JP2001048819A - Method for hydrogenating dicarboxylic acid compounds at two stages - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for hydrogenating a dicarboxylic acid compound at two stages, by which the corresponding alcohol and the cyclic ether are obtained in high yields, by hydrogenating the dicarboxylic acid in the presence of a catalyst containing a specific metal to produce the reaction mixture containing a lactone compound and further hydrogenating the reaction mixture in the presence of a copper-containing catalyst. SOLUTION: This method for hydrogenating a dicarboxylic acid at two stages comprises hydrogenating (A) the dicarboxylic acid and/or the dicarboxylic anhydride, such as succinic anhydride or maleic anhydride in the presence of (B) a catalyst containing a metal, preferably palladium, selected from the metals in the group VIII and a metal, preferably rhenium, silver or tungsten, selected from metals in the groups IB, VIB and VIIB to produce the reaction mixture containing a lactone, and further hydrogenating the reaction mixture in the presence of (C) a copper-containing catalyst (for example, copper zinc chromate catalyst) to produce the dialcohol and/or the cyclic ether. In the reactions, the hydrogenation pressures are preferably the atmospheric pressure to 10 MPa at a temperature of 120 to 300 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for hydrogenating dicarboxylic acids, and more particularly to a process for hydrogenating dicarboxylic acids in two steps to produce the corresponding dialcohols and / or cyclic ethers.

[0002]

2. Description of the Related Art Conventionally, various methods for producing a corresponding dialcohol and / or cyclic ether by hydrogenating carboxylic acids have been known, and they are roughly classified into a one-step hydrogenation method and a two-step hydrogenation method. .

Japanese Patent Application Laid-Open No. 51-133212 discloses that when producing 1,4-butanediol from maleic anhydride or the like,
A method for hydrogenating in one step in the presence of a catalyst comprising a Group VII synchronous element or a compound thereof and a Group VIII element or a compound thereof or a mixture of the above-mentioned elements and compounds is disclosed. Hydrogenation is carried out under pressures of more than 170 bar. JP-A-64-70422 discloses that dicarboxylic acids are catalytically hydrogenated at a temperature of 100 to 350 ° C. and a pressure of 50 to 350 bar, wherein a catalyst containing cobalt and at least one element of copper and phosphorus is used. A process for producing 1,4-butanediol and / or tetrahydrofuran, characterized in that it is used, is disclosed in Examples.
Hydrogenation is carried out at very high pressures of ~ 300 bar. Thus, any one-step hydrogenation method described above has a problem that the hydrogenation conditions, especially the pressure, must be extremely severe in order to improve the yields of 1,4-butanediol and tetrahydrofuran. Was.

Japanese Patent Application Laid-Open No. 8-193040 discloses a process for producing tetrahydrofuran and 1,4-butanediol, in which a hydrogenatable precursor is mixed with a hydrogen-containing gas and palladium supported on a carbon carrier. A process is disclosed that includes contacting with a hydrogenation catalyst containing silver and rhenium to catalytically hydrogenate to produce a product containing a majority of the 1,4-butanediol. However, in the one-step method, tetrahydrofuran and 1,4-
There is a disadvantage that by-products other than butanediol are generated in a relatively large amount.

JP-A-63-218636 discloses that the precursors capable of being hydrogenated are selected from the group consisting of aqueous reaction media, and palladium or its combination with rhenium, and oxides of titanium, zirconium and hafnium. At least one
A method for producing butyrolactone, butanediol and mixtures thereof by hydrogenation in a single step in the presence of a catalyst comprising a support of the formula: In the examples, the concentrations of the precursors which can be hydrogenated, succinic acid, itaconic acid and maleic acid in aqueous solution are 5%, 4% and 5%, respectively.
And thus the productivity of tetrahydrofuran and butanediol was extremely low.

