RU2451005C1 - Compound method for catalytic processing of natural gas to obtain lower olefins - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method involves oxidative chlorination of methane, pyrolysis of the methyl obtained from methane oxychlorination, and is characterised by that after extracting chloromethanes from the methane oxychlorination step, the remaining still liquor, which primarily contains methylene chloride and chloroform, undergoes hydrodechlorination at temperature 150°-300°C on a palladium or nickel-molybdenum catalyst on a support, and the obtained stream of reaction gas is split into two fractions. One of said fractions with high-boiling point hydrodechlorination products, which contain unreacted methylene chloride and chloroform, is fed into a chloromethane separation unit for the methane oxychlorination step, and the other fraction with low-boiling point gases from the chloromethane hydrodechlorination process, which contain hydrogen, methane, hydrogen chloride and partially methyl chloride, is merged with the gas stream coming from the methyl chloride pyrolysis step, followed by combined separation thereof into hydrogen, methane, lower olefins and unreacted methyl chloride, which is returned to the catalytic pyrolysis step.

EFFECT: use of present method enables to increase output of methyl chloride and, consequently, light olefins obtained during conversion thereof.

1 cl, 1 tbl, 2 ex, 2 dwg

Description

The invention relates to the field of chemical industry, and in particular to a technology for the production of lower olefins and, first of all, ethylene and propylene from methane, which can be contained mainly in natural gas, as well as associated gas, biogas and other sources.

Currently, the main source of lower olefins is petroleum feed. However, limited oil reserves limit the possibility of increasing the growth of ethylene production, the market demand for which has a constant, solid upward trend. In this regard, the expansion of the raw material base for ethylene production is an urgent problem and, first of all, the use of natural gas as a raw material.

Alternative methods for producing light olefins involve the use of methanol, dimethyl ether and methyl chloride as a raw material for the production of ethylene. All of these compounds can be obtained by chemical processing of methane.

For example, a method is known for producing lower alkenes by the conversion of methanol and / or dimethyl ether on crystalline aluminosilicate zeolite ZSM-34 containing oxides of magnesium / platinum and manganese (US 4471150, B01J 29/50, 1984.09.11).

The disadvantage of the methods for producing olefins from natural gas through methanol and / or dimethyl ether is the need for preliminary conversion of natural gas to synthesis gas using water vapor, oxygen or carbon dioxide; the subsequent conversion of the synthesis gas to methanol and / or dimethyl ether, and finally, in the third stage, the conversion of methanol and / or dimethyl ether to light olefins.

In the absence of the first stage, the process through the intermediate production of methyl chloride by the method of oxidative chlorination of methane and the subsequent conversion of methyl chloride [Fox J.M., Chen TP., Degen B.D. / An Evaluation of Direct Methane Conversion Processes // Chem. Eng. Progr. 1990. V.86. No. 1. P.86-98].

The use of methyl chloride as a feedstock reduces the process for producing olefins from methane to two stages:

- direct or oxidative chlorination of methane to obtain methyl chloride;

- direct conversion of methyl chloride to olefins in the presence of zeolites.

A known catalytic method for the production of C ₂ -C ₄ olefins by converting methyl chloride-containing feedstock onto decationated H-ZSM-5 type zeolite as a catalyst at temperatures of 294-440 ° C [SU 1214644, C07C 1/26, 11/02, 1986.02.28].

High methyl chloride conversions and selectivities for ethylene and propylene were obtained on a CVM (Russian analogue ZSM-5) and silicoaluminophosphate catalyst SAPO-34 [Treger Yu.A., Rozanov V.N., Lunkov S.A., Murashova O.P. ., Dasaeva G.S. // Catalysis in industry. 2009. No2. S.14-18]. The preparation of light olefins from methyl chloride on an SAPO-34 catalyst is also described in [Wei Y., Zhang D., Liu Z., Su B-L. // Journal of Catalysis. 2006. V.238. P.46-57].

