JP4479537B2 - Methods for preparing copper-containing hydrogenation catalysts and producing alcohols - Google Patents

Description

  The present invention relates to a copper-containing hydrogenation catalyst which provides an alcohol in a high yield with little degradation when producing an alcohol by reducing an ester with a hydrogen, a method for preparing the same, and a method for preparing an alcohol using the catalyst. It relates to the manufacturing method.

One method for producing alcohols is to reduce esters with hydrogen in the presence of a catalyst. This method is a simple method for converting esters to the corresponding alcohols, and includes not only the synthesis of various monoalcohols, but also 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol. It is widely applied to the production of dihydric alcohols.
Here, copper-based catalysts and noble metal-based catalysts are known as esters reduction catalysts.
As a copper-based catalyst, for example, a copper-chromium-oxygen-based catalyst (Cu-Cr-O-based catalyst) is known (Non-Patent Document 1).
As a method for preparing a copper-chromium-oxygen-based catalyst, a catalyst precursor (Cu (OH) NH ₄ CrO ₄ ) composed of copper and chromium is formed as a precipitate by a liquid phase method. A method in which the catalyst precursor is washed, dried and then calcined, and a copper compound (eg, copper nitrate, copper acetate) and a chromium compound (eg, chromium nitrate, chromic anhydride) are dissolved in the liquid phase. Then, it is concentrated and dried, dried, baked and decomposed (for example, Non-Patent Document 2).

  Moreover, as a copper-type catalyst which does not contain chromium, the copper-zinc oxide catalyst (CuO-ZnO catalyst) is known, for example (patent document 1).

  The copper-zinc oxide catalyst is a typical copper-based catalyst that does not contain chromium. As described in Non-Patent Document 3, for example, the copper-zinc oxide catalyst is first prepared by a coprecipitation method in a liquid phase. And by precipitating a catalyst precursor comprising zinc and washing, drying and then calcining the resulting precipitate.

  In addition, as a copper-based catalyst used for the reduction of esters, various metal oxide combinations have been reported, for example, copper-zinc-aluminum-oxygen-based catalyst, copper-silica-based catalyst, copper-zirconia-based catalyst. Catalysts and the like are known. These are all prepared by the same preparation method as described above or by a supporting method. (For example, Patent Document 2, Patent Document 3, and Patent Document 4)

Although copper-based catalysts generally require reaction conditions at high hydrogen pressure, they are widely used not only for reduction reactions of esters but also for reduction reactions because the catalysts are inexpensive and have relatively high selectivity. .
However, during the reaction, elution of copper and other catalyst constituents (metal atoms), catalyst deterioration, and activity decrease are often observed. Although various causes are considered, it is considered to be due to elution of a copper component or the like by a small amount of acid component present in the reaction raw material or reduction aggregation. The elution of the metal component is described in Patent Document 5, and the aggregation of the metal component is described in Non-Patent Document 4.

  As a countermeasure against such catalyst deterioration, Patent Document 6 describes that the acid component in the reaction raw material is reduced to prevent catalyst deterioration.

In the reduction reaction of esters, it is important to reduce the acid content in the raw material ester in order to maintain the catalytic activity of the copper catalyst.
Therefore, it is desirable that the raw material ester does not contain an acid component, but it is often difficult to remove the acid component. In addition, even when raw material esters that do not contain acid components are used, some of the generated alcohol undergoes hydrocracking, and water is produced in the reaction system, and the ester is hydrolyzed to contain acid components. This will cause the catalyst to deteriorate.
That is, when a small amount of an acid component is present during the liquid phase reaction or when water is generated during the reaction, the copper-based catalyst deteriorates, resulting in a low yield of the target alcohol. As a result, the used catalyst is discarded after one or several uses.

Examples of the catalyst used for the reduction reaction of esters other than the copper catalyst include, for example, a ruthenium catalyst (such as Patent Document 7), a palladium catalyst (Patent Document 8), a rhenium catalyst (such as Non-Patent Document 5), and the like. Noble metal-based catalysts are known.
In general, noble metal catalysts have acid resistance, but often do not exhibit satisfactory selectivity, and are expensive, so they are not economical.

