RU1799865C - Method of methanol production - Google Patents

Abstract

Usage: mainly organic synthesis. The inventive product is methanol, BP, the degree of conversion of carbon oxides to methanol is 92-97%, the productivity of 1 m3 of catalyst: stage I 1.16-2.0 t CHzON / h, stage II: 1.02-1.28 t SNzone / h Reagent 1: carbon monoxide, reagent 2: carbon dioxide, reagent 3: hydrogen. Reaction conditions: at elevated temperature and pressure in two stages. At stage I, synthesis gas is supplied to the flow reactor at a volume ratio of H2 / CO + CO2 of 1.47-3.65. At stage II, the process is carried out in a recycle reactor at a volumetric ratio of CO / H20 + CO2 in the gas at the outlet of the reactor in the range of 0.82-2.89. 1 wpp, 4 tab. SB with

Description

The invention relates to the field of basic organic synthesis, in particular to the production of methanol from carbon oxides and hydrogen.

The purpose of the invention is to increase the specific productivity of the catalyst.

To achieve the goal, a method is proposed for producing methanol by contacting a mixture of carbon oxides and hydrogen with a copper-containing catalyst at elevated temperature and pressure in two stages, where the first stage is carried out in a flow reactor and the second in a reactor with recycle, followed by methanol evolution after each stage, in which, according to the invention, synthesis gas is supplied to the first stage with a volume ratio of H2 / CO + CO2 equal to 1.47-3.65, and in the second stage the process is conducted so that the volume ratio of CO / H20 + CO2 in the gas at the outlet of the reactor and is in the range 0,82-2,89, wherein the volume ratio of C0 / H20 + C0A

at the outlet of the second stage reactor, they are controlled by adding to the gas supplied to the second stage an additional gas stream containing an excess of hydrogen or carbon oxides.

An essential distinguishing feature of the proposed method for the production of methanol is that synthesis gas is supplied to the first stage with a volume ratio of Н2 / СО + С02 equal to 1.47-3.65, and in the second stage, the process is conducted so that the volumetric ratio СО / H20 + CO2 in the gas at the outlet of the reactor was in the range of 0.82-2.89, and the volumetric ratio CO / H20 + CO2 at the exit of the second stage reactor was controlled by adding to the gas supplied to the second stage an additional gas stream containing excess hydrogen or carbon oxides.

The essence of the proposed method for producing methanol is as follows.

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The initial synthesis gas with a volume ratio of H2 / CO + CO2 equal to 1.47-3.65 is heated in a heat exchanger and, at elevated temperature and pressure, is fed to the first stage in a flow reactor with increased heat removal, for example, into a tubular reactor. In the reactor, the feed gas is contacted with a copper-containing catalyst having the following composition, wt.%: Cu053.2; Zn027.1; ABOzb.B. By contacting the synthesis gas with a copper-containing catalyst, methanol and water are formed. The heat generated in this case is removed from the reaction zone and is used, for example, to produce water vapor. After separating methanol and water, a gas stream containing an excess of hydrogen or carbon oxides is added to the gas mixture leaving the flow reactor, thereby adjusting the ratio C0 / H20 + C0g in the gas at the outlet of the second stage reactor within 0.82- 2.89. The resulting gas stream is fed to the second stage, which is carried out in the reactor by circulating the gas mixture with a space velocity of at least 7500. In this case, the temperature and pressure in the second stage are the same as in the first stage. The circulating gas mixture leaving the second