The presence of catalysts usually does not affect selectivity. However, a known method (US 4523040, C07C 17/10, publ. 11.06.1985), in which on a catalyst containing 20% tantalum oxyfluoride on alumina, at a temperature of 240 ° C and a methane / chlorine ratio of 8: 1 chlorine conversion is 99% and the selectivity for methyl chloride is 99%. On other catalysts, chlorine conversion is low, and 99% methyl chloride selectivity is achieved only on platinum and palladium.

A similar high selectivity of the catalytic process of methane chlorination on a platinum catalyst is given in the patent (RU 2330834 C1, C07C 19/03, B01J 21/08, C07C 17/10, 2007.06.28). To increase the selectivity, active centers with increased acidity are additionally formed on the catalyst, characterized by a deuterium-hydrogen exchange depth of at least 10%.

However, the production of methyl chloride by direct chlorination of methane has a major drawback associated with the fact that at least half of the consumed chlorine is converted to abhase hydrogen chloride, the sale of which is very difficult. From this point of view, it is much more profitable to obtain methyl chloride by oxidative chlorination of methane, when the process is completely balanced by chlorine. In this case, the process of obtaining ethylene from methane is as follows:

2CH ₄ + 2HCl + O ₂ → 2CH ₃ Cl + 2H ₂ O

2CH ₃ Cl → C ₂ H ₄ + 2HCl

A known catalytic method for producing chloromethanes, which consists in carrying out the process of oxychlorination of methane at low stationary partial pressures of chlorine (0.1 kPa) and hydrogen chloride (5 kPa) in the reaction zone by distribution of oxygen and hydrogen chloride and / or chlorine or mixtures thereof in volume ratios 1: 0.5-1: 2 between sections of the adiabatic reactor when methane and / or chloromethanes are mixed with oxygen and hydrogen chloride in volume ratios of 10: 0.1: 0.2-10: 1: 2, respectively. The process is carried out either in a fixed or in a "boiling" bed of a tribrach catalyst. As tribrach catalysts, combinations of copper chlorides with alkali, alkaline earth and rare earth chlorides on porous supports with a specific surface area of up to 30 m ² / g (RU 94029797 A1, C07C 19/01, C07C 17/154, 1996.06.20) are used.

An analogue of the present invention is a method for the oxidative halogenation of C ₁ hydrocarbons (methane) to halogenated C ₁ hydrocarbons and associated integrated methods (RU 2286329, C07C 17/154, 2005.05.10). The method includes: (a) contacting methane, halogenated methane or a mixture thereof with a halogen source and with an oxygen source in the presence of a catalyst under the conditions of an oxidative halogenation process sufficient to produce methyl halide and optionally dihalogenomethane; then, in a further step (b), the methyl halide is condensed to form light olefins and / or gasolines by contacting the methyl halide and optionally dihalogenomethane thus obtained with a condensation catalyst under conditions sufficient to produce at least one light olefin.

In this method, the source of the halogen is hydrogen chloride, the condensation catalyst is selected from the group consisting of aluminosilicates with structural codes DSM-2 and ZSM, aluminophosphates, borosilicates, silicates and silicoaluminophosphates.

The test results of the SAPO-34 silicoaluminophosphate catalyst in the conversion of methyl chloride to light olefins are shown in [Wei Y., Zhang D., Liu Z., Su B-L. // Journal of Catalysis. 2006. V.238. P.46-57]. The maximum selectivity for the formation of light olefins during the catalytic conversion of methyl chloride (~ 80%) is achieved on the SAPO-34 catalyst at a temperature of 450 ° C.

In the work [Treger Yu.A., Rozanov V.N., Lunkova S.A., Murashova O.P., Dasaeva G.S. // Catalysis in industry. 2009. No2. S.14-18] on the same catalyst and at the same temperature, the selectivity of ethylene and propylene formation of ~ 85% was achieved. The conversion of methyl chloride was ~ 75%. In the conversion of methyl chloride to zeolite CVM (analogue of ZSM-5), the maximum selectivity for the sum of ethylene and propylene was ~ 40% at a temperature of 400 ° C. In this case, a 98-100% conversion of methyl chloride was achieved.

