Method for catalytic chlorination of lower alkanes for value product manufacturing

FIELD: chemical industry, in particular method for production of value products from lower alkanes.

SUBSTANCE: claimed method includes passing of gaseous reaction mixture containing at least one lower alkane and elementary chlorine through catalytic layer. Used catalyst represents geometrically structured system comprising microfiber with diameter of 5-20 mum. Catalyst has active centers having in IR-spectra of adsorbed ammonia absorption band with wave numbers in region of ν = 1410-1440 cm-1, and contains one platinum group metal as active component, and glass-fiber carrier. Carrier has in NMR29Si-specrum lines with chemical shifts of -100±3 ppm (Q3-line) and -110±3 ppm (Q4-line) in integral intensity ratio Q3/Q4 from 0.7 to 1.2; in IR-specrum it has absorption band of hydroxyls with wave number of ν = 3620-3650 cm-1 and half-width of 65-75 cm-1, and has density, measured by BET-method using argon thermal desorption, SAr = 0.5-30 m2/g, and specific surface, measured by alkali titration, SNa = 10-250 m2/g in ratio of SAr/SNa = 5-30.

EFFECT: method of increased yield.

3 cl, 4 ex

 

The invention relates to the field of chemical industry, and in particular to methods of obtaining valuable products from lower alkanes, primarily methane. The proposed method can be used for the production of methane and natural gas products such as methyl chloride, vinyl chloride, light olefins (ethylene, propylene) and many others.

Known processes for the chlorination of methane with obtaining valuable products (ethane, ethylene, propylene, aromatic hydrocarbons, etc.), in which the chlorination of methane carry out elementary chlorine in the gas phase at elevated temperatures without the use of catalysts (U.S. Patent No. 4199533, C 07 C 9/06, C 07 C 11/04, priority from 03.11.78, publ. 22.04.80; U.S. Patent No. 4804797, C 07 C 2/00, priority. from 24.08.87, publ. 14.02.89; U.S. Patent No. 5157189, C 07 C 2/00, priority from 21.11.90, publ. 20.10.92).

The main disadvantage of these known methods is the formation of a considerable amount trudnoozhidaemyh waste, such as polychloroprene and polychloroethene.

Known methods for catalytic oxidative chlorination of methane using a catalyst based on the chlorides of copper and other metals with the additional introduction into the reaction mixture of oxygen (the Federal Republic of Germany Patent No. 1249246, B 01 J 27/06, C 07 C 17/154, publ. 07.09.67; Ed. mon. The USSR № 1237657, C 07 C 19/02, 17/154, priority from 10.09.84, publ. 15.06.86; U.S. Patent No. 6452058, 07 is 17/15, 27/00, 51/14, 2/00, priority from 21.05.01, publ. 17.09.02). The application of catalytic methods can improve the yield of target products of chlorination (in these known methods - methyl chloride).

The disadvantage of these known methods is the formation of unwanted side chlorophenothane products (polychloroprene, polychloroethene), moreover, in the presence of oxygen is not excluded also the formation of dioxins, phosgene, and other highly toxic compounds. In addition, a common disadvantage of known methods is the rapid deactivation of the catalysts and the need for periodic replacement or regeneration, which complicates and limits the applicability of these methods.

Closest to the present invention is a method of catalytic chlorination of methane using silicalite catalyst with a mean refractive index of 1.39±0.01 and a specific gravity at 25°With equal 1.70±0.05 g/cm3(U.S. patent No. 4795843, 07 With 11/20, 11/32, 1/00, priority of 08.10.87, publ. 03.01.89). The process of chlorination without adding to the reaction mixture of oxygen provides the lack of reaction products of highly toxic dioxins, phosgene and WITH.

The disadvantages of this method is the formation of a significant amount trudnoozhidaemyh waste, such as p is dichloropropene and polychloroethene, as well as the low yield of the target products.

The authors sought to develop a way catalytic chlorination of lower alkanes with obtaining valuable products

The problem is solved in that in a method of catalytic chlorination of lower alkanes with obtaining valuable products, including the transmission of gas of the reaction mixture containing at least one of the lower alkanes and elemental chlorine through a layer of catalyst, using a catalyst comprising a geometrically structured system of microfibers with a diameter of 5-20 μm, having active centers, which are characterized in the IR spectra of adsorbed ammonia in the presence of absorption bands with wave numbers in the range ν=1410-1440 cm-1containing the active ingredient, which is one of the platinum group metals, and glass fiber media, characterized by the presence of the NMR spectrum29Si lines with chemical shifts -100±3 ppm (line Q3and -100±3 ppm (line Q4) when the ratio of the integral intensities of the lines of Q3/Q4from 0.7 to 1.2, in the infrared spectrum absorption band of hydroxyl groups with wave number ν=3620-3650 cm-1and the width of 65-75 cm-1having a specific surface area measured by the BET method by thermal desorption of argon, SAr=0.5 to 30 m 2/g, the magnitude of the surface, measured by the method of alkaline titration, SNa=10-250 m2/g at a ratio of SNa/SAr=5-30. The active component of the catalyst is at least one of platinum group metals, in particular platinum. Fiberglass catalyst carrier can be structured as either non-woven or extruded material such as wool or felt, material, woven from filaments with a diameter of 0.5-5 mm

The technical effect of the proposed method lies in the possibility of selective chlorination of lower alkanes and achieve a high yield of the target products.

