JP2011104458A - Method of preparing catalyst for synthesis of methanol and method of producing methanol - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of preparing a catalyst for synthesis of methanol which catalyst shows a reduced tendency of lowering of the activity, compared with conventional catalysts for low-temperature liquid-phase synthesis of methanol, even when the raw material gas for synthesis of methanol involves carbon dioxide, water, etc. and exerts a higher catalytic activity and a method of synthesizing methanol in a liquid phase by using the catalyst prepared by the method. <P>SOLUTION: The method of preparing the catalyst for synthesis of methanol is used in a liquid-phase methanol synthetic reaction in which methanol is synthesized from a raw material gas containing carbon monoxide and hydrogen in the presence of an alcohol solvent. In drying a precipitation obtained from an aqueous solution of a copper (Cu) type catalyst ingredient and a precursor substance of the second catalyst ingredient by coprecipitation, the precipitation is brought in contact with a supercritical fluid. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a methanol synthesis catalyst used in a liquid phase methanol synthesis reaction for synthesizing methanol from a raw material gas containing carbon monoxide and hydrogen in the presence of an alcohol solvent, and a method for producing methanol. More specifically, when producing methanol from a raw material gas, a catalyst for methanol synthesis that can maintain high catalytic activity even if carbon dioxide, water, etc. that cause a decrease in catalytic activity are present in the raw material gas. And a method for producing methanol capable of producing methanol with high efficiency using the catalyst for methanol synthesis produced by the production method.

  In general, industrial synthesis of methanol uses as raw material a synthesis gas (mainly composed of carbon monoxide and hydrogen) obtained by steam reforming natural gas mainly composed of methane. It is carried out under severe conditions of 200 to 300 ° C. and 5 to 25 MPa by a fixed bed gas phase method using a catalyst (for example, see Non-Patent Document 1). Although this reaction is an exothermic reaction, efficient removal of heat is difficult due to poor heat conduction in the gas phase method, so the conversion rate when passing through the reactor is kept low, and unreacted high-pressure source gas is removed. The process of recycling is adopted. This method for synthesizing methanol has a drawback in production efficiency, but has an advantage that it is difficult to inhibit reaction by a small amount of carbon dioxide or water contained in the synthesis gas, and various plants are in operation.

  On the other hand, several methods for synthesizing methanol in the liquid phase and improving the heat removal rate have been studied. Among them, a method using a highly active catalyst comprising a transition metal carbonyl complex and an alkoxide at a low temperature (about 100 to 180 ° C.) is attracting attention because it is thermodynamically advantageous for the production system (for example, (See Patent Document 1 and Non-Patent Document 2). However, in these methods, if a causative substance such as carbon dioxide and water is present even in a small amount in the synthesis gas, the activity of the catalyst is lowered, and none of them has been put into practical use (for example, see Non-Patent Document 3). ).

  Therefore, the present inventors, as a catalyst suitable for low-temperature liquid-phase methanol synthesis reaction, first, even in the presence of a small amount of the causative agent of catalytic activity reduction such as carbon dioxide, water, etc. in the synthesis gas. A Cu / Mg-based (Cu / MgO-based) methanol synthesis catalyst was developed and proposed with predetermined results (see, for example, Patent Document 2).

  In addition, the present inventors have higher catalytic activity than the previously developed and proposed Cu / Mg (Cu / MgO) catalyst for low-temperature liquid phase methanol synthesis reaction, and carbon dioxide is contained in the raw material gas. Polyethylene glycol is used in the preparation of Cu / Zn catalysts by coprecipitation as a new method for producing a catalyst for methanol synthesis that can suppress the decrease in catalyst activity even in the presence of causative substances such as water. A method of addition has been developed and proposed with a predetermined result (see Patent Document 3).

US Patent Brother 4,992,480 Specification JP 2005-095872 A JP 2009-214077

J. C. J. Bart et al., Catal. Today, 2, 1 (1987) Seiichi Oyama, PETROTECH, 18 (1), 27 (1995) S. Ohyama, Applied Catalysis A: General, 180, 217 (1999)

  In the course of further developing a methanol synthesis catalyst suitable for the low-temperature liquid phase methanol synthesis reaction as described above, the catalyst activity of carbon dioxide, water, etc. is reduced in the raw material gas and / or alcohol solvent. It has been found that even if a causative substance is present in a small amount, it is possible to produce a catalyst having higher activity than the catalysts described in Patent Documents 2 and 3 having excellent resistance. In other words, Cu-based catalysts such as Cu / Mg-based catalysts and Cu / Zn-based catalysts with excellent resistance to carbon dioxide and water in raw material gases and / or alcohol solvents (suppression of decrease in activity) are produced by the coprecipitation method. In this case, the catalyst for methanol synthesis produced by bringing the precipitate produced by the coprecipitation operation into contact with the supercritical fluid is produced in a small amount in the raw material gas and / or alcohol solvent, such as carbon dioxide, water, etc. As a result, the inventors have found that the catalyst can be more highly activated while maintaining excellent resistance to the causative substance of the decrease in catalyst activity.

  Accordingly, the object of the present invention is to compare the catalytic activity of carbon dioxide, water, etc. in the reaction system derived from the raw material gas and / or alcohol solvent, in particular, compared with the conventional methanol synthesis catalyst used in the liquid phase methanol synthesis reaction. A method for producing a catalyst for methanol synthesis that can produce a catalyst with higher activity compared to a Cu-based catalyst that has excellent resistance to a causative agent of reduction (less deactivation with respect to carbon dioxide and water) It is to provide.

