JPS58128331A - Preparation of higher alcohol - Google Patents

Abstract

PURPOSE:To obtain a higher alcohol, e.g. ethanol or butanol, in high selectivity, by homologating methanol in the presence of an inexpensive and noncorrosive catalytic system containing a transition metallic compound as a main catalyst and an organic base as a cocatalyst in combination. CONSTITUTION:Methanol is reacted with carbon monoxide or carbon monoxide containing hydrogen to prepare a higher alcohol. In the process, a catalytic system containing a transition metallic compound, e.g. iron carbonyl or cobalt carbonyl, as a main catalyst and an organic base, e.g. N-methylpyrrolidine or N-methylpiperidine, as a cocatalyst in combination is used. The introduction of hydrogen into the system reduces the amount of by-products and increases the selectivity. Carbon dioxide produced and accumulated in the reaction is removed, and the unreacted synthetic gas is reacted with methanol while supplied separately with the synthetic gas. The addition of a ruthenium compound as a cocatalyst other than the organic base may improve the selectivity of ethanol.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a higher alcohol (in this specification, refers to an alcohol having more carbon atoms than methanol) by a homologation reaction of methanol. More specifically, methanol is reacted with -carbon oxide or hydrogen-containing carbon monoxide (e.g., synthesis gas) using a catalyst system in which a transition metal compound is used as the main catalyst and an organic base is used as a co-catalyst. This invention relates to a method for synthesizing higher alcohols such as butanol.

The method for producing higher alcohols by homologation reaction of methanol has been known for a long time, but methanol,
Hydrogen and carbon oxides have been the subject of renewed research in recent years, as useful products such as ethanol, previously produced from petroleum-based feedstocks, can be obtained. A cobalt compound is usually used as the main catalyst for methanol homologation, but if no co-catalyst component is added to it, it may not be advantageous in terms of catalyst stability, activity or selectivity. do not have. To overcome this problem, methods have been proposed to add tertiary phosphine, arsine, iodine compounds, or ruthenium compounds as co-catalyst components, but these co-catalysts are expensive or require equipment. It has not yet been recognized as an industrially advantageous method because it corrodes the catalyst and its addition does not necessarily improve the stability, activity, and selectivity of the catalyst at the same time.

In order to overcome the above-mentioned problems in the conventionally known catalyst systems for methanol homologation reaction, the present inventors have conducted extensive research to discover new catalyst systems, and as a result, we have found that organic We discovered the unexpected and interesting fact that a catalyst system containing a base exhibits excellent catalytic action in the reaction of producing ethanol from methanol and carbon monoxide, and furthermore, we found that the reaction in this case was significantly accelerated by the presence of hydrogen. It was discovered that butanol could also be obtained depending on the conditions and conditions, and as a result of comprehensive research based on these findings, the present invention was completed.

That is, the present invention is characterized in that methanol and carbon monoxide or carbon monoxide containing hydrogen (e.g., synthesis gas) are reacted using a catalyst system containing a combination of a transition metal compound and an organic base as basic components. Higher alcohol (
ethanol and butanol).

The content of the present invention will be explained in detail below, dividing it into catalyst, solvent, reaction temperature, pressure, and gas composition.

i) Catalyst In the method of the present invention, a transition metal compound is used as the main catalyst, and an organic base is used as the co-catalyst.

It is believed that the transition metal compound is transformed into a catalytically active form under the reaction conditions of the present invention, and in this case, this active species coordinates carbon monoxide by reaction with the reaction component carbon monoxide. Therefore, it goes without saying that the most preferred form of the transition metal compound is metal. The transition metal compound can be selected from a wide range of transition metal compounds known as catalysts for general lc carbonylation reactions. The transition metal components in these transition metal compounds include Cr,
Mo, W, Fe, Ru, Os.

Co, RA, Ir5Ni, Pd, Pt, etc. are preferred.

Specific examples of transition metal compounds include simple transition metals,
Examples include complexes coordinated with halides, oxides, carboxylates, acetylacetonates, carbonyls, and at least one selected from cyclopentadienyl groups, alkyl groups, phosphines, olefins, etc. be able to. Among these, cobalt or iron compounds are superior in terms of catalytic activity and selectivity, and iron carbonyl is particularly preferred.