stages and containing carbon monoxide, carbon dioxide, hydrogen, methanol vapors and water are fed to a heat exchanger to remove heat, and then methanol and water are separated from said gas mixture in a separator. The proposed H2 / CO + CO2 volumetric limit of 1.47-3.65 for the first step is selected from the following considerations. A reduction in the volume ratio below 1.47 is impractical, since it will lead to an increase in the rate of formation of by-products and to a deterioration in the quality of the crude methanol, and consequently, product losses during rectification and rectification costs will increase. It was experimentally established that with a ratio of H2 / CO + CO2. equal to 2.18, the content of crude methanol is 98.97 wt.%, with a ratio of 1.67-96.34 wt.% with a ratio of 0.76-95.6 wt.%. When the ratio of Н2 / СО + С02 is higher than 3.65, the first stage of methanol synthesis does not work efficiently, because most of the methanol is obtained in the second stage, in a recycling reactor. At a H2 / CO + C02 ratio above 3.65, methanol productivity of the catalyst decreases. If the amount of catalyst is increased, the specific productivity of the catalyst during methanol synthesis sharply decreases, which follows from Examples 9 and 10.

The second stage is carried out so that the volumetric ratio of CO / H20 + CO2 in the gas at the outlet of the reactor is in the range of 0.82-2.89, and this ratio is adjusted if necessary by adding a gas stream containing excess hydrogen or carbon oxides. Carrying out the methanol synthesis process outside the specified ratio reduces the specific productivity of the catalyst.

The examples of the present invention illustrate the practical implementation of the proposed 5th method.

Example 1 (comparative). At the first stage, 135,000 gas mixtures of the following composition, vol.%: 0 С022,0 Н2, are fed into the flow reactor. 66.7 N2 0.8 CH4 0.5 CO 30.0 5 with a bulk velocity of 4500.

In a flow reactor at a pressure of 7 MPa, a temperature of 240 ° C, the gas mixture is contacted with a copper-containing catalyst of the following composition, wt%: 0 CuO54.0 ZnO 25.0 Cr20z 12.6 397 taken in an amount of 30 m. In the first stage 5, 33.6 t / h of methanol are formed.

A gas mixture leaving the flow reactor having, after separation of water and methanol, the following composition, vol.%:

С024.07 0 Н2 66.31 Н20 0.03 N2 1.68 СН4 1.05 СО 26.32 5 СНзОН 0.54

in the amount of 64413 nm3 / h serves on the second stage,

In the second stage, this gas is processed in a shaft reactor, into which 40 m3 of copper-containing catalyst is loaded, divided into 4 layers. The temperature of the circulating mixture at the inlet to the reactor is 220 ° C, at the outlet of the reactor it is 290 ° C. The flow rate of the circulating gas 5 mixture at the inlet of the reactor is 400,000 Nm3 / h, the volumetric rate is 10,000 hours 1. The volumetric ratio CO / H20 + C02 is 3.44. In the second stage, 26 t / h of methanol are formed. The total amount of methanol obtained in the first and second stages is 59.6 t / h. 2268 nm3 of gas is consumed for the formation of 1 ton of methanol.

Example 2. An initial gas mixture of the following composition, vol.%: С022.0 СО 38.0 At 58.7 Ma, 0.8 СНо 0.5 in an amount of 140,000 nm3 / h is fed to the first stage of methanol synthesis in a flow reactor, where it at a temperature of 250 ° C and a pressure of 8 MPa in contact with a copper-containing catalyst of the following composition, wt.%:

CuO53.2 ZnO 27.1 5.5 The amount of catalyst in the first stage is 30 m3. The volume ratio of hydrogen to the sum of carbon oxides is 1.47. In the first step, 34.75 t / h of methanol is formed. The gas mixture leaving the flow reactor after separation of the crude methanol has the following composition, vol.%: С02 4.03 Н2 49.66 N2 1.69 СН4 1.05 СО 43.14 СНзОН 0.43 This gas in the amount of 66106 nm3 / h goes to the second stage with a bulk velocity of 10530 h in a shaft reactor operating with recycling. The shaft reactor contains per m3 of catalyst, divided into 4 layers. 400,000 Nm3 / h of circulating gas is fed to the reactor inlet. The temperature at the entrance to each catalyst layer: 1 - 21 0 ° C; 2 - 220 ° C; 3 - 230 ° C; 4 - 230 ° C, at the outlet of the reactor 260 ° C. The volumetric ratio of CO / H20 + CO2 is 6.01.