As a reduction reaction of esters using a copper-based catalyst, there is a production method of 1,6-hexanediol in which an esterification solution of organic acids recovered from an oxidation solution of cyclohexane containing adipic acid diester is hydrogen-reduced. Although known (Patent Document 9), the catalytic activity is not high, and some of the components of the catalyst may be eluted during the reaction, leading to catalyst degradation. There was a problem that the yield was not good.
European Patent No. 0661255 JP 2003-277303 A Japanese Patent Laid-Open No. 2-164449 JP-A-8-125702 Japanese Patent No. 3033882 Japanese Patent Publication No.53-33567 JP-A-7-213901 US Pat. No. 5,319,129 Japanese Patent Publication No.53-33567 JP-A-3-115237 H. “Organic Reaction” by Adkins, Vol. 8 (1984), p. 1-27 "catalyst". , Vol. 38, 1996, p. 236 Ozaki et al., “Catalyst Preparation Chemistry”, Kodansha, 1980, p. 244 J. et al. Mol. Catal. A: Chemical. , Vol. 191, 2003, p. 123 J. et al. Mol. Catal. A: Chemical. , Vol. 198, 2003, p. 297 4. Ullmann's Encyclopedia of Industrial Chemistry, 5. ed, 1987, Vol. A8, S.A. 2/9, p. 219

  The present invention provides a method for producing alcohols for reducing esters, which provides the desired alcohols in a high yield, and does not elute the catalyst components (metal atoms) during the reaction, that is, does not easily deteriorate copper-containing hydrogenation. Providing a catalyst and an efficient production method of alcohols using the catalyst, in particular, reducing an esterification solution of organic acids recovered from an oxidation solution of cyclohexane containing adipic acid diester and the like, It is an object to provide a production method for efficiently synthesizing 1,6-hexanediol.

The present inventors have used a copper-containing hydrogenation catalyst having a specific shape as a precursor (hereinafter, also referred to as “ copper-containing hydrogenation catalyst precursor ” ) having 2 to 20 carbon atoms. By contacting with a polyvalent carboxylic acid such as a carboxylic acid, it is possible to produce a copper-containing hydrogenation catalyst in which the catalyst component (metal atom) is difficult to elute during the reduction reaction of the esters. It was found that alcohols can be obtained in high yield in the production of alcohols for reducing esters with hydrogen.
That is, the present invention is as follows.

  The first invention is characterized in that a copper-containing hydrogenation catalyst precursor is brought into contact with a divalent or trivalent carboxylic acid having 4 to 20 carbon atoms at a temperature of 50 to 300 ° C. in an ester solvent or an ether solvent. The present invention relates to a method for producing a copper-containing hydrogenation catalyst.

  The second invention relates to a process for producing alcohols, characterized in that the copper-containing hydrogenation catalyst of the first invention is used in a process for producing corresponding alcohols by reducing esters with hydrogen. .

By using the copper-containing hydrogenation catalyst contact-treated with the polyvalent carboxylic acid of the present invention, the corresponding alcohols are produced with good yields by reducing the esters with hydrogen without eluting the catalyst components (metal atoms). be able to.
In particular, an esterification solution of organic acids recovered from an oxidation solution of cyclohexane containing adipic acid diester and the like can be reduced with hydrogen to efficiently produce 1,6-hexanediol.

Details of the present invention will be described below.
The method for preparing a copper-containing hydrogenation catalyst of the present invention is carried out by bringing a polyvalent carboxylic acid into contact with a molded copper-containing hydrogenation catalyst precursor.

  Examples of the copper-containing hydrogenation catalyst precursor include a copper-chromium-oxygen-based catalyst, a copper-zinc-oxygen-based catalyst, a copper-zinc-aluminum-oxygen-based catalyst, a copper-silica-based catalyst, and a copper-zirconia-based catalyst. Although a precursor is mentioned, it is not specifically limited to these. However, the copper content is preferably in the range of 5 to 80% by weight, more preferably 10 to 60% by weight, based on the total weight of the catalyst precursor. A catalyst in which these catalyst precursors are supported on silica, alumina, zirconium oxide, titanium oxide, silica-alumina or the like may be used. In this case, the total weight of the catalyst precursor here refers to the weight including these carriers.

  Examples of the shape of the copper-containing hydrogenation catalyst precursor include tableting or extrusion molding, spherical particles, and powder.

  Examples of the polyvalent carboxylic acid include divalent or trivalent carboxylic acids having 4 to 20 carbon atoms, preferably divalent or trivalent carboxylic acids having 4 to 14 carbon atoms, and further, succinic acid, Divalent carboxylic acids having 4 to 8 carbon atoms such as glutaric acid and adipic acid are preferred.

