JP5645065B2 - Method for producing δ-valerolactone - Google Patents

Description

  In the present invention, 1,5-pentanediol (hereinafter also referred to as PDL) is cyclized and dehydrogenated by a gas phase method to produce δ-valerolactone (hereinafter also referred to as DVL). Regarding the method.

  δ-valerolactone is useful as a raw material for various chemical products. Cyclodehydrogenation of 1,5-pentanediol by a gas phase method using a solid catalyst is known as an industrially preferred method for synthesizing δ-valerolactone. In general, the obtained reaction solution containing δ-valerolactone is subjected to a distillation recovery step or the like, and δ-valerolactone is isolated as a product. However, in this distillation operation, when the reaction solution is heated as a can, there is a problem that the ring-opening polymerization reaction of δ-valerolactone proceeds in the can. This leads to deterioration in operability due to an increase in viscosity of the can liquid and a decrease in the distillation yield of δ-valerolactone (recovery rate of δ-valerolactone during distillation), resulting in an industrial disadvantage.

  In order to solve such problems, for example, JP-A-2004-331626 (Patent Document 1) discloses a method of performing distillation at a can liquid temperature of 180 to 400 ° C. to recover δ-valerolactone, By controlling the temperature of the can within the above range, distillation can be performed while depolymerizing the ring-opening polymerization product of δ-valerolactone, and δ-valerolactone can be recovered efficiently and stably. Yes.

  However, in this method, in order to promote depolymerization, it is necessary to carry out a distillation operation at a can temperature that greatly exceeds the boiling point of δ-valerolactone at the operating pressure, and there is a problem that a large amount of energy is consumed. . Further, since distillation is performed while depolymerizing the ring-opening polymerization product, it is a problem that the recovery rate of δ-valerolactone is limited by the depolymerization reaction rate in the can part.

  On the other hand, a catalyst plays an important role in the synthesis of δ-valerolactone by the cyclization dehydrogenation reaction of 1,5-pentanediol, and its research is being advanced.

  For example, Japanese Patent Laid-Open No. 04-261167 (Patent Document 2) is characterized in that dehydrogenation and cyclization are performed in the presence of a catalyst composed of copper, a fourth periodic transition metal element, and an eighth group platinum group element. A process for the production of lactones is disclosed. The specifically disclosed synthesis of δ-valerolactone is carried out using a catalyst in which copper, zinc and ruthenium are supported on zeolite. However, since this method is carried out by a liquid phase reaction, it is necessary to separate the catalyst by an operation such as filtration after the reaction, and it can be mentioned that an expensive noble metal is necessary for the catalyst.

  On the other hand, Japanese Patent Application Laid-Open No. 2002-371075 (Patent Document 3) includes at least one metal selected from the group consisting of zinc oxide, chromium oxide, aluminum oxide and silicon oxide, containing copper and zirconium oxide as essential components. Disclosed is a process for the production of lactones from diols with catalysts containing oxides and prepared in a specific way. However, specifically, only the synthesis of γ-butyrolactone from 1,4-butanediol and the synthesis of ε-caprolactone from 1,6-hexanediol are described, and from 1,5-pentanediol. There is no specific example relating to the synthesis of δ-valerolactone.

  Further, JP 2001-219067 A (Patent Document 4) discloses a catalyst for producing lactones in which a support is supported with a copper compound, a zinc compound and at least one alkaline earth metal compound. However, specifically, the synthesis of γ-butyrolactone from 1,4-butanediol is only described, and there is no specific example regarding the synthesis of δ-valerolactone from 1,5-pentanediol.

JP 2004-331626 A JP 04-261167 A Japanese Patent Laid-Open No. 2002-371075 Japanese Patent Laid-Open No. 2001-219067

  As described above, in order to recover δ-valerolactone efficiently and stably from a reaction solution containing δ-valerolactone obtained by cyclization dehydrogenation reaction from 1,5-pentanediol in the gas phase, It is important to suppress ring-opening polymerization of δ-valerolactone in the distillation recovery process. However, a method for suppressing the ring-opening polymerization has not been established, and as in Patent Document 1, a recovery method via a depolymerization operation with high energy consumption is only known.

