JPS6260938B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a catalyst for hydrogenating lower hydroxycarboxylic acid esters. Conventionally, a method for producing a corresponding glycol by hydrogenating a hydroxycarboxylic acid ester in the gas phase has been known, and various proposals have been made regarding catalysts for the hydrogenation. For example, British Patent No. 575380 proposes the use of a copper-chromium catalyst, a copper-silica catalyst obtained by melting copper oxide and silicon dioxide, etc. as a hydrogenation catalyst. U.S. Patent No. 2093159 describes materials such as chromium, molybdenum or tungsten.
The use of copper catalysts containing activating substances has been proposed. Also, in US Patent No. 2094611,
Again, the use of a copper-chromium catalyst is disclosed. However, in the methods using these known hydrogenation catalysts, the hydrogenation reaction of higher hydroxycarboxylic acid esters is mainly targeted, the hydrogenation reaction needs to be carried out under high pressure of, for example, 10 atmospheres or more, and the catalyst They have some drawbacks, such as the system being complex, and furthermore, the yield and selectivity of the target product are not always satisfactorily high. Furthermore, the mainstream of known catalysts for hydrogenation of hydroxyl carboxylic acid esters is copper-chromium catalysts. However, the use of such chromium-containing catalysts poses problems from a practical standpoint. In other words, it is not impossible to efficiently recover chromium from used chromium-containing catalysts and to perform recovery treatment so that no chromium remains in the spent catalysts, if expensive and complicated operations are performed. However, it is extremely difficult and unsuitable for industrial implementation. Furthermore, chromium is highly toxic to the human body even in minute amounts, so disposal of chromium-residual waste catalysts into the general environment should be avoided as it has the potential to cause serious pollution in terms of environmental hygiene. be. Thus, copper-
Chromium-based hydrogenation catalysts have a major drawback, which is the difficulty in disposing of the spent catalyst. Furthermore, it is known that various metals or metal compounds can be used as general hydrogenation catalysts in addition to copper-chromium catalysts. Examples of such metals or metal compounds include metals such as Raney nickel, nickel, cobalt, copper, iron, platinum, and palladium, as well as oxides and sulfides of these metals. However, not all such generally known metals or metal compounds are equally useful in any hydrogenation reaction. In other words, unless a catalyst suitable for the specific hydrogenation reaction is selected according to the reaction mode, reaction conditions, etc. of each hydrogenation reaction, the specific hydrogenation reaction cannot be carried out efficiently. This is well known. Furthermore, it is well known that there are no established guidelines for selecting such suitable catalysts. The present inventors conducted research with the aim of developing a catalyst for the hydrogenation of lower hydroxycarboxylic acid esters that exhibits a superior catalytic effect than the conventionally known catalysts mentioned above and does not contain chromium. came. As a result, in an aqueous solution containing copper ammine complex,
We discovered that by mixing silica gels having a specific particle size and subjecting the resulting copper-containing silica gel to a reduction treatment, it is possible to produce a catalyst for hydrogenation of lower hydroxycarboxylic acid esters that meets the purpose.