  Another object of the present invention is to carry out a liquid phase methanol synthesis reaction using the catalyst for methanol synthesis produced by the above production method, so that carbon dioxide derived from the raw material gas and / or alcohol solvent, water, etc. An object of the present invention is to provide a method for producing methanol that can produce methanol more efficiently in a Cu-based catalyst that is less deactivated by a causative substance that lowers the catalytic activity of the catalyst.

That is, the features of the present invention are as described below.
(1) In a method for producing a catalyst for methanol synthesis used in a liquid phase methanol synthesis reaction in which methanol is synthesized from a source gas containing carbon monoxide and hydrogen in the presence of an alcohol solvent via a formate, copper (Cu) A catalyst for methanol synthesis, characterized in that, when a precipitate obtained by coprecipitation from an aqueous solution of a precursor material of a system catalyst component and a second catalyst component is dried, the precipitate is brought into contact with a supercritical fluid. Production method.

  (2) The method for producing a catalyst for methanol synthesis as described in (1) above, wherein the second catalyst component is at least one of zinc (Zn) -based and magnesium (Mg) -based catalyst components.

  (3) The method for producing a catalyst for methanol synthesis as described in (2) above, wherein the second catalyst component is a zinc (Zn) -based catalyst component.

  (4) The method for producing a catalyst for methanol synthesis according to any one of (1) to (3) above, wherein the supercritical fluid is supercritical carbon dioxide.

  (5) When the precipitate is coprecipitated from the aqueous solution of the copper-based catalyst component and the precursor material of the second catalyst component by the coprecipitation method, the pH value of the solution that becomes the precipitate generation site is adjusted to 7.5 to 10.5. The method for producing a catalyst for methanol synthesis according to any one of the above (1) to (4), wherein the catalyst is maintained at a constant value within the range.

  (6) When producing methanol by a liquid phase methanol synthesis reaction in which methanol is synthesized from a raw material gas containing carbon monoxide and hydrogen in the presence of an alcohol solvent, the catalyst as described in any one of (1) to (5) above A method for producing methanol, comprising using the catalyst for methanol synthesis produced by the method of 1.

  (7) The method for producing methanol as described in (6) above, wherein the raw material gas contains at least one of carbon dioxide and / or water vapor.

  (8) The method for producing methanol as described in (6) or (7) above, wherein the alcohol solvent is a primary alcohol or a secondary alcohol and is a monohydric alcohol.

  The catalyst for methanol synthesis produced in the present invention is a Cu-based catalyst that has a low degree of decrease in catalytic activity even when a causative substance such as carbon dioxide and water is mixed in the raw material gas and / or alcohol solvent. Further, it can have higher catalytic activity.

  Moreover, according to the methanol production method of the present invention, methanol can be efficiently produced by using the above methanol synthesis catalyst in a methanol synthesis reaction using a Cu-based catalyst in a liquid phase.

  In the present invention, the methanol synthesis catalyst is used for synthesizing methanol from a source gas containing carbon monoxide (or carbon monoxide and carbon dioxide) and hydrogen in the presence of an alcohol solvent via a formate ester. A catalyst containing a copper (Cu) -based catalyst component and a second catalyst component to be used, and its production method basically comprises coprecipitation from an aqueous solution of the above-mentioned copper-based catalyst component and the precursor material of the second catalyst component. In a method in which the precipitate obtained by precipitation by the method is dried, calcined, and further subjected to an activation treatment such as reduction after sizing, if necessary, the precipitate containing water obtained by the coprecipitation operation It is in contact with a supercritical fluid. Here, the catalyst produced by the coprecipitation method is the one after the calcination of the precipitate and before the activation treatment, and the precipitate containing moisture is substantially brought into contact with the supercritical fluid. To be dried.

  In the present invention, for example, the catalyst is specifically produced by the following procedure.

  First, a precursor material aqueous solution in which a precursor material (precursor) of a copper-based catalyst component that is active in the reaction and a precursor material (precursor) of a second catalyst component that can serve as a catalyst carrier are dissolved, and a precipitant is dissolved Prepare three kinds of solutions and liquids, such as ion-exchanged water, which will be the place where precipitates are formed by dropping these aqueous solutions (precipitate generation field), and then precipitate formation A precursor substance aqueous solution and a precipitating agent aqueous solution are respectively dropped into the solution that becomes the place to produce a precipitate, and after aging the produced precipitate, filtration is performed to collect the precipitate. If necessary, the catalyst is produced by washing with ion-exchanged water or the like, then contacting with a supercritical fluid and drying, followed by calcination.

  Here, as a precursor material for preparing the precursor material aqueous solution of the copper-based catalyst component and the second catalyst component, copper (Cu) or a metal element (for example, Zn, Mg, Ce, or the like) that becomes the second catalyst component Mn, Re, etc.) nitrates, acetates, sulfates, chlorides, etc. can be used, as long as they are soluble in water and are not particularly limited, but it is common to use highly soluble nitrates Is.

  Moreover, as a precipitant for preparing the precipitant aqueous solution, it is sufficient to dissolve in water to show basicity, and alkali carbonate, aqueous ammonia, etc. can be used, and it is not particularly limited. Is easy to obtain.