The amount of the transition metal compound used as the main catalyst is not particularly limited and can be used in any amount, but usually 140 or less (molar ratio) of the amount of methanol charged is sufficient. The amount used can be appropriately determined depending on factors such as price, synthesis gas composition and pressure, reaction temperature, solvent, type and amount of co-catalyst.

In the method of the present invention, the presence of an organic base as a cocatalyst is essential, and without it, the reaction will not substantially proceed. As the organic base, A is preferable to chain amines, and diamines tend to have higher activity than monoamines, but there are exceptions. Examples of amines suitable for the practice of this invention include N-methylpyrrolidine, N-methylpiperidine, N-methylhexamethyleneimine, N-methylmorpholine, N,N'-dimethylpiperazine, N
, N, N', N'-tetramethylethylenediamine, trimethylamine, pyridine, and the like.

The amount of organic base used as a cocatalyst is usually preferably above -LQ-Q (molar ratio) to methanol used.
1 It's delicious. If the amount is too large, the ethanol selectivity will decrease, and if it is too small, the reaction will not substantially proceed. Therefore, the amount to be added is determined by taking into account the type of organic base used, the reaction rate, and the selectivity of the product.

Note that the selectivity of ethanol may be improved by adding a ruthenium compound in addition to the organic base as a cocatalyst.

In this case, the amount of the ruthenium compound added is expressed as the number of moles per transition metal of the transition metal compound that is the main catalyst.
A molar ratio of 1/1 is preferred.

Regarding the action of organic bases, such as amines, in the process of the invention, this acts as a ligand to the main catalyst, activates methanol as an acid and increases its nucleophilicity towards the main catalyst, which is formed after the reaction. It is thought that it acts to trap carbon dioxide and maintain the main catalyst in an activated state, but it is not yet clear, but it is thought that the above functions and effects are intricately related to each other.

ii) Solvent In the method examples of the present invention, the reaction proceeds without a solvent, but it is preferable to carry out the reaction in an appropriate solvent from the viewpoint of reaction rate and product selectivity. Examples of such solvents include aliphatic or aromatic hydrocarbons, amides, ketones, ethers, nitriles, and alcohols other than methanol.

The specific solvent used is determined depending on the type of main catalyst and co-catalyst.

iii) Reaction temperature The reaction temperature in the method of the present invention varies depending on the pressure, type of catalyst, concentration, solvent and other reaction conditions, but is usually 50°C.
~350°C.

When iron carbonyl is used as the main catalyst and the reaction is carried out under high syngas pressure, the methanol conversion rate increases at low temperatures, but the ethanol selectivity is low, and if the reaction temperature is too high, the amount of by-product methyl formate increases significantly. Since it increases, 130~2
A temperature range of 50°C is preferred.

iv) Pressure and gas composition In the method of the present invention, the reaction proceeds even under pressure of carbon monoxide alone, and ethanol is produced, but its selectivity tends to be low. In this case, introducing hydrogen into the system reduces the amount of by-products and increases selectivity. The process of the invention is therefore more preferably carried out under pressure of synthesis gas. The higher the hydrogen partial pressure and the lower the carbon oxide partial pressure, the higher the ethanol selectivity, but these partial pressures have a large effect on the reaction rate and the composition of other products, and the manifestation of these effects is Since the method depends on other reaction conditions, it can be determined by comprehensively considering these factors.

In addition, in the method of the present invention, carbon dioxide generated during the reaction and accumulated in the system is led into the carbon dioxide absorbent together with unreacted gas (for example, unreacted synthesis gas), and a part of it is absorbed and removed. The unreacted gas after this treatment is mixed with separately supplied raw material gas and used again.

As described above, the method of the present invention uses a catalyst system in which a transition metal compound is used as a main catalyst in combination with an organic base as a catalyst, and the catalyst is relatively inexpensive and does not exhibit corrosive properties. According to the method of the invention, the desired ethanol, butanol, etc. can be obtained from methanol with high selectivity, so it is suitable as a method for industrial implementation.

Next, the present invention will be explained in more detail based on examples. In addition, the structure of the product after the reaction in the example was determined by GCMS,
All composition calculations were performed by gas chromatography. The columns used are as follows.