  The method for contacting the copper-containing hydrogenation catalyst precursor with the polyvalent carboxylic acid is such that the copper-containing hydrogenation catalyst precursor is 0.01% with respect to 1 mol of copper metal atoms contained in the copper-containing hydrogenation catalyst precursor. It is immersed in the above-mentioned polycarboxylic acid in a molar amount or more and heated at 50 to 300 ° C. without particular limitation, but after heat treatment for 0.5 to 10 hours, it is collected by filtration, and the solvent (water, alcohol (methanol, ethanol, etc.), Washing with a solvent for dissolving the polyvalent carboxylic acid such as acetone) and drying at 50 to 150 ° C. for 0.5 to 10 hours.

  Here, as the polyvalent carboxylic acid, one dissolved in a solvent inert to a catalyst such as an ester solvent such as methyl adipate or methyl glutarate, or an ether solvent such as diethyl ether or diethylene glycol can also be used. . The amount of these solvents used is 1 to 100 g with respect to 1 g of the polyvalent carboxylic acid.

  Here, the inert solvent means a solvent that does not cause elution or irreversible adsorption of a copper component of a copper-containing hydrogenation catalyst precursor such as metallic copper and generation of a compound with copper.

  The copper-containing hydrogenation catalyst of the present invention is used for the production of the corresponding alcohols by reducing esters with hydrogen, as well as hydrogenation reduction of aldehyde groups or ketone groups, hydrogenation reduction of olefins, It can also be used for various hydroreduction reactions such as hydroreduction.

  The method for producing alcohols of the present invention is characterized in that the copper-containing hydrogenation catalyst is used in the method for producing the corresponding alcohols by reducing esters with hydrogen.

  Here, the esters may be linear, branched, cyclic, or combinations thereof, the main chain excluding the side chain having 1 to 20 carbon atoms, and saturated aliphatic , Esters of unsaturated aliphatic or aromatic monovalent or divalent carboxylic acids.

Such esters include formic acid ester, acetic acid ester, caproic acid ester, caprylic acid ester, capric acid ester, undecenoic acid ester, lauric acid ester, myristic acid ester, palmitic acid ester, stearic acid ester, isostearic acid ester, Examples include oleic acid ester, arachidic acid ester, behenic acid ester, oxalic acid ester, maleic acid ester, adipic acid ester, sebacic acid ester, cyclohexanecarboxylic acid ester, benzoic acid ester, and phthalic acid ester. Here, although the alcohol site | part which comprises these esters is not specifically limited, It consists of a linear or branched C1-C22 saturated aliphatic alcohol.
Further, an esterification solution of organic acids recovered from an oxidation solution of cyclohexane containing adipic acid diester or the like can also be used as a raw material for producing 1,6-hexanediol and 1,5-pentanediol.

  Examples of the reaction format for hydrogenating and reducing the esters of the present invention include a liquid phase suspension bed reaction format and a fixed bed catalytic reaction format.

  In the hydrogenation reduction of esters in the liquid phase suspension bed of the present invention, the amount of the copper-containing hydrogenation catalyst used is 0.1 to 50% by weight based on the esters, and the reaction temperature is It is 150-300 degreeC, Preferably it is 200-290 degreeC, and a hydrogen pressure is 1-30 Mpa, Preferably it is 15-30 Mpa.

  In the hydrogen reduction reaction of esters on a fixed bed, esters are supplied at LHSV (liquid space velocity) of 0.01 to 10 g / ml · h, preferably 0.1 to 5 g / ml · h, and hydrogen gas is supplied to GHSV. (Gas space velocity) Supply at 10 to 10000 / hr, preferably 100 to 3000 / hr, hydrogen pressure 1 to 30 MPa, preferably 5 to 20 MPa, reaction temperature 150 to 300 ° C., preferably 180 to 250 ° C. Is called. Here, the copper-containing hydrogenation catalyst may be subjected to hydrogen reduction pretreatment if necessary.

  In the present invention, the hydrogen reduction of the esters is carried out without a solvent, but a solvent such as alcohol or ether can also be used.

