate of 10 K / min, or / and additionally, copper or zinc or silver is added to the active component. 2. The method according to claim 1, characterized in that the catalyst carrier is in the form of microfibers with a diameter of from 1 to 20 microns. 3. The method according to claim 2, characterized in that the microfibers are structured in the form of 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 weaving type satin, canvas, openwork with cell diameter 0.5-5 mm.