For implementing the method, the reaction mixture containing at least one of the lower alkanes and elemental chlorine is passed through the catalyst layer containing the active component and glass fiber media, and IR spectra of adsorbed ammonia on the specified catalyst have characteristic bands in the range 1410-1440 cm-1and as the active component uses at least one of platinum group metals, in particular platinum. The presence of these bands in the IR spectra of adsorbed ammonia is clear evidence of the presence on the surface of the specific catalyst active centers, providing a high activity and selectivity cat who lyst in the chlorination reaction of lower alkanes, as well as high activity and stability of catalyst. The establishment of such centres can be carried out by targeted modification of the catalyst surface in a variety of ways at the stage of its preparation.

For implementing the method using a catalyst formed into flexible, permeable to flow of the reaction mixture of fiberglass structures, made in the form of a woven or extruded materials. Such structuring facilitates the placement and fixation of the catalyst in the catalytic reactor and prevents entrainment of the microfibers of the catalyst from the reaction stream.

Chlorinated lower alkanes by the described method provides a high yield of valuable products, such as methyl chloride, vinyl chloride, olefins (ethylene, propylene) and others. The catalyst has high activity, stability and high durability without the need for procedures regeneration and reactivation. It also provides mechanical stability of the catalyst layer, allowing you to create different types of catalyst (axial, radial, and others) and to have a catalytic reactor in any geometric orientation (vertical, horizontal etc), which significantly increases efficiency and extends the application of the method.

Example 1

-1. There is a complete conversion of chlorine, and the conversion of methane is ~38%. The main product of chlorination is methyl chloride, the selectivity of the conversion of methane into methyl chloride is 96%. The selectivity of the formation of methylene chloride does not exceed 1%, polychlorinated hydrocarbons not more than 4%, chloroform, carbon tetrachloride, phosgene, carbon monoxide and dioxins in the products of the reaction are absent completely.

In similar conditions, the process adopted for the prototype provides the selectivity of the formation of methyl chloride is not higher than 70%. Thus, the application of the proposed method allows to increase the yield of the target product by ~40%, and reduce the amount of by-products and waste is not less than 7.5 times.

Example 2

Same as in example 1, but the process is conducted at a temperature of 450-500°and the ratio of natural gas/chlorine 1:1. The conversion of chlorine - 100%, methane is about 80%. There education is the use of light olefins (ethylene, propylene with a selectivity of up to 70%, and vinyl chloride with selectivity up to 15%. When increasing the ratio of natural gas/chlorine to a value of 4:1 conversion of methane is reduced to ~ 25%, while the selectivity of the formation of olefins reaches almost 100%.

The process adopted for the prototype, is not able to provide these valuable products (olefins, vinyl chloride).

Example 3

Chlorination on the specified catalyst is subjected to propane, the process is carried out at 160°C, atmospheric pressure and at an initial ratio of propane/chlorine/inert gas is 1:1:1. Achieved conversion of propane to 55%, while the selectivity of the formation of monochloropropane reaches 80%. With increasing the reaction temperature above 350°With monochloropropane turn to propylene with a selectivity close to 100%

The process adopted for the prototype, is not able to provide these valuable products (monochloropropane, propylene).

Example 4

To the same as in examples 1-3, but using the catalyst, in which the optical fiber is structured in the form of a nonwoven extruded felt. Achieved results similar to those described.

1. Way catalytic chlorination of lower alkanes, comprising passing the gaseous reaction mixture containing at least one of the lower alkanes and elemental chlorine through a layer of catalyst,characterized in that using a catalyst comprising a geometrically structured system of microfibers with a diameter of 5-20 μm, having active centers, which are characterized in the IR spectra of adsorbed ammonia in the presence of absorption bands with wave numbers in the range ν= 1410-1440 cm-1containing the active ingredient, which is one of the platinum group metals, and glass fiber media, characterized by the presence of the NMR spectrum29Si lines with chemical shifts -100±3 ppm (line Q3and -110±3 ppm (line Q4) when the ratio of the integral intensities of the lines of Q3/Q4from 0.7 to 1.2, in the infrared spectrum absorption band of hydroxyl groups with wave number ν=3620-3650 cm-1and the width of 65-75 cm-1having a specific surface area measured by the BET method by thermal desorption of argon, SAr=0.5 to 30 m2/g, the magnitude of the surface, measured by the method of alkaline titration, SNa=10-250 m2/g at a ratio of SNa/SAr=5-30.

2. The method according to claim 1, characterized in that the active component of the catalyst is platinum.

3. The method according to claims 1 to 2, characterized in that the optical fiber catalyst is structured in the form of either non-woven or extruded material such as wool or felt or material, woven from filaments with a diameter of 0.5-5 mm



 

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4 tbl, 30 ex

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8 cl, 1 tbl, 16 ex

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