JP2007055974A - Methanol-producing device and methanol-producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a methanol-producing device which is used for producing methanol from a gas containing carbon dioxide and hydrogen as a raw material gas, can sufficiently enhance a methanol conversion rate, can eliminate the problem of catalyst deterioration due to water of reaction product, and does not need a methanol distillation process. <P>SOLUTION: This methanol-producing device for reacting a raw material gas containing hydrogen and carbon dioxide in a reactor in the presence of a catalyst and an organic solvent to produce the methanol is characterized in that the reactor is formed to react the raw material gas in such reaction conditions that the methanol as one of the reaction products becomes a gas and by-produced water as the other forms an organic solvent hydrate of liquid, and has a dehydration reactor for extracting a part of the hydrate-containing liquid phase from the reactor and then dehydrating the liquid phase to regenerate the hydrate into the original unsaturated bond-having organic solvent, and a separator for separating a liquid phase comprising a mixture of the regenerated organic solvent with water into the water and the phase rich in the organic solvent, so that the phase rich in the organic solvent is returned and circulated to the reactor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a methanol production apparatus and a methanol production method for producing methanol by reacting a raw material gas containing hydrogen and carbon dioxide in the presence of a catalyst.

As a method for synthesizing methanol, a catalytic hydrogenation method is generally known in which a raw material gas composed of hydrogen and carbon monoxide and / or carbon dioxide is subjected to a catalytic reaction under predetermined reaction conditions. These synthesis methods include a gas phase synthesis method and a liquid phase synthesis method. These reaction formulas are as follows.

CO + 2H ₂ = CH ₃ OH (1)
CO ₂ + 3H ₂ = CH ₃ OH
+ H ₂ O (2)

When a raw material gas containing hydrogen and carbon dioxide is used, methanol and equimolar water are generated as shown in the above formula (2). This water has a problem of deteriorating the catalyst.

  Further, the above formula (2) is an exothermic reaction and is an equilibrium reaction with a reduced number of moles. Therefore, in terms of chemical equilibrium, the reaction is more advantageous for methanol synthesis at lower temperature and higher pressure conditions.

  The equilibrium conversion rate of methanol is determined by the thermodynamic equilibrium constant of the above equation (2), and is as low as 21% under the condition of 250 ° C. and 5 MPa, for example. Increasing the reaction pressure to 15 MPa, for example, improves the equilibrium conversion rate to 40%, but increases the compression power of the raw material gas. Therefore, in a methanol synthesis reaction using a raw material gas containing hydrogen and carbon dioxide, a high one-pass conversion rate cannot be obtained unless it is freed from restrictions on chemical equilibrium. In order to release from the constraint of chemical equilibrium, it is necessary to shift the chemical equilibrium to the production side, and the following methods have been studied so far.

(A) A liquid phase synthesis method in which dodecane or the like that hardly dissolves an aqueous methanol solution is used as a reaction solvent, and the reaction solvent and the aqueous methanol solution are continuously discharged out of the reaction vessel from the reaction vessel is disclosed in Japanese Patent Publication No. 7-47554 (Patent Document 1). ) Or JP-A-9-227423 (Patent Document 2).
In the former publication, when methanol is produced from a raw material gas, the reaction is carried out under a high enough pressure so that at least a part of methanol and water in the reactor exist as a liquid, and methanol as a reaction product and It is described that water is separated and removed as an aqueous methanol solution and discharged out of the reactor.

(B) Liquid phase synthesis in which a catalyst is suspended in a solvent insoluble in water, a raw material gas (CO base) is blown from the bottom of the reactor, and the generated methanol and unreacted raw material gas are discharged in a gas from the top of the reactor. The method is described in JP-A-5-97732 (Patent Document 3).

Japanese Patent Publication No. 7-47554 JP-A-9-227423 JP-A-5-97732

In the methanol synthesis method described in the above Japanese Patent Publication No. 7-47554 of (A), the temperature is lowered in order to separate the liquid phase taken out from the reactor into an organic solvent and an aqueous alcohol solution. The recycled organic solvent must be reheated to the reaction temperature before being recycled and returned to the reactor.
Furthermore, since the reaction product is separated as an aqueous methanol solution, a methanol distillation step is further required to separate methanol and water. For this reason, the energy for the said reheating and distillation was added and became the hindrance of the cost reduction.