A prototype of the present invention is a catalytic method for the processing of methane, including direct and / or oxidative chlorination of methane to methyl chloride, while for the oxychlorination of methane, hydrogen chloride is taken in volume ratio to methane as 0.5-1: 1, oxygen, in total volume ratio to hydrogen chloride in the range of 0.58-0.68: 1 and at the stage of oxidative chlorination in the process in a mass quantitative ratio of 3.5-4: 1 to unreacted hydrogen chloride is introduced water, with which unreacted chlorine hydrogen true in part formed hydrochloric acid is recycled to step oxychlorination of methane; pyrolysis of methyl chloride obtained by chlorination and / or oxychlorination of methane to obtain lower olefins, mainly ethylene [RU 2394805, cl. C07C 17/154, publ. 07/20/2010]. In the process, the full use of hydrogen chloride is achieved.

The main disadvantage of the prototype method for producing light olefins is the production of a large amount of a by-product, dichloromethane (methylene chloride), which, when methyl chloride is converted to light olefins, is completely converted to hydrogen chloride and carbon, which is deposited on the surface of the catalyst and therefore reduces its activity.

According to the examples given in patent RU 2286329, the amount of methylene chloride from the sum of methyl chloride, methylene chloride, chloroform and carbon oxides ranges from 10.2 to 18.0%. In the prototype RU 2394805, methylene chloride selectivity in the same amount of products is 6.5%.

The technical result of the present invention is to increase the yield of methyl chloride, and, accordingly, of light olefins obtained during its conversion.

To obtain the above technical result, a complex method is proposed for the catalytic processing of methane from natural gas to produce lower olefins, mainly ethylene, through intermediate synthesis of methyl chloride by the method of oxidative chlorination of methane and subsequent catalytic pyrolysis of methyl chloride, including oxidative chlorination of methane, pyrolysis of methane chloride during the oxychlorination stage methyl, characterized in that after the separation of methyl chloride from the stage of oxychl at a temperature of 150-300 ° C on a palladium or nickel-molybdenum catalyst on a support is subjected to hydrodechlorination, and the reaction gas stream obtained after hydrodechlorination is divided into two fractions, one of which with high boiling hydrodechlorination products containing unreacted methylene chloride and chloroform are sent to the methane chlorine separation unit at the methane oxychlorination stage, and the other with low boiling process gases odehlorirovaniya chloromethanes comprising hydrogen, methane, hydrogen chloride and partly methyl chloride, is combined with the gas effluent from step pyrolysis of methyl chloride with subsequent joint separation into hydrogen, methane, lower olefins and unreacted methyl chloride, which is recycled to the catalytic pyrolysis step.

In accordance with the technological scheme, the proposed complex method for the catalytic processing of methane includes: stage (a) oxidative chlorination of methane, the release of hydrogen chloride from the reaction gas stream of methane oxychlorination in the form of hydrochloric acid, its rectification with the removal of reaction water and obtaining a hydrochloric azeotrope returned to the reactor oxychlorination of methane, isolation and separation of chloromethanes to obtain methyl chloride; stage (b) methyl chloride pyrolysis, including, in fact, a pyrolysis unit, units for isolating the methane fraction, ethylene, hydrogen chloride, propylene, methyl chloride recycling, fractions C ₄ and C ₅ ; stage (c), in which the bottom liquid from the methane oxychlorination stage, containing mainly methylene chloride, chloroform and traces of CFCs, is subjected to hydrodechlorination, returning the fraction of high boiling hydrodechlorination products to the chloromethane separation unit and attaching the fraction of low boiling products to the catalytic pyrolysis gases of methyl chloride for their subsequent joint separation.

The by-products found in the bottom liquid after methane oxychlorination: methylene chloride, a small amount of chloroform and a trace amount of carbon tetrachloride (CFC), are separated from the obtained methyl chloride and are hydrodechlorinated with hydrogen in the presence of a palladium or nickel-molybdenum catalyst in order to additionally produce methyl chloride, methane and hydrogen chloride.