  In view of such a situation, the present inventors diligently studied a method for producing δ-valerolactone using a cyclization dehydrogenation reaction of 1,5-pentanediol in a gas phase. It has been found that a specific minor by-product triggers the ring-opening polymerization of the main product, δ-valerolactone. The present invention is based on this finding and provides an efficient and easy method for producing δ-valerolactone.

The present invention
(A) cyclizing dehydrogenation reaction of 1,5-pentanediol by a gas phase method to obtain a reaction liquid containing δ-valerolactone; and (b) distilling the obtained reaction liquid to obtain δ A method for producing δ-valerolactone, comprising the step of recovering valerolactone,
The ratio of the total number of moles of free carboxyl groups and hydroxyl groups contained in the reaction liquid to the number of moles of δ-valerolactone contained in the reaction liquid subjected to distillation in the step (b) is 0.05 or less. Features
The present invention relates to a method for producing δ-valerolactone.

The present invention also provides:
(A) cyclizing dehydrogenation reaction of 1,5-pentanediol by a gas phase method to obtain a reaction liquid containing δ-valerolactone; and (b) distilling the obtained reaction liquid to obtain δ A method for producing δ-valerolactone, comprising the step of recovering valerolactone,
In the cyclization dehydrogenation reaction in the step (a), the amount of CuO supported is 35 to 65% by mass, and the total amount of NH ₃ adsorption measured by thermal desorption analysis is 150 to 250 μmol / g. Characterized in that it is carried out at a temperature of 180-280 ° C. using a catalyst,
The present invention relates to a method for producing δ-valerolactone.

  According to the present invention, in the production of δ-valerolactone using cyclized dehydrogenation of 1,5-pentanediol in the gas phase, ring-opening polymerization in the can is suppressed in the distillation recovery step of δ-valerolactone. it can. As a result, the depolymerization operation by treating the can liquid at a high temperature becomes unnecessary, so that the distillation separation can be carried out at a relatively low temperature, and δ-valerolactone can be produced efficiently and easily. Become. According to the present invention, δ-valerolactone can be obtained in a good yield in a production process including not only the reaction step but also the separation of products, and is highly useful.

  Hereinafter, the present invention will be described in detail.

The present invention includes (a) a step of cyclizing and dehydrogenating 1,5-pentanediol by a gas phase method to obtain a reaction liquid containing δ-valerolactone; and (b) distilling the obtained reaction liquid. Then, regarding the method for producing δ-valerolactone, which comprises the step of recovering δ-valerolactone, in the first aspect, with respect to the number of moles of δ-valerolactone contained in the reaction solution subjected to distillation in step (b). The ratio (r) of the total number of moles of free carboxyl groups and hydroxyl groups contained in the reaction solution is 0.05 or less. This is because, in step (b), the by-product that can trigger ring-opening polymerization of δ-valerolactone has at least one of a carboxyl group (—COOH) and a hydroxyl group (—OH) as a functional group. Based on the knowledge of. Specific examples of the by-product include valeric acid (hereinafter sometimes referred to as PA), water, and unreacted 1,5-pentanediol. In the cyclization dehydrogenation reaction of 1,5-pentanediol, dihydropyran (hereinafter also referred to as DHP) and tetrahydropyran (hereinafter also referred to as THP) may be formed as by-products. It has no group and no hydroxyl group, and it is understood that the direct influence on ring-opening polymerization is low.

  The ratio (r) of the total number of moles of free carboxyl groups and hydroxyl groups contained in the reaction solution to the number of moles of δ-valerolactone contained in the reaction solution is:

It is represented by When r is larger than 0.05, the ring-opening polymerization of δ-valerolactone tends to proceed. r is preferably 0.03 or less.

  The number of moles of δ-valerolactone, the number of moles of carboxyl groups and hydroxyl groups in the reaction solution can be measured by gas chromatography and a Karl Fischer moisture meter.

  The reaction solution subjected to distillation in the step (b) may be the reaction solution obtained in the step (a) as it is.

<Step a>
Step (a) is a step of obtaining a reaction liquid by subjecting 1,5-pentanediol to cyclization dehydrogenation by a gas phase method.

