WO2011136345A1

WO2011136345A1 - Process for producing methanol

Info

Publication number: WO2011136345A1
Application number: PCT/JP2011/060405
Authority: WO
Inventors: 達己松下; 司芳賀沼; 大祐藤田
Original assignee: 三井化学株式会社
Priority date: 2010-04-30
Filing date: 2011-04-28
Publication date: 2011-11-03

Abstract

A process for producing methanol is provided by which it is possible to highly efficiently produce methanol even when a device which is similar to a conventional device, e.g., a fixed-bed reactor, and has a thick catalyst bed is used. The process for methanol production is a process for producing methanol by reacting hydrogen with carbon dioxide in a reactor having a catalyst bed constituted of a copper-containing catalyst. The process is characterized by including a step in which hydrogen and carbon dioxide are supplied from the upstream side of the catalyst bed of the reactor and a reaction mixture containing methanol is obtained from the downstream side of the catalyst bed. The process is further characterized in that the catalyst bed has a thickness of 1 m or more, the molar ratio of the hydrogen to the carbon dioxide which come into contact with the catalyst bed (hydrogen/carbon dioxide) exceeds 3.0, the molar ratio of an inert gas to the carbon dioxide (inert gas/carbon dioxide) is 0 or more, and the molar ratio of the sum of the hydrogen and the inert gas to the carbon dioxide ((sum of hydrogen and inert gas)/carbon dioxide) is 3.5 or more.

Description

Method for producing methanol

The present invention relates to a method for producing methanol under specific conditions using carbon dioxide and hydrogen as raw materials.

Methanol is used as a raw material and fuel for dimethyl ether, MTBE (methyl tertiary butyl ether), petrochemical intermediate products, and the like.

Conventionally, methanol uses fossil fuels such as hydrocarbons and coke as raw materials, obtains synthesis gas (including CO and H ₂ and a small amount of CO ₂ ) by steam reforming, and synthesizes the resulting synthesis gas as the main raw material. It is manufactured by. However, since this method uses fossil raw materials as main raw materials, it consumes global resources and increases CO ₂ in the atmosphere, which causes global warming.

On the other hand, a technique for synthesizing methanol using CO ₂ and hydrogen as raw materials is known. This method converts carbon dioxide, which is a cause of global warming, into an organic compound, so that it contributes not only to production activities by various chemistry but also to reduce carbon dioxide, which is regarded as a warming gas, that is, global warming. This is a very desirable technique from the viewpoint of prevention.

Methanol synthesis from raw material gas with high carbon dioxide content is more active and durable than methanol synthesis from synthesis gas due to the thermodynamic equilibrium of reaction and the reaction inhibition effect of water generated with methanol The catalyst is required.

From this point of view, copper-based multicomponent catalysts such as copper / zinc oxide / aluminum oxide / zirconium oxide and copper / zinc oxide / aluminum oxide / zirconium oxide / gallium oxide have been developed (for example, JP-A-7-39755). (Patent Document 1), JP-A-6-312138 (Patent Document 2), Applied Catalysis A: Gernal, 38, 311-318 (1996) (Non-Patent Document 1)). Further, a highly active catalyst in which 0.3 to 0.9 wt% of colloidal silica or silica dissolved in water is added as silica and calcined at 480 to 690 degrees has been developed (Japanese Patent Laid-Open No. 10-309466 (Patent Document 3). )).

In any of the above examples and experimental examples, the reaction condition is the stoichiometric ratio of the reaction (CO ₂ + 3H ₂ → CH ₃ OH + H ₂ O) in the synthesis of methanol using CO ₂ and hydrogen as raw materials. The reaction is carried out at H ₂ / CO ₂ = 3 (molar ratio) or H ₂ / (CO ₂ + CO) (molar ratio) = 3 in consideration of CO by-product. Japanese Patent Laid-Open No. 7-173088 (Patent Document 4) describes that 3 out of 1 to 10 is optimal for H ₂ / CO ₂ (molar ratio).