CH ₂ Cl ₂ + H ₂ → CH ₃ Cl + HCl

CH ₂ Cl ₂ + 2H ₂ → CH ₄ + 2HCl

CHCl ₃ + 2H ₂ → CH ₃ Cl + 2HCl

CHCl ₃ + 3H ₂ → CH ₄ + 3HCl

The proposed integrated method for the catalytic processing of methane from natural gas allows to achieve a higher yield of ethylene, a by-product of propylene and a C ₄ fraction by obtaining an additional amount of methyl chloride and methane during hydrodechlorination of bottoms. In addition, during hydrodechlorination, methane spent on methylene chloride, chloroform, and CFCs is partially regenerated. This significantly reduces the carbonization of the methyl chloride pyrolysis catalyst due to the decomposition of methylene chloride and chloroform during the following reactions.

CH ₂ Cl ₂ → C + 2HCl

CHCl ₃ → C + HCl + Cl ₂

CCl ₄ → C + 2Cl ₂

The implementation of the proposed integrated method for the catalytic processing of methane extracted from natural gas to produce lower olefins is illustrated in the diagrams shown in figures 1 and 2, where figure 1 shows the process diagram of the proposed invention of the invention, figure 2 shows for comparison technological scheme of the process of the prototype [patent RU 2394805].

An integrated method for the catalytic processing of methane extracted from natural gas is as follows.

Example 1

Fresh methane in the amount of 107.9 nm ³ / h is sent to the reactor 1 (Fig. 1), which is a cylindrical apparatus with an internal diameter of 800 mm, made of carbon steel and lined from the inside with acid-resistant brick, equipped with four shelves with a catalyst placed on them. , hydrogen chloride (93.2 nm ³ / h) from the stage of separation of reaction products 6 and methane recycling (406 nm ³ / h), containing in nm ³ / h: 282.6 СН ₄ , 45.1 CO ₂ , 43, 4 CO, 30.4 N ₂ and 4.5 O ₂ . The oxygen supply (58.7 nm ³ / h) is carried out separately for each shelf with a catalyst: 8.6 nm ³ / h, the second 11.4 nm ³ / h, the third 16.5 nm ³ / h and the fourth 22.2 nm ³ / h. The pressure in the reactor is 2-10 atm.

The methane processing catalyst is a mixture of copper, potassium and lanthanum chlorides in a molar ratio of 1: 1: 0.3, applied in an amount of 3-30 wt.%, Mainly 22 wt.%, On a porous support with a specific surface area of 1-60 m ² / g, for example on the surface of steamed silica gel with a specific surface of 30 m ² / g The amount of catalyst on the shelves along the gas is distributed in an increasing progression in the ratio of 1: 1.3: 1.9: 2.6 (in volume terms, respectively, 120, 160, 230 and 310 l). When starting the process for cooling the reaction gas between the shelves of the reactor, water is injected in a total amount of 216 kg / h, which evaporates and removes the reaction heat. Then, when this water is extracted from the reaction gas and recycled to the reactor 1, unreacted hydrogen chloride in the amount of 54 kg / h in the form of ~ 20% hydrochloric acid is returned together with water. As a result, full utilization of the starting hydrogen chloride at the methane chlorination stage is achieved.

20% hydrochloric acid is introduced onto the reactor shelves with an increase in its amount from shelf to shelf: after the first shelf, in the amount of 65 kg / h, after the second 85 kg / h and after the third 120 kg / h. The total amount of introduced water and dissolved in it hydrogen chloride is 216 kg / h and 54 kg / h, respectively, a total of 270 kg / h. The gas temperature at the inlet to the catalyst bed is maintained at 300-320 ° C by injection of hydrochloric acid, and the gas temperature at the outlet of the catalyst bed is controlled by the supply of oxygen to each reactor shelf within 400-420 ° C.