  Furthermore, the liquid such as ion-exchanged water used as a precipitate generation site is not particularly limited, and any water can be used. However, from the viewpoint of the reaction activity of the prepared catalyst, high purity water is used. The more preferable. This is because if water containing impurities and having low purity is used, the impurities may remain in the catalyst and adversely affect the reaction activity. When a large amount of catalyst is produced, the amount of the solution used as a precipitate generation field is increased, so that in addition to the reaction activity of the catalyst, from the viewpoint of cost, it is possible to use clean water, industrial water, etc. desirable.

  The temperature conditions for producing the precipitate by the coprecipitation method are not particularly limited, but are usually 40 ° C. or higher and 80 ° C. or lower, preferably 60 ° C. or higher and 70 ° C. or lower. If it is kept constant, it is easy to obtain good results.

  Further, the pH at which the precipitate is generated by the coprecipitation method is not particularly limited, but a highly active catalyst can be obtained by keeping it constant at a certain value within the range of 7.5 to 10.5. It is preferable to install a pH meter and keep the pH constant within this range. The pH kept constant is more preferably 8 or more and 10 or less, and further preferably 8 or more and 9 or less. However, in order to maintain a high pH, a large amount of a precipitating agent such as sodium carbonate is required. Therefore, it is usually produced by setting a pH value in the range of 7.5 to 10.5 from the viewpoint of economy. Is done. In order to keep the pH constant, the pH of the solution in which the precipitate is formed is measured with a pH meter, and the precursor material aqueous solution in which the precursor material showing acidity (precursor) is dissolved, and the precipitating agent showing alkalinity It is necessary to adjust the dropping rate of the aqueous precipitant solution in which is dissolved.

  The precipitate prepared by the above method is left for a certain time for aging. The aging time is not particularly limited, but is usually about 5 to 500 hours. After aging, the precipitate is filtered and washed with ion-exchanged water or the like to remove a precipitant component such as sodium carbonate. The washing conditions are not particularly limited, but are usually carried out at a temperature from room temperature to 80 ° C. After washing, the precipitate is dried and calcined (for example, 350 ° C-1h in air). After sizing as necessary, it is subjected to an activation treatment such as reduction (for example, 200 ° C-10h in a hydrogen stream) for reaction. To be served. If it is necessary to handle the catalyst in air, a surface passivation treatment can be applied. The conditions for these steps are not particularly limited as long as they are in a range that is usually performed.

  The catalyst produced by the coprecipitation method from the precursor material of the Cu-based catalyst component and the precursor material of the second catalyst component is a catalyst such as carbon dioxide and water in the reaction system derived from the source gas and / or alcohol solvent. The reason why it has excellent resistance to the causative substance of the decrease in activity is that the alkali metal alkoxide (homogeneous catalyst) used in the conventional low-temperature liquid phase method is not used. Alkali metal alkoxide was changed to an inactive component during the reaction by carbon dioxide, water and the like, but it is considered that the catalytic properties of the solid catalyst of the present invention are not dramatically changed by carbon dioxide, water and the like. Conventional Cu-based catalysts could not be used because the activity was very low under the reaction conditions of the low-temperature liquid phase method. However, in the Cu-based catalysts of the present invention, the second catalyst component is a fine catalyst of Cu as the main catalyst. It is presumed that a certain activity is expressed even under the reaction conditions of the low temperature liquid phase method because the surface area of Cu is increased by promoting the formation and high dispersion.

  In the present invention, the precipitate is brought into contact with the supercritical fluid in the step of drying the precipitate, and the precipitate is substantially supercritically dried by contact with the supercritical fluid. Here, the supercritical drying is to remove moisture in the precipitate by bringing the precipitate into contact with a supercritical fluid. Since the supercritical fluid has a small surface tension, it is considered that the supercritical fluid can also diffuse into the fine pores of the precipitate, dissolve the water, and be removed from the pores. In the normal drying process (for example, 120 ° C-10h) and the baking process after the normal drying process, heat is applied while moisture is present in the pores, so the expansion of moisture present in the pores It is conceivable that the fine pore structure is destroyed by the above. On the other hand, when the supercritical drying process is adopted, the removal of moisture is performed in the temperature range around the critical point of the supercritical fluid. It is considered that the surface area of the produced catalyst becomes relatively large.

  The method and conditions for bringing the supercritical fluid into contact with the precipitate in the supercritical drying process are not particularly limited, but a supercritical fluid that takes a supercritical state under a low temperature condition of room temperature to 100 ° C. is used. It is preferable to place a precipitate in the flow of the critical fluid and to circulate the supercritical fluid through the precipitate. This is based on the idea that a good result can be obtained when the applied heat is low in the drying step of removing moisture from the precipitate as described above, and the temperature condition capable of taking a supercritical state is 100 ° C. This is because, when a supercritical fluid exceeding 1 is used, heat similar to that of normal drying (for example, 120 ° C.-10 h) performed in air for a long time is applied. Examples of the supercritical fluid that takes a supercritical state under low temperature conditions include carbon dioxide (critical point: 31 ° C., 7.38 MPa), and good results can be obtained by using this supercritical carbon dioxide. The pressure is not particularly limited as long as the fluid is in a supercritical state. Further, as a property of the supercritical fluid, those capable of dissolving water are preferable.