In Japanese Patent Application Laid-Open No. 6-1884023 (Patent Document 5), the reaction is performed by adding the amount of CO ₂ dissolved and separated in an aqueous methanol solution to the stoichiometric ratio, and H ₂ / CO ₂ (Molar ratio) is 2.8. As described above, the methanol synthesis reaction is performed at 3 or near the stoichiometric ratio of H ₂ / CO ₂ (molar ratio).

In addition, since the catalyst is solid, it is common to use a fixed bed reactor for the methanol synthesis reaction. As a type of the reactor, a multitubular reactor can be generally used.

JP-A-7-39755 Japanese Patent Laid-Open No. 6-312138 Japanese Patent Laid-Open No. 10-309466 JP 7-173088 A Japanese Patent Laid-Open No. 6-1884023

According to the study by the present inventors, the above-described method for producing methanol from carbon dioxide and hydrogen reduces the production efficiency when the production apparatus is scaled up, and further, the pressure between the catalyst layer inlet and the outlet is reduced. It was found that a difference occurred.

Process Reactor Program 43D MEGA METHANOLPLANT, 2003 is a reactor that synthesizes methanol from synthesis gas (mainly CO and H ₂ ) by filling the reaction tube with catalyst at a height of 4-12 m. , page7-73. Here, gas flows from the upper part of the reactor, and the reaction proceeds by gas-solid contact with the catalyst in the reaction tube, and the unreacted raw material and product mixed gas flows out from the lower part. At this time, the reactor outlet pressure is lower than the inlet due to the pressure loss caused by the reaction gas passing through the catalyst filling portion. The reaction for synthesizing methanol from the above synthesis gas is an equilibrium reaction, and the lower the pressure, the lower the equilibrium conversion rate. Therefore, if the reactor outlet pressure decreases, that is, the pressure loss in the catalyst filling section increases, the methanol production decreases. There is a problem of doing. Therefore, it is known to use a radial flow type reactor in order to suppress a pressure drop in the catalyst filling portion.

In such a reactor, the pressure loss is reduced by reducing the thickness of the catalyst packed portion, and the decrease in methanol production is prevented (Petertech Vol. 20, No. 8, P638, JP-A-3-47134). ).

However, in the case of the reactor described above, the amount of catalyst that can be filled is relatively reduced. Therefore, increasing the size of the reaction tank is one way to increase productivity. However, the increase in the size of the reaction tank is disadvantageous for removing the heat of reaction and keeping the reaction temperature constant because of the specific surface area. For this reason, a complicated structure of providing a large number of heat transfer tubes for heat removal in the catalyst layer is required, which may lead to an increase in equipment cost. In addition, it is considered that the problem of pressure loss cannot be completely solved with a large reaction layer. For this reason, there is a demand for an efficient method for producing methanol with a simple structure.

The inventors of the present application have studied in view of the above problems, and as a result, by controlling the molar ratio of gas components such as hydrogen and carbon dioxide that are in contact with the catalyst layer to a specific range, It has been found that methanol can be efficiently produced even with a small facility, and the present invention has been completed.

That is, the method for producing methanol of the present invention is a method for producing methanol by reacting hydrogen and carbon dioxide in a reactor having a catalyst layer formed from a catalyst containing copper, and the catalyst possessed by the reactor. Supplying hydrogen and carbon dioxide from the upstream side of the layer, and obtaining a reaction mixture containing methanol from the downstream side of the catalyst layer, wherein the catalyst layer has a thickness of 1 meter or more, The molar ratio of hydrogen and carbon dioxide contacting the catalyst layer (hydrogen / carbon dioxide) exceeds 3.0, and the molar ratio of the reaction inert gas to carbon dioxide (reactive inert gas / carbon dioxide) is 0. The molar ratio of hydrogen and reaction inert gas to carbon dioxide (total of hydrogen and reaction inert gas / carbon dioxide) is 3.5 or more.

The molar ratio of hydrogen to carbon dioxide (hydrogen / carbon dioxide) is 3.5 to 5.5, and the molar ratio of the total of hydrogen and reaction inert gas to carbon dioxide (hydrogen and reaction inert gas) Of carbon dioxide) is preferably 3.5 to 6.0.

It is preferable that the catalyst containing copper is a catalyst containing copper, zinc, aluminum, and silicon.

It is preferable that the reactor is a fixed bed reactor.

The particle size of the catalyst containing copper is preferably 3 to 20 mm.

The reaction is preferably performed at a pressure of 1 to 10 MPaG.

According to the method for producing methanol of the present invention, the influence of pressure loss can be effectively reduced by controlling the ratio of the supply amount (use amount) of the raw material in contact with the catalyst layer to a specific range. It is not necessary to use a reactor having a structure, and even a reactor such as a conventional fixed-bed multi-tubular reactor can produce methanol with high efficiency.

It is a flowchart figure for demonstrating the apparatus used by the Example and the comparative example.

Next, the present invention will be specifically described.

The method for producing methanol of the present invention is a method for producing methanol by reacting hydrogen and carbon dioxide in a reactor having a catalyst layer formed from a catalyst containing copper, and the catalyst layer possessed by the reactor. A step of supplying hydrogen and carbon dioxide from the upstream side to obtain a reaction mixture containing methanol from the downstream side of the catalyst layer, wherein the catalyst layer has a thickness of 1 meter or more, The molar ratio of hydrogen to carbon dioxide in contact with the layer (hydrogen / carbon dioxide) exceeds 3.0, and the molar ratio of reactive gas to carbon dioxide (reactive inert gas / carbon dioxide) is 0 or more. The molar ratio of the sum of hydrogen and reaction inert gas to carbon dioxide (total of hydrogen and reaction inert gas / carbon dioxide) is 3.5 or more. Normally, a fixed bed reactor is used as the reactor.

As hydrogen and carbon dioxide used in the present invention, those obtained by known methods can be used without limitation. As hydrogen, for example, hydrogen that is generated (by-product) by a steam reforming reaction, hydrogen that is generated by an electrolytic reaction, hydrogen obtained by photolysis of water, or the like can be used.

For example, carbon dioxide generated by burning various chemical reactions and fuels in a petrochemical industrial plant can be used.

In the method for producing methanol of the present invention, methanol and water are synthesized by the reaction of carbon dioxide and hydrogen. The reaction mixture obtained by the reaction contains the methanol and water, and usually further contains unreacted raw materials (for example, hydrogen and carbon dioxide) and by-products (for example, carbon monoxide). In the method for producing methanol of the present invention, usually, unreacted raw materials (for example, hydrogen and carbon dioxide) and by-products (for example, carbon monoxide) are separated from the obtained reaction mixture to obtain a mixture of methanol and water, Next, methanol is obtained by dehydrating the mixture by a known method.

The unreacted raw material and by-products can be recycled to the reactor, preferably as a gaseous mixture, to increase the reaction efficiency.

In the present invention, hydrogen and carbon dioxide are supplied from the upstream side of the catalyst layer of the reactor, but the molar ratio of hydrogen to carbon dioxide in contact with the catalyst layer (hydrogen / carbon dioxide) is 3.0. Exceed. Preferably, it is 3.5 or more, more preferably 4.0 or more. Below the above range, due to an increase in pressure loss due to the catalyst layer, the equilibrium conversion rate decreases and the methanol productivity decreases. Further, the upper limit of the molar ratio of hydrogen and carbon dioxide that contacts the catalyst layer is not particularly limited, but if the molar ratio of hydrogen and carbon dioxide is too high, the productivity of methanol may decrease. . For this reason, the upper limit of the molar ratio of hydrogen to carbon dioxide is preferably 20.0, more preferably 10.0, even more preferably 6.0, particularly preferably 5.5, particularly preferably 5.0. .

The following factors can be considered as factors causing the effects of the present invention.

By setting the molar ratio of hydrogen to carbon dioxide to a value that exceeds the stoichiometric ratio of 3.0, preferably 3.5 or more, the proportion of hydrogen that does not substantially contribute to the reaction increases. Hydrogen that does not contribute to this reaction (excess hydrogen) serves to alleviate the pressure drop due to the reaction in the production of methanol.