Coming out of the oxychlorination reactor 1 gas stream containing in nm ³ / h: CH ₄ 302.1, CH ₃ Cl 80, CH ₂ Cl ₂ 6, CHCl ₃ 0,4, CO ₂ 48,2, CO 46,4, N ₂ 32.5, O ₂ 4.8, HCl 33.1, H ₂ O 374.2, subjected to cooling to condense hydrochloric acid in distillation column 2. Due to the heat of condensation, the reaction water is distilled off. 270 kg / h of 20% hydrochloric acid (216 kg / h of water and 54 kg / h of hydrogen chloride) are discharged from the bottom of the distillation column 2, which returns unreacted hydrogen chloride to the reactor and is simultaneously used to remove the heat of reaction.

The reaction gas stream leaving column 2 after separation by cooling in a condenser 3 of reaction water is supplied to column 4 for condensation and extraction of chloromethanes in an amount of 180.2 kg / h (80 nm ³ / h) methyl chloride, 22.7 kg (6 nm ³ / h) methylene chloride and 2.1 kg / h (0.4 nm ³ / h) chloroform.

The remaining, not condensed and freed from chloromethanes gas stream containing ~ 70% methane and ~ 30% inerts (N ₂ , CO, CO ₂ ) is returned to the oxychlorination shelf reactor 1. Moreover, a portion of this gas stream in an amount of 28 nm ³ / h is deflated to remove inert, nitrogen enters the system with methane (1.1 nm ³ / h) and oxygen (1 nm ³ / h), CO and CO ₂ in the amount of 3 and 3.1 nm ³ / h are formed in the reactor, respectively oxychlorination. Purge is used as fuel gas.

The methyl chloride (80 nm ³ / h) isolated in column 4, in contrast to the prototype, is simultaneously separated in this column 4 from methylene chloride (6 nm ³ / h) and chloroform (0.4 nm ³ / h) and sent to the catalytic pyrolysis stage in reactor 5 for the production of olefins.

The process of catalytic pyrolysis is carried out in a reactor 5 with a fluidized bed of a silicoaluminophosphate catalyst of the SAPO-34 type at a pressure of 2-5 atm, preferably 2 atm, and a temperature of 470 ° C. The diameter of the reactor is 260 mm. The amount of catalyst 55 liters During pyrolysis due to the decomposition of chloromethanes, a constant carbonization of the catalyst occurs. Therefore, an apparatus (not shown in FIG. 2) is installed near the olefin production reactor for regenerating the catalyst by burning carbon deposits by air. The regeneration process is carried out in a fluidized bed at a temperature of 550 ° C and a pressure of 2 atm. The diameter of the reactor is 50 mm, the amount of catalyst in regeneration is 5 l.

Carbonized during the pyrolysis process, the catalyst constantly flows from the reactor to the regenerator, and the regenerated catalyst rises and falls into the reactor by pneumatic transport. The amount of coke deposited on the catalyst due to the absence of methylene chloride and chloroform in the initial mixture in comparison with the prototype is reduced from 3.6 to 0.2 kg / h. 3 nm ³ / h of air is supplied for regeneration. The gases leaving the regenerator contain 0.4 nm ³ / h CO ₂ , 0.2 nm ³ / h O ₂ and 2.4 nm ³ / h N ₂ .

The bottom liquid remaining after the isolation of methyl chloride in the column 4 and containing methylene chloride (6 nm ³ / h) and chloroform (0.4 nm ³ / h) is sent to a hydrodechlorination reactor 7 with a diameter of 150 mm, where chloromethanes in the bottom liquid evaporated, mixed with hydrogen (14.3 nm ³ / h) and subjected to hydrodechlorination at a temperature of 150-300 ° C in the presence of palladium catalyst manufactured by the industry according to TU 2172-004-9409069-2005 (4.7 l). 1.2 nm ³ / h of methyl chloride, 5.2 nm ³ / h of methane and 12.0 nm ³ / h of hydrogen chloride are obtained as reaction products.