In the second stage, 20.87 t / h of methanol are formed. The total amount of methanol obtained in the first and second stages is 55.62 t / h. The production of 1 ton of methanol requires 2517 nm of the feed gas.

Example 3. The first stage is the same as in Example 2. To the gas stream exiting the first stage, 35009 nm3 / h of hydrogen are added. In this case, 101115 nm3 / h of gas of the following composition is formed, vol.%:

С022.64 Н2 67.09 N2 1.10 СН4 0.69 СО 28.20 СНЗОН 0.18

This gas is processed in a shaft reactor, which is loaded with 40 m of copper-containing catalyst. 600,000 Nm3 / h of circulating cyan gas is supplied to the inlet of the shaft reactor at a space velocity of 15,000. The temperature at the inlet to each of the catalyst layers is the same as in example 2, the temperature at the outlet of the reactor is 286 ° C. The volumetric ratio of CO / H20 + CO2 is 2.76. In this case, 43.54 t / h of methanol is formed in the second stage. The total amount of methanol obtained in the first and second stages is 78.29 t / h. The formation of 1 ton of methanol requires 2235 nm3 of the feed gas.

Example 4. The first stage is similar to that described in Example 2. Then, 25966 nm / h of hydrogen are added to the gas stream leaving the first stage. In this case, 92072 nm3 / h of a gas mixture of the following composition is formed, vol.%:

С022.89 Н2 63.87 N2 1.21 СН4 0.75 СО 30.97 СНзОН 0.31 This gas enters the second stage — into the shaft reactor, where it is processed at the parameters described in Example 2. The temperature at the outlet of the reactor 274 ° C. The volumetric ratio C0 / H20 + C02 is 2.89. 39.20 t / h of methanol are formed. The total amount of methanol obtained in the first and second stages is 73.95 t / h; 2244 Nm3 of the feed gas is consumed to produce 1 ton of methanol.

Example 5. The first stage is similar to that described in Example 2. Then, 63,386 nm / h of hydrogen are added to the gas stream leaving the first stage. In this case, 129,492 nm3 / h of a gas mixture is formed, of the following composition, vol.%:

С022.06 Н2 74.30 No. 0.86 СН4 0.54 СО 22.02 СНзОН 0.22 This gas is processed in a shaft reactor at the parameters described in Example 2. The temperature at the outlet of the reactor is 288 ° С. The volumetric ratio C0 / H20 + C02 is 2.85. In a second step, 42.23 t / h of methanol are formed. The total amount of methanol obtained in the first and second stages is 76.98 t / h; 2642 nm of gas is consumed per 1 ton of methanol.

Example 6. The first stage is carried out in a cascade of three flow reactors. In the first flow reactor serves 140200 nm / h of the initial gas mixture of the following composition, vol. %:

С022.00 Н2 58.61 N2 0.86 СН4 0.58 СО 37.95, where it is in contact with a copper-containing catalyst at a temperature of 250 ° С and a pressure of 8 MPa, 10 m3 of catalyst are loaded into the reactor, Volumetric ratio of hydrogen to total carbon oxides equal to 1.47. 19.01 t / h of methanol are formed in the first reactor.

The gas mixture leaving the first flow reactor after separation of the crude methanol has the following composition, vol.%:

С022.74 Н2 55.31 N2 1.23 СН4 0.81 СО 39.55 СНзОН 0.36. this gas in an amount of 96321 nm / h is sent to a second flow reactor and is contacted with 10 m of catalyst at a temperature of 250 ° C and a pressure of 8 MPa. In a second flow reactor, 16.26 t / h of methanol is formed.