The reaction that produces methanol and water from carbon dioxide and hydrogen is an equilibrium reaction, and the total amount of methanol and water produced is less than the sum of the reacting carbon dioxide and hydrogen. For this reason, the decrease in pressure is considered to increase the rate of so-called reverse reaction that generates carbon dioxide and hydrogen from methanol and water (decreases the productivity of methanol).

It is considered that the excessive hydrogen described above suppresses the influence in an environment where pressure loss occurs and improves productivity. Usually, the presence of excess hydrogen means a decrease in the concentration of carbon dioxide when the pressure is constant. Therefore, it is common knowledge that the productivity of methanol should decrease. However, if methanol is produced under the conditions within the scope of the present invention, this productivity decrease can be compensated for and a significant improvement in productivity can be brought about.

Also, the methanol production method of the present invention may involve a reaction of generating carbon monoxide and water from carbon dioxide and hydrogen. For reasons similar to the above, it is considered that a decrease in pressure loss also brings about an effect of relatively suppressing the rate of the reaction for generating carbon monoxide.

In addition, since hydrogen has a low density as a gas, the gas density is relatively lowered if the ratio of hydrogen and carbon dioxide of the present invention is used. This low gas density is considered to show the effect of reducing the pressure loss due to the catalyst layer. That is, the condition of the present application having a high hydrogen ratio is considered to be another factor that increases the productivity of methanol.

In the methanol production method of the present invention, water is synthesized in addition to methanol. In general, water may be adsorbed on a catalyst to inhibit the methanol production reaction, which may cause a reduction in methanol production efficiency. In the present invention, since the supply amount of hydrogen to carbon dioxide is large, the generated water is diluted, and the water concentration is lowered as compared with the conventional case. Since a decrease in water concentration leads to a decrease in the amount of water adsorbed on the catalyst, it is thought that a decrease in methanol production efficiency due to water may be suppressed. For this reason, in the methanol manufacturing method of this invention, it is guessed that methanol production efficiency is high.

In the method for producing methanol of the present invention, a gas other than hydrogen and carbon dioxide may be supplied. Examples of gases other than hydrogen and carbon dioxide include reaction inert gases. The reaction inert gas may be a compound that does not substantially react when hydrogen and carbon dioxide are reacted. If a reaction inert gas is supplied to the reaction, it is considered that the influence of pressure loss can be reduced, that is, the productivity of methanol can be increased. Preferably, the reaction inert gas includes a substance having a molecular weight equal to or lower than that of carbon dioxide, and specifically includes nitrogen; a rare gas such as helium and argon; and a hydrocarbon such as methane, ethane and propane. Can do. This reaction-inert gas is considered to bring about an improvement in methanol productivity for the same reason as the hydrogen that does not substantially contribute to the reaction.

In the present invention, the molar ratio of the reaction inert gas to carbon dioxide (reaction inert gas / carbon dioxide) in contact with the catalyst layer is 0 or more. For the same reason as the preferable range of the molar ratio of hydrogen to carbon dioxide, the upper limit of the molar ratio of the reaction inert gas to carbon dioxide is preferably 17.0, more preferably 10.0, Preferably it is 5.0, particularly preferably 1.0, particularly preferably 0.5.

In the present invention, the molar ratio of the total of hydrogen and inert gas to carbon dioxide (total of hydrogen and inert gas / carbon dioxide) in contact with the catalyst layer is 3.5 or more, preferably 4 0.0 or more. The upper limit of the molar ratio of hydrogen and inert gas to carbon dioxide is not particularly limited, but is preferably 20.0, more preferably 10.0, and still more preferably from the viewpoint of methanol productivity. Is 6.0.

In the method for producing methanol of the present invention, the hydrogen and carbon dioxide are reacted in the presence of a catalyst containing copper. As the catalyst containing copper, a catalyst containing copper can be used without limitation as long as it is a catalyst capable of producing methanol from hydrogen and carbon dioxide. As a catalyst containing copper used for this invention, the catalyst of patent document 3 is mentioned as a preferable example. Specifically, the catalyst containing copper is preferably a catalyst containing copper, zinc, aluminum, and silicon. More preferably, the catalyst contains at least one element selected from zirconium, palladium, and gallium. Such a catalyst containing a component such as copper can be suitably used in the method for producing methanol of the present application for the reason that there is little decrease in activity due to water produced as a by-product when methanol is produced from carbon dioxide. .