A solid catalyst can be used for the cyclization dehydrogenation reaction of 1,5-pentanediol, and a solid catalyst containing copper is preferable. The type of the copper compound as the form of the copper component is not particularly limited, and copper oxide (CuO), copper chloride (CuCl ₂ ), copper bromide (CuBr ₂ ), copper acetate (Cu (OAc) ₂ ), acetylacetone copper (Cu (C ₅ H ₇ O ₂ ) ₂ ) and the like. Copper oxide (CuO) is preferable. In particular, it is preferable that copper oxide (CuO) is 35-65 mass% in a solid catalyst, More preferably, it is 40-60 mass%. When using a copper compound other than copper oxide (CuO), the concentration range of the copper oxide (CuO) is converted into a concentration range as copper, and the copper compound may be contained so as to satisfy this.

  Examples of components other than the copper compound in the solid catalyst include silica, alumina, chromia, and zinc oxide. Among these, alumina and chromia are preferable.

  The solid catalyst can be used after being reduced with hydrogen gas or the like. The reduction operation may be performed separately outside the reaction system or may be performed inside the reaction system.

The solid catalyst preferably has an NH ₃ adsorption amount of 150 to 250 μmol / g per gram of the catalyst. When the NH ₃ adsorption amount exceeds 250 μmol / g, byproducts such as valeric acid and water tend to increase. On the other hand, when the NH ₃ adsorption amount is less than 150 μmol / g, sufficient activity cannot be obtained, and unreacted 1, The 5-pentanediol tends to increase, and the ratio (r) of the total number of moles of free carboxyl groups and hydroxyl groups contained in the reaction solution to the number of δ-valerolactone contained in the reaction solution is 0. .05 or less will be difficult. In particular, copper oxide (CuO) is supported at 35 to 65% by mass, preferably 40 to 60% by mass, and the NH ₃ adsorption amount per 1 g of the catalyst is preferably 150 to 250 μmol / g. The NH ₃ adsorption amount of the solid catalyst is more preferably 160 to 240 μmol / g. When the adsorption amount of NH ₃ is too high, this can be adjusted by immersing the catalyst in an aqueous solution containing an alkali such as NaOH to neutralize acidic sites in the catalyst.

The amount of NH ₃ adsorption can be measured by temperature programmed desorption analysis. Specifically, it is measured by the following operation.
The catalyst is placed in a chemisorption amount measurement cell and dried at 240 ° C. during He flow, and then the flow gas is switched to H ₂ for 1 hour. Next, after the temperature is lowered to 100 ° C. under He circulation, He containing 5% NH ₃ is circulated to adsorb NH ₃ . Thereafter, steam is introduced at 100 ° C. to remove NH ₃ adsorbed by hydrogen bonds. Furthermore, after maintaining the He circulation condition for 1 hour or more and the observation state (focusing on m / z = 16) of the gas exiting the cell by the mass spectrometer is stabilized, the temperature is also kept at 100 ° C. under the He circulation condition. The NH ₃ gas that comes out when the temperature is raised to 700 ° C. (5 ° C./min) is measured using a mass spectrometer.

  In the step (a), 1,5-pentanediol can be cyclized and dehydrogenated in the gas phase, and cooled and collected to obtain a reaction solution. In carrying out the cyclization dehydrogenation reaction, a carrier gas may be used to supply 1,5-pentanediol to the reaction apparatus. The type of carrier gas is not particularly limited, and any gas that does not adversely affect the reaction can be used. Hydrogen and nitrogen can be preferably used.

The supply amount of 1,5-pentanediol can be set to 0.1 to 5.0 as the supply amount LHSV (h ⁻¹ ) of liquid 1,5-pentanediol per volume of the catalyst packed bed. .4 to 4.0 are preferred.

  The temperature for carrying out the cyclization dehydrogenation reaction of 1,5-pentanediol can be 180 to 280 ° C. When the temperature is higher than this range, by-products tend to increase. On the other hand, when the temperature is lower than this range, unreacted 1,5-pentanediol increases due to a decrease in the reaction rate. It is difficult to make the ratio (r) of the total number of moles of free carboxyl groups and hydroxyl groups contained in the reaction solution to the number of δ-valerolactone contained in the reaction solution 0.05 or less. turn into. The temperature for carrying out the reaction is preferably 190 to 270 ° C.