Japanese Patent Publication No. 62-54289 discloses a method for producing 1,4-butanediol by hydrogenating maleic anhydride in the presence of a monohydric aliphatic alcohol using a copper chromite catalyst in a one-step method. A method is disclosed. In this method, even if a free acid or an acid-containing ester that rapidly inactivates the copper chromite catalyst is produced, the hydrogenation in the presence of a monohydric aliphatic alcohol can increase the activity of the copper chromite catalyst. Can be maintained,
1,4-butanediol can be produced in a high yield. JP-A-51-98204 discloses a method for producing 1,4-butanediol by hydrogenating γ-butyrolactone containing water or a carboxylic acid or a mixture thereof. A method using a chromium oxide catalyst is disclosed. If the pretreated copper-based catalyst is used, 1,4-butanediol can be produced in high yield without significantly reducing the catalyst activity without removing water and carboxylic acid before hydrogenation. is there. However, any of the methods has a problem that the hydrogenation pressure must be increased. Further, the latter method has not yet been said to be sufficient for preventing the activity of the catalyst from decreasing.

[0007] Japanese Patent Publication No. 48-823 discloses that in a first stage, an impure maleic acid is hydrogenated in the presence of a catalyst mainly composed of a platinum group element, and then the platinum group catalyst is converted from the reaction product. A process for producing one or more of γ-butyrolactone, 1,4-butanediol and tetrahydrofuran, characterized in that it is removed and then, in a second stage, further hydrogenated in the presence of a rhenium-based catalyst. ing. In addition, JP-A-5
No. 2,238,971 discloses a method for producing 1,4-butanediol by catalytic hydrogenation of maleic anhydride in the presence of an alcohol using a cobalt-containing catalyst. ~ 200 ℃ and pressure 30 ~
Partially hydrogenate at 200 bar and subsequently without working up the mixture from the first hydrogenation step, at a higher temperature and higher pressure than the first hydrogenation step, 200-300 ° C
And a process for preparing 1,4-butanediol which is further hydrogenated in a second hydrogenation step at 200 to 350 bar. Both of the above methods aim at maintaining the catalytic activity more effectively for a long period of time by hydrogenation in two stages, but solve the problem that the hydrogenation conditions, especially the pressure, must be very severe. I couldn't.

[0008] Japanese Patent Application Laid-Open No. 9-59190 discloses that in producing hydrogenated maleic acid in two steps in the presence of a hydrogenation catalyst to produce 1,4-butanediol and / or tetrahydrofuran, a first-stage hydrogenation step is carried out. Is subjected to a hydrogenation reaction in the presence of a catalyst having a C ＝ C double bond reducing ability, and the first-stage hydrogenation reaction product is supported in a second-stage hydrogenation step on a supported noble metal-Sn-based catalyst A hydrogenation reaction in the presence of is disclosed. In the examples, a Pd / C catalyst is used as a catalyst in the first-stage hydrogenation step. In the method, in the first step, C =
The purpose is to selectively reduce the C double bond to reduce the acidity of the maleic acid, thereby preventing a decrease in the activity of the supported noble metal-Sn catalyst used in the second hydrogenation step. However, in the first step, succinic acid is obtained by hydrogenation, and it cannot be said that the presence of the acid sufficiently prevents a decrease in the activity of the catalyst.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a reaction mixture in which the hydrogenation pressure in both the first stage and the second stage is extremely low and the acid concentration in the reaction mixture obtained by the first stage hydrogenation is extremely low. Due to their low potential, hydrogenation over copper-containing catalysts is possible without removing the acid from the reaction mixture, and is therefore very economical, the corresponding alcohols from dicarboxylic acids in a two-stage hydrogenation. And / or a method for producing a cyclic ether.

[0010]

JP-A-51-75009 discloses a method for producing 1,4-butanediol and / or tetrahydrofuran by catalytic hydrogenation of maleic anhydride or succinic anhydride. Hydrogenation in a step using a nickel-containing catalyst to obtain a product containing γ-butyrolactone, and then separating γ-butyrolactone from succinic anhydride and succinic acid, and product water, followed by the resulting γ A process is disclosed in which -butyrolactone is hydrogenated in a second stage using a copper-containing catalyst to convert to 1,4-butanediol and / or tetrahydrofuran. In the method, after removing acids that cause a decrease in the activity of the copper-containing catalyst from γ-butyrolactone, hydrogenating γ-butyrolactone using the copper-containing catalyst yields 1,4-butanediol and / or tetrahydrofuran. . The presence of such a step of removing acids results in high cost of the product.

The present inventors have made various studies to omit such a step of removing acids. As a result, when the dicarboxylic acids are hydrogenated in the first step using the following predetermined catalyst, surprisingly, there are almost no by-products of the acids and γ-
Butyrolactone can be produced. Therefore, γ-butyrolactone can be hydrogenated using a copper-containing catalyst in the second step without purifying the first-stage hydrogenation reaction mixture to separate out acids that adversely affect the activity of the copper-containing catalyst. To give 1,4-butanediol and / or tetrahydrofuran. Furthermore, using the method of the present invention, the hydrogenation pressure can be significantly reduced as compared with the conventional method.

That is, according to the present invention, (1) in the first step, a dicarboxylic acid and / or dicarboxylic anhydride is hydrogenated in the presence of a catalyst to obtain a reaction mixture containing lactones. In a process for hydrogenating the reaction mixture in the presence of a catalyst to produce the corresponding dialcohol and / or cyclic ether, at least one metal selected from Group VIII as a catalyst in the first stage hydrogenation; Group, a catalyst comprising at least one metal selected from the group consisting of Group VIB and Group VIIB, and using a catalyst comprising copper as the catalyst in the second stage hydrogenation. How to In a preferred embodiment, (2) a catalyst containing palladium and one or more metals selected from the group consisting of rhenium, silver, tungsten and molybdenum as a catalyst in the first step is used. (1) The method according to (1), wherein (3) the catalyst in the first-stage hydrogenation is one supported on any of graphitized carbon, graphite, activated carbon, silica, alumina, silica / alumina or zirconia. Or (4) the method according to (1) to (3), wherein the acid concentration in the reaction mixture obtained by the first-stage hydrogenation is 1% by weight or less based on the weight of the mixture. (5) The method according to (1), wherein the acid concentration in the reaction mixture obtained by the first-stage hydrogenation is 0.7% by weight or less based on the weight of the mixture. Any one of ~ (3) The method according to (6) The method according to any one of the above dicarboxylic acids and dicarboxylic acid anhydride is succinic anhydride and maleic anhydride (1) to (5),
(7) The reaction mixture obtained by the first stage hydrogenation is
The method according to any one of the above (1) to (6), which contains 70% by weight or more of γ-butyrolactone with respect to the weight of the mixture, (8) copper used in the second stage hydrogenation The method according to any one of the above (1) to (7), wherein the catalyst comprises a copper chromite catalyst, a zinc-containing copper catalyst, or an aluminum / magnesium-containing copper catalyst, (9) first-stage hydrogenation The method according to any one of the above (1) to (8), wherein the reaction mixture obtained later is hydrogenated in the second stage without purification, (10) in the hydrogenation in the first and second stages. (1) to above using a solvent
(9) The method according to any one of (9), (11) the method according to (10) above, wherein γ-butyrolactone is used as a solvent, and (12) the resulting dialcohol and cyclic ether are 1,4-butanediol. And the method according to any one of the above (1) to (11), which is tetrahydrofuran.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The catalyst used in the first stage hydrogenation of the present invention comprises at least one metal selected from Group VIII and Group IB, Group VIB and Group VIIB. A catalyst containing at least one metal selected from the group.
The metal selected from Group VIII is preferably palladium, platinum, rhodium, ruthenium, osmium, and iridium, and particularly preferably palladium. No. I
The metal selected from the group consisting of Group B, Group VIB and Group VIIB is preferably silver, rhenium, molybdenum or tungsten, and particularly preferably silver or rhenium. Preferably, one or more catalysts selected from the group of palladium-rhenium containing catalysts, palladium-silver containing catalysts and palladium-rhenium-silver containing catalysts are used for the first stage hydrogenation.

The above catalyst is preferably used in combination with a carrier. Known carriers can be used as the carrier, and examples thereof include graphitized carbons, graphites, activated carbons, silicas, aluminas, silica / aluminas, and zirconia.