The copper-containing catalyst preferably has an average particle size of 0.5 to 20 mm, more preferably 1 to 20 mm, and still more preferably 2 to 20 mm. Further, the average particle size is preferably 3 to 20 mm, more preferably 3 to 15 mm, and particularly preferably 3 to 10 mm. When the particle size of the catalyst containing copper is within the above range, not only the handling of the catalyst is easy, but also, for example, a catalyst layer is formed by loading the catalyst on a fixed bed, and methanol is produced by the method of the present invention. This is suitable for suppressing a decrease in productivity due to pressure loss. As a method for producing the catalyst having the above particle diameter, a known method can be used without limitation. A tableting method is preferably used.

As the reactor used in the present invention, a known reactor can be used without limitation. For example, the catalyst containing copper is preferably packed in a fixed bed reactor. A radial flow reactor can also be suitably used. Since the pressure loss can be reduced by using the method of the present invention, the productivity can be improved even in a relatively large radial flow reactor, and methanol can be efficiently produced.

In the method for producing methanol of the present invention, hydrogen and carbon dioxide are reacted in a reactor having a catalyst layer formed from the catalyst containing copper. In this reaction, hydrogen and carbon dioxide are supplied from the upstream side of the catalyst layer of the reactor, and a reaction mixture containing methanol is obtained from the downstream side of the catalyst layer (hereinafter, also referred to as step (A)). It is done in the following. The thickness of the catalyst layer included in the reactor is 1 meter or more. The thickness of the catalyst layer is preferably 2 meters or more, more preferably 3 meters or more, and even more preferably 4 meters or more. There is no positive meaning in setting the upper limit of the thickness, but if it becomes too thick, the negative effect of pressure loss tends to increase, so the upper limit is preferably 20 meters, more preferably 15 meters. . In addition, the catalyst layer thickness in this application is not necessarily determined only by the positional relationship between the upstream side and the downstream side, but indicates a substantial length considering the shape of the catalyst layer.

It should be noted that the thickness of the catalyst layer according to the present invention need not be the same at any position, and it is preferable that the thickness of the thinnest portion satisfies the above-mentioned requirements. More preferably, the catalyst layer thickness is preferably uniform. If a portion having a thin catalyst layer is present, source gases such as carbon dioxide and hydrogen may be concentrated relatively on the portion, and the apparent catalytic reaction efficiency may be reduced.

The catalyst layer according to the methanol production method of the present invention is not particularly limited as long as hydrogen and carbon dioxide can pass through. For example, the catalyst layer may be a single block, or may be formed from a plurality of particles or powder. The catalyst layer is preferably formed by filling a reactor with a catalyst containing copper having an average particle diameter of 1 to 20 mm, more preferably 3 to 20 mm, that is, catalyst particles. preferable. Moreover, in the manufacturing method of methanol of this invention, you may have a some catalyst layer.

The direction in which the reaction apparatus is installed can be set in any direction regardless of whether it is vertical or horizontal. Of course, a shape like a curved pipe may be used, but a substantially straight pipe shape is preferable. The positional relationship between the upstream and downstream is also arbitrary. For example, it may be a downflow reactor or an upflow reactor. Of course, the aforementioned radial flow reactor may be used.

With the methanol production method of the present invention, even if the same reactor is used with the same amount of catalyst as in the conventional method, the productivity drop due to pressure loss is reduced compared to the conventional methanol production method. Therefore, it is possible to produce methanol with high production efficiency without increasing the diameter of the reactor so that the catalyst thickness and the catalyst amount are not highly balanced.

In the methanol production method of the present invention, the reaction is usually carried out under conditions of a reaction temperature of 150 to 300 ° C., a reaction pressure of 1 to 10 MPaG, and a GHSV (Gas Hourly Space Velocity) of 1000 to 30000 h ⁻¹ .