  The pressure for carrying out the cyclization dehydrogenation reaction of 1,5-pentanediol is not particularly limited, and can be operated at various pressures as long as the gas phase reaction can be carried out. Usually, it is carried out at normal pressure.

  In the step (a), a reaction solution in which the ratio (r) of the total number of moles of free carboxyl groups and hydroxyl groups contained in the reaction solution to the number of δ-valerolactone contained in the reaction solution is 0.05 or less This can be used as it is for the step (b).

<Process b>
Step (b) is a step of distilling and recovering δ-valerolactone from the reaction solution. In the reaction solution subjected to distillation, the ratio (r) of the total number of moles of free carboxyl groups and hydroxyl groups contained in the reaction solution to the number of moles of δ-valerolactone contained in the reaction solution is 0.05 or less. is there. Such a reaction solution has a low concentration of by-products that promote ring-opening polymerization, and suppresses ring-opening polymerization of δ-valerolactone, which is a problem in ordinary distillation recovery processes. It is possible to efficiently and easily recover δ-valerolactone without performing a depolymerization operation that is maintained at 180 to 400 ° C.

  The can liquid temperature in the distillation recovery in the step (b) can be set to 100 to 170 ° C. When the temperature of the can liquid is higher than this range, the ring-opening polymerization of δ-valerolactone tends to proceed. On the other hand, when the temperature of the can liquid is lower than this range, excessive decompression is required and the equipment load increases. End up. The can solution temperature is preferably 110 to 160 ° C.

  The pressure in the step (b) can be arbitrarily set as long as the distillation recovery can be carried out at the above can liquid temperature.

Furthermore, the present invention includes (a) a step of cyclizing and dehydrogenating 1,5-pentanediol by a gas phase method to obtain a reaction solution containing δ-valerolactone; and (b) the obtained reaction solution. In the second embodiment, the cyclization dehydrogenation reaction of step (a) is carried out with a CuO loading of 35 to 35, which comprises the step of recovering δ-valerolactone by distillation. It is characterized by carrying out at a temperature of 180 to 280 ° C. using a solid catalyst that is 65 mass% and has a total NH ₃ adsorption amount measured by temperature programmed desorption analysis of 150 to 250 μmol / g. This is based on the knowledge that when the above solid catalyst and reaction temperature are employed in step (a), the production of by-products that can trigger ring-opening polymerization of δ-valerolactone is suppressed in step (b). Based on. Examples of by-products include those having at least one of a carboxyl group (—COOH) or a hydroxyl group (—OH) as a functional group, and specifically, valeric acid, water, unreacted 1,5-pentanediol. Is mentioned.

  In addition, by employing the above solid catalyst and reaction temperature, the total number of free carboxyl groups and hydroxyl groups contained in the reaction solution relative to the number of moles of δ-valerolactone contained in the reaction solution obtained in the step (a). The mole ratio (r) can be easily reduced to 0.05 or less.

In the second embodiment, the solid catalyst used in the cyclization dehydrogenation reaction in step (a) has a CuO loading of 35 to 65% by mass, preferably 40 to 60% by mass, and an NH ₃ adsorption amount. Is 150 to 250 μmol / g, preferably 160 to 240 μmol / g.

Components other than CuO in the solid catalyst include copper chloride (CuCl ₂ ), copper bromide (CuBr ₂ ), copper acetate (Cu (OAc) ₂ ), acetylacetone copper (Cu (C ₅ H ₇ O ₂ ) ₂ ), and the like. Examples thereof include copper compounds other than CuO, silica, alumina, chromia, and zinc oxide. Of these, alumina and chromia are preferable.

  The solid catalyst can be used after being reduced with hydrogen gas or the like. The reduction operation may be performed separately outside the reaction system or may be performed inside the reaction system.

  In the second embodiment, the cyclization dehydrogenation reaction in the step (a) is performed at a temperature of 180 to 280 ° C, preferably 200 to 260 ° C.