  Specific embodiments of the production of alcohols for hydrogen reduction of the esters of the present invention include, for example, production of ethanol from acetic acid ester, production of propanol from propionic acid ester, production of butanol from butanoic acid ester, pentane Production of pentanol from acid ester, production of hexanol from hexanoic acid ester, production of corresponding monoalcohol from monoacid ester such as production of higher alcohol from higher fatty acid ester, ethylene glycol from oxalate ester Production, production of 1,4-butanediol from succinic acid ester, production of 1,5-pentanediol from glutaric acid ester, production of 1,6-hexanediol from adipic acid ester, from dodecanedioic acid ester Production of dodecanediol, cyclohex From an esterification solution (containing adipic acid diester, etc.) of a carboxylic acid mixture recovered from a water oxidation reaction solution by water extraction, alkali extraction, or extraction with a neutralized organic solvent (such as methyl isobutyl ketone). , Production of 1,6-hexanediol and / or 1,5-pentanediol.

  Specific examples of the present invention are shown below, but the present invention is not limited thereto.

Example 1
(Preparation of copper-containing hydrogenation catalyst)
Place 250 ml of 14.5 wt% ammonium carbonate aqueous solution in a 2 L (liter) glass container (catalyst preparation tank) and keep it at 80 to 85 ° C., and maintain the pH at 6.5 with stirring. Thus, an aqueous solution in which 0.157 mol of copper nitrate and 0.125 mol of zinc nitrate were dissolved in 250 ml of water was added dropwise over 30 minutes. After completion of the dropwise addition, the mixture was allowed to cool with continued stirring. During this time, the pH of the solution in the catalyst preparation tank rose to 8.2. The precipitate formed was filtered and washed, dried at 120 ° C. in air, and then passed through a 70-mesh sieve to obtain a basic carbonate ((Cu, Zn) ₅ (CO ₃ ) ₂ (OH) ₂ containing copper and zinc. 4 g of an auricalcite type compound) was obtained. This basic carbonate is placed in a glass boat-like container, charged into a glass tube with an inner diameter of 25 mm, heated to 350 ° C. while flowing air at a flow rate of 36 L / hr, and fired by holding at that temperature for 6 hours. did. The catalyst precursor was taken out after cooling to room temperature.
4 g of this calcined copper-zinc-oxygen catalyst precursor was added to a solution obtained by dissolving 2.26 g of glutaric acid in 50 g of dimethyl adipate, and heat-treated at 200 ° C. for 2 hours while flowing nitrogen under stirring. Thereafter, it was filtered, washed with acetone and dried to obtain an acid treatment catalyst.
The physical properties of the obtained catalyst are shown below.

XRF: catalyst precursor: Cu / Zn (atomic ratio) = 1
Catalyst obtained in Example 1: Cu / Zn (atomic ratio) = 1

XRD diffraction angle 2θ (deg.)
Catalyst precursor: 31.78, 34.46, 35.90 (all based on ZnO
38.96 (peak based on CuO)
Catalyst obtained in Example 1: 31.78, 34.46, 35.90, 38.96,
12.32, 18.86, 20.62, 22.46,
26.64 (Note that the peak after 12.32 is the catalyst precursor.
It is a new peak that cannot be seen. )

Diffuse reflection IR:
Catalyst precursor: No peak at 1600 to 2000 cm ⁻¹ .
Catalyst obtained in Example 1: 1738.1 cm ⁻¹

ESCA surface element concentration (atomic%)
Catalyst precursor: C: 20.9, O: 46.2, Cu: 13.8, Zn: 19.2
Catalyst obtained in Example 1: C: 53.1, O: 37.5, Cu: 3.9, Zn: 5.6

Example 2
In the same manner as described in Non-Patent Document 6, a carboxylic acid mixture (32.1 wt% adipic acid and 33.7 wt% oxycaproic acid) obtained by water extraction of a reaction solution subjected to liquid phase air oxidation of cyclohexane. %, Glutaric acid 6.1% by weight, and succinic acid 1.2% by weight) and hydrocracking reaction liquid containing 1,6-hexanediol 50% or more, carboxylic acid mixture / hydrocracking Reaction mixture (weight ratio) = 1 / 0.77 ratio, 40 g of esterified product (acid value 2 mg-KOH / g-sample) obtained by heating at 200 to 250 ° C. while draining water and Examples 1.0 g of the catalyst obtained in 1 was charged into a SUS autoclave having an internal volume of 200 ml, hydrogen gas was injected to 90 kg / cm ² (gauge pressure), and then heated to 250 ° C. with stirring (800 rpm). This hydrocracking reaction solution was prepared by the method described in Example 1 of Patent Document 10, and 61.1% by weight of 1,6-hexanediol, and 8,5-pentanediol. It contained 5% by weight and 0.8% by weight of 1,4-butanediol.
Next, hydrogenolysis was performed at a reaction temperature of 250 ° C. for 3 hours while maintaining a constant hydrogen pressure of 90 kg / cm ² (gauge pressure) while replenishing hydrogen gas. After completion of the reaction, the reaction solution was filtered, and the obtained filtrate was analyzed by gas chromatography.
As a result, the ester conversion was 50.2%, and the reaction solution contained 26.9% by weight of 1,6-hexanediol. Further, the elution amounts of copper and zinc into the reaction solution were analyzed by fluorescent X-ray, but no elution of copper was observed and the elution amount of zinc was 11 ppm.