The catalyst used for the second stage hydrogenation of the present invention is a catalyst containing copper, and any known catalyst can be used.
Preferably, a copper chromite catalyst, a copper catalyst containing zinc hydroxide or zinc oxide, or a copper catalyst containing aluminum oxide, optionally magnesium or the like is used. Copper chromite catalysts include, for example, 30-50% by weight CuO, 30-6%.
It can contain 0% by weight of Cr ₂ O ₃ and 0 to 10% by weight of BaO. Copper catalysts containing zinc hydroxide or zinc oxide are preferred for obtaining mainly alcohols such as 1,4-butanediol, and copper catalysts containing aluminum oxide, optionally magnesium etc. are mainly used for obtaining cyclic ethers such as tetrahydrofuran. preferable.

The water in the first and second stages of the present invention
Any of the soaking conditions can be selected from the following ranges.
Here, the conditions of the first stage and the second stage may be the same.
It is preferable because the operation is simplified. Hydrogenation pressure is good
Preferably normal pressure ~ 10MPa, particularly preferably 1 ~ 9MPa,
The hydrogenation temperature is preferably from 120 to 300 ° C., particularly preferably
170-250 ° C. The gas space velocity is preferably between 100 and 3
0,000hr^-1Particularly preferably 200 to 15,000 hr^-1so
Yes, the liquid hourly space velocity is preferably 0.05 to 10 hours ^-1, Special
Preferably 0.1 to 5 hours^-1It is. Also in the first stage
The hydrogen / maleic anhydride molar ratio in the
5,0005,000, particularly preferably 5-1500.

In the present invention, the catalyst can be used in either a fixed bed or a fluidized bed, and the hydrogenation reaction can be carried out in either a batch system or a continuous system.

The hydrogenation of the present invention is preferably carried out in both the first and second stages in the presence of a solvent. This makes it easier to remove the heat of reaction generated in the hydrogenation, thereby making the operation easier. The solvent is not particularly limited, and a solvent conventionally used for hydrogenating carboxylic acids can be used. For example, γ-butyrolactone, water, ethers such as dioxane, tetrahydropyran, tetrahydrofuran, diethyl ether or triglyme, alcohols such as methanol, ethanol, isopropanol, n-propanol, hexanol, n-butanol or isobutanol are used. Preferably, γ-butyrolactone is used.

In the present invention, the upper limit of the concentration of the dicarboxylic acid to be subjected to the first-stage hydrogenation is preferably 50% by weight, more preferably 40% by weight, based on the weight of the solvent.
It is particularly preferably 30% by weight, and the lower limit is preferably 1%.
% By weight, more preferably 3% by weight, particularly preferably 5% by weight. Exceeding the above upper limit makes it difficult to remove the heat of reaction generated in the hydrogenation, and below the above lower limit is not preferred because the production efficiency of the lactones deteriorates.

The dicarboxylic acids and / or dicarboxylic anhydrides to be subjected to the hydrogenation of the present invention preferably include saturated or unsaturated dicarboxylic acids and dicarboxylic anhydrides having 3 to 7 carbon atoms. Preferably, maleic acid,
Examples thereof include fumaric acid, succinic acid, maleic anhydride, and succinic anhydride, and particularly preferably, maleic anhydride and succinic anhydride are used.

In the first step of the present invention, the dicarboxylic acid and / or dicarboxylic anhydride is hydrogenated to produce the corresponding lactone-based hydrogenated product. The reaction mixture obtained after the first stage hydrogenation contains preferably at least 70% by weight, particularly preferably at least 80% by weight, of lactones, based on the weight of the mixture. By using the above catalyst, dicarboxylic acids can be hydrogenated to the corresponding lactones under the above relatively mild hydrogenation conditions, and almost no acids are formed. The acid concentration in the reaction mixture obtained after the first stage hydrogenation is preferably at most 1% by weight, particularly preferably at most 0.7% by weight, based on the weight of the mixture. Therefore, the reaction mixture can be supplied to the second stage as it is without being purified to remove the acid and hydrogenated using a catalyst containing copper.

In the second step of the present invention, the reaction mixture containing mainly the lactones obtained in the first step is hydrogenated in the presence of a catalyst containing copper to form the corresponding dialcohol and / or cyclic ether. can get.

When maleic anhydride and succinic anhydride are used as dicarboxylic acid and dicarboxylic anhydride to be subjected to hydrogenation, the first-stage hydrogenation gives a reaction mixture containing mainly γ-butyrolactone, Two-stage hydrogenation gives 1,4-butanediol and / or tetrahydrofuran.

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

[0025]

[Example] <Preparation of catalyst>

[0026]Catalyst used for the first stage hydrogenation (1) Catalyst: 2% Pd-2% Re / C 3.358 grams of Pd (NO₃)₂And 1.973 grams of Re₂O₇
Is 6.72 grams of acetonitrile and 21.9 grams of distilled
After uniformly dissolving in water, add more distilled water to
The volume was made up to 64 ml. Activated carbon [grain]
Shirasagi Gc ™, 4/8 inch, Takeda Pharmaceutical Company Limited
Manufactured), and those having a particle size of 1 to 2 mm were used. the above
The solution is impregnated with 72 grams of the activated carbon and then room temperature for 4 hours.
After heating at 120 ° C for 15 hours, the catalyst precursor
Obtained. The obtained catalyst precursor was heated from room temperature to 280 in a stream of hydrogen.
Temperature over 11 hours, and kept at that temperature for 5 hours
Then, it was allowed to cool to room temperature. After that, the hydrogen stream is changed to a nitrogen stream.
After switching and completely replacing hydrogen, 0.5% by volume of oxygen
In a nitrogen stream containing
Collected after stabilization. (2) Catalyst: 2% Pd-2% Re-2% Ag / C 3.470 grams of Pd (NO₃)₂, 2.000 g Re₂O₇Passing
And 2.471 grams of Ag (NO ₃) With 6.95 grams of acetonitrile
Dissolve evenly in toril and 27.4 grams of distilled water
Except that the activated carbon as the body was 70.5 grams
A catalyst was prepared in the same manner as in (1). (3) Catalyst: 2% Pd-2% Ag / ZrO₂ 1.973 g Re₂O₇Instead of 2.359 grams of Ag (NO
₃) And instead of activated carbon as a carrier,
Konia (XZ 16154 (TM), 1/16 inch, Norton
Except that the catalyst was used in the same manner as in (1) above.
Prepared.

Was dissolved in a Cu-Cr-Mn-Na oxide 178.7 g of _{Na 2 Cr 2 O 7 · 2H} 2 O 900 ml of distilled water,: [0027] Catalyst (4) catalyst used for the hydrogenation in the second stage Further, a solution a was prepared by adding 225 ml of 28% ammonia water. Separately, 260.4 grams of C
_{u (NO 3) 2 · 3H} 2 O and 17.5 g of Mn (NO _{3) 2} ·
After dissolving 6H ₂ O in 900 ml of distilled water, 80 ℃
To prepare a solution b. Then, while stirring the solution a, the solution b was added to the solution a, and the resulting precipitate was separated by filtration. The precipitate was washed with water, dried and pulverized.
Pyrolyzed at 0 ° C. The obtained powder was washed with a 10% aqueous acetic acid solution, then washed with water and dried to obtain a catalyst precursor. To 10 grams of the catalyst precursor, 0.6 grams of Na ₂ CO ₃ dissolved in a small amount of water was added and then dried. The obtained material was calcined at 450 ° C. for 3 hours, and then graphite was added thereto to 0.5% by weight of the total weight, and pelletized to obtain a catalyst. The composition of the obtained catalyst was 33.5% by weight of Cu, 28.6% by weight of Cr, 4.0% by weight of Mn, and 2.2% by weight of Na. (5) Catalyst: Cu-Cr-Mn-Ba -Na oxide 260.4 g of _{Cu (NO 3) 2 · 3H} 2 O, 17.5 g of Mn
(NO _{3) 2} · 6H ₂ O and 15.8 grams of Ba a (NO _{3) 2}
After dissolving in 900 ml of distilled water, the mixture was heated to 80 ° C. to prepare a solution c. A catalyst was prepared in the same manner as in the above (6) except that this was used in place of the solution b. (6) Catalyst: Cu-based catalyst DRD92 / 89 (trademark), manufactured by KVAERNER PROCESS TECHNOLOGY

Comparative catalyst (7) Catalyst: Ni-based (catalyst used in the first step of Comparative Example 1) Ni-Al according to the examples described in JP-A-51-75009.
A catalyst was prepared.

<Charging and Reduction of Catalyst into Reactor> Both are sieved to 1-2 mm in SUS316 steel reactors A (first stage) and B (second stage) each having an inner diameter of 15 mm and a length of 600 mm. Each of the catalysts thus filled was filled in an amount of 10 ml. Where reactor A
The combinations of the catalysts to be charged into B and B were as shown in Table 1. All the combinations were subjected to the reduction treatment and then subjected to hydrogenation of maleic anhydride. After the catalyst is filled, the inside of the reactor is sufficiently replaced with nitrogen gas, and then the nitrogen space velocity (GHS
V) is set to 1500hr- ¹ and the pressure in the reactor is 3kg / c
Nitrogen gas was flowed into the reactor at room temperature, set to m ² G. Next, under the same conditions, while switching the nitrogen gas to nitrogen gas containing 0.1% by volume of hydrogen and flowing into the reactor,
The temperature of the catalyst layer in the reactor was raised to 120 ° C. After confirming that the hydrogen concentration at the inlet and the outlet of the reactor became equal at this temperature, the temperature of the catalyst layer was gradually raised to 160 ° C. After heating to 160 ° C, at that temperature,
The hydrogen concentration in the gas was slowly increased from 0.1% by volume to 0.5% by volume, and then gradually increased to 170 ° C. Subsequently, at this temperature, the hydrogen concentration in the gas was slowly increased from 0.5% by volume to 100% by volume, and after switching to 100% hydrogen gas, the temperature was gradually raised to 200 ° C. to reduce the catalyst. finished.

In the above-mentioned temperature raising process and the process of increasing the hydrogen concentration in the gas, the temperature is slowly increased so that the hydrogen concentrations at the inlet and the outlet of the reactor become equal, and the hydrogen concentration is gradually increased. When the hydrogen concentration at the inlet and outlet of the vessel was different, the temperature or the hydrogen concentration was maintained until the concentrations became equal.

[0031]

Examples 1-4 and Comparative Examples 1-2 Maleic anhydride and γ
-Maleic anhydride so that the concentration of maleic anhydride with respect to the total amount of -butyrolactone was 27.5% by weight;
-Dissolved in butyrolactone. Next, after the charging of the catalyst into the reactor and the reduction treatment were completed, the maleic anhydride solution was supplied to the hydrogenation reactor, and a continuous operation was performed for about 100 hours. The hydrogenation conditions are as shown in Table 1.

The results are shown in Table 1. Each product composition was measured by gas chromatography.

[0033]

[Table 1] In the table, each abbreviation indicates the following content. GBL: γ-butyrolactone THF: tetrahydrofuran BDO: 1,4-butanediol SAH: succinic anhydride MAH: maleic anhydride

Examples 1 and 2 both use 2% Pd-2% Re / C as the first stage hydrogenation catalyst and Cu-Cr-Mn-Na oxide as the second stage hydrogenation catalyst. Used, but with a different hydrogenation temperature in the second stage. In each case, generation of acids was hardly observed after the first stage hydrogenation. Therefore, no decrease in the activity of the copper catalyst in the second stage was observed,
In each case, THF and 1,4-butanediol were obtained in high yield. Also, when the hydrogenation temperature in the second stage is increased, TH
The yield of F increased. Up to γ-butyrolactone, which was used as a solvent in the second step of Example 2, was converted to THF. Example 3 uses 2% Pd-2% Re-2% Ag / C as the first stage hydrogenation catalyst. As in Examples 1 and 2, almost no acid formation was observed in the first stage hydrogenation. Therefore, the activity of the copper catalyst was not reduced in the second step, and THF and 1,4-
Butanediol was obtained. In Example 4, 2% Pd-2% Ag /
ZrO ₂ was used as the first stage hydrogenation catalyst. The formation of acids by the first stage hydrogenation was very low. Accordingly, no decrease in the activity of the copper catalyst in the second step was observed, and THF and 1,4-butanediol were obtained in high yield.

On the other hand, in Comparative Example 1, a Ni-containing catalyst described in JP-A-51-75009 was used as the first stage hydrogenation catalyst. In the first stage, the formation of acids by the hydrogenation was very high, and in the second stage, the catalyst containing copper showed a significant decrease in activity, and the yields of THF and 1,4-butanediol were significantly reduced. Therefore, when a Ni-containing catalyst was used as the first-stage hydrogenation catalyst, it was found that after removing acids from the first-stage hydrogenation product, it was necessary to perform hydrogenation with a catalyst containing copper. Was. Comparative Example 2 uses a catalyst containing copper as the first stage catalyst and 2% Pd-2% Re-2% Ag / C as the second stage catalyst.
The yields of THF and 1,4-butanediol could not be increased.

[0036]

Example 5 and Comparative Example 3 Using the same catalyst and conditions as in Example 1 and Comparative Example 1, continuous operation was performed for about 1200 hours, respectively. Table 2 shows the results. Each product composition was measured by gas chromatography in the same manner as described above for samples collected 500 hours and 1200 hours after the start of operation.

[0037]

[Table 2]

In Example 5, the acid concentration in the first-stage hydrogenation product was significantly lower both at 500 hours and 1200 hours after the start of operation, and thus the activity of the copper-containing catalyst in the second stage was reduced. Little decrease was observed, and in both cases, THF and 1,4-butanediol could be obtained in high yield.

On the other hand, in Comparative Example 3, the acid concentration in the hydrogenation product in the first stage was high both after 500 hours and 1200 hours after the start of operation, and thus the activity of the catalyst containing copper was decreased. And the yields of THF and 1,4-butanediol showed a significant decrease.

[0040]

According to the present invention, the hydrogenation pressure in both the first stage and the second stage is extremely low, and the acid concentration in the reaction mixture obtained by the first stage hydrogenation is extremely low. The hydrogenation over copper-containing catalysts is possible without removing the acid from the reaction mixture, and is therefore considerably more economical, the dihydric acids being converted to the corresponding alcohols and / or cyclic compounds in a two-stage hydrogenation. A method for producing an ether is provided.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C07D 307/08 C07D 307/08 // C07B 61/00 300 C07B 61/00 300 (72) Inventor Takeshi Ishihara 272-16 Namiki, Kawagoe-shi, Saitama F-term (reference) 4C037 BA02 BA06 BA07 BA08 4H006 AA02 AC41 BA05 BA06 BA07 BA09 BA14 BA75 BD70 BE20 FE11 FG28 4H039 CA42 CA60 CB40 CH20 CH50

Claims (5)

[Claims] In the first step, a dicarboxylic acid and / or
Alternatively, the dicarboxylic anhydride is hydrogenated in the presence of a catalyst to obtain a reaction mixture containing lactones. In the subsequent second step, the reaction mixture is hydrogenated in the presence of a catalyst to form the corresponding dialcohol and / or cyclic ether. In the method of producing, at least one metal selected from Group VIII as a catalyst in the first stage hydrogenation, a group IB, VI
A process comprising using a catalyst comprising at least one metal selected from the group consisting of Group B and Group VIIB, and using a catalyst comprising copper as the catalyst in the second stage hydrogenation. 2. The method according to claim 1, wherein the catalyst used in the first step is a catalyst containing palladium and one or more metals selected from the group consisting of rhenium, silver, tungsten and molybdenum. the method of. 3. The process according to claim 1, wherein the acid concentration in the reaction mixture obtained by the first stage hydrogenation is less than 1% by weight, based on the weight of the mixture. 4. The dicarboxylic acid and dicarboxylic anhydride are succinic anhydride and maleic anhydride.
3. The method according to any one of 3. 5. The process as claimed in claim 1, wherein the reaction mixture obtained in the first stage hydrogenation is hydrogenated in the second stage without purification.