  The other conditions in step (a) (how to supply 1,5-pentanediol to the reaction apparatus, the supply amount, the pressure for carrying out the cyclodehydrogenation of 1,5-pentanediol, etc.) The description of the embodiment applies.

  Step (b) is a step of distilling and recovering δ-valerolactone from the reaction solution, and the description of the first aspect is applied to the distillation recovery conditions (can solution temperature, pressure, etc.).

  Hereinafter, the present invention will be described by way of examples. However, the present invention is not limited to these examples.

Thermal desorption analysis: Autosorb-1-C / VP / TCD / MS manufactured by QUANTACHROME was used for measurement. Desorbed NH ₃ was detected by a mass spectrometer (Prisma QMS200F2 type). The specific operation is as follows.
The catalyst was placed in a chemisorption amount measurement cell and dried at 240 ° C. during He flow, and then the flow gas was switched to H ₂ for 1 hour. Next, after the temperature was lowered to 100 ° C. under He circulation, He containing 5% NH ₃ was circulated to adsorb NH ₃ . Thereafter, steam was introduced at 100 ° C. to remove NH ₃ adsorbed by hydrogen bonds. Furthermore, after maintaining the He circulation condition for 1 hour or more and the observation state (focusing on m / z = 16) of the gas exiting the cell by the mass spectrometer is stabilized, the temperature is also kept at 100 ° C. under the He circulation condition. The NH ₃ gas that comes out when the temperature was raised to 700 ° C. (5 ° C./min) was measured using a mass spectrometer.
Measurement of amount of δ-valerolactone etc. in reaction solution: Analysis of products and unreacted raw materials in the reaction solution was carried out using GC-8A (FID detector) manufactured by Shimadzu Corporation. The column used was Inertcap WAX (0.53 mm × 60 m).

<Example 1>
[Synthesis of δ-valerolactone]
A quartz reaction tube with a mesh plate was filled with a CuO / Al ₂ O ₃ catalyst (CuO concentration: 55.1% by mass). The adsorption amount of NH ₃ per weight of the present catalyst measured by temperature programmed desorption analysis was 232 μmol / g. After inserting the thermocouple protection tube into contact with the catalyst, an electric furnace was attached to the reaction tube. Hydrogen was circulated in the reaction tube as a carrier gas under the conditions of GHSV 4.4 × 10 ³ h ⁻¹ and held for 0.5 hour to replace the atmosphere in the reaction tube. Next, with the hydrogen flowing, a thermocouple was inserted into the thermocouple protective tube, and the control temperature by this thermocouple was set to 260 ° C. to heat the reaction system. After pretreatment of the catalyst by maintaining at 260 ° C. for 1 hour, 1,5-pentanediol (hereinafter referred to as PDL) was supplied to the reaction tube under the conditions of LHSV 3.9h ⁻¹ at this temperature, After mixing with the carrier gas, the reaction was carried out by contacting with the catalyst. The mixed gas that passed through the catalyst layer was recovered by an ice-cooled trap. The trap was replaced every hour, and the collected liquid was subjected to GC analysis. Analysis of the recovered solution at 5 hours after the start of the reaction revealed a PDL conversion rate of 99.3% and a δ-valerolactone (hereinafter referred to as DVL) selectivity of 98.4%. Further, dihydropyran (hereinafter referred to as DHP), tetrahydropyran (hereinafter referred to as THP), and valeric acid (hereinafter referred to as PA) were detected as by-products at selectivities of 0.2, 0.2, and 0.5%, respectively. The water content in the reaction solution was 0.10% by mass, and the ratio r of the total value of the molar amount of carboxyl groups and hydroxyl groups relative to the molar amount of DVL contained in the reaction solution was 0.03.
[DVL distillation recovery]
Next, 200.4 g of the reaction solution obtained by the gas phase synthesis was distilled under reduced pressure at a pressure of 16-18 mmHg using a distillation column packed with 5 regular packings (sulzer packing EX). After refluxing for 1 hour at the beginning of distillation, DVL was distilled at a reflux ratio of 3. The temperature of the can during the total reflux and distillation operations was 112-117 ° C, and the top temperature was in the range of 102-113 ° C. The purity of the DVL obtained by this distillation operation by GC analysis was 99.5%, and the recovery rate based on the weight of the charged reaction solution was 86%. The liquid remaining in the can portion after distillation was colored brown, of which 85.6% was DVL.