  The methanol synthesis method described in JP-A-5-97732 of the above (B) is limited in chemical equilibrium with respect to the methanol conversion rate in the methanol synthesis reaction in terms of apparatus configuration and description, and has a high one-pass conversion rate. Still can not get.

  In any of the above prior arts, since the reaction product water is produced in a liquid phase containing a catalyst, the water and the catalyst are in contact with each other even if the catalyst is slightly in contact. There was a risk of deterioration.

  An object of the present invention is methanol synthesis using a gas containing carbon dioxide and hydrogen as a raw material gas, which can sufficiently increase the methanol conversion rate exceeding the equilibrium conversion rate under a certain temperature and pressure, Methanol production apparatus and methanol production that can eliminate the problem of catalyst degradation due to water and eliminate the need for a methanol distillation step for separating methanol and water as a reaction product, thereby reducing costs. It is to provide a method.

  In order to achieve the above object, a methanol production apparatus according to the first aspect of the present invention reacts a raw material gas containing hydrogen and carbon dioxide in a reactor in the presence of a catalyst and an organic solvent having an unsaturated bond. In the methanol production apparatus for producing methanol, in the reactor, one methanol in the reaction product becomes a gas, the other by-product water becomes a hydrate of an organic solvent, and the hydrate is a liquid. A part of the liquid phase containing the hydrate produced as a by-product from the reactor is subjected to a dehydration reaction in the presence of a dehydration catalyst to obtain a hydrate of the organic solvent. Separation for separating a dehydration reactor that regenerates an organic solvent having an unsaturated bond, and a liquid phase that is a mixture of the organic solvent and water regenerated by the dehydration reaction into a phase rich in the organic solvent and water And the separator That is configured to circulate back the rich phase separated organic solvent into the reactor is characterized in.

  According to the present invention, methanol as a reaction product becomes a gas at the same time as generation and is separated from the reaction liquid phase, and water produced as a by-product uses an unsaturated bond of the organic solvent to form a hydrate of the organic solvent. Stays in the reaction liquid phase in the form and in liquid form. Since the organic solvent hydrate is dehydrated, the organic solvent-rich phase separated from the water by the separator is continuously returned to the reactor to remove water from the reaction system. As a result, the equilibrium reaction shifts to the methanol production side, and the methanol conversion can be increased.

According to the present invention, in particular, by allowing the reaction originally produced in the state of water in the hydrogenation methanol synthesis reaction of CO ₂ to occur in an organic solvent having an unsaturated bond, for example, the following reaction formula (3) As shown, water is produced in the form of organic solvent hydrate, and as a result, the methanol synthesis reaction proceeds without producing water in the reaction system. The effect which can improve durability of is obtained. Equation (4) represents a dehydration reaction by a dehydration catalyst.

CO ₂ + 3H ₂ + CH ₂ ═CHR → RCH ₂ CH ₂ OH + CH ₃ OH (3)

RCH ₂ CH ₂ OH → CH ₂ ═CHR + H ₂ O [Dehydration reaction] (4)

  In addition, methanol and water can be separated simultaneously with the synthesis reaction, eliminating the need for a methanol distillation step. In addition to greatly reducing the energy required for the distillation, the third component required for azeotropic distillation is also unnecessary. Therefore, a significant cost reduction can be achieved.

  The phase rich in organic solvent means that the liquid phase, which is a mixture of the organic solvent and water regenerated by dehydration reaction, is subjected to separation treatment by a separator, and the proportion of water is reduced compared to that before the separation treatment. A liquid phase with an increased proportion of organic solvent. That is, it means a liquid phase that is separated by a separator in a state in which the proportion of the organic solvent is larger than that of the liquid phase in the reactor and the proportion of water is small.

  The methanol production apparatus according to the second aspect of the present invention is the methanol production apparatus according to the first aspect, wherein the separator performs separation under substantially the same conditions of at least one of a reaction temperature and a reaction pressure set in the reactor. It is comprised so that it may carry out.