  The catalyst for methanol synthesis produced by the above-described coprecipitation method is suitable for a catalyst having a copper (Cu) -based catalyst component, and is particularly Cu / ZnO in which the second catalyst component is a zinc (Zn) -based catalyst component. A catalyst is preferred. When preparing a Cu / ZnO catalyst, an aqueous solution in which a precursor material of a copper-based catalyst component and a precursor material of a zinc-based catalyst component are dissolved may be used as the precursor material aqueous solution used in the coprecipitation method. In addition, examples of the metal element that constitutes the second catalyst component include Zn, Mg, Ce, Mn, Re, etc. As precursor material aqueous solution, the precursor material of the copper-based catalyst component and these metal elements Catalysts such as Cu / MgO, Cu / CeO, Cu / MnO, and Cu / ReO can also be prepared by using an aqueous solution in which the precursor material of the second catalyst component having s is dissolved.

  A catalyst other than the above composition can also be prepared by the above-described method, and the molar ratio of the copper-based catalyst component and the second catalyst component is not particularly limited, but is about 1: 1. Suitable results can be obtained. Further, it is also possible to prepare a catalyst by adding a precursor material of a third catalyst component to an aqueous solution in which a precursor material of a copper catalyst component and a second catalyst component is dissolved in a coprecipitation method, After the preparation by the coprecipitation method, it is also possible to add the third catalyst component by an ordinary catalyst preparation method such as an impregnation method.

  By using the catalyst prepared by the coprecipitation method, methanol can be produced with high efficiency from a raw material gas containing carbon monoxide and hydrogen in a low-temperature liquid phase methanol synthesis reaction.

  In the liquid phase methanol synthesis reaction of the present invention, for example, when the alcohol solvent is a chain or alicyclic hydrocarbon having a hydroxyl group attached thereto, it is based on one of the following reaction formulas. Thus, it is considered that formate is first produced and then methanol is produced.

R-OH + CO → HCOOR (1)
HCOOR + 2H ₂ → CH ₃ OH + R-OH (2)
(Here, R represents an alkyl group.)

However, when water is present in the reaction system, it is considered to be based on the following reaction formula, and formate ester or methanol is considered to be generated in parallel with the above reaction formula.
CO + H ₂ O → CO ₂ + H ₂ (3)
CO ₂ + H ₂ + R-OH → HCOOR + H ₂ O (4)
HCOOR + 2H ₂ → CH ₃ OH + R-OH (5)

In addition, since the catalyst of the present invention is a copper (Cu) -based catalyst, it is considered that formate or methanol is generated by the following reaction formula in parallel with the above reaction formula.
CO + H ₂ O → CO ₂ + H ₂ (6)
CO ₂ + 1 / 2H ₂ + Cu → HCOOCu (7)
HCOOCu + ROH → HCOOR + CuOH (8)
HCOOR + 2H ₂ → CH ₃ OH + ROH (9)
CuOH + 1/2 H ₂ → H ₂ O + Cu (10)

  Therefore, in the present invention, as a raw material for producing methanol, either a raw material gas containing carbon monoxide and hydrogen or a raw material gas containing carbon dioxide and hydrogen can be considered, but the raw material for production contains carbon dioxide and hydrogen. In the case of a raw material gas, the reaction rate is slower than in the case of a raw material gas mainly containing carbon monoxide and hydrogen. Therefore, a raw material gas mainly containing carbon monoxide is preferred. Further, according to the method of the present invention, even if a causative substance such as carbon dioxide and water is present in the raw material gas mainly composed of carbon monoxide as a carbon source, the carbon dioxide, water, etc. The degree of catalyst activity reduction due to this is small.

  In the present invention, examples of the alcohol solvent used in the liquid phase methanol synthesis reaction include those in which a chain or alicyclic hydrocarbon is attached with a hydroxyl group, phenol and its substitute, and further, thiol and Substitutes thereof can also be used. These alcohol solvents may be any of primary, secondary, and tertiary, but primary alcohols or secondary alcohols are preferred from the viewpoint of reaction efficiency, etc., such as methanol, ethanol, propanol, etc. The lower alcohols are the most common. Moreover, although monohydric alcohol is preferable from points, such as reaction efficiency, polyhydric alcohols, such as a bivalent and a trihydric alcohol, can also be used. Further, in the conventional method, when water is contained in the alcohol solvent of the solvent, the catalytic activity is reduced as in the case where water is present in the raw material gas. However, in the method of the present invention, the degree of the catalytic activity is reduced. small.

Next, FIG. 1 shows an example of a process flow for producing methanol using the catalyst produced by the production method according to the present invention.
A semi-batch type reactor 2 is charged with the methanol synthesis catalyst produced by the method of the present invention together with an alcohol solvent, and the synthesis gas 1 is supplied to the reactor 2. The reaction mixture 3 [product (formic ester, methanol) and unreacted gas] discharged from the outlet of the reactor 2 is introduced into the cooler 4 and cooled, and the liquid mixture 6 of unreacted gas 5 and formate ester and alcohol 6 is cooled. And to separate. The latter liquid mixture 6 is separated into formate ester 8 and methanol 9 in a distillation column 7 installed in the next stage. Here, when the conversion rate of the raw material gas to be converted into formate ester and methanol is low, the former unreacted gas 5 can be supplied again to the semi-batch reactor 2, but the conversion rate is high. When obtained, the unreacted gas 5 can also be used as a heat source (fuel) for producing synthesis gas (raw material gas).

  The methanol synthesis reaction in the present invention is a liquid phase reaction, and mild reaction conditions can be adopted (generally, conditions called a low temperature liquid phase methanol synthesis reaction can be adopted). Specifically, the temperature is 70 ° C. or more and 250 ° C. or less, the pressure is 3 atmospheres or more and 100 atmospheres or less, preferably the temperature is 120 ° C. or more and 200 ° C. or less, and the pressure is 15 atmospheres or more and 80 atmospheres or less, but is not limited thereto. The alcohol solvent only needs to have an amount sufficient for the reaction to proceed, but an amount larger than that can also be used as the solvent. In the above reaction, an organic solvent can be used in addition to the alcohol solvent. Further, the produced methanol can be separated from the alcohol solvent by distillation.

  The formic acid ester and methanol in the liquid mixture recovered in the latter stage of the reactor can be separated into formic acid ester and methanol by distillation, and the formic acid ester can be used for the production of methanol as it is. That is, methanol can be produced by hydrocracking the formate after separation from the liquid mixture. For this hydrocracking, a hydrocracking catalyst is used. For example, a general hydrocracking catalyst such as a Cu-based, Pt-based, Ni-based, Co-based, Ru-based, or Pd-based catalyst is used. In addition, without separating the liquid mixture of formate ester and methanol recovered in the subsequent stage of the reactor, the hydrocracking catalyst and hydrogen can coexist to hydrocrack the formate ester in the liquid mixture into methanol. it can. Furthermore, in the present invention, by allowing these hydrocracking catalysts to coexist in the reaction system for producing formate ester and methanol from the raw material gas and the alcohol solvent, the selectivity of methanol is increased, thereby efficiently. Methanol can also be produced. In addition, by the hydrogenolysis reaction of the formate ester described above, a mixture comprising methanol, residual formate ester and alcohol solvent [R-OH of the formula (2)] is obtained, but these can be separated by distillation. Can be purified.

Hereinafter, based on an Example and a comparative example, the manufacturing method of the catalyst for methanol synthesis of this invention and the manufacturing method of methanol using the obtained catalyst are demonstrated.
In Examples 1 to 14 and Comparative Examples 1 to 4 below, the CO conversion rate, the CO ₂ conversion rate, the C conversion rate, the formate ester selectivity, the methanol selectivity, and the methanol yield are calculated as follows. Calculated by the formula.

CO conversion rate (%) = [1- (number of moles of CO recovered after reaction) / (number of moles of charged CO)] × 100
CO ₂ conversion rate (%) = [1- (number of moles of recovered CO ₂ after reaction) / (number of moles of charged CO ₂ )] × 100

C conversion rate (%) = CO conversion rate (%) × [(number of moles of charged CO) / (number of charged CO + CO ₂ moles)] + CO ₂ conversion rate (%) × [(number of moles of charged CO ₂ ) / ( Preparation CO + CO ₂ moles)]

Formate ester selectivity (%) = [(mol formate ester recovered after reaction) / [(C conversion rate (%)) × (charged CO + CO ₂ moles)]] × 100

Methanol selectivity (%) = [(number of moles of methanol recovered after reaction) / [(C conversion ratio (%)) × (number of charged CO + CO ₂ moles)]] × 100

[Example 1]
Precursor aqueous solution in which Cu nitrate and Zn nitrate are dissolved so that Cu: Zn has a molar ratio of Cu: Zn = 1: 1, precipitant aqueous solution in which sodium carbonate is dissolved, and these aqueous solutions Was added dropwise and ion-exchanged water to be a precipitate generation field.

  While maintaining the temperature of the ion-exchanged water used as the precipitate generation field at 65 ° C., the pH of the precipitate generation field (reaction system) is controlled by controlling the dropping rate of the precursor substance aqueous solution and the precipitant aqueous solution. A Cu / Zn precipitate was produced while maintaining the value at 8.5. After aging for 24 hours, the precipitate was washed with ion-exchanged water, and dried under reduced pressure (35 ° C.-3 h) at 35 ° C. for 3 hours in a temperature-controlled desiccator.

Next, the thus obtained Cu / Zn precipitate was charged into an autoclave having an internal volume of 150 ml, and a supercritical carbon dioxide (CO ₂ ) liquid feed pump (manufactured by JASCO, SCF-Get type intelligent supercritical CO ₂ feed). Supercritical CO ₂ is fed at 8.0 MPa and 5 cc / min using a liquid pump, and the Cu / Zn precipitate is superfluous at 35 ° C. for 3 hours in this supercritical CO ₂ flow. The Cu / Zn precipitate was supercritically dried (35 ° C.-3 h) by contacting with critical CO ₂ .

After this supercritical drying, it is fired under conditions of 350 ° C. for 1 hour (350 ° C.-1 h), and then reduced (220 ° C.-10 h) under conditions of 220 ° C. and 10 hours under 5% H ₂ flow. Then, a surface passivation treatment was performed to obtain a Cu / ZnO catalyst for methanol synthesis according to Example 1.

The following methanol synthesis reaction was carried out using the Cu / ZnO catalyst of Example 1 thus prepared as a catalyst for methanol synthesis.
That is, an autoclave having an internal volume of 85 ml was charged with 40 ml of 2-butanol containing 1% by mass of water as an alcohol solvent and 1 g of the Cu / ZnO catalyst of Example 1 above, and further a synthesis gas (CO: 33.00 vol%, CO2) as a raw material gas. ₂ : 5.27 vol%, Ar: 3.09 vol%, H ₂ : balance) was filled to 5 MPa, and a continuous reaction was performed at 170 ° C. for 20 hours, and the reaction products were analyzed by gas chromatography. The results are as follows: CO conversion 51.9%, CO ₂ conversion 12.4%, Total C conversion 46.4%, methyl formate selectivity 1.6%, butyl formate selectivity 1.8%, and methanol selectivity It was 96.6%.

[Example 2]
In the catalyst production method described in Example 1, the Cu / ZnO catalyst of Example 2 was prepared in the same manner as in Example 1 except that the pressure of the supercritical CO ₂ liquid feed pump was set to 7.5 MPa. . Further, a methanol synthesis reaction was performed in the same manner as described in Example 1 except that the Cu / ZnO catalyst of Example 2 was used as a catalyst for methanol synthesis. The results are as follows: CO conversion 48.2%, CO ₂ conversion 8.2%, Total C conversion 42.7%, methyl formate selectivity 0.2%, butyl formate selectivity 1.2%, and methanol selectivity It was 98.6%.

[Example 3]
In the method for producing the catalyst described in Example 1, the Cu / Zn precipitate was brought into contact with supercritical CO _{2 under} the conditions of 35 ° C. and 1 hour without carrying out vacuum drying, and supercritical drying (35 ° C.-1 h ) To prepare the Cu / ZnO catalyst of Example 3. In addition, a methanol synthesis reaction was performed in the same manner as described in Example 1 except that the Cu / ZnO catalyst of Example 3 was used as a catalyst for methanol synthesis. The results are as follows: CO conversion 42.8%, CO ₂ conversion 2.5%, Total C conversion 37.1%, methyl formate selectivity 1.2%, butyl formate selectivity 2.8%, and methanol selectivity It was 96.0%.

[Example 4]
In the method for producing the catalyst described in Example 1, the Cu / Zn precipitate was brought into contact with supercritical CO _{2 under} the conditions of 35 ° C. for 3 hours without performing vacuum drying, and supercritical drying (35 ° C.−3 h ) To prepare the Cu / ZnO catalyst of Example 4. Further, a methanol synthesis reaction was carried out in the same manner as described in Example 1, except that the Cu / ZnO catalyst of Example 4 was used as a catalyst for methanol synthesis. Results, CO conversion was 47.3% CO ₂ conversion was -4.7% TotalC conversion 40.2%, methyl formate selectivity of 0.5%, butyl formate selectivity of 3.0%, and methanol selectivity The rate was 96.6%.

[Example 5]
In the method for producing the catalyst described in Example 1, the Cu / Zn precipitate was brought into contact with supercritical CO _{2 under} the conditions of 35 ° C. and 5 hours without carrying out vacuum drying, and supercritical drying (35 ° C.-5 h ) To prepare the Cu / ZnO catalyst of Example 5. Further, a methanol synthesis reaction was performed in the same manner as described in Example 1 except that the Cu / ZnO catalyst of Example 5 was used as a catalyst for methanol synthesis. The results are as follows: CO conversion 45.9%, CO ₂ conversion -3.6%, Total C conversion 39.2%, methyl formate selectivity 1.7%, butyl formate selectivity 2.7%, and methanol selection The rate was 95.6%.

[Example 6]
In the method for producing the catalyst described in Example 1, the Cu / Zn precipitate was brought into contact with supercritical CO _{2 under} the conditions of 50 ° C. and 3 hours without carrying out vacuum drying, and supercritical drying (50 ° C.−3 h ) To prepare the Cu / ZnO catalyst of Example 6. Further, a methanol synthesis reaction was performed in the same manner as described in Example 1 except that the Cu / ZnO catalyst of Example 6 was used as a catalyst for methanol synthesis. The results are as follows: CO conversion 43.3%, CO ₂ conversion 1.4%, Total C conversion 37.4%, methyl formate selectivity 2.2%, butyl formate selectivity 3.0%, and methanol selectivity It was 94.9%.

[Example 7]
In the method for producing the catalyst described in Example 1, the Cu / Zn precipitate was brought into contact with supercritical CO ₂ under conditions of 70 ° C. for 3 hours without carrying out vacuum drying, and supercritical drying (70 ° C.−3 h ) To prepare a Cu / ZnO catalyst of Example 7. In addition, a methanol synthesis reaction was performed in the same manner as described in Example 1 except that the Cu / ZnO catalyst of Example 7 was used as a catalyst for methanol synthesis. The results are as follows: CO conversion 42.9%, CO ₂ conversion 0.2%, TotalC conversion 36.9%, methyl formate selectivity 2.0%, butyl formate selectivity 2.7%, and methanol selectivity It was 95.3%.

[Example 8]
In the method for producing the catalyst described in Example 1, the Cu / Zn precipitate was brought into contact with supercritical CO ₂ at 90 ° C. for 3 hours without performing vacuum drying, and supercritical drying (90 ° C.−3 h ) To prepare the Cu / ZnO catalyst of Example 8. In addition, a methanol synthesis reaction was performed in the same manner as described in Example 1 except that the Cu / ZnO catalyst of Example 8 was used as a catalyst for methanol synthesis. The results are as follows: CO conversion 43.1%, CO ₂ conversion -4.3%, Total C conversion 36.4%, methyl formate selectivity 3.5%, butyl formate selectivity 1.8%, and methanol selection The rate was 94.7%.

[Example 9]
A methanol synthesis reaction was carried out in the same manner as described in Example 1 using the methanol synthesis catalyst of Example 1 except that ethanol was used as the alcohol solvent. The results are: CO conversion 49.5%, CO ₂ conversion 11.4%, Total C conversion 44.3%, methyl formate selectivity 4.5%, ethyl formate selectivity 1.5%, and methanol selectivity It was 94.0%.

[Example 10]
A Cu / MgO catalyst was prepared as a methanol synthesis catalyst of Example 10 in the same manner as in Example 1 except that Mg nitrate was used instead of Zn nitrate in the method for producing the catalyst described in Example 1. .

The methanol synthesis reaction was carried out in the same manner as described in Example 1 except that the Cu / MgO catalyst of Example 10 prepared in this way was used as a catalyst for methanol synthesis and 40 ml of ethanol was used as the alcohol solvent. . The results are as follows: CO conversion 33.7%, CO ₂ conversion 19.8%, Total C conversion 31.8%, methyl formate selectivity 1.5%, ethyl formate selectivity 47.8%, and methanol selectivity It was 50.7%.

[Example 11]
In the method for producing the catalyst described in Example 1, the same procedure as in Example 1 was conducted, except that a precipitate of Cu / Zn was prepared by maintaining the pH value of the precipitate generation field (reaction system) at 7.0. A Cu / ZnO catalyst was prepared, and methanol synthesis reaction was performed in the same manner as in Example 1. The results are as follows: CO conversion 34.8%, CO ₂ conversion 7.6%, Total C conversion 31.1%, methyl formate selectivity 2.5%, butyl formate selectivity 3.1%, and methanol selectivity It was 94.4%.

[Example 12]
In the method for producing the catalyst described in Example 1, the same procedure as in Example 1 was conducted, except that a precipitate of Cu / Zn was prepared by maintaining the pH value of the precipitate generation field (reaction system) at 7.8. A Cu / ZnO catalyst was prepared, and methanol synthesis reaction was performed in the same manner as in Example 1. The results are as follows: CO conversion 48.7%, CO ₂ conversion 10.6%, Total C conversion 43.5%, methyl formate selectivity 1.5%, butyl formate selectivity 2.1%, and methanol selectivity It was 96.4%.

[Example 13]
In the method for producing the catalyst described in Example 1, the same procedure as in Example 1 was conducted, except that a precipitate of Cu / Zn was prepared by maintaining the pH value of the precipitate generation field (reaction system) at 9.5. A Cu / ZnO catalyst was prepared, and methanol synthesis reaction was performed in the same manner as in Example 1. The results are: CO conversion 47.1%, CO ₂ conversion 11.2%, Total C conversion 42.2%, methyl formate selectivity 2.1%, butyl formate selectivity 2.5%, and methanol selectivity It was 95.4%.

[Example 14]
In the method for producing a catalyst described in Example 1, the same procedure as in Example 1 was conducted, except that a precipitate of Cu / Zn was prepared while maintaining the pH value of the precipitate generation field (reaction system) at 10.7. A Cu / ZnO catalyst was prepared, and methanol synthesis reaction was performed in the same manner as in Example 1. The results are: CO conversion 41.5%, CO ₂ conversion 10.2%, Total C conversion 37.2%, methyl formate selectivity 1.9%, butyl formate selectivity 2.3%, and methanol selectivity It was 95.8%.

[Comparative Example 1]
In the method for producing the catalyst described in Example 1, after drying under reduced pressure (35 ° C.-3 h), drying was further performed at 120 ° C. for 10 hours without performing supercritical drying (35 ° C.-3 h) ( A Cu / ZnO catalyst of Comparative Example 1 was prepared in the same manner as in Example 1 except that 120 ° C.-10 h) was carried out, and a methanol synthesis reaction was performed in the same manner as described in Example 1. The results were as follows: CO conversion 41.4%, CO ₂ conversion -0.5%, Total C conversion 36.1%, methyl formate selectivity 1.5%, butyl formate selectivity 1.8%, and methanol selection The rate was 96.7%.

[Comparative Example 2]
In the method for producing the catalyst described in Example 1, the drying (120 ° C.-10 h) was performed at 120 ° C. for 10 hours without performing reduced pressure drying (35 ° C.-3 h) and supercritical drying (35 ° C.-3 h). The Cu / ZnO catalyst of Comparative Example 2 was prepared in the same manner as in Example 1, except that the methanol synthesis reaction was performed in the same manner as described in Example 1. The results are as follows: CO conversion 40.8%, CO ₂ conversion -1.2%, Total C conversion 35.1%, methyl formate selectivity 1.8%, butyl formate selectivity 1.9%, and methanol selection The rate was 96.3%.

[Comparative Example 3]
Cu nitrate [Cu (NO ₃ ) ₂ · 3H ₂ O] and Mg nitrate [Mg (NO ₃ ) ₂ · 6H ₂ O] are converted to Cu: Zn = 1: 1 as the molar ratio of Cu and Mg. Prepared precursor aqueous solution, Na ₂ CO ₃ dissolved precipitant aqueous solution, and ion-exchanged water in which these aqueous solutions are dropped to form a precipitate generation site, and after obtaining the precipitate, The Cu / MgO catalyst (corresponding to the catalyst described in Patent Document 2), which is a catalyst for methanol synthesis according to Comparative Example 3, was obtained by drying, calcination and reduction.

Using the thus prepared Cu / MgOx catalyst of Comparative Example 3 as a catalyst for methanol synthesis, the following methanol synthesis reaction was carried out.
That is, in a semi-batch reactor (autoclave) having an internal volume of 100 ml, 20 ml of ethanol containing 1% by mass of water as an alcohol solvent and the Cu / MgOx catalyst of Comparative Example 3 above (corresponding to the catalyst described in Patent Document 2) 1 g DOO charged, further raw material gas as synthesis gas _{(CO: 32.6vol%, CO 2} : 5.2vol%, H 2: 59.2vol%, Ar: 3.0vol%) supplies, 170 ° C., a continuous reaction under the conditions of 3MPa (170 ° C.-3 MPa). After 20 hours, the conversion rate was stable. The results were as follows: CO conversion rate 25.5%, CO ₂ conversion rate 16.9%, Total C conversion rate 24.3%, ethyl formate selectivity 53.4%, methanol The selectivity was 46.6% and the methanol yield was 11.3%.

[Comparative Example 4]
Precursor aqueous solution in which Cu nitrate and Zn nitrate are dissolved so that Cu: Zn has a molar ratio of Cu: Zn = 1: 1, precipitant aqueous solution in which sodium carbonate is dissolved, and these aqueous solutions Was added dropwise and ion-exchanged water to be a precipitate generation field.

  Polyethylene glycol (mole number 5.8 times that of Cu) is added to the ion-exchanged water that forms the precipitate generation field, and the above precursor material aqueous solution and precipitant aqueous solution are added under stirring. While controlling the dropping rate, the pH was maintained at 8.5 to form a Cu / Zn precipitate, and after aging for 24 hours, filtration was performed. The obtained precipitate was washed with ion-exchanged water, and then dried ( Cu / ZnO catalyst of Comparative Example 4 after baking in air (450 ° C-2h in air), hydrogen reduction (200 ° C-2h in hydrogen stream), surface passivation treatment (Corresponding to the catalyst described in Patent Document 3) was prepared.

Using the Cu / ZnO catalyst of Comparative Example 4 thus prepared as a catalyst for methanol synthesis, the following methanol synthesis reaction was carried out.
That is, an autoclave having an internal volume of 85 ml was charged with 40 ml of 2-butanol as an alcohol solvent and 1 g of the Cu / ZnO catalyst of Comparative Example 4 above, and further, synthesis gas (CO: 34.90 vol%, carbon dioxide: 5.20 vol%, (Ar: 3.09 vol%, hydrogen: balance) was charged to 5 MPa, a continuous reaction was performed at 170 ° C. for 20 hours, and the reaction product was analyzed by gas chromatography. The results are as follows: CO conversion 40.1%, CO ₂ conversion -2.4%, Total C conversion 34.6%, methyl formate selectivity 0.3%, butyl formate selectivity 0.2%, and methanol selection The rate was 99.5%.

Table 1 (Examples 1 to 14) and Table 2 (Comparison) show the characteristics of the operations and the results of the CO conversion, CO ₂ conversion, and Total C conversion in Examples 1 to 14 and Comparative Examples 1 to 4, respectively. Examples 1-4).

  As is clear from the results of Examples 1 to 14 and Comparative Examples 1 to 4 shown in Tables 1 and 2 above, methanol production efficiency is increased by performing supercritical drying in the production of Cu / ZnO catalysts. Became clear. That is, in a Cu-based catalyst capable of suppressing deactivation due to carbon dioxide or water, if the catalyst component is the same, a highly active catalyst capable of improving the conversion can be produced by performing the supercritical drying of the present invention. It became clear that it was possible.

FIG. 1 is a flowchart for explaining an example of a reaction apparatus for carrying out the liquid phase methanol synthesis reaction of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Syngas, 2 ... Semi-batch type reactor, 3 ... Reaction mixture [Product (formic ester, methanol) and unreacted gas), 4 ... Cooler, 5 ... Unreacted gas, 6 ... Liquid mixture (Formic acid Esters and alcohols), 7 ... distillation tower, 8 ... formic acid ester, 9 ... methanol.

Claims (8)

  In a method for producing a catalyst for methanol synthesis used in a liquid phase methanol synthesis reaction in which methanol is synthesized from a source gas containing carbon monoxide and hydrogen in the presence of an alcohol solvent via a formate, a copper (Cu) catalyst component And a method for producing a catalyst for methanol synthesis, comprising drying a precipitate obtained by coprecipitation from an aqueous solution of a precursor material of the second catalyst component, and bringing the precipitate into contact with a supercritical fluid.   The method for producing a catalyst for methanol synthesis according to claim 1, wherein the second catalyst component is at least one of zinc (Zn) -based and magnesium (Mg) -based catalyst components.   The method for producing a catalyst for methanol synthesis according to claim 2, wherein the second catalyst component is a zinc (Zn) -based catalyst component.   The method for producing a catalyst for methanol synthesis according to any one of claims 1 to 3, wherein the supercritical fluid is supercritical carbon dioxide.   When the precipitate is co-precipitated from the aqueous solution of the precursor material of the copper-based catalyst component and the second catalyst component by the co-precipitation method, the pH value of the solution serving as the precipitate generation field is within the range of 7.5 to 10.5. The method for producing a catalyst for methanol synthesis according to any one of claims 1 to 4, wherein the catalyst is maintained at a constant value.   When methanol is produced by a liquid phase methanol synthesis reaction in which methanol is synthesized from a raw material gas containing carbon monoxide and hydrogen in the presence of an alcohol solvent, the catalyst is produced by the method according to any one of claims 1 to 5. A method for producing methanol, comprising using a catalyst for methanol synthesis.   The method for producing methanol according to claim 6, wherein the raw material gas contains at least one of carbon dioxide and / or water vapor.   The method for producing methanol according to claim 6 or 7, wherein the alcohol solvent is a primary alcohol or a secondary alcohol and is a monohydric alcohol.

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