The gas mixture leaving the second reactor after separation of methanol and water has the following composition, vol%: С024.13 Н2 49.54 N2 1.93 СН4 1.23 СО 42.70 СНзОН 0.47 Its amount is 59980 nm / h sent to a third flow reactor. Said gas mixture is contacted at a temperature of 250 ° C and a pressure of 8 MPa with 10 m3 of catalyst. In this case, 11.01 t / h of methanol are formed. The total amount of catalyst in three flow reactors is 30 m3. A total of 46.28 t / h of methanol is formed in the first stage. The gas mixture leaving the first stage (34649 nm / h) after separation of the crude methanol has the following composition, vol.%:

С026.70 Н2 38.80 N2 3.22 СЦ 2.00 СО 48.46 СНзОН 0.82

To it was added 66468 nm3 / h of a gas mixture of the composition, vol.%:

С020.51 Н2 81.85 СО 17.64

In this case, 101115 nm3 / h of a gas mixture of the following composition is formed, vol.%: С022.64 Н2 67.09 N2 1.10 СН4 0.69 СО 28.20 СНзОН 0.28 This gas is processed in a shaft reactor with parameters as indicated in example 3. The volumetric ratio of CO / H20 + CO2 at the exit of the second stage is 2.76. In the second stage, 43.54 t / h of methanol are formed. The total amount of methanol obtained in the first and second stages is 89.82 t / h. The production of 1 ton of methanol requires 2301 nm3 of the feed gas.

The conditions and results of examples 1-6 are shown in table 1.

Example. The source gas mixture of the following composition, vol.%:

C021.96 H2 67.10 N2 0.90 CO 30.04

156042 nm3 / h is fed to the first stage of methanol synthesis in a flow reactor, where they are contacted with a copper-containing catalyst at a temperature of 250 ° C and a pressure of 8 MPa. The amount of catalyst in the first stage is 32 m3. The volumetric ratio of H2 / CO + CO2 is 2.10. In the first step, 38.94 t / h of methanol is formed. The gas mixture leaving the flow reactor after separation of the crude methanol has the following composition, vol%: С024.03 Н2 67.03 Н20 О N2 1.89 СО 26.42 СНзОН 0.35

All gas in the amount of 73653 nm3 / h enters the second stage in the shaft reactor operating with recycle. 36 m3 of catalyst are charged into the shaft reactor. 500,000 Nm3 / h of circulating gas is fed to the reactor inlet. Volumetric speed 13889. The temperature at the entrance to each catalyst bed is equal to: 1 - 220 ° C; 2 - 220 ° C; 3 - 230 ° C; 4 - 240 ° C. The temperature at the outlet of the reactor is 268 ° C. The volumetric ratio C0 / H20 + C02 is 1.68. In the second stage, 30.13 t / h of methanol are formed. The total amount of methanol obtained in the first and second stages is 69.07 t / h. The formation of 1 ton of methanol requires 2259 nm3 of synthesis gas.

Example 8. The first stage is carried out in a cascade of three flow reactors, 132520 nm / h of the initial gas mixture of the following composition, vol.%: COa 2.41; At 74.69; N2 4.84; СО 18.06, where it is in contact with 5 m3 of a copper-containing catalyst at a temperature of 250 ° С and a pressure of 7 MPa. The volume ratio of hydrogen to the sum of carbon oxides is 3.65. In the first reactor, 10 t / h of methanol is formed. The gas mixture leaving the first flow reactor after separation of the crude methanol has the following composition, vol%: C022.62; H2 76.03; N2, 5.86; СО 15.08; CHzone 0.41. This gas in an amount of 109064 nm / h is sent to a second flow reactor, where it is contacted with 5 m3 of catalyst at a temperature of 250 ° C and a pressure of 7 MPa. In a second flow reactor, 9.72 t / h of methanol is produced. The gas mixture leaving the second reactor after separation of the crude methanol has the following composition, vol%: C022.84; H2 78.22; N27.27; СО 11.27; CHzone 0.40. This amount of 87323 nm3 / h is sent to a third flow reactor. Said gas mixture is contacted with 5 m3 of catalyst at a temperature of 250 ° C and a pressure of 7 MPa. This produces 8 t / h of methanol. The total amount of catalyst in the three flow reactors is 15 m. In the first stage, a total of 27.72 t / h of methanol is formed. The gas mixture leaving the first stage (69168 nm3 / h) after separation of the crude methanol has the following composition, vol.%:

С022.88 Н2 80.91 Н20 0.01 N2 9.11 СО 6.60 СНзОН 0.49 To it are added 25420 nm3 / h of a gas mixture of the following composition, vol.%: С02 25.15 Н2 23.19 СО 51.66 This produces 94588 nm3 / h of a gas mixture of the following composition, vol.%: CO2 8.86 H2 65.41 N2 6.66 СО 18.71 СНзОН 0.36 This gas is processed in a shaft reactor, in which 38 m3 of a copper-containing catalyst divided into 4 layers. The temperature at the entrance to each catalyst bed: 1 - 220 ° C; 2 - 220 ° C; 3 - 230 ° C; 4 - 230 ° C. The temperature at the outlet of the reactor is 261 ° C. The flow rate of the circulating gas mixture at the inlet to the reactor is 570000 nm3 / h. In the second stage, 30.45 t / h of methanol is formed. The volumetric ratio of CO / H20 + CO2 is 0.82. The total amount of 0 methanol obtained in the first and second stages is 58.17 t / h. The gas flow rate per 1 ton of methanol is 2715 nm3.

Example 9. At the first stage, 90,000 nm / h of feed gas having a composition of vol.% Is supplied to the flow reactor: vol. C023.0 H2 73.0 N2 7.0 CO 17.0 0 In a flow reactor at a pressure of 7 MPa At a temperature of 250 ° C, the gas mixture is in contact with a copper-containing catalyst, taken in an amount of 5 m3. In the first step, 8.49 t / h of methanol is formed. To the gas stream 5 exiting the first stage, 15931 nm3 / h of gas of the following composition, vol.%:

С0237.62 Н2 60.28 0 СО 2.10

In this case, 86349 nm3 / h of a gas mixture of the following composition is formed, vol.%: С029.71 Н2 71.64 5 Н20 0.03 N2 7.30 СО 10.93 СНзОН 0.39 This gas is processed for the second day at shaft reactor at the parameters described in example 8. The temperature at the outlet of the reactor 248 ° C. In a second step, 24.57 t / h of methanol is formed. The volumetric ratio of CO / H20 + CO2 is 0.31. The total 5 amount of methanol obtained in the first and second stages x is 33.06 t / h. Raw material consumption per 1 ton of methanol is 3204 nm3.

Example 10. At the first stage, 90,000 nm / h of the initial gas mixture of the following composition, vol.%, Are fed into the flow reactor.

C027.0 H2 78.0 N2 7.0 5 CO. 8.0

In a flow reactor at a pressure of 7 MPa and a temperature of 250 ° C, the gas mixture is contacted with a copper-containing catalyst, taken in an amount of 1.5 m. In the first step, 1.93 t / h of methanol is formed.

Example 11. At the first stage - in the flow reactor serves 90,000 nm / h of the initial gas mixture of the following composition, vol.%:

C027.0

H278.0

N27.0

СО8,0

In a flow reactor at a pressure of 7 MPa and a temperature of 250 ° C, the gas mixture is in contact with a copper-containing catalyst, taken in an amount of 30 m3. Here 9.96 t / h of methanol are formed.

The conditions and results of methanol synthesis according to examples 6-11 are given in table.2.

As follows from Tables 1 and 2, the specific productivity of the catalyst increases both in the second stage and in the entire process as a whole, if the volumetric ratio of CO / H20 + CO2 in the gas at the outlet of the second stage reactor is maintained within 0.82 -2.89. Both an increase and a decrease in this ratio in the gas leaving the second-stage reactor leads to a decrease in the specific productivity of the catalyst (Examples 2 and 9). In the indicated limit of the volumetric ratio of CO / H20 + CO2, a high degree of conversion of carbon oxides to methanol is observed. The degree of conversion of carbon oxides refers to the ratio of the amount of carbon oxides converted to methanol to the initial amount of carbon oxides. In the process of methanol synthesis, only carbon oxides, which are continuously purged and dissolved in methanol, are not used. They are withdrawn from the process and used as fuel. In Examples 3, 4, and 5, using a starting gas of approximately the same composition in the second stage, a gas significantly different in composition is obtained at the outlet of the reactor. This is explained by the fact that in Example 3 the functional of the H2-CO2 / CO2 + CO2 gas supplied to the second stage is 2.08, i.e. is close to stoichiometry, in example 4 it is lower than stoichiometry (1.83), in example 5 it is much larger (3.0). Therefore, in Example 3, the ratio of H2-CO2 / CO + CO2 at the outlet of the reactor becomes 4.6, i.e. increasing. In Example 4, where it is less than 2.0, it decreases and becomes equal to 0.56. In Example 5, where the ratio of H2-CO2 / CO + CO2 at the inlet of the reactor is 3.0, at the outlet of the reactor it becomes 19.7. Thus, if the ratio of reacting components in the feed gas is lower than stoichiometry, then after the reaction is carried out in a circulating gas, those components that were in excess, i.e. carbon oxides. If the ratio of the reacting components is higher than stoichiometry, then hydrogen accumulates in the reaction mixture.

The greatest positive effect is observed if the first stage is carried out in a cascade of several flow reactors. This can be seen from a comparison of Examples 3 and 6 of Table 1 and Examples 8 and 9 of Table 2. The increase in the specific productivity of the catalyst during the first stage in the cascade of flow reactors is explained by the fact that after each of the flow reactors the reaction products (methanol and water) are discharged. Therefore, the thermodynamic inhibition of the process by reaction products is reduced and higher methanol production rates are achieved in each individual reactor as compared to the reaction rate when the first stage is carried out in one flow reactor.

Tables 3 and 4 show the material balances of all flows.

The proposed method for producing methanol has a positive effect: an increase in the specific productivity of the catalyst with a rather low specific consumption of synthesis gas: from 2235 to 2715 nm3 / t. This makes it possible to use this method for producing methanol in two stages, using gas mixtures containing hydrogen and carbon oxides as a source gas over a wider range of concentrations than indicated in the prototype, i.e. significantly expand the raw material base for methanol production. In this case, gases departing from other industries, as well as those obtained by high temperature conversion or gasification of solid fuel, can be used.

Claims (1)

SUMMARY OF THE INVENTION 1. A method for producing methanol by contacting mixtures of carbon oxides and hydrogen with a copper-containing catalyst at elevated temperature and pressure in two stages, where the first stage is carried out in a flow reactor and the second in a recycle reactor, with methanol evolution after each stage, which differs in order to increase the specific productivity of the catalyst, synthesis gas is supplied to the first stage at a volumetric ratio of Н2 / СО + С02 of 1.47-3.65, and at the second stage, the process is carried out at a volumetric ratio of СО / Н20 + С02 in ha at the outlet of the reactor in the range of 0.82-2.89. 2, The method according to claim 1, characterized in that the volumetric ratio CO / H20 + CO2 at the outlet of the second stage reactor is controlled by adding to the gas supplied to the second stage an additional gas stream containing excess hydrogen or carbon oxides. Table 1 The conditions and results of methanol synthesis according to examples 1-6 Conditions and results of methanol synthesis according to examples 7-11 Table 2 Continuation of the table. 1 Continuation of the table. 2 Material flow balances Table / i Continuation of table 1