JPH0420658B2 - - Google Patents

Description

[Detailed description of the invention]

B. Object of the Invention Industrial Application Field The present invention relates to an adsorbent that selectively adsorbs and separates β-methylnaphthalene from a mixture containing α-methylnaphthalene and β-methylnaphthalene. Prior Art Alkylnaphthalenes, especially methylnaphthalene, are useful as solvents, dyeing intermediates, and raw materials for various organic synthesis, but β-methylnaphthalene in particular is a raw material for vitamin K, and its demand has increased in recent years. ing. For this reason, it is important to separate β-methylnaphthalene from methylnaphthalene, but the boiling point of α-methylnaphthalene is 244.8°C and the boiling point of β-methylnaphthalene is 241.4°C, which are close to each other and difficult to separate by distillation. Furthermore, since α-methylnaphthalene forms a eutectic mixture with 17.5 wt% β-methylnaphthalene, it is difficult to separate it by cooling crystallization. JP-A-59-88432 discloses that when separating and obtaining β-methylnaphthalene from a mixture of organic compounds containing α- and β-methylnaphthalene, zeolites with an aperture diameter of about 6 Å or more, especially X- or Y-type zeolites, are used. A method for separating the mixture by bringing the mixture into contact with each other and developing it chromatically with a developing agent is described, in which the aperture diameter of the zeolite is changed by ion-exchanging X or Y type zeolite with metal ions, and the metal ions and the substance to be separated are separated. This changes the interaction between the two, and changes the selective separability due to both effects. Since this method is chromatographically developed, the use of suitable developing agents, especially tetralin or anisole, is essential. Japanese Patent Application Laid-open No. 19556-1989 discloses that crude methylnaphthalene fraction, which is a by-product from petroleum decomposition or refining processes, is treated with a porous adsorbent, specifically activated clay, zeolite, etc., and then distilled. A method for purifying methylnaphthalene is described,
The main purpose of this method is to separate the blue-colored substance contained in the crude methylnaphthalene fraction, and it is not intended to separate α- and β-methylnaphthalene from each other. Problems to be Solved by the Invention An object of the present invention is to provide an adsorbent that selectively adsorbs and separates β-methylnaphthalene from a mixture containing α- and β-methylnaphthalene. B. Means for Solving the Constituent Problems of the Invention The adsorbent for separating β-methylnaphthalene according to the present invention is obtained by modifying faujasite-type zeolite with a SiO ₂ layer-forming agent, and is 20 from the outer surface of zeolite obtained by
Based on the measured value of the Si/Al atomic ratio at a depth of Å, the degree of SiO _two layer formation = (Si/Al) - (Si/Al)/1 + (Si/Al
) × 20 [1] However, (Si/Al): Si/Al atomic ratio obtained from X-ray photoelectron spectroscopy of modified zeolite (): Si/Al obtained from X-ray photoelectron spectroscopy of untreated zeolite Made of zeolite with a SiO ₂ layer formation degree calculated from the Al atomic ratio of 12.5 or more. This adsorbent is produced by modifying faujasite-type zeolite with a SiO ₂ layer forming agent.
SiO ₂ layer-forming zeolite, which has two SiO ₂ layers formed therein, has a particularly remarkable adsorption performance, and has a degree of SiO ₂ layer formation of 12.5 or more. The modification treatment method using the SiO ₂ -layer forming agent may be any method as long as the above-mentioned SiO ₂ -layer forming zeolite can be obtained, for example, adding a vapor phase, liquid phase or gas-liquid mixed phase SiO _2- layer forming agent to faujasite type zeolite. 10～
It can be suitably obtained by contacting at a temperature of 250°C and then firing at a temperature of 300 to 600°C. However, when a liquid phase or gas-liquid mixed phase SiO ₂ layer forming agent is used, it is necessary to sufficiently remove unreacted SiO ₂ layer forming agent and side reaction products before firing. [Zeolite] Examples of the zeolite include natural fauziasite zeolite, X-type zeolite, Y-type zeolite, and the like. In addition to proton bodies, these may be one or more ion exchangers of alkali metals, alkaline earth metals, group B, group B, and group B, and the ion exchange rate is 0 to 100% with respect to Al. That's fine. [SiO ₂ layer forming agent] The SiO ₂ layer forming agent for modifying the zeolite may be any agent that can suitably form a SiO ₂ layer mainly on the outer surface of the zeolite and at the pore entrances, such as orthosilicic acid. General formula represented by methyl, ethyl orthosilicate, etc. However, R ₁ , R ₂ , R ₃ , and R ₄ are C _o H _2o+1 (n=1 to 10) or R _k SiX _4-k (1 ≦k≦3) However, R is an alkyl group having up to 5 C atoms or a phenyl group, and X is a halogen or a general formula represented by hexamethyldisilazane H ₃ Si (-NHSiH ₂ )-NHSiH ₃ where n= 1 to 5 etc. can be used. [SiO ₂ layer forming conditions] In the reaction between zeolite and SiO ₂ layer forming agent,
The SiO ₂ layer forming agent may be used in any state: gas phase, liquid phase, or gas-liquid mixed phase. The SiO ₂ layer forming agent may be used alone, or a diluent may be used to lower the concentration. As the diluent, oxygen-containing organic substances such as paraffin, aromatic hydrocarbons, and alcohol are preferred, and the concentration of the SiO ₂ layer forming agent is 0.1% to 100%. When using a SiO ₂ layer forming agent with a molecular diameter smaller than the zeolite pore diameter, using a diluent will prevent it from entering the pores.
It is also preferable because the intrusion of the SiO ₂ layer forming agent is suppressed. The contact temperature between the SiO _two- layer forming agent and zeolite is 10℃
-250°C, preferably 50°C - 250°C is suitable.
The appropriate temperature range is thought to be influenced by the acidity of the zeolite, and the appropriate temperature range is approximately 170°C or less for protons and 250°C or less for ion exchangers. The reaction time for forming the SiO ₂ layer is 1 minute to 100 hours, but since the reaction is fast, a long time is meaningless in terms of practical effect, and preferably 10 minutes to 20 hours. [Post-treatment] The post-treatment is slightly different between the gas phase reaction and the liquid phase or gas-liquid mixed phase reaction of the SiO ₂ layer forming agent. In the case of a gas phase reaction, the unreacted _SiO2 layer forming agent and side reaction products are removed in the temperature-raising firing process, but in the case of a liquid phase or gas-liquid mixed phase reaction, unreacted SiO is removed by washing, drying, etc. before firing. It is necessary to remove the _two- layer forming agent and side reaction products. Cleaning agents include paraffin, alcohol, and aromatic hydrocarbons, but considering the drying process, they are low boiling point substances (below 80℃).
is desirable. In the case of gas phase, immediately after the SiO ₂ layer forming reaction, in the case of liquid phase or gas-liquid mixed phase, after removing unreacted SiO ₂ layer forming agent and side reaction products, the heating temperature is increased from 0.1℃/min.
It is heated at 50°C/min, preferably 1°C/min to 10°C/min, and fired at a predetermined firing temperature. The firing temperature is
300-600°C, preferably 300-530°C. Rapid temperature rise causes rapid carbonization and oxidation of the SiO ₂ layer forming agent, which has a negative effect on adsorption performance. It is necessary to sufficiently remove unreacted SiO ₂ layer forming agent or diluent and side reaction products remaining in the zeolite. For this purpose, sufficient washing, drying, etc. should be performed. If the cleaning is incomplete, the unreacted SiO ₂ layer forming agent, diluent, etc. can be sufficiently removed by initially maintaining the temperature at a relatively low temperature during the drying process and firing. [Multiple SiO ₂ layer forming treatment] The reaction between zeolite and SiO ₂ layer forming agent may be done in one step, but the degree of SiO ₂ layer formation can be increased by forming 1 SiO ₂ layer.
If 12.5 is not reached, the reaction between the SiO ₂ layer forming zeolite obtained by calcination and the SiO ₂ layer forming agent is repeated. The higher the reaction temperature and the greater the number of repetitions, the higher the degree of SiO ₂ layer formation. [SiO ₂ layer formation degree] The SiO ₂ layer formation degree is determined by X-ray photoelectron spectroscopy (X-ray
Photoelectron Spectroscopy;
Measured values of the atomic ratio of Al (M.Niwa et al.; J.Chem.
(See the measurement method described in Soc. Faraday Trans. I, 1984, 80, 3135) and is calculated using the above formula [1]. The degree of SiO ₂ layer formation of zeolite is 12.5 or more. Below this, the adsorption selectivity of β-methylnaphthalene does not improve and is comparable to that of zeolite that has not been treated to form _two SiO layers. Further, even if the degree of SiO ₂ layer formation is increased more than necessary, the degree of improvement in adsorption selectivity is small.