The preferable lower limit of the reaction pressure is 2 MPaG, more preferably 3 MPaG, and particularly preferably 3.5 MPaG. On the other hand, a preferable upper limit is 9 MPaG, more preferably 8.5 MPaG, and particularly preferably 8 MPaG.

When the reaction pressure is too high, the aforementioned pressure loss hardly occurs in the first place, and the effect of the present invention tends to be relatively small. Moreover, a high pressure resistant material is required for the reaction apparatus, and the fixed cost tends to be high. On the other hand, if the reaction pressure is too low, the absolute value of the reaction rate may decrease, leading to a decrease in productivity. In order to compensate for the low reaction rate and increase the production volume, there is a method of increasing the size of the equipment, but this also tends to increase the fixed cost.

The step (A) is performed using a reactor having a catalyst layer as described above. For example, the reactor may have spaces on the upstream side and downstream side of the catalyst layer, the upstream side of the catalyst layer may be directly connected to the raw material supply line, or the downstream side of the catalyst layer may be the reactor. May be directly connected to the outlet (reactant take-out line).

In the production method of the present invention, even if the catalyst layer is thick, the productivity of methanol can be increased. The reason for this is that the present inventors can reduce the decrease in productivity due to pressure loss by using a raw material having a specific composition that was previously thought to decrease the productivity, resulting in a difference from the conventional knowledge. It was estimated that the productivity of methanol was excellent.

Further, since the pressure loss is small and the equilibrium conversion rate can be kept high, there is a possibility that the energy required for pressurization can be reduced when the unreacted raw materials and by-products described above are recovered and reused as a gaseous mixture. is there. That is, it is expected that the energy consumption of the entire process can be reduced.

In the methanol production method of the present invention, hydrogen and carbon dioxide react in a reactor having the catalyst layer. The reaction mixture obtained from the outlet of the reactor usually contains hydrogen and carbon dioxide as unreacted raw materials and carbon monoxide as a by-product, in addition to methanol and water obtained by the reaction. The reaction mixture is usually obtained as a gas. That is, the reaction mixture is preferably a gaseous reaction mixture.

The gaseous reaction mixture is usually cooled and then separated into a liquid mixture and a gaseous mixture by a gas-liquid separator. The separation is usually carried out under conditions of a pressure of 1 to 10 MPa and a temperature of −10 to 50 ° C. The liquid mixture obtained in the separation is formed from methanol, water and carbon dioxide dissolved in them, and the gaseous mixture is formed from the unreacted raw material and carbon monoxide as a by-product. It should be noted that at least a part of the gaseous mixture is preferably recycled to the reactor.

As described above, the gaseous mixture may contain carbon monoxide as a by-product. Carbon monoxide may be supplied to the reactor as an impurity of the raw material, or carbon monoxide can be introduced as necessary. Preferably, the ratio of carbon dioxide to carbon monoxide is 100/0 to 60/40, more preferably 100/0 to 70/30, still more preferably 100/0 to 75/25, particularly preferably 100/0 to 80 / 20, particularly preferably 100/0 to 85/15.

The methanol production method of the present invention can reduce the productivity drop due to the pressure loss as compared with the conventional methanol production method. However, when the reaction is performed on a small scale, the conventional production method can be used. The effect of pressure loss may not be apparent when compared to the method. This is presumably because the pressure loss does not become apparent because the catalyst layer is mainly thin on a small scale.

For this reason, the method for producing methanol of the present invention is substantially performed on a scale where the effect of reducing the effect of pressure loss is manifested. Specifically, the catalyst layer is often used in combination with a temperature control tank having a shape such as a jacket. In this temperature control tank, the catalyst layers may be combined in a single layer, or a plurality of catalyst layers may be stored in one temperature control tank, that is, a multi-tube type. The multi-tubular shape is preferably used in industrialization. Assuming industrialization, the upper limit of the scale of the entire catalyst layer in this shape is not particularly limited, and is preferably 500 cubic meters, more preferably 400 cubic meters, more preferably 200 cubic meters, depending on the thickness of the catalyst layer. Further preferred, particularly preferred is 150 cubic meters. On the other hand, the lower limit is 1 cubic meter, more preferably 10 cubic meters, and still more preferably 20 cubic meters. A plurality of these devices can be used in combination.