Comparative Example 1
Except not using the glutaric acid treatment, the catalyst prepared in the same manner as in Example 1, that is, the hydrogen reduction reaction of the esterified product in the same manner as in Example 2 except that 1.0 g of the catalyst precursor after air calcination was used. Went.
As a result, the ester conversion was 44.0%, and the reaction solution contained 23.8% by weight of 1,6-hexanediol. In the reaction solution, 5 ppm of eluted copper and 100 ppm of eluted zinc were present.

Example 3
1.0 g of the catalyst obtained in Example 1 and 40 g of dimethyl adipate were charged into a SUS autoclave having an internal volume of 200 ml, hydrogen gas was injected to 90 kg / cm ² (gauge pressure), and then stirred (800 rpm). Heated to 250 ° C. Next, hydrogenolysis was performed at a reaction temperature of 250 ° C. for 3 hours while maintaining a constant hydrogen pressure of 90 kg / cm ² (gauge pressure) while replenishing hydrogen gas. After completion of the reaction, the reaction solution was filtered, and the obtained filtrate was analyzed by gas chromatography.
As a result, the ester conversion was 54.6%, and the reaction solution contained 26.3% by weight of 1,6-hexanediol.

Comparative Example 2
A catalyst prepared in the same manner as in Example 1 except that no glutaric acid treatment was performed, that is, 1.0 g of a catalyst precursor after air calcination, was used to carry out a hydrogen reduction reaction of dimethyl adipate in the same manner as in Example 3. went.
As a result, the ester conversion was 52.5%, and the reaction solution contained 24.2% by weight of 1,6-hexanediol.

Claims (10)

Copper-containing hydrogen treated by contact with a polyvalent carboxylic acid, characterized in that a copper-containing hydrogenation catalyst in the form of a tablet, extruded product, spherical particles, or powder as a precursor is brought into contact with the polyvalent carboxylic acid. Preparation method of catalyst. The contact treatment with the polyvalent carboxylic acid according to claim 1, wherein the contact between the copper-containing hydrogenation catalyst as the precursor and the polyvalent carboxylic acid is performed in an ester solvent or an ether solvent at a temperature of 50 to 300 ° C. Of the prepared copper-containing hydrogenation catalyst. The method for preparing a copper-containing hydrogenation catalyst contact-treated with a polyvalent carboxylic acid according to claim 1 or 2, wherein the polyvalent carboxylic acid is a divalent or trivalent carboxylic acid having 4 to 20 carbon atoms. The method for preparing a copper-containing hydrogenation catalyst that has been contact-treated with a polyvalent carboxylic acid according to any one of claims 1 to 3, wherein the copper-containing hydrogenation catalyst as a precursor is a copper-zinc-oxygen-based catalyst. A copper-containing hydrogenation catalyst prepared by the preparation method according to any one of claims 1 to 4 and contact-treated with a polyvalent carboxylic acid. The copper-containing hydrogen contact-treated with the polyvalent carboxylic acid according to claim 5, which has peaks at 12.32, 18.86, 20.62, 22.46 and 26.64 at an XRD diffraction angle 2θ (deg.). Catalyst. In the diffuse reflection IR method, 1738.1 cm ^-1 A copper-containing hydrogenation catalyst contact-treated with the polyvalent carboxylic acid according to claim 5 or 6 having a peak. The copper-containing hydrogenation catalyst which has been contact-treated with the polyvalent carboxylic acid according to any one of claims 5 to 7, wherein the copper-containing hydrogenation catalyst as a precursor is a copper-zinc-oxygen-based catalyst. A method for producing a corresponding alcohol by reducing an ester with hydrogen, characterized by using a copper-containing hydrogenation catalyst contact-treated with a polyvalent carboxylic acid according to any one of claims 5 to 8. A method for producing alcohols. The method for producing an alcohol according to claim 9, wherein the alcohol is at least one alcohol selected from 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol.