JP2009007288A - Cleaning method for solid matter and purification method for meta-cresol - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an efficient cleaning method for a solid matter separated by solid-liquid separation of a mixture containing an addition complex comprised of meta-cresol and urea, and an industrially advantageous method for separating and purifying meta-cresol including a step of using the cleaning method. <P>SOLUTION: The cleaning method for a solid matter includes cleaning the solid matter, separated by solid-liquid separation from the mixture containing the addition complex composed of meta-cresol and urea, by using a solution of an aromatic hydrocarbon compound and an aliphatic hydrocarbon compound. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides an efficient method for washing a solid separated from a mixture containing an addition complex of metacresol and urea by solid-liquid separation. Further, the present invention provides an industrially advantageous method for purifying metacresol, which includes a step using the washing method and separates and purifies metacresol with high purity and high yield.

  Cresol has three types of isomers, ortho, meta, and para, depending on the positional relationship between a methyl group and a hydroxyl group. Generally, cresol is a mixture of three types of isomers. As its use, it is widely used as a disinfectant, a synthetic resin, a plasticizer raw material, etc., and depending on the intended use, it is necessary to separate into each isomer. For example, metacresol or the like is sometimes used as a raw material for pharmaceuticals and requires high purity. Usually, a distillation operation is often used industrially as a method for separating a mixture. However, in the case of cresol isomers, the boiling points of the meta isomer and the para isomer are 202.7 ° C. and 201.9 ° C., respectively, and the difference is within 1 ° C., which is difficult to separate by distillation (Non-Patent Documents). 1).

  Therefore, an addition complex separation method using complex formation is known as a separation and purification method for a mixture of a meta isomer and a para isomer. In the addition complex separation method, a compound that forms an addition complex only with either the meta or para isomer is added to a mixture containing the meta isomer and the para isomer to form an addition complex, and the resulting addition complex is removed from the mixture. In this method, separation and washing are performed, and the addition complex is decomposed again into cresol to obtain only the meta or para isomer. In particular, urea is known to selectively form an addition complex with a meta isomer, and its application to industrial processes is being developed. In Patent Document 1, production of metacresol is characterized in that metacresol is reacted with urea in the presence of an aromatic compound such as toluene that dissolves cresol but does not dissolve urea or its addition complex. A method is disclosed. In this document, when washing the cake obtained by centrifuging the reaction mixture slurry after the addition complex formation, the same aromatic compound as toluene such as the reaction solution is used. Non-Patent Document 1 discloses the development of an industrialization process using the above addition complex separation method for the purpose of separating cresol isomers. In this document, there is no description relating to washing of the cake obtained by solid-liquid separation of the reaction mixture slurry.

Japanese Patent Publication No. 48-10143 Separation technology vol.6 (4) p10-17 (1993)

  Conventionally, regarding the purification method of metacresol using the addition complex separation method, the reaction solvent involved in complex formation has mainly been studied for the purpose of improving the reaction rate of metacresol and urea or improving the handling property of the reaction mixture slurry. (Patent Document 1 and Non-Patent Document 1). Regarding the washing of the cake separated from the reaction mixture slurry, the same solvent as the reaction solvent is usually used as in Patent Document 1 for reasons such as recovery and reuse of the solvent. That is, in the prior art, the selection of the cleaning solvent is not particularly considered from the viewpoint of cleaning efficiency, and has not yet been examined in detail.

  On the other hand, when the purity of metacresol obtained by the above addition complex separation method in an industrial process is low, a high number of stages and a large reflux amount are required in the distillation column in the subsequent distillation operation, which requires energy cost and construction cost. It is possible. From an industrial point of view, an efficient method for separating and purifying metacresol by a simple process while satisfying both purity and yield is desired.

  In view of the problems of the prior art as described above, the present invention provides an efficient washing method for solids separated by solid-liquid separation of a mixture containing an addition complex of metacresol and urea, and the washing method An object of the present invention is to provide an industrially advantageous method for separating and purifying metacresol, which includes a step using the above.