  According to the present invention, in the separator, since the separation is performed at the same temperature and pressure as the reaction temperature and reaction pressure set in the reactor, the phase rich in organic solvent after separation is returned to the reactor. When recirculating, there is no need to reheat and it can be returned almost as it is. Therefore, auxiliary heating means for solvent recirculation and the like are not necessary, and the cost of the entire apparatus can be reduced.

  The methanol production method according to the third aspect of the present invention is a method for producing methanol by reacting a raw material gas containing hydrogen and carbon dioxide in a reactor in the presence of a catalyst and an organic solvent having an unsaturated bond. In the reactor, one methanol of the reaction product becomes a gas, and the other by-product water becomes a hydrate of an organic solvent and the hydrate is reacted under a reaction condition that is a liquid. A part of the liquid phase containing the hydrate produced as a by-product from the inside is extracted and subjected to a dehydration reaction in the presence of a dehydration catalyst to regenerate the hydrate of the organic solvent into an organic solvent having an original unsaturated bond, The liquid phase, which is a mixture of the organic solvent and water regenerated by dehydration reaction, is separated into a phase rich in the organic solvent and water by a separator, and the phase rich in the organic solvent is returned to the reactor and circulated. It is characterized by making it. According to the present invention, the same effect as the first aspect can be obtained.

  According to the present invention, methanol synthesis using a gas containing carbon dioxide and hydrogen as a raw material gas, the methanol conversion rate can be sufficiently increased beyond the equilibrium conversion rate at a certain temperature and pressure, and catalyst degradation There is almost no problem and a methanol distillation step for separating the reaction product methanol and water is not required, so that the cost can be reduced.

  Hereinafter, an embodiment of a methanol production apparatus according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a methanol production apparatus according to the present embodiment.

As shown in FIG. 1, the reactor 1 of the methanol production apparatus according to the present embodiment includes a raw material gas 15 containing hydrogen and carbon dioxide containing a catalyst and an organic solvent having an unsaturated bond in the reactor 1. Reaction is performed in the reaction liquid phase 2 to produce methanol. The reactor 1 is configured to react under reaction conditions in which one methanol of the reaction product becomes a gas, and the other by-product water becomes a hydrate of an organic solvent and becomes a liquid.
This reaction condition is realized by setting the reaction temperature to 100 ° C. to 220 ° C. and the reaction pressure to 2 MPa to 7 MPa, and is maintained by temperature adjusting means and pressure variable means (not shown). Desirable reaction conditions are a reaction temperature of 150 ° C. to 170 ° C. and a reaction pressure of 3 MPa to 5 MPa.

  Then, a part of the liquid phase containing the hydrate is extracted from the reactor 1 and subjected to a dehydration reaction in the presence of the dehydration catalyst 12 so that the hydrate of the organic solvent has an original unsaturated bond. A dehydration reactor 11 regenerated into an organic solvent, a liquid phase that is a mixture of the organic solvent regenerated in the dehydration reaction and water, a phase rich in the organic solvent, and a separator 13 that separates into water. The organic solvent-rich phase separated by the separator 13 is returned to the reactor 1 and circulated.

  In the liquid phase 2 in the reactor 1, a compound containing Cu / ZnO as a catalyst is used, and the size and shape thereof are appropriately set depending on the configuration and method of the reactor 1.

  In addition, the organic solvent having an unsaturated bond of the present invention is a hydrocarbon having a double bond or a triple bond, and by-product water becomes a hydrate of the organic solvent under the reaction conditions of methanol synthesis, and the liquid. Can be selected and include 1-octene, 1-nonene, 1,7-octadiene and the like. In addition, a plurality of types of organic solvents can be used in combination. A solvent that does not participate in the reaction may be added for dilution.

  A more specific structure, operation principle, and operation of the apparatus according to the present embodiment having such a configuration will be described. The raw material gas 15 is supplied from below the reactor 1 through the compressor 3 and the preheater 4. The raw material gas 15 comes into contact with the catalyst in the reaction liquid phase 2 and reacts while passing through. Methanol is produced in a gaseous state, and an organic solvent hydrate is produced as a by-product in a liquid state.