<Example 2>
[DVL synthesis]
Using the same catalyst as in Example 1, the pretreatment temperature and reaction temperature of the catalyst were both set to 200 ° C., and the carrier gas at the time of the reaction was changed to nitrogen and circulated under conditions of GHSV 2.2 × 10 ³ h ⁻¹ . In addition, DVL was synthesized from PDL by a vapor phase method in the same manner as in Example 1 except that LHSV when supplying PDL to the reaction tube was set to 0.5 h- ¹ . GC analysis of the collected liquid at 5 hours after the start of the reaction revealed that the PDL conversion rate was 100% and the DVL selectivity was 98.7%. Further, DHP and THP were detected as by-products with a selectivity of 0.2 and 0.3%, respectively. On the other hand, PA was not detected. The water content in the reaction solution was 0.11% by mass, and the ratio r of the total value of the molar amount of carboxyl groups and hydroxyl groups relative to the molar amount of DVL contained in the reaction solution was 0.01.
[DVL distillation recovery]
Next, 199.5 g of the reaction solution obtained by the gas phase synthesis was subjected to vacuum distillation at a pressure of 16-18 mmHg using a distillation column packed with 5 regular packings (sulzer packing EX). After refluxing for 1 hour at the beginning of distillation, DVL was distilled at a reflux ratio of 3. The temperature of the can during the total reflux and distillation operations was 112-117 ° C, and the top temperature was in the range of 102-113 ° C. The purity of the DVL obtained by this distillation operation by GC analysis was 99.6%, and the recovery rate based on the weight of the charged reaction solution was 88%. The liquid remaining in the can portion after distillation was colored brown, 90.6% of which was DVL.

<Comparative Example 1>
[DVL synthesis]
DVL synthesis from PDL by a gas phase method was carried out in the same manner as in Example except that the same catalyst as in Example 1 was used and the catalyst pretreatment temperature and reaction temperature were both changed to 300 ° C. GC analysis of the collected liquid at 5 hours after the start of the reaction revealed that the PDL conversion rate was 98.5% and the DVL selectivity rate was 95.3%. Moreover, as a by-product, both DHP and THP were detected with a selectivity of 0.6%. The selectivity for PA was 2.0%. The water content in the reaction liquid was 0.27% by mass, and the ratio r of the total value of the molar amount of carboxyl groups and hydroxyl groups relative to the molar amount of DVL contained in the reaction liquid was 0.07.
[DVL distillation recovery]
Next, 193.0 g of the reaction solution obtained by the above gas phase synthesis was collected and distilled under reduced pressure at a pressure of 16-17 mmHg using a distillation column packed with 5 regular packings (sulzer packing EX). It was. After refluxing for 1 hour at the beginning of distillation, DVL was distilled at a reflux ratio of 3. During the total reflux and distillation operations, the temperature of the can liquid was 109 to 114 ° C., and the column top temperature was in the range of 104 to 111 ° C. The purity of the distilled DVL was 98.7%, but the DVL stopped distilling even though the sample remained in the can part during the distillation operation, and the weight of the charged reaction liquid. The recovery rate based on was as low as 46%. The liquid remaining in the can liquid portion after distillation was colored brown and had a high viscosity and low fluidity.