  The inventors of the present invention focused attention on the washing step as one of the processes affecting the purity and yield in the separation and purification step of metacresol for the first time, and conducted intensive research to solve the above problems. As a result, it was found that the type of solvent used greatly affects the purity and yield of the target product, metacresol, in the washing step before forming the addition complex and decomposing the separated addition complex. Specifically, after the formation of the addition complex, many impurities are attached to the solid cake separated by solid-liquid separation, and the final product is obtained by selectively removing these impurities from the addition complex by washing. It was found that the purity and yield of metacresol was greatly improved. Therefore, the present invention is based on the above knowledge, and treats the separated addition complex with a washing solvent of an aromatic hydrocarbon compound and an aliphatic hydrocarbon compound, thereby efficiently removing impurities from the addition complex with a simple operation. I found out what I could do and came to complete it.

That is, the present invention provides the following (1) to (6).
(1) A solid substance for washing a solid substance separated by solid-liquid separation from a mixture containing an addition complex composed of metacresol and urea using a solution of an aromatic hydrocarbon compound and an aliphatic hydrocarbon compound. Cleaning method.
(2) The solid washing | cleaning method as described in (1) whose ratio of the aromatic hydrocarbon compound in the washing | cleaning solvent of an aromatic hydrocarbon compound and an aliphatic hydrocarbon compound is 20-70 mass%.
(3) The method for washing a solid material according to (1) or (2), wherein the boiling point of the washing solvent for the aromatic hydrocarbon compound and the aliphatic hydrocarbon compound is 205 ° C. or higher.
(4) The method for washing solid matter according to any one of (1), (2) and (3), wherein the aromatic hydrocarbon compound is 1-methylnaphthalene and the aliphatic hydrocarbon compound is tetradecane .
(5) A method for purifying metacresol, comprising a step using the solid washing method according to (1) to (4) and a step of decomposing the washed solid and recovering metacresol.
(6) An addition complex formation step in which urea is added to a mixture of cresol isomers containing metacresol to form an addition complex of the metacresol and the urea, and an addition complex formed in the addition complex formation step The purification method of metacresol as described in (5) including the isolation | separation process which isolate | separates.

The present invention relates to an efficient method for washing a solid separated by solid-liquid separation of a mixture containing an addition complex of metacresol and urea, and high purity and high yield of metacresol using the washing method. A method capable of separation and purification is provided. Thereby, energy saving and process simplification can be greatly advanced. Therefore, the industrial value of the present invention is great.
In the present invention, since the aliphatic hydrocarbon compound is less toxic than the aromatic hydrocarbon compound, it provides a process that is safer from the viewpoint of ease of handling and working environment.

Next, the present invention will be described in more detail with reference to preferred embodiments.
Although it does not specifically limit as a mixture of cresol used by this invention, It can obtain from coal-type tar or a petroleum-type raw material. As a method for obtaining a mixture of cresol from coal-based tar, first, coal tar is produced from coal, subjected to distillation and extraction with an alkaline aqueous solution, and further subjected to decomposition treatment with carbon dioxide or sulfuric acid to obtain a mixture containing cresol. . The mixture of cresol isomers can then be obtained by removing phenol, xylenol, etc. from the mixture. As a method for obtaining a mixture of cresols from petroleum-based raw materials, there are a sulfonated fusion method, a Raschig method, a cymene method and the like. In particular, the cymene method is now widely known in which cymene is synthesized using toluene and propylene as starting materials, further oxidized with oxygen, and the resulting tertiary hydroperoxide is decomposed to obtain a cresol mixture.

  The mixing ratio of metacresol in the cresol mixture is 30% by mass or more, preferably 40% by mass or more. When it is less than 30% by mass, the selectivity of the addition complex of urea and paracresol is lowered.

  In the present invention, urea is used as a compound that forms an addition complex with metacresol. A commercially available product can be used for this purpose, and specific examples thereof include industrial urea.

  In addition to the cresol isomer, other compounds may be contained in the mixture of cresol which is an object of the present invention. Examples of the compound other than the cresol isomer include impurities such as xylenol and phenol. The concentration of these impurities is usually 10% by mass or less, preferably 5% by mass or less in total. This is because if the amount is more than 10% by mass, impurities cannot be sufficiently removed. In addition, in order to improve the content of metacresol in the mixture of cresol isomers, ortho-cresol may be distilled off in advance before the complex formation step with urea.