  The generated methanol and unreacted gas are discharged from the gas phase discharge line 5 provided at the top position of the reactor 1. The gas phase discharge line 5 is provided with a cooler 6 so that the organic solvent and the hydrate of the organic solvent are not discharged together with methanol and unreacted gas. The organic solvent is cooled and condensed by the cooler 6. The organic solvent hydrate is returned to the reactor 1 through the return line 16. Thereafter, the methanol and unreacted gas are sent to the gas-liquid separator 8 via the condenser 7 and separated into methanol and unreacted gas. A part of the unreacted gas is removed as a purge gas if necessary, and is returned to the supply flow path of the raw material gas 15 via the compressor 9.

On the other hand, a part of the reaction liquid phase 2 containing the hydrate of the organic solvent by-produced is continuously taken out from the reactor 1 through the liquid phase take-out line 10. The liquid phase 2 taken out from the reactor 1 is supplied into the dehydration reactor 11 from above, contacts with the dehydration catalyst 12, undergoes a dehydration reaction while passing through, and the hydrate of the organic solvent is converted into the original unsaturation. It regenerates to an organic solvent having a bond and generates water. That is, it becomes a mixture of water and an organic solvent having an unsaturated bond. Here, the dehydration catalyst may be used, for example, _Al 2 _{O 3} and _SiO 2 / _Al 2 _{O 3} or the like.

  The liquid phase containing the regenerated organic solvent having an unsaturated bond and the generated water is continuously discharged from the dehydration reactor 11, and the temperature and pressure are the same as the reaction temperature and pressure of the reactor 1 through the line 17. Is supplied to the liquid-liquid separator 13. And it isolate | separates into water and the solvent phase rich in an organic solvent, water is discharged | emitted out of the system from the water line 14, and the solvent phase rich in an organic solvent goes into the reactor 1 via the circulation pump 19 through the circulation pump 19. Recirculated. In addition, by removing a part of the reaction liquid phase 2 from the reactor 1 in this way, a part of the reaction heat absorbed by the reaction liquid phase 2 is also extracted outside, and the reaction heat is reduced from the reaction system. Has the same effect.

  As described above, the reaction product methanol is generated as a gas and removed from the system as it is, while the by-product water remains in the liquid phase as a hydrate of an organic solvent. A part is taken out to a dehydration reactor in the subsequent stage, dehydrated, and the mixture of the regenerated organic solvent having an unsaturated bond and water is sent to a separator to be separated into water and an organic solvent having an unsaturated bond. Since the organic solvent having an unsaturated bond is returned to the reactor, the methanol synthesis reaction can be continued while shifting the chemical equilibrium to the production side. As a result, the methanol synthesis reaction is promoted, and a high reaction conversion rate that is not restricted by chemical equilibrium can be obtained. And since the one-pass conversion rate exceeding an equilibrium conversion rate can be obtained, the amount of unreacted gas can be reduced and the gas circulation power can be reduced.

In particular, water is produced in the form of a hydrate of an organic solvent by causing a reaction that is essentially produced as a by-product in the state of water in the hydrogenated methanol synthesis reaction of CO ₂ in an organic solvent having an unsaturated bond, As a result, since the methanol synthesis reaction proceeds in a state where water is not generated in the reaction system, the problem of catalyst deterioration due to water is eliminated, and the durability of the catalyst activity can be improved.

  Moreover, since the organic solvent which became the hydrate is regenerated to the original organic solvent having an unsaturated bond by the dehydration reactor and the liquid-liquid separator, the replenishment of the organic solvent can be reduced. Furthermore, since the conventional complicated separation and distillation steps related to methanol, organic solvent, and water can be omitted, the required energy can be greatly reduced. Furthermore, the reaction heat of methanol synthesis can be efficiently removed out of the reaction system (outside the reactor) by the separation process in which a part of the reaction liquid phase is taken out.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, the technical scope of this invention is not limited by the following Example. The following examples show results using the bench test class experimental apparatus of the methanol production apparatus shown in FIG.

A raw material gas 15 (composition CO ₂ : 25% by volume, H ₂ : 75% by volume) was supplied to the compressor 3 at a flow rate of 126 NL / h. This raw material gas merges with the unreacted gas (flow rate 56.6 NL / h) sent from the compressor 9 and is supplied to the reactor 1. The reactor 1 was charged with 1.2 L of 1-octene and 240 g of Cu / ZnO / Al ₂ O ₃ catalyst as solvents and reacted at 170 ° C. and 3 MPa.

From the liquid phase take-out line 10, a solution containing 18.5% by weight of 1-octanol and 80.4% by weight of 1-octene is sent to the dehydration reactor 11 at 1.26 L / h. The dehydration reactor 11 was filled with 450 g of Al ₂ O ₃ catalyst as a dehydration reaction catalyst. Under these conditions, 1-octanol undergoes a dehydration reaction to produce water and 1-octene. Water produced by the reaction was recovered in the separator 13 from the water line 14 at 24.8 g / h. 1-octene produced by the dehydration reaction is separated from water by the separator 13, and circulated to the reactor 1 through the circulation line 18 by the circulation pump 19.

  Methanol etc. evaporate from the reactor 1 to the gas phase side. A part of the gas is condensed in the cooler 6 and the condenser 7 and returned to the reactor 1 through the line 16. By maintaining the temperature of the cooler 6 at 110 ° C., a liquid of 96.8 wt% methanol and 3.2 wt% 1-octene was recovered from the gas-liquid separator 8 at 45.6 g / h. The unreacted gas separated by the gas-liquid separator 8 merges with the raw material gas 15 through the compressor 9. At this time, the one-pass methanol conversion was 67.8%. In the conventional gas phase reaction reactor, the equilibrium reaction rate of methanol under the reaction conditions of 170 ° C. and 3 MPa does not exceed 33.1%, but the equilibrium conversion rate is exceeded by the device of this FIG. % Conversion could be achieved.

  INDUSTRIAL APPLICABILITY The present invention is applicable to a methanol production apparatus and a methanol production method for producing methanol by reacting a raw material gas containing hydrogen and carbon dioxide in the presence of a catalyst.

It is a schematic block diagram which shows the methanol manufacturing apparatus which concerns on embodiment.

Explanation of symbols

1: Reactor 2: Reaction liquid phase 3: Compressor 4: Preheater 5: Gas phase discharge line 6: Cooler 7: Condenser 8: Gas-liquid separator 9: Compressor 10: Liquid phase take-out line 11: Dehydration reactor 12: Dehydration catalyst 13: Liquid-liquid separator 14: Water line 15: Raw material gas 16: Return line 17: Line 18: Circulation line 19: Circulation pump

Claims (3)

A methanol production apparatus for producing methanol by reacting a raw material gas containing hydrogen and carbon dioxide in a reactor in the presence of a catalyst and an organic solvent having an unsaturated bond,
The reactor is configured to react under reaction conditions in which one methanol of the reaction product becomes a gas and the other by-product water becomes a hydrate of an organic solvent and the hydrate becomes a liquid,
A part of the liquid phase containing the hydrate produced as a by-product from the reactor is extracted and subjected to a dehydration reaction in the presence of a dehydration catalyst to regenerate the hydrate of the organic solvent into an organic solvent having an unsaturated bond. A dehydration reactor,
A liquid phase that is a mixture of the organic solvent regenerated by the dehydration reaction and water, a phase rich in the organic solvent, and a separator that separates into water,
An apparatus for producing methanol, wherein the organic solvent-rich phase separated by the separator is returned to the reactor and circulated.   2. The methanol production apparatus according to claim 1, wherein the separator is configured to perform separation under substantially the same conditions of at least one of a reaction temperature and a reaction pressure set in the reactor. A method for producing methanol by reacting a raw material gas containing hydrogen and carbon dioxide in a reactor in the presence of a catalyst and an organic solvent having an unsaturated bond,
In the reactor, one methanol of the reaction product becomes a gas, and the other by-product water becomes a hydrate of the organic solvent, and the reaction is performed under reaction conditions in which the hydrate becomes a liquid.
A part of the liquid phase containing the hydrate produced as a by-product from the reactor is extracted and subjected to a dehydration reaction in the presence of a dehydration catalyst to regenerate the hydrate of the organic solvent into an organic solvent having an unsaturated bond. And
The liquid phase, which is a mixture of the organic solvent and water regenerated by the dehydration reaction, is separated into a phase rich in the organic solvent and water by a separator, and the phase rich in the organic solvent is returned to the reactor. A method for producing methanol, characterized by being circulated.

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