(Component) (Column packing material) Hydrogen
MS 5A, 4 m Methane, -carbon oxide MS 13
t), N-methylpyrrolidine 1.62 mt, and iron pentacarbonyl 0.27 mAC2mmot),
-80 atm of carbon oxide (at room temperature)? was introduced and reacted at 180°C for 24 hours. A pressure drop of 21.5 atmospheres was observed in terms of room temperature. After completion of the reaction, the contents were analyzed for gaseous phase components by an absolute calibration curve method and for liquid phase components by an internal standard method in which 100 μt of toluene was added. The results were as follows. It should be noted that the structure of the product of unknown structure estimated from the carbon balance is approximately 26.3 mmot in terms of the required amount of methanol.

Acetaldehyde 0.08 // CH4 production amount 3.03 mmot Production amount CO remaining amount 67.4 mmot Methyl formate production t 0.24
pCO3 production amount: 38.2 mmot Methyl acetate production amount: 0.47 tt #Bowa crystal WO, 07tt Ethanol production amount: 1.03 tt n-butanol 0.30 // Production amount example 2 Except for introducing 20 atm of hydrogen. The reaction was carried out in exactly the same manner as in Example 1. A pressure drop of 31.5 atmospheres (at room temperature) was observed, and the results of component analysis of the gas phase and liquid phase were as follows.

The amount of the structurally unknown substance produced, estimated from the carbon balance, is approximately 17.1 mmot in terms of the required amount of methanol.

Gas phase analysis Liquid phase analysis H2 remaining amount 16.6 mmot Methanol remaining amount 11
．． 73 mmot Remaining amount of CO 71.7 mmot Amount of aceto I produced - cH4 generated amount 4.45 mmot
Methyl formate production amount 0.37 pCO2//2
9.4 mmot Methyl acetate -ethanol // 5.04 ttn-phytanol/
/ 0.65p By comparing the results of Examples 1 and 2, it was found that although the presence of hydrogen is not necessarily required for the production of ethanol, introducing hydrogen into the system improves the mass balance with respect to methanol, and It can be seen that the selectivity is improved. In addition, when hydrogen was introduced, the amount of acetaldehyde and its acetal produced decreased, and furthermore, n-butanol was produced even though no n-glopanol was observed, and comparative experiments showed that Under the same conditions, ethanol itself was recovered without much reaction. Examples 3 to 10 Various transition metal compounds were used as the main catalyst instead of iron pentacarbonyl, and KN-methyl was used instead of N-methylpyrrolidine as a co-catalyst. The results of a reaction using piperidine under the same conditions as in Example 2 are shown in Broom 1k.

-13--252- 12- Examples 11 to 18 Using various bases instead of N-methylpyrrolidine as a cocatalyst, the reaction was carried out under the same conditions as in Example 2. The results are shown in Table 2. .

254- Examples 19-24 Reacted under the same conditions as in Example 2 using 2 mmot of iron pentacarbonyl as the main catalyst, 1.62 mt of N-methylpiperidine as the m catalyst, and 1.62 ml of various solvents k. The results are shown in Table 3.

-17=256- Examples 25 to 29 The selectivity of methanol consumed by the reaction of the main product when the hydrogen partial pressure or -carbon oxide partial pressure is changed according to Example 6 is shown in Figure 1 or It is shown in Figure 2.

Example 30 The reaction was carried out in exactly the same manner as in Example 6 except that ruthenium supported on activated carbon (supported amount 5q6) was added at 0.1 mmot per Ru atom. As a result, the amount of ethanol produced was 9.46 on the same side, -carbon oxide It is a graph showing the relationship between partial pressure and product selectivity.

=19- Figure 1 Figure 2 - Kii F - Kegen Hanichi

Claims (1)

[Scope of Claims] (1) A method for producing a higher alcohol, which comprises reacting methanol and carbon monoxide in the presence of a catalyst consisting of a transition metal compound and an organic base. (2) The method according to claim 1, which uses carbon monoxide containing hydrogen. (8) The method according to claim 1 or 2, wherein the metal component of the transition metal compound is iron or cobalt. (4) The method according to claim 1.2 or 3, wherein the organic base is a tertiary amine. (5) Carbon dioxide generated during the reaction and accumulated in the system is removed, and the remaining unreacted synthesis gas is reacted with methanol while being separately supplemented with synthesis gas.Claim 1.2.3 or 4 Method described. (6) The method according to claim 1.2.3.4 or 5, wherein the catalyst contains a ruthenium compound.