JP2012111702A - Method for producing alcohol - Google Patents

Abstract

The present invention provides a novel alcohol production method in which an alcohol can be obtained with a high selectivity by a catalyst using a metal other than a noble metal.
A method for producing an alcohol comprising a step of reacting carbon monoxide and hydrogen in the presence of a catalyst represented by the following general formula (1).
_{X a Co b Mo c S d} ···· (1)
(Wherein X is an alkali metal; a, b, c and d are numbers greater than 0 and d / c is 1 to 3)
[Selection figure] None

Description

  The present invention relates to a method for producing an alcohol having high selectivity using carbon monoxide and hydrogen as raw materials.

A hydrocarbon synthesis method using a synthesis gas (mixed gas of carbon monoxide and hydrogen) obtained by reforming natural gas as a raw material is widely known as a Fischer-Tropsch method, and the resulting hydrocarbons. Is linear, does not contain aromatic components, and does not contain sulfur or nitrogen, so it is considered promising as a clean fuel.
On the other hand, in the Fischer-Tropsch process, it is also known that alcohol is generated as a by-product, and various attempts have been made to improve the selectivity by adjusting reaction conditions and to establish a method for producing alcohol. It was.

In the reaction in which carbon monoxide is reacted with hydrogen to obtain an alcohol, among the reaction conditions, the type of catalyst is particularly important in improving the alcohol selectivity.
Conventionally, for example, a relatively high alcohol (ethanol) selectivity has been achieved with a catalyst in which rhodium (Rh), which is a noble metal, is supported on a carrier (see Patent Document 1). However, since the selectivity of hydrocarbons is still high and the catalyst is expensive above all, there is a problem that the practicality at the industrial level is poor. Thus, various catalysts using relatively inexpensive metals such as transition metals instead of noble metals have been studied. For example, catalysts containing cobalt (Co), molybdenum (Mo), etc. have been studied.

JP-A 63-000412

  However, in a catalyst using a conventional transition metal or the like, the activity is not always satisfactory, such as high selectivity of hydrocarbons and carbon dioxide as by-products, and it is high using an inexpensive catalyst. There has been a demand for a new method capable of producing alcohol with selectivity.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the manufacturing method of the novel alcohol with which alcohol can be obtained with high selectivity with the catalyst using metals other than a noble metal.

To solve the above problem,
The present invention provides a method for producing an alcohol, comprising a step of reacting carbon monoxide and hydrogen in the presence of a catalyst represented by the following general formula (1).
_{X a Co b Mo c S d} ···· (1)
(Wherein X is an alkali metal; a, b, c and d are numbers greater than 0 and d / c is 1 to 3)
In the alcohol production method of the present invention, X is preferably K (potassium).
In the method for producing an alcohol of the present invention, in the catalyst represented by the general formula (1), b / c is preferably 0.2 to 0.7.
In the method for producing an alcohol of the present invention, in the catalyst represented by the general formula (1), a / c is preferably 0.05 to 0.6.
In the alcohol production method of the present invention, the carbon monoxide and hydrogen are preferably supplied and reacted at a space velocity of 3000 to 25000 h- ¹ .
In the method for producing an alcohol of the present invention, the reaction is preferably performed under a pressure condition of 4 to 10 MPa.
In the method for producing an alcohol of the present invention, the reaction is preferably performed under heating conditions of 200 to 400 ° C.

  According to the present invention, an alcohol can be produced with high selectivity by a catalyst using a metal other than a noble metal.

In the method for producing an alcohol of the present invention, carbon monoxide (CO) and hydrogen (H ₂ ) are reacted in the presence of a catalyst represented by the following general formula (1) (hereinafter abbreviated as catalyst (1)). It has the process.
_{X a Co b Mo c S d} ···· (1)
(Wherein X is an alkali metal; a, b, c and d are numbers greater than 0 and d / c is 1 to 3)
In the present invention, by using the catalyst (1), production of hydrocarbons and carbon dioxide can be suppressed more than before, and various alcohols including methanol can be produced with high production efficiency.

  In the formula, X is an alkali metal, and lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr) can be exemplified, and potassium is more preferable.