The present invention has now been completed. That is, the present invention provides a catalyst for hydrogenation of lower hydroxycarboxylic acid esters by mixing fine particulate silica gel with an average particle size of 200 μm or less into an aqueous solution containing a copper ammine complex, and reducing the resulting copper-containing silica gel. It provides a manufacturing method. The catalyst obtained by the production method of the present invention has a better conversion rate and selectivity than known catalysts such as chromium-containing catalysts, and can efficiently and industrially convert the corresponding glycol from lower hydroxycarboxylic acid ester. It is a catalyst that can be advantageously produced and that can overcome the above-mentioned pollution troubles associated with the use of chromium-containing catalysts. The aqueous solution containing the copper ammine complex used in the present invention can be produced by a method known per se. For example, it can be produced by adding ammonia to an aqueous solution containing copper ions to make the aqueous solution alkaline. It can also be produced, for example, by adding copper pieces to concentrated ammonia water and passing air through the system. The above-mentioned aqueous solution containing copper ions can be obtained by dissolving a water-soluble copper compound (including copper salt) in water. Examples of such copper compounds include copper nitrate, copper sulfate, copper oxalate, copper chloride, copper carbonate, copper acetate, and the like. The most preferred copper compound is cupric nitrate. Furthermore, the silica gel used in the catalyst production method of the present invention needs to be fine particles with an average particle size of 200 μm or less. When silica gel having an average particle diameter of more than 200 μm is used, the amount of copper supported on the silica gel is reduced, and the activity of the resulting catalyst is significantly low. In addition, there is no need to set a special limit on the lower limit of the average particle diameter of silica gel, but it is approximately 1
A value up to about mμ is good. A more preferable average particle diameter is about 5 mμ to about 150μ. These particulate silica gels prepared by any method are useful. The preparation methods include dry methods such as decomposition of silicon halides and organosilicon compounds, heating reduction of silica sand and coke with an arc, vaporization, and oxidation, or wet methods in which sodium silicate is decomposed with acid. law,
For example, Hereinafter, one embodiment of the method for producing a catalyst according to the present invention will be described in detail. First, a water-soluble copper compound as exemplified above, such as cupric nitrate, is dissolved in water, and concentrated ammonia water is added to the copper ion-containing aqueous solution formed until the pH of the system is about 10 or more, for example about 10 to about 12. Add until mixed. A deep blue aqueous solution is thus formed. Fine particles or ultrafine silica gel having an average particle size of 200 μm or less are added to this deep blue aqueous solution, and the two are thoroughly mixed and brought into contact with each other by stirring. Mixing can be carried out under atmospheric pressure or increased pressure, at room temperature or under heated conditions, for example, at temperatures from room temperature to about 150°C, preferably from about 40 to about 100°C. In this way, a copper-containing silica gel in which copper ions are supported on the silica gel is formed. The catalyst of the present invention can be obtained by thoroughly washing the solid residue obtained by evaporating the copper-containing silica gel formed system, drying it, and then subjecting it to reduction treatment. Can be done. Concentration treatment can be used instead of the above-mentioned evaporation to dryness. For example, approximately half of the liquid is evaporated, a solid residue is collected from this concentrated system, for example by filtration, and treated in the same manner as above.
It is also possible to obtain the catalyst of the invention. The above-mentioned evaporation to dryness treatment and concentration treatment can be performed under atmospheric pressure conditions or under reduced pressure conditions. Further, these treatments can be carried out at room temperature or under heating conditions, but heating conditions such as about 60°C to about 90°C are preferably employed. For example, the reduction treatment of the copper-containing silica gel that can be obtained as described above involves reducing the copper-containing silica gel in the presence of hydrogen according to a method known per se.
This can be done by heat treatment. For example, in a hydrogen stream at a temperature of about 150 to about 500°C, preferably about 200 to about 400°C, about 1
An example of reduction treatment conditions of ~15 hours can be given. Prior to such a reduction treatment, a preliminary heating treatment can be employed. For example, the above-mentioned copper-containing silica gel is heated at about 400°C to about 800°C in air.
Preferably, the preheating treatment conditions include firing at a temperature of about 500° C. to about 700° C. for about 1 to about 10 hours. In the catalyst produced according to the present invention, the content of copper supported on silica gel can be determined by appropriately selecting the amounts of the copper ammine complex and silica gel used in the preparation of the catalyst.