The gas stream after hydrodechlorination from the reactor 7 is sent to a condensation-stripping column 8, in which a fraction of low boiling gases (hydrogen 2.3 nm ³ / h, methane 5.2 nm ³ / h, hydrogen chloride 12 nm ³ / h and partially methyl chloride 0.6 nm ³ / h) and combine it with a gas stream leaving the catalytic pyrolysis stage from reactor 5. A fraction of high boiling products containing partially remaining methyl chloride in an amount of 0.6 nm ³ / is discharged from the bottom of the condensation-stripping column 8. h and unreacted chloride 2.0 ^Nm3 / h and x oroform 0.1 Nm ³ / hr, which is sent back to the column 4 to be combined with chloromethanes derived from the oxychlorination of methane.

Together with an additional amount of chloromethanes in the column 4, methyl chloride (80.6 nm ³ / h) is isolated from the top and sent to the reactor 5 to the catalytic pyrolysis stage to produce olefins. There, recycling of unreacted methyl chloride in an amount of 20.6 nm ³ / h comes from separation system 6. Methylene chloride (8 nm ³ / h) and chloroform (0.5 nm ³ / h) from the bottom of column 4 are sent to the hydrodechlorination reactor 7.

Reactor 5 exits a mixture containing 19.1 nm ³ / h of ethylene, 9.8 nm ³ / h of propylene, 3.3 nm ³ / h of butylenes, 81.2 nm ³ / h of hydrogen chloride and 20 nm ³ / h of unreacted methyl chloride.

The combination of the fraction of low-boiling products from the condensation-stripping column 8 with a gas stream leaving the catalytic pyrolysis stage from reactor 5 allows 19.1 nm ³ / h of ethylene, 9.8 nm ³ / h of propylene to be obtained from the separation system of reactor 6 3.3 nm ³ / h of butylenes, 20.6 nm ³ / h of methyl chloride returned to recycling, 2.3 nm ³ / h of hydrogen, 5.2 nm ³ / h of methane and 93.2 nm ³ / h of hydrogen chloride , which is fed to the methane oxychlorination step to synthesize the amount of methyl chloride needed to produce olefins, which makes the process Using the fully balanced chlorine.

Thus, by introducing the hydrodechlorination step of higher chloromethanes (methylene chloride and chloroform) contained in bottoms, 5.2 nm ³ / h methane and 1.2 nm ³ / h methyl chloride are additionally obtained, from which, in turn, additionally 0.3 nm ³ / h of ethylene and 0.2 nm ³ / h of propylene are obtained.

Example 2

Oxychlorination of methane in an amount of 110.6 nm ³ / h, to obtain methyl chloride, and its subsequent catalytic pyrolysis is carried out as described in example 1.

The bottom liquid remaining after the isolation of methyl chloride in column 4 containing, taking into account unreacted amounts of methylene chloride (8 nm ³ / h) and chloroform (0.5 nm ³ / h), is sent to hydrodechlorination reactor 7 with a diameter of 150 mm, where chloromethanes located in a still liquid, evaporate, mix with hydrogen (14.3 nm ³ / h) and undergo hydrodechlorination at a temperature of 150-300 ° C in the presence of a nickel-molybdenum catalyst manufactured by the industry according to TU 2177-047-46693103-2009 (4.7 l ) 2.4 nm ³ / h of methyl chloride, 5.0 nm ³ / h of hydrogen, 2.5 nm ³ / h of methane, 0.3 nm ³ / h of ethylene, 0.3 nm ³ / h of propylene are obtained as reaction products and 10.8 nm ³ / h of hydrogen chloride.

The gas stream after hydrodechlorination from the reactor 7 is sent to a condensation-stripping column 8, in which the fraction of low-boiling gases (5.0 nm ³ / h of hydrogen, 2.5 nm ³ / h of methane, 0.3 nm ³ / h of ethylene, is separated from above 0.3 nm ³ / h of propylene, hydrogen chloride 10.8 nm ³ / h, partially 1.8 nm ³ / h of methyl chloride) and combine them with a gas stream leaving the catalytic pyrolysis stage from reactor 5.

Bottom of the condensation-stripping column 8 displays a fraction of high-boiling products. 0.6 nm ³ / h remaining in this fraction is combined in column 4 with methyl chloride (80 nm ³ / h) obtained in oxychlorination reactor 1 and sent to a catalytic pyrolysis reactor 5. Unreacted 2.0 nm methylene chloride ³ / h and chloroform 0.1 nm ³ / h in the column are combined with methylene chloride 6.0 nm ³ / h and chloroform 0.4 nm ³ / h obtained in the methane oxychlorination step.

By introducing the hydrodechlorination step of higher chloromethanes (methylene chloride and chloroform) contained in the bottoms, additionally 0.3 nm ³ / h of ethylene, 0.3 nm ³ / h of propylene, 2.5 nm ³ / h of methane and 2.4 nm ³ / h of methyl chloride, from which, in turn, additionally receive 0.6 nm ³ / h of ethylene and 0.2 nm ³ / h of propylene.

Thus, the gas stream leaving the stage of catalytic pyrolysis of methyl chloride from reactor 5, combined with the fraction of low boiling gases of the condensation-stripping column 8 at the stage of separation of products in the reactor 6 allows to obtain 19.7 nm ³ / h of ethylene, 10.3 nm ³ / h of propylene and 3.3 nm ³ / h of butylenes, as well as 21.8 nm ³ / h of methyl chloride, recycled to the catalytic pyrolysis reactor of methyl chloride 5, 93.2 nm ³ / h of hydrogen chloride and 2.5 nm ³ / h of methane fed to reactor 1 to the methane oxychlorination step, 5 nm ³ / h of hydrogen and returned to the hydrodechlorination reactor 7.

The proposed complex catalytic method for the processing of methane to produce lower olefins allows to increase the amount of methyl chloride obtained by processing the bottom liquid by hydrodechlorination, sharply reduce the carbonization of the catalyst of the methyl chloride pyrolysis stage and increase the yield of lower olefins (see table).

The use of the claimed technological scheme on an industrial scale will make it possible to organize our own production of ethylene and propylene from methane, which will comprehensively fit into the overall technological structure. In an enterprise producing organochlorine products, ethylene can be used for the production of vinyl chloride, and propylene for the production of allyl chloride. The proposed scheme for the production of ethylene and propylene will ensure non-volatility through the use of by-products of this technological unit in the production of its own energy resources.

The table shows the data in comparison with the production of lower olefins from natural gas according to the prototype and the present invention

Comparison of the catalytic processing of natural gas (methane) with the production of lower olefins Note
Ry Fresh methane consumption, nm ³ / h The carbonization of the catalyst, kg / h Number of Products Received ethylene propylene nm ³ / h kg / h nm ³ / h kg / h Prototype 113.1 3 18.8 23.5 9.6 18.0 Example 1 107.9 0.2 19.1 23.9 9.8 18,4 Example 2 110.6 0.2 19.7 24.0 10.3 19.3

Claims (1)

An integrated method for the catalytic processing of methane from natural gas to obtain lower olefins, mainly ethylene, through the intermediate synthesis of methyl chloride by the method of oxidative chlorination of methane and subsequent catalytic pyrolysis of methyl chloride, including the oxidative chlorination of methane, pyrolysis of methylene chloride obtained at the oxychlorination stage, characterized in that after the isolation of chloromethanes from the methane oxychlorination step, the remaining bottoms liquid containing predominantly o methylene chloride and chloroform, at a temperature of 150-300 ° C on a palladium or nickel-molybdenum catalyst on a support is subjected to hydrodechlorination, and the reaction gas stream obtained after hydrodechlorination is divided into two fractions, one of which with high boiling hydrodechlorination products containing unreacted methylene chloride and chloroform sent to the methylene chloride separation unit of the methane oxychlorination stage, and the other with low-boiling gases of the hydrodechlorination of chloromethanes, including hydrogen, methane , hydrogen chloride and partially methyl chloride are combined with a gas stream leaving the methyl chloride pyrolysis stage, followed by their joint separation into hydrogen, methane, lower olefins and unreacted methyl chloride, which are returned to the catalytic pyrolysis stage.

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