In the present invention, separation and purification of metacresol is performed in the following four steps.
(1) Addition complex formation step in which urea is added to a mixture of cresol isomers containing metacresol to form an addition complex of metacresol and urea (2) Addition formed in the addition complex formation step Separation step for separating the complex (3) A washing step for washing the addition complex separated in the separation step using a solution of an aromatic hydrocarbon compound and an aliphatic hydrocarbon compound (4) Washed in the washing step Decomposition and recovery steps for decomposing the addition complex and recovering metacresol are described in detail below.

(1) Addition complex formation process In a 1st process, the mixture of the cresol isomer containing the target object metacresol and urea are made to contact, and the addition complex which consists of metacresol and urea is formed. At this stage, metacresol is incorporated as an addition complex according to the selectivity of complex formation with urea.

  Although it does not specifically limit in an addition complex formation process, A solvent can be used or it can also carry out without a solvent. When carried out in the absence of a solvent, urea is allowed to act on the mixture of metacresol isomers in the solid phase without a solvent. A mixture of cresol isomers and urea are mixed and stirred and allowed to stand for a certain period of time to precipitate the complex. Since the process without solvent does not require a reaction solvent recovery process, the process is simplified and the cost is reduced. The stirring time and the standing time after stirring are controlled according to the experimental scale, temperature conditions, and the like.

  In the case of using a solvent, examples thereof include aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, methylnaphthalene, dimethylnaphthalene, and trimethylnaphthalene. These solvents may be used alone, or a plurality of arbitrary solvents may be mixed and used. If the same solvent as that used in the washing step and decomposition and recovery step of the present invention to be described later is used in the complex formation step, the step can be simplified, which is preferable. In addition, although the usage-amount of these solvents is not specifically limited, Generally it is the range of 20-200 mass parts with respect to 100 mass parts of the mixture of cresol isomers.

  The mixing ratio of the mixture of cresol isomers and urea at the time of addition complex formation is not particularly limited, but the amount of urea added is usually 1 to 2 times mol, preferably 1 to 1.5 times mol with respect to metacresol. Range. An addition complex composed of metacresol and urea is considered to be a crystalline molecular compound formed from 1 mole of metacresol and 1 mole of urea by a hydrogen bonding mode. Therefore, this addition complex is completely different from a compound containing a linear portion as a main skeleton and a so-called urea adduct obtained from urea in terms of formation method, structure, composition and the like. When the amount of urea added is less than 1 mol, metacresol that does not act on urea remains, and the recovery rate decreases. On the other hand, when the amount is more than 2 times, the amount of solids to be transported and washed increases, which is uneconomical. The method of mixing these cresol isomers and urea is not particularly limited, but it is also possible to first add the whole amount of urea to the cresol isomer mixture and carry out the complex formation reaction. It is also possible to add both of them.

  In the addition complex formation step, heating the mixture of cresol isomers and urea is disadvantageous in terms of complex formation, so it is usually preferable to carry out at room temperature. Further, if necessary, the temperature may be lower than room temperature by forced cooling or cooling with a refrigerant in order to increase the recovery rate of the complex.

  The operating pressure during complex formation is usually atmospheric pressure. When a solvent is used, the pressure can be increased or reduced depending on the boiling point of the solvent used. The time required for complex formation varies depending on the scale to be used, the apparatus to be used, the solvent to be used, etc., but is usually about 15 minutes to 10 hours. In addition, it is preferable to carry out by the reactor provided with the stirring apparatus.

(2) Separation step Next, the second step will be described. In the second step, solid-liquid separation is performed between the addition complex produced in the first step and the mixture of cresol isomer and urea remaining without participating in the complex formation. The method of solid-liquid separation is not particularly limited, and examples thereof include filtration, centrifugation, and decantation. Specific examples include natural filtration, suction filtration, pressure filtration, centrifugal filtration, filter press, screw press, and centrifugal decantation. Further, by addition of distillation, the remaining raw material mixture can be distilled off regardless of complex formation, and an addition complex can be obtained as a residue.

  The purity of metacresol in the cake containing the addition complex separated in the second step varies depending on the raw material mixture, the amount of urea added, etc., but is typically 50% or more. In the above calculation method of purity, the cake is subjected to gas chromatography analysis and calculated from the peak area obtained for each component. Specifically, the purity can be calculated from (the peak area of metacresol in the cake / the total peak area of each cresol isomer in the cake). The purity is not particularly limited to the above range.

(3) Cleaning Step Next, the third step will be described. The third step is a step of washing the addition complex separated in the second step with a solvent of an aromatic hydrocarbon compound and an aliphatic hydrocarbon compound. In the present invention, even if the addition complex formation step is carried out in the absence of a solvent only by washing with a solution of an aromatic hydrocarbon compound and an aliphatic hydrocarbon compound as a solvent, the metacresol which has been achieved in many steps in the past has been achieved. Purity and recovery can be achieved with a simple process. Further, by changing the mass ratio of the aromatic hydrocarbon compound and the aliphatic hydrocarbon compound within a predetermined range, optimum purity and recovery rate can be achieved according to the composition change of the object to be cleaned. If the washing treatment is insufficient, the purity of the finally obtained metacresol is lowered. Further, if the washing treatment is excessive, even the addition complex is dissolved, and the recovery rate is lowered.

  The washing method using the washing solvent is not particularly limited, but the method is a method in which the cake containing the addition complex separated in the separation step is brought into contact with the washing solvent, mixed and stirred in a container, and then the washing solvent is removed by filtration or centrifugation. There is. There is also a method in which a washing solvent is directly applied to a cake containing an addition complex. The washing method is not particularly limited even when it is carried out on an industrial scale. For example, a method of filtering the washing solvent by showering on the separated cake, and the separated cake and the solvent are the same. Examples of the method include a method in which a container is charged and the slurry is stirred and washed with a stirring blade and then filtered. In the cleaning step, the above cleaning operation may be repeated a plurality of times as necessary. The washing solvent may be used repeatedly.

  The aromatic hydrocarbon compound used in the washing step is not particularly limited, but monocyclic aromatic hydrocarbon compounds such as benzene, toluene and xylene, naphthalene, methylnaphthalene, dimethylnaphthalene, biphenyl, acenaphthene, fluorene, anthracene, Mention may be made of polycyclic aromatic hydrocarbon compounds such as phenyl, or mixtures thereof.

  Although it does not specifically limit with the aliphatic hydrocarbon compound used at a washing | cleaning process, n-hexane, n-heptane, n-dodecane, n-tridecane, or a mixture thereof can be mentioned.

  The combination of the aromatic hydrocarbon compound and the aliphatic hydrocarbon compound is not particularly limited, but a combination of 1-methylnaphthalene and tetradecane is preferable.

  The mixing ratio of the aromatic hydrocarbon compound and the aliphatic hydrocarbon compound is not particularly limited, but the ratio of the aromatic hydrocarbon compound in the mixed solvent is preferably 20 to 70% by mass, more preferably 30 to 60% by mass. %. For this reason, when the mixing ratio is more than 70% by mass, the recovery rate decreases. On the other hand, when the mixing ratio is less than 20% by mass, the purity is lowered. In addition, the usage-amount of these mixtures in the case of washing | cleaning is although it does not specifically limit, Generally, it is 20-100 mass parts with respect to 100 mass parts of an addition complex. When the amount is less than 20 parts by mass, the washing becomes insufficient. On the other hand, when the amount is more than 100 parts by mass, the loss of the addition complex increases.

  The boiling point of the mixture of the aromatic hydrocarbon compound and the aliphatic hydrocarbon compound is not particularly limited, but is 205 ° C or higher, more preferably 210 ° C or higher. In addition, the boiling point of the mixture of the aromatic hydrocarbon compound and the aliphatic hydrocarbon compound means the boiling point of the lowest component of the mixed component of the aromatic hydrocarbon compound and the aliphatic hydrocarbon compound. When the said mixture is an azeotrope, it means the boiling point of the azeotrope. An azeotrope is a mixture of two or more liquids that behave as if they were one substance, with no difference between the composition of the liquid and the gas phase under a certain pressure. This azeotrope exhibits a substantially constant boiling point. The reason for this is that if the boiling point of the washing solvent is higher than that of cresol, cresol will be distilled first, and separation from the washing solvent and urea can be performed in one operation, leading to simplification of the process.

  In addition, although it is the calculation method of the purity and recovery rate of the metacresol in the cake after washing | cleaning, the washed cake is analyzed by gas chromatography and it calculates from the peak area obtained for every component. Specifically, the purity is calculated from (the peak area of metacresol in the cake / the total peak area of each cresol isomer in the cake), and the recovery rate is calculated from (the amount of metacresol in the cake / the amount of metacresol in the raw material mixture). To do.

  The time required for the washing step varies depending on the scale to be used, the apparatus to be used, the kind of the mixture, and the like, but is usually about several seconds to 0.5 hours. The washing step is carried out under normal pressure, and can be carried out under pressure or under reduced pressure as necessary.

  The washing step can be performed at any temperature, but is usually room temperature. In order to further remove impurities adhering to the addition complex, it may be room temperature or higher or room temperature or lower as necessary.

(4) Separation and Recovery Step Next, the fourth step will be described. The fourth step is a step of decomposing the washed addition complex and recovering metacresol. By decomposition of the addition complex, urea is precipitated as a solid, and then a solution containing the target product, metacresol, is recovered by solid-liquid separation.

  The decomposition method of the addition complex is not particularly limited, and examples thereof include a thermal decomposition method and a polar solvent decomposition method. In the method by thermal decomposition, the addition complex is heated to the decomposition temperature or higher to dissociate metacresol from the addition complex. At this time, using a tank equipped with a distiller, the operation can be performed under normal pressure or reduced pressure, and metacresol can be evaporated simultaneously with thermal decomposition to be recovered as a distillation fraction. You may use a solvent as needed. If the same solvent as that used for washing, such as 1-methylnaphthalene and tetradecane, is used, the operation becomes advantageous. Usually, the heating temperature is in the range of 50 to 190 ° C.

  The decomposition method using a polar solvent is a method in which urea and metacresol are decomposed by mixing a washed addition complex and a polar solvent. Specific examples of the polar solvent include water, methanol and the like, or a mixture thereof. Moreover, you may be more than room temperature or below room temperature as needed. In addition, although the usage-amount of these solvents is not specifically limited, Generally, it is the range of 5-100 mass parts with respect to 100 mass parts of mixture of cresol isomers. When the amount is less than 5 parts by mass, the decomposition is insufficient. When the amount is more than 100 parts by weight, the amount of liquid to be operated increases, which is uneconomical.

  The solid-liquid separation method is not particularly limited, and urea precipitated as crystals and metacresol remaining as a liquid are separated by filtration or decantation. Specific methods include natural filtration, suction filtration, pressure filtration, centrifugal filtration, filter press, screw press, centrifugal separation, and centrifugal decantation. Moreover, the solution containing metacresol can also be recovered by distillation operation.

  The recovered solution containing metacresol can be further purified and used by general methods such as distillation, crystallization, and extraction, as necessary.

  The atmosphere in which the operation is performed through all the first to fourth steps in the present invention is not particularly limited, but is usually an air atmosphere. If necessary, an inert gas atmosphere such as nitrogen, carbon dioxide, argon, helium, or a reduced pressure can be used.

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples unless the gist thereof is exceeded.
<Gas chromatography measurement method>
Column: Chrome Science Capillary Column (cp-cresol) manufactured by GL Sciences Inc.
Carrier gas: Helium detector: FID
Inlet temperature: 200 ° C
Column bath temperature: 110 ° C (constant)

Example 1
As a raw material mixture, a cresol isomer mixture containing 65% by mass of metacresol and 35% by mass of para-cresol was used. After adding and stirring 40 parts by mass of urea to 100 parts by mass of the raw material mixture, the mixture was left at room temperature for 4 hours. After standing, the obtained reaction mixture slurry was subjected to suction filtration to obtain 108.6 parts by mass of cake and 31.4 parts by mass of filtrate. When a part of the obtained cake was dissolved in methanol and analyzed by gas chromatography, the cresol composition in the cake was 76.5% by mass of metacresol and 23.5% by mass of para-cresol. 50 parts by mass of a mixed solvent consisting of 50% by mass of 1-methylnaphthalene and 50% by mass of tetradecane is added to 100 parts by mass of the cake and mixed. The obtained slurry mixture was subjected to suction filtration to obtain a cake. The washing operation using the mixed solvent was repeated 3 times. When a part of the finally obtained cake was dissolved in methanol and analyzed by gas chromatography, the composition of cresol in the cake was 98.7% of metacresol. The recovery rate of metacresol was 52.9%.

Example 2
The operations of addition complex formation, washing and filtration were carried out in the same manner as in Example 1 except that a mixed solvent of 50% by mass of toluene and 50% by mass of isooctane was used as the washing solvent. When the cake was analyzed by gas chromatography in the same manner as in Example 1 after washing three times, the composition of cresol in the cake was 99.1% meta-cresol. The recovery rate of metacresol was 51.5%.

Example 3
The operations of addition complex formation, washing, and filtration were carried out in the same manner as in Example 1 except that a mixed solvent of 40% by mass of 1-methylnaphthalene and 60% by mass of tetradecane was used as a washing solvent. When the cake was analyzed by gas chromatography in the same manner as in Example 1 after washing three times, the composition of cresol in the cake was 99.0% for metacresol. The recovery rate of metacresol was 58.2%.

Comparative Example 1
The operations of addition complex formation, washing, and filtration were carried out in the same manner as in Example 1 except that only toluene was used as the washing solvent. When the cake was analyzed by gas chromatography in the same manner as in Example 1 after washing three times, the composition of cresol in the cake was 95.5% of metacresol. The recovery rate of metacresol was 39.5%.

Comparative Example 2
The operations of addition complex formation, washing, and filtration were carried out in the same manner as in Example 1 except that only tetradecane was used as the washing solvent. When the cake was analyzed by gas chromatography in the same manner as in Example 1 after washing three times, the cresol composition in the cake was 85.6% of metacresol. The recovery rate of metacresol was 69.8%.

Comparative Example 3
Except that only 1-methylnaphthalene was used as the washing solvent, the operations of addition complex formation, washing and filtration were carried out in the same manner as in Example 1. When the cake was analyzed by gas chromatography in the same manner as in Example 1 after washing three times, the composition of cresol in the cake was 99.0% for metacresol. The recovery rate of metacresol was 38.1%.

Comparative Example 4
The operations of addition complex formation, washing, and filtration were carried out in the same manner as in Example 1 except that only isooctane was used as the washing solvent. When the cake was analyzed by gas chromatography in the same manner as in Example 1 after washing three times, the composition of cresol in the cake was 86.2% of metacresol. The recovery rate of metacresol was 70.6%.

Table 1

  From the results of Table 1, as shown in Examples 1, 2, and 3, the use of a mixed solvent of an aromatic hydrocarbon compound and an aliphatic hydrocarbon compound as a cleaning solution yielded metacresol with a high purity and a high recovery rate. I found out that

  According to the present invention, a mixture containing an addition complex composed of metacresol and urea can be efficiently washed, and metacresol can be easily and efficiently separated and purified from a cresol isomer mixture.

Claims (3)

  A solid washing method for washing a solid separated from a mixture containing an addition complex consisting of metacresol and urea by solid-liquid separation using a solution of an aromatic hydrocarbon compound and an aliphatic hydrocarbon compound.   A method for purifying metacresol, comprising a step of using the solid washing method according to claim 1 and a step of decomposing the washed solid and recovering metacresol.   Addition of urea to a mixture of cresol isomers containing metacresol to form an addition complex of metacresol and urea, and to separate the addition complex formed in the addition complex formation step The method for purifying metacresol according to claim 2, comprising a separation step.