<Example 3>
[DVL synthesis]
DVL synthesis from PDL by a vapor phase method was performed by the same operation as in Example 1 except that the catalyst was changed to a CuO / Cr ₂ O ₃ catalyst (CuO concentration: 44.9% by mass). The adsorption amount of NH ₃ per weight of the present catalyst measured by temperature programmed desorption analysis was 161 μmol / g. The collected liquid at 5 hours after the start of the reaction was analyzed by GC. As a result, the PDL conversion rate was 99.0% and the DVL selectivity was 97.6%. Further, DHP and THP were detected as by-products with a selectivity of 0.1 and 0.9%, respectively. The selectivity for PA was 0.4%. The water content in the reaction solution was 0.20% by mass, and the ratio r of the total value of the molar amount of carboxyl groups and hydroxyl groups relative to the molar amount of DVL contained in the reaction solution was 0.04.
[DVL distillation recovery]
Next, 201.1 g of the reaction solution obtained by the gas phase synthesis was distilled under reduced pressure at a pressure of 15-18 mmHg using a distillation column packed with 5 regular packings (sulzer packing EX). After refluxing for 1 hour at the beginning of distillation, DVL was distilled at a reflux ratio of 3. During the total reflux and distillation operations, the temperature of the can was 110-118 ° C, and the top temperature was in the range of 105-108 ° C. The purity of the DVL obtained by this distillation operation by GC analysis was 99.2%, and the recovery rate based on the weight of the charged reaction solution was 86%. The liquid remaining in the can part after distillation was colored brown, and 83.5% of the liquid was DVL.

<Comparative example 2>
[DVL synthesis]
DVL synthesis from PDL by a vapor phase method was carried out in the same manner as in Example 1 except that the catalyst was changed to a CuO / ZnO catalyst (CuO concentration: 48.7% by mass). The adsorption amount of NH ₃ per weight of the present catalyst measured by temperature programmed desorption analysis was 28 μmol / g. GC analysis of the collected liquid at 5 hours after the start of the reaction revealed that the PDL conversion rate was 82.3% and the DVL selectivity was 93.1%. As a byproduct, DHP was detected with a selectivity of 0.4%. The water content in the reaction solution was 0.09% by mass, and the ratio r of the total value of the molar amount of carboxyl group and hydroxyl group relative to the molar amount of DVL contained in the reaction solution was 0.47.
[DVL distillation recovery]
Next, 170.8 g of the reaction solution obtained by the above gas phase synthesis was collected and distilled under reduced pressure at a pressure of 15-16 mmHg using a distillation column packed with 5 regular packings (sulzer packing EX). It was. After refluxing for 1 hour at the beginning of distillation, DVL was distilled at a reflux ratio of 3. During the total reflux and distillation operation, the temperature of the can liquid was 110 to 113 ° C., and the column top temperature was in the range of 104 to 111 ° C. Although the purity of the distilled DVL was 98.9%, the DVL was not distilled even though the sample remained in the can part during the distillation operation, and the weight of the charged reaction solution The recovery rate based on the standard was as low as 34%. The liquid remaining in the can liquid portion after distillation was colored brown and had a high viscosity and low fluidity.

<Comparative Example 3>
[DVL synthesis]
The same operation as in Example 1 except that the catalyst was changed to a CuO / SiO ₂ catalyst (CuO concentration: 33.5% by mass) and that the pretreatment temperature and reaction temperature of the catalyst were both 240 ° C. The DVL synthesis from PDL was performed by the gas phase method. The adsorption amount of NH ₃ per weight of the catalyst measured by temperature programmed desorption analysis was 215 μmol / g. GC analysis of the recovered solution at 5 hours after the start of the reaction revealed that the PDL conversion rate was 79.9% and the DVL selectivity was as low as 31.0%. As by-products, DHP and THP were detected with selectivity of 63.2 and 0.8%, respectively. A large amount of water was produced with by-products such as DHP and THP, and the reaction solution was separated into two phases.

  δ-valerolactone is useful as a raw material for various chemical products, and the present invention relating to its efficient and easy production method has high industrial utility.

Claims (2)

(A) cyclizing dehydrogenation reaction of 1,5-pentanediol by a gas phase method to obtain a reaction liquid containing δ-valerolactone; and (b) distilling the obtained reaction liquid to obtain δ A method for producing δ-valerolactone, comprising the step of recovering valerolactone,
The cyclization dehydrogenation reaction in the step (a) is carried out using a solid catalyst having a CuO loading of 35 to 65% by mass and an NH ₃ adsorption of 150 to 250 μmol / g measured by temperature programmed desorption analysis. Using, performed at a temperature of 180-280 ° C.,
A method for producing δ-valerolactone. The method for producing δ-valerolactone according to claim 1 , wherein the step (b) is performed at a can liquid temperature of 100 to 170 ° C.