It can be prepared. The amount is preferably
Weight of silica gel (silicon dioxide): Weight of copper =
1: about 0.001 to 1: about 2.0, more preferably 1: about 0.01 to 1: about 1.0. The catalyst produced in the present invention is produced by hydrogenating a lower hydroxycarboxylic acid ester in the gas phase,
It exhibits an extremely excellent effect as a catalyst for producing the corresponding glycol. When using the catalyst obtained in the present invention, the lower hydroxycarboxylic acid ester that is the above-mentioned reaction raw material can be appropriately selected. Specific examples include methyl glycolate, ethyl glycolate, propyl glycolate, butyl glycolate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl-α-hydroxybutyrate, ethyl-α-hydroxybutyrate. Examples include lower hydroxycarboxylic acid esters such as ester and propyl-α-hydroxybutyrate. When using the catalyst obtained according to the present invention, preferable hydrogenation reaction conditions for lower hydroxycarboxylic acid ester are as follows. Reaction temperature: 140-300℃, preferably 170-260℃,
More preferably 180-230°C Contact time: 0.01-20 seconds, preferably 0.1-3 seconds Reaction pressure: 0.1-200 atm, preferably 1-40 atm Hydrogen/hydroxycarboxylic acid ester molar ratio:
2 or more, preferably 10 to 500 The hydrogenation reaction is carried out using the catalyst obtained in the present invention,
The reaction can be carried out in any manner in which hydrogen gas and lower hydroxycarboxylic acid ester are brought into contact in a gas phase, and either a fixed catalyst bed method or a fluidized catalyst bed method can be adopted. Furthermore, the reaction can be carried out either batchwise or continuously. By carrying out the hydrogenation reaction of lower hydroxycarboxylic esters using the catalyst obtained according to the present invention, for example, ethylene glycol can be produced from glycolic esters, propylene glycol can be produced from lactic esters, and α-hydroxybutylene glycol can be produced from lactate esters. Butanediol can be obtained from the rate. The catalyst obtained by the present invention does not contain chromium, as is clear from its production method. Although it does not contain chromium, the catalyst obtained according to the present invention can efficiently accomplish the reaction of hydrogenating lower hydroxycarboxylic acid ester to convert it into the corresponding glycol as described above, and has a high space-time ratio. The desired product is obtained in yield (STY). Furthermore, with many conventionally known catalysts, the desired product could not be efficiently produced unless the hydrogenation reaction was carried out at a high pressure of 10 atm or higher, whereas when using the catalyst obtained in the present invention, There is also the advantage that the target product can be obtained efficiently even if the hydrogenation reaction is carried out under a lower pressure. Next, Examples, Comparative Examples, and Reference Examples of the present invention will be given. Example 1 Cupric nitrate trihydrate (Cu(NO ₃ ) _{2.3H 2} O)
101.2 g was dissolved in 300 ml of water, and 300 ml of concentrated ammonia water was added thereto to give a concentration of about 11-12, to obtain a deep blue solution containing a copper ammine complex. A suspension of 40 g of fine-particle silica gel (manufactured by Fuji Davison, SYLO1D150) having an average particle size of 2.5 μm suspended in 450 ml of water was added to this deep blue solution, and the mixture was stirred at room temperature for several hours. Next, the temperature of the mixture is about 85°C to about 100°C.
temperature to evaporate most of the water, and then raise the temperature to 120℃.
and dried for 12 hours. The dried product was thoroughly washed with water and dried again in air at 140°C for 14 hours. The dried product was reduced at 350° C. for 2 to 3 hours in a hydrogen stream to prepare a catalyst. The copper content of the catalyst was about 40 wt%, and the weight ratio of copper to silicon dioxide was about 0.67. Reference Examples 1 to 3 5 ml of the catalyst prepared according to Example 1 was heated to an inner diameter of 10 mm.
Fill a stainless steel reaction tube with a diameter of 130 mm and
Catalytic hydrogenation reaction of ethyl glycolate,
The reaction was carried out at a predetermined temperature under the conditions of SV 20000 hr ^-1 , reaction pressure 6 Kg/cm ² ·G, and hydrogen/ethyl glycolate (molar ratio) 100. The results are shown in Table 1.

[Table] Reference Example 4 5 ml of the catalyst prepared in Example 1 was filled into a stainless steel reaction tube with an inner diameter of 10 mmφ and a length of 130 mm, and the catalytic hydrogenation reaction of ethyl lactate was carried out at SV 6000 hr ^-1 and reaction pressure 6 Kg/cm ² . G, hydrogen/ethyl lactate (molar ratio)
60, and the reaction temperature was 185°C. The results were a conversion rate of ethyl lactate of 96.2% and a selectivity to propylene glycol of 90.5%. Example 2 253 g of cupric nitrate trihydrate was dissolved in 750 ml of water, and 750 ml of concentrated ammonia water was added to the solution to bring the pH to approx.
11-12, and a deep blue solution containing a copper ammine complex was obtained. In this deep blue solution, the average particle size is 10 to 20 m.
A suspension of 100 g of μ ultrafine silica gel suspended in 1000 ml of water was added, and the mixture was stirred at room temperature for several hours. Next, the temperature of the mixture is about 85°C to about 100°C.
temperature to evaporate most of the water, and then raise the temperature to 120℃.
and dried for 16 hours. Rinse the dried material thoroughly with water and re-
After drying at 120℃ for 24 hours, drying at 200℃ in a hydrogen stream for 12 hours
A catalyst was prepared by performing a time reduction treatment. The copper content of the catalyst was about 40 wt%, and the weight ratio of copper to silicon dioxide was about 0.67. Reference Examples 5 to 7 5 ml of the catalyst prepared according to Example 2 was heated to an inner diameter of 10 mm.
Fill a stainless steel reaction tube with a diameter of 130 mm and
A catalytic hydrogenation reaction of ethyl glycolate was carried out at a predetermined temperature under the conditions of a reaction pressure of 6 kg/cm ² ·G, a SV of 20000 hr ⁻¹ , and a hydrogen/ethyl glycolate (molar ratio) of 100. The results are shown in Table 2.

[Table] Example 3 Dissolve 50 g of cupric nitrate trihydrate in 150 ml of water, add 200 ml of concentrated ammonia water, and adjust the pH to approx.
11-12, and a deep blue solution containing a copper ammine complex was obtained. This deep blue solution contains particles with an average particle size of 100 μm.
19.2 g of fine particle silica gel was added and stirred at room temperature for several hours. Next, the temperature of the mixture is about 85°C to about 100°C.
temperature to evaporate most of the water, and then raise the temperature to 120℃.
and dried for 16 hours. Rinse the dried material thoroughly with water and re-
After drying at 120℃ for 24 hours, drying at 200℃ in a hydrogen stream for 12 hours
A catalyst was prepared by performing a time reduction treatment. The copper content of the catalyst was about 40 wt%, and the weight ratio of copper to silicon dioxide was about 0.67. Reference Examples 8 and 9 25 ml of the catalyst prepared in Example 3 was heated to an inner diameter of 19.4 mmφ.
A stainless steel reaction tube with a length of 700 mm was filled, and the hydrogenation reaction of ethyl glycolate was carried out at a specified temperature under the conditions of a reaction pressure of 20 Kg/cm ² G, SV 20000 hr ^-1 , and a hydrogen/ethyl glycolate (molar ratio) of 100. I did it. The results are shown in Table 3.

[Table] Comparative Example 1 19.2g of silica gel with an average particle diameter of 250μ was used instead of silica gel with an average particle diameter of 100μ.
A catalyst was prepared in the same manner as in Example 1. The copper content of the catalyst was about 40 wt%, and the weight ratio of copper to silicon dioxide was about 0.67. Reference Examples 10 to 12 5 ml of the catalyst prepared according to Comparative Example 1 was heated to an inner diameter of 10 mm.
Fill a stainless steel reaction tube with a diameter of 130 mm and
A catalytic hydrogenation reaction of ethyl glycolate was carried out at a predetermined temperature under the conditions of a reaction pressure of 6 Kg/cm ² ·G, a SV of 20000 hr ⁻¹ , and a hydrogen/ethyl glycolate (molar ratio) of 100. The results are shown in Table 4.

[Table] Comparative example 2 Cupric nitrate [Cu(NO ₃ ) ₂・3H ₂ O] 24.2g at 220
ml of water and add zinc nitrate [Zn(NO ₃ ) ₂ .
A solution of 29.7 g of 6H ₂ O] dissolved in 270 ml of water was mixed, and then ammonium chromate [(NH ₄ ) ₂ .
A solution obtained by dissolving 45.6 g of CrO ₄ ] in 140 ml of water was mixed to obtain a brown precipitate. Ammonia was added to this precipitate solution to adjust the pH to 7, and then the mixture was stirred for 1 to 2 hours to age, and the resulting mixture was heated to 120°C.
and dried for 15 hours. The dried product was placed little by little into a container kept at about 400°C to undergo thermal decomposition. At this time, the catalyst changed from brown to black. Next, this blackened catalyst was heated with hydrogen at 200℃ for 5 minutes.
A time reduction treatment was performed to obtain a copper-chromium-zinc catalyst. Reference Examples 13-15 Using 5 ml of the catalyst prepared in Comparative Example 2, a catalytic hydrogenation reaction of ethyl glycolate was carried out under the same conditions as in Reference Examples 1-3. The results are shown in Table 5.

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Claims (1)

[Claims] 1. A method for producing a catalyst for hydrogenation of lower hydroxycarboxylic acid esters, which comprises mixing particulate silica gel with an average particle size of 200 μm or less into an aqueous solution containing a copper ammine complex, and subjecting the resulting copper-containing silica gel to a reduction treatment. .