In the formula, a, b, c, and d are numbers representing the composition ratio (ratio of the number of atoms) of X (alkali metal), Co (cobalt), Mo (molybdenum), and S (sulfur), respectively. It is a large number (positive number). However, d / c is 1-3.
a to d can be adjusted by, for example, a method for preparing the catalyst (1).
For example, when d is 2, b / c, that is, the ratio of Co / Mo (ratio of the number of atoms) is preferably 0.1 to 1, more preferably 0.2 to 0.7. preferable.
When d is 2, the ratio of a / c, that is, K / Mo (ratio of the number of atoms) is preferably 0.02-1, more preferably 0.05-0.6. preferable.

  In the present invention, alcohol refers to all compounds in which one or more hydrogen atoms of a hydrocarbon are substituted with a hydroxyl group (—OH), and may be linear, branched or cyclic, but linear Or a branched saturated aliphatic alcohol is preferred. The alcohol is preferably a monohydric alcohol having one hydroxyl group. And a C1-C5 alcohol is preferable, A C1-C4 alcohol is more preferable, Methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol And 2-methyl-2-propanol.

In the present invention, methane (CH ₄ ), ethane (C ₂ H ₆ ), propane (C ₃ H ₈ ), butane (C ₄ H ₁₀ ), 2-methylpropane (CH ₃ CH ( Hydrocarbons such as CH ₃ ) CH ₃ ); by-products such as carbon dioxide (CO ₂ ) are suppressed, and the production efficiency of alcohol is high.
The production ratio for a specific product such as alcohol, hydrocarbon, carbon dioxide in the reaction can be easily determined by calculating “selectivity (%)” calculated by the following formula (2).
[Product selectivity (%)] = [Product carbon number × Product production flow rate (mol / hour)] / Σ [Product carbon number × Product production flow rate (mol / hour)] × 100 (2)
In the formula, the numerator on the right side multiplied by 100 is the product of the carbon number and the production flow rate (mol / hour) for the specific product (one type) for which the selectivity is calculated, and the denominator is related to all the products. It is the sum total of the product of the number of carbon atoms and the production flow rate (mol / hour). For example, the “product production flow rate (mol / hour)” can be calculated by measuring the amount (mol) of product gas that passes per unit time on the gas outlet side of the production apparatus.

In the present invention, the alcohol selectivity can be easily increased to 30% or higher by appropriately adjusting the production conditions, and can be as high as 50% or higher.
Moreover, the selectivity of hydrocarbons and carbon dioxide can both be 45% or less.

The degree of consumption efficiency for a specific raw material such as carbon monoxide can be easily determined by calculating the “conversion rate (%)” calculated by the following formula (3).
[Conversion rate of raw material (%)] = {[feed amount of raw material (mol / hour)] − recovered amount of raw material (mol / hour)} / [feed amount of raw material (mol / hour)] × 100・ (3)
In the formula, the molecule on the right side multiplied by 100 is the difference between the supply amount (mol / hour) at the time of reaction and the recovered amount (mol / hour) after the reaction for the specific raw material (one type) whose conversion is to be calculated. Yes, the denominator is the supply amount (mol / hour) at the time of reaction with respect to the specific raw material. For example, “feed amount (mol / hour) of raw material” is the amount (mol) of raw material gas that passes per unit time on the gas inlet side of the production apparatus, and “recovered amount of raw material (mol / hour)” is production. It can be calculated by measuring the amount (moles) of unreacted source gas that passes per unit time on the gas outlet side of the apparatus.

Furthermore, the yield for a specific product can be easily determined by calculating the “space-time yield (g / (h · kg-cat))” calculated by the following formula (4). The unit “h” represents “time”.
[Space-time yield of product (g / (h · kg-cat))] = [Product mass flow rate of product (g / h)] / [Mass of catalyst (kg)] (4)
In the formula, the numerator on the right side is the generated mass flow rate for the specific product (one type) for which the space-time yield is calculated, and the denominator is the mass of the catalyst used. For example, the “product mass flow rate (g / h)” can be calculated by measuring the amount (mass) of the product gas passing per unit time on the gas outlet side of the production apparatus.

The reaction is preferably performed in the presence of the catalyst (1) while simultaneously or sequentially supplying carbon monoxide (CO) gas and hydrogen (H ₂ ) gas and recovering the product.
Further, in this case, carbon monoxide and hydrogen, it is preferable to feed at a space velocity of 2000～50000H ^-1, and more preferably supplied at a space velocity of 3000~25000h ^-1.

The amount of carbon monoxide (CO) and hydrogen (H ₂ ) at the time of the reaction may be appropriately adjusted in consideration of other reaction conditions, and is not particularly limited, but the H ₂ / CO ratio (molar ratio) is 0. 3 to 7 is preferable, and 0.5 to 5 is more preferable.

The usage-amount of a catalyst (1) is not specifically limited, What is necessary is just to adjust suitably in consideration of other reaction conditions.
Moreover, catalyst (1) may be used individually by 1 type, may use 2 or more types together, and when using 2 or more types together, the combination and ratio may be suitably adjusted according to the objective. good.

  The reaction is preferably carried out under pressure, and the pressure during the reaction is preferably 3 to 12 MPa, more preferably 4 to 10 MPa.

  The reaction is preferably performed under heating conditions, and the temperature during the reaction is preferably 150 to 500 ° C, more preferably 200 to 400 ° C.

  In the present invention, for example, the catalyst (1) is filled in the cylindrical reaction layer, and the reaction is performed by supplying carbon monoxide gas and hydrogen gas as raw materials from the inlet side of the reaction layer while adjusting the temperature. The reaction product and unreacted raw material may be recovered from the outlet side of the reaction layer. The target product and the unreacted raw material are usually recovered as a mixed gas. For example, by cooling the mixed gas, the target alcohol can be separated.

In the present invention, alcohol can be produced with high selectivity by using the catalyst (1). In particular, by containing an alkali metal, the production efficiency of alcohol is dramatically improved. For example, when the activity is compared with a catalyst represented by the following formula (i) (hereinafter abbreviated as catalyst (i)), The difference is clear.
_{Co p Mo q S r ···· (} i)
(Wherein p, q and r are numbers greater than 0)

  In the formula, p, q and r are numbers larger than 0, and are the same as b, c and d in the general formula (1).

Further, in the present invention, by using the catalyst (1), it is high without using a carrier widely used in conventional catalysts such as activated carbon (C) and aluminum oxide (Al ₂ O ₃ ). Alcohol can be produced with selectivity. Usually, it is considered that it is advantageous to improve the selectivity of the product by increasing the surface area by supporting the catalyst on the support. However, in the present invention, surprisingly, the selectivity of the support is improved to improve the selectivity of alcohol. Combination is not necessary.

The catalyst (1) can be prepared by a known method. Specific examples of preferred preparation methods include the following methods.
First, ammonium molybdate ((NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O) was mixed with an aqueous ammonia solution and reacted by adding ammonium sulfide ((NH ₄ ) ₂ S). A compound represented by “NH ₄ ) ₂ MoO ₂ S ₂ ” is taken out, and the ammonia is removed by heat treatment under an inert gas atmosphere. The general formula “Mo _x OS _Y (wherein x and y are 0 or more) And x + y is 1 to 3.) ”.
Next, this compound is mixed with distilled water and cobalt nitrate (II) hexahydrate (Co (NO ₃ ) ₂ .6H ₂ O), and further reacted with an alkali metal nitrate such as potassium nitrate (KNO ₃ ). Thereafter, the product is taken out and dried to obtain a compound represented by the formula “X _a Co _b Mo _c O _e S _d ”. Here, X, a, b, c, and d are the same as X, a, b, c, and d in the formula (1). Moreover, e is a positive number and is determined depending on a, b, c, and d.
Next, the obtained compound is heat-treated in a hydrogen sulfide (H ₂ S) gas atmosphere to be sulfided, whereby catalyst (1) (a catalyst represented by the general formula “X _a Co _b Mo _c S _d ”) is obtained. ) Is obtained. a, b, c, and d can be appropriately adjusted by adjusting the conditions such as the amount of cobalt nitrate used, the amount of alkali metal nitrate used, the temperature and time of the sulfurization reaction in the above steps. Moreover, in the said preparation method, it may replace with alkali metal nitrate and may use alkali metal carbonate.

  According to the present invention, the reaction is carried out in the presence of the catalyst (1) using alkali metal (X), cobalt (Co) and molybdenum (Mo), which are inexpensive and highly versatile metals. The alcohol can be produced at a lower cost than when a conventional catalyst is selected. Moreover, by using the catalyst (1), alcohol can be produced with high selectivity. Moreover, by adjusting the reaction conditions, alcohol having 2 or more carbon atoms including ethanol can be easily obtained in addition to methanol. Methanol may produce a highly toxic by-product in the process of use, but ethanol and the like have few such by-products, so the use value is high, and the production method of the present invention is extremely useful industrially. .

Examples of the catalyst containing alkali metal (X), cobalt (Co), molybdenum (Mo), and sulfur (S) include unsaturated aldehydes such as (meth) acrolein, (meth) acrylic acid, etc. by gas phase catalytic oxidation reaction. A catalyst for synthesizing an unsaturated carboxylic acid is known (for example, JP-A-10-066874). However, these catalysts are complex oxides containing oxygen (O) and are not known to have alcohol synthesis activity.
On the other hand, the catalyst (1) in the present invention is completely novel as a catalyst for alcohol synthesis reaction using alcohol as a main product.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the following examples.

<Preparation of catalyst (1)>
[Production Example 1]
(Preparation of catalyst (1) where b / c is 0.4 and a / c is 0.2 when d is 2)
Ammonium molybdate ((NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O) (22.08 g), a 25% by mass aqueous ammonia solution (56 ml), and distilled water (34 ml) were mixed, and 40 to 48 were mixed therein. A mass% ammonium sulfide ((NH ₄ ) ₂ S) aqueous solution (50 ml) was added and allowed to react at room temperature.
Next, the resulting precipitate was filtered off and vacuum dried at 25 ° C. for 6 hours to obtain a compound (9.61 g) represented by the formula “(NH ₄ ) ₂ MoO ₂ S ₂ ”.
Next, this compound was heat-treated at 500 ° C. for 2 hours under a nitrogen gas atmosphere at a flow rate of 15 ml / min to remove ammonia, and the general formula “Mo _x OS _Y (wherein x and y are the same as above). It is the same.) The obtained compound was molded at a pressure of 60 MPa for 3 minutes and then pulverized to 20 to 80 mesh to obtain a powder.
To the obtained powdery compound (5.29 g), cobalt (II) nitrate hexahydrate (Co (NO ₃ ) ₂ .6H ₂ O) (3.50 g) and distilled water (1.5 ml) were added. Further, potassium nitrate (KNO ₃ ) (0.61 g) and distilled water (2.5 ml) were added and reacted, and the resulting product was filtered and further molded, and then 20-80 The mesh was pulverized to form powder. Furthermore, the obtained powder was dried at 500 ° C. for 4 hours under a nitrogen gas atmosphere at a flow rate of 30 ml / min, whereby the general formula “K _a Co _b Mo _c O _e S _d (a, b, c, d, e Is the same as above.) ”Was obtained.
Next, this compound was subjected to sulfidation by heat treatment at 400 ° C. for 3 hours in a hydrogen sulfide (H ₂ S) gas atmosphere at a flow rate of 30 ml / min to obtain a catalyst (1) when X is potassium. .
It was confirmed by fluorescent X-ray analysis (XPS) that the obtained product was a catalyst (1).

[Production Example 2]
(Preparation of catalyst (1) where b / c is 0.6 and a / c is 0.2 when d is 2)
To a compound (5.29 g) represented by a powdered general formula “Mo _x OS _Y (wherein x and y are the same as above)”, cobalt (II) nitrate hexahydrate (Co _{(NO 3) 2 · 6H 2} O) and added (5.25 g) and distilled water (2 ml), and further potassium nitrate _(KNO 3) (the reaction by adding and 0.61 g) and distilled water (2.5 ml) A catalyst (1) was obtained in the same manner as in Production Example 1 except that.
It was confirmed by fluorescent X-ray analysis (XPS) that the obtained product was a catalyst (1).

[Production Example 3]
(Preparation of catalyst (1) where b / c is 0.4 and a / c is 0.1 when d is 2)
To a compound (5.23 g) represented by a powdery general formula “Mo _x OS _Y (wherein x and y are the same as above)”, cobalt (II) nitrate hexahydrate (Co _{(NO 3) 2 · 6H 2} O) and added (3.46 g) and distilled water (1.5 ml), further potassium nitrate _(KNO 3) _(0.30g) and added to distilled water (1.5 ml) A catalyst (1) was obtained in the same manner as in Production Example 1, except that the reaction was performed.
It was confirmed by fluorescent X-ray analysis (XPS) that the obtained product was a catalyst (1).

[Production Example 4]
(Preparation of catalyst (1) where b / c is 0.4 and a / c is 0.4 when d is 2)
To a compound (5.23 g) represented by a powdery general formula “Mo _x OS _Y (wherein x and y are the same as above)”, cobalt (II) nitrate hexahydrate (Co _{(NO 3) 2 · 6H 2} O) and added (3.46 g) and distilled water (1.5 ml), and further potassium nitrate _(KNO 3) (the reaction by adding and 1.20 g) and distilled water (5ml) A catalyst (1) was obtained in the same manner as in Production Example 1 except that.
It was confirmed by fluorescent X-ray analysis (XPS) that the obtained product was a catalyst (1).

<Manufacture of alcohol>
[Examples 1 to 19]
Using 3.0 g of catalyst (1), alcohol was produced under the conditions shown in Table 1. The results are shown in Tables 2-3. In Tables 2 and 3, “MeOH” represents methanol, “EtOH” represents ethanol, “PrOH” represents 1-propanol, and “BuOH” represents 1-butanol.
Further, the product was identified by gas chromatography (GC) and gas chromatograph mass spectrometry (GC-MS) using the following apparatus and standard substance.
(GC)
GC-9A (manufactured by Shimadzu Corporation), detector: flame ionization detector (FID), column: G-250
GC-323 (manufactured by GL Sciences Inc.), detector: thermal conductivity detector (TCD), column: Porpak Q
(GC-MS)
・ QP5050 (manufactured by Shimadzu Corporation)
In addition, alcohol, oxygen atom containing compounds other than alcohol, and C5 or more hydrocarbon were quantified using said "GC-9A" among products. Carbon monoxide, carbon dioxide, and hydrocarbons having 4 or less carbon atoms were quantified using the above-mentioned “GC-323”.

[Comparative Examples 1-3]
Example 1 except that catalyst (i) (p / q is 0.1 when r is 2) was used instead of catalyst (1) and the reaction conditions were as shown in Table 1. In the same manner as in Example 1, alcohol was produced. The results are shown in Tables 2-3.

[Comparative Examples 4 to 6]
Instead of catalyst (1), the following general formula a catalyst aluminum oxide is a carrier represented by (ii) catalyst supported on _{(Al 2 O 3) (X} α Co β Mo γ / Al 2 O 3) Alcohol was produced in the same manner as in Example 1 except that the reaction conditions were as shown in Table 1. The results are shown in Tables 2-3.
X _α Co _β Mo _γ (ii)
(Wherein X is an alkali metal; α, β and γ are numbers greater than 0.)

In the formula, X is an alkali metal, and is the same as X in the general formula (1).
In the formula, α, β and γ are numbers larger than 0, and are the same as a, b and c in the general formula (1).

As is clear from Tables 1 and 2, the selectivity of alcohol was significantly higher when the catalyst (1) was used than when the catalysts (i) and (ii) were used.
Further, from Examples 1 to 10, when b / c was 0.4, when the pressure was 8 MPa, and when the temperature was 250 to 300 ° C., the alcohol selectivity tended to be further improved. On the other hand, the selectivity of carbon dioxide (CO ₂ ) tended to be further suppressed when b / c was 0.6. Then, tends with increasing H 2 _/ CO (molar ratio) increases the conversion of carbon monoxide (CO), ethanol selectivity is improved with decreasing H 2 _/ CO (molar ratio) It was seen.
On the other hand, from Examples 11 to 19, the alcohol selectivity was further improved as a / c was increased, and the conversion rate of carbon monoxide (CO) was increased as a / c was decreased. It was.

  The present invention can be used for the production of various alcohols.

Claims (7)

The manufacturing method of alcohol characterized by having the process of making carbon monoxide and hydrogen react in presence of the catalyst represented by following General formula (1).
_{X a Co b Mo c S d} ···· (1)
(Wherein X is an alkali metal; a, b, c and d are numbers greater than 0 and d / c is 1 to 3)   The method for producing an alcohol according to claim 1, wherein X is K (potassium).   The method for producing an alcohol according to claim 1 or 2, wherein the catalyst represented by the general formula (1) has b / c of 0.2 to 0.7.   In the catalyst represented by the said General formula (1), a / c is 0.05-0.6, The manufacturing method of the alcohol as described in any one of Claims 1-3 characterized by the above-mentioned. The method for producing an alcohol according to any one of claims 1 to 4, wherein the carbon monoxide and hydrogen are reacted by being supplied at a space velocity of 3000 to 25000 h- ¹ .   The method for producing an alcohol according to any one of claims 1 to 5, wherein the reaction is performed under a pressure of 4 to 10 MPa.   It reacts on 200-400 degreeC heating conditions, The manufacturing method of the alcohol as described in any one of Claims 1-6 characterized by the above-mentioned.