The scale of the reactor is naturally larger than the capacity of the catalyst layer.

In the method for producing methanol of the present invention, a known method can be used without any limitation as a method for stopping the reaction. Specifically, without purging the residual gas in the reaction system with a reaction inert gas or the like, hydrogen is supplied instead of supplying the raw material mixed gas, and the residual gas remains in the reaction system under the same conditions as described above. Carbon monoxide and carbon dioxide A preferred example is a method in which substantially the entire amount is converted to methanol by reacting with.

One aspect of the method for producing methanol of the present invention will be described below with reference to FIG. In this embodiment, no reaction inert gas is used. A mixed gas in which the molar ratio of hydrogen to carbon dioxide (hydrogen / carbon dioxide) is within a predetermined range is used as the raw material gas. It is done. The raw material mixed gas that has entered the reaction circulation system is heated together with the gaseous mixture circulated by the circulation compressor 6 to a temperature suitable for the reaction in the heater 2 and then sent to the reactor 3 to synthesize methanol. Subject to reaction. Note that a catalyst layer formed from a catalyst containing copper is present in the reactor. In the reactor 3, hydrogen and carbon dioxide react with each other to obtain a gaseous reaction mixture containing methanol. The gaseous reaction mixture (reaction mixture gas) exiting the reactor 3 is cooled to below normal temperature by the cooler 4, and mainly produced methanol and water are liquefied and sent to the gas-liquid separator 5. After the liquid mixture and the gaseous mixture are separated from the gas-liquid separator 5, the liquid mixture and the gaseous mixture are respectively extracted, and most of the gaseous mixture is circulated to the reactor 3 by the circulation compressor 6. A part of the gaseous mixture can be purged out of the system.

In addition, although not shown in FIG. 1, carbon dioxide or the like dissolved in the liquid mixture may be appropriately separated from the liquid mixture extracted from the gas-liquid separator 5 and separated. Gas is usually discharged out of the system. Usually, the liquid mixture composed of methanol and water separated by the gas-liquid separator 5 is dehydrated by a known method to obtain methanol.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Examples and Comparative Examples were performed using the apparatus shown in FIG. The apparatus includes a booster compressor 1 for supplying a mixed gas as a raw material, a heater 2 for heating the raw material, a reactor 3 for performing a reaction, and a cooler 4 for cooling the obtained reaction mixture. A gas-liquid separator 5 for dividing the reaction mixture into liquid and gas, and a circulation compressor 6 for circulating at least a part of the separated gas to the reactor 3 are provided.

[Production Example 1]
(Preparation of catalyst containing copper)
A catalyst was prepared substantially in accordance with the method of Example 1 of Patent Document 3 (Japanese Patent Laid-Open No. 10-309466). The composition of the resulting catalyst CuO: 45.2wt%, ZnO: 27.1wt %, Al 2 O 3: 4.5wt%, ZrO 2: 22.6wt%, SiO 2: was 0.6 wt%.

[Example 1]
Using the apparatus shown in FIG. 1, after reaching a steady state under the following conditions, the reaction was performed for 24 hours.

Reaction pressure: 5.0 MPaG
Reaction temperature: 250 ° C
Catalyst filling amount: 11L
Catalyst layer thickness: 6 meters GHSV: 10,000 hr ⁻¹
Hydrogen / carbon dioxide molar ratio: 4.88
After the reaction reached a steady state, the composition, temperature and pressure were measured at the analysis points (ad) in FIG. The results are shown in Table 1.

The pressure loss of the reactor was 0.18 MPa, and the amount of methanol produced was 626 g-methanol / L-Cat / hr in STY (space-time yield).

[Example 2]
Using the apparatus shown in FIG. 1, after reaching a steady state under the following conditions, the reaction was performed for 24 hours.

Reaction pressure: 5.0 MPaG
Reaction temperature: 250 ° C
Catalyst filling amount: 11L
Catalyst layer thickness: 6 meters GHSV: 10,000 hr ⁻¹
Hydrogen / carbon dioxide molar ratio: 5.22
The composition, temperature and pressure were measured at the analysis points (ad) in FIG. 1 in the steady state. The results are shown in Table 2.

The pressure loss of the reactor was 0.16 MPa, and the amount of methanol produced was 610 g-methanol / L-Cat / hr in STY (space-time yield).

[Comparative Example 1]
Using the apparatus shown in FIG. 1, the reaction was performed for 24 hours after reaching a steady state under the following conditions.

Reaction pressure: 5.0 MPaG
Reaction temperature: 250 ° C
Catalyst filling amount: 11L
Catalyst layer thickness: 6 meters GHSV: 10,000 hr ⁻¹
Hydrogen / carbon dioxide molar ratio: 3.40
After reaching the steady state, the composition, temperature and pressure were measured at the analysis points (ad) in FIG. The results are shown in Table 3.

The pressure loss of the reactor was 0.24 MPa, and the amount of methanol produced was 594 g-methanol / L-Cat / hr in STY (space-time yield).

Example 3
Using the apparatus shown in FIG. 1, after reaching a steady state under the following conditions, the reaction was performed for 24 hours.

Reaction pressure: 5.0 MPaG
Reaction temperature: 250 ° C
Catalyst filling amount: 11L
Catalyst layer thickness: 6 meters GHSV: 10,000 hr ⁻¹
Hydrogen / carbon dioxide molar ratio: 4.15
The composition, temperature and pressure were measured at the analysis points (ad) in FIG. 1 in the steady state. The results are shown in Table 4.

The pressure loss of the reactor was 0.21 MPa, and the amount of methanol produced was 644 g-methanol / L-Cat / hr in STY (space-time yield).

As can be seen from the above results, when methanol is produced under conditions outside the scope of the present application, the productivity is low and high pressure loss occurs. When the pressure loss increases, when unreacted raw materials are recycled and reused for the reaction, the pressure applied by the compressor is increased, and productivity and energy efficiency are deteriorated. For this reason, the method for producing methanol of the present invention having a small pressure loss is useful from various aspects.

DESCRIPTION OF SYMBOLS 1 ... Booster compressor 2 ... Heater 3 ... Reactor 4 ... Cooler 5 ... Gas-liquid separator 6 ... Circulating compressor

Claims

In a reactor having a catalyst layer formed from a catalyst containing copper, hydrogen and carbon dioxide are reacted to produce methanol,
Supplying hydrogen and carbon dioxide from the upstream side of the catalyst layer of the reactor, and obtaining a reaction mixture containing methanol from the downstream side of the catalyst layer;
The catalyst layer has a thickness of 1 meter or more;
The molar ratio of hydrogen to carbon dioxide (hydrogen / carbon dioxide) in contact with the catalyst layer exceeds 3.0, and the molar ratio of reaction inert gas to carbon dioxide (reactive inert gas / carbon dioxide) is Methanol production characterized in that the molar ratio of hydrogen and reaction inert gas to carbon dioxide (total of hydrogen and reaction inert gas / carbon dioxide) is 3.5 or more. Method.
The hydrogen to carbon dioxide molar ratio (hydrogen / carbon dioxide) is 3.5 to 5.5;
2. The molar ratio of the sum of hydrogen and reaction inert gas to carbon dioxide (total of hydrogen and reaction inert gas / carbon dioxide) is 3.5 to 6.0. A method for producing methanol.
The method for producing methanol according to claim 1, wherein the catalyst containing copper is a catalyst containing copper, zinc, aluminum, and silicon.
The method for producing methanol according to claim 1, wherein the reactor is a fixed bed reactor.
The method for producing methanol according to claim 1, wherein the catalyst containing copper has a particle size of 3 to 20 mm.
The method for producing methanol according to claim 1, wherein the reaction is carried out at a pressure of 1 to 10 MPaG.