The upper limit of the degree of SiO ₂ layer formation is about 18, preferably 12.5-17, more preferably 12.5-15. [Object] The object to which the adsorbent for separating β-methylnaphthalene of the present invention is used is a mixture of α- and β-methylnaphthalene, such as those obtained by fractional distillation of coal tar, or petroleum cracking and refining processes. Examples include the crude methylnaphthalene fraction produced as a by-product, and may contain dialkylnaphthalene and the like. By contacting the adsorbent of the present invention with a mixture containing α- and β-methylnaphthalene, β
- Methylnaphthalene can be selectively adsorbed and separated. The contact between the adsorbent and the mixture containing α- and β-methylnaphthalene is carried out at normal pressure and around normal temperature, i.e. 25
Perform at ~40℃. At the time of contact, α-methylnaphthalene and β-methylnaphthalene may be separated by chromatographic development with a developing agent, but usually the above mixture is brought into contact with this adsorbent to adsorb β-methylnaphthalene, and then adsorption is performed. The resulting β-methylnaphthalene is desorbed using a desorbing agent. For contacting, a fixed bed, fluidized bed, moving bed, etc. can be used. [Test Example 1] Proton type Y type zeolite (H-Y type) 50
300 c.c. of butyl orthosilicate was brought into contact with g at 150° C. for 2 hours to cause a SiO ₂ layer formation reaction. After the reaction was completed, it was washed with butanol, filtered, and dried. In order to completely remove unreacted butyl orthosilicate from the dried zeolite, the temperature was raised to 520°C at a rate of 1°C/min, and the temperature was maintained for 12 hours for firing. Note that this operation was performed in air. Obtained modified zeolite (sample S1-1)
with an n-hexane solution containing 2 vol% each of α-methylnaphthalene and β-methylnaphthalene at 25°C.
adsorption selectivity was tested by contacting with The liquid in which adsorption equilibrium was reached was analyzed by gas chromatography to determine the ratio of β-methylnaphthalene adsorbed on the adsorbent. In addition, the atomic ratio of Si and Al on the outer surface of the obtained modified zeolite was
It was measured by XPS, and the degree of SiO ₂ layer formation was determined by formula [1]. The results are shown in Table 1. [Test Example 2] Zeolite sample modified under the same conditions as Test Example 1 except that the SiO ₂ layer formation temperature was 120°C
S2-1 was obtained. 45 g of this zeolite (S2-1) and 270 c.c. of butyl orthosilicate were treated again under the same conditions to obtain a modified zeolite (sample S2-2). Furthermore, 40 g of this zeolite (S2-2) and 240 c.c. of butyl orthosilicate were treated again under the same conditions to obtain a modified zeolite sample S2-3. Regarding these samples S2-1, S2-2, and S2-3, the adsorption performance of α- and β-methylnaphthalene and the degree of SiO ₂ layer formation were measured using the same evaluation liquid as in Test Example 1. The results are shown in Table 1. [Test Example 3] Zeolite (sample) modified under the same conditions as Test Example 1 except that the SiO ₂ layer formation temperature was 100℃
S3-1) was obtained. Similar to Test Example 2, the modified zeolite:butyl orthosilicate ratio was 1:6 (g/cc) under the same conditions.
Repeating the SiO _two layer formation process, sample S3-2,
S3-3, S3-4, and S3-5 were obtained, and the adsorption performance of α- and β-methylnaphthalene and the degree of SiO ₂ layer formation were measured using the same evaluation liquid as in Test Example 1. The results are shown in Table 1. [Test Example 4] Zeolite (sample) modified under the same conditions as Test Example 1 except that the SiO ₂ layer formation temperature was 80°C.
S4-1) was obtained. Similar to Test Example 2, the modified zeolite:butyl orthosilicate ratio was 1:6 (g/cc) under the same conditions.
Repeating the SiO ₂ layer formation process, sample S4-2,
S4-3, S4-4, S4-5, S4-6, and S4-7 were obtained, and the adsorption performance of α- and β-methylnaphthalene and the degree of SiO ₂ layer formation were measured using the same evaluation liquid as in Test Example 1. . The results are shown in Table 1.

【table】

[Table] [Test Example 5] α- and β-methylnaphthalene adsorption performance and SiO ₂ layer formation using the same evaluation solution as Test Example 1 for untreated H-Y zeolite (sample S5-1) with SiO ₂ layer formation The degree of formation was measured. The results are shown in Table 1. Effect As is clear from the test results shown in Table 1,
If a modified zeolite with a degree of SiO ₂ layer formation of 12.5 or more is used, a β-methylnaphthalene adsorption rate of 90 vol% or more can be obtained. On the other hand, when a modified zeolite with a degree of SiO ₂ layer formation of less than 12.5 is used, the β-methylnaphthalene adsorption rate is 50 vol% or less, which is the same as that of untreated zeolite. C. Effects of the Invention When the adsorbent according to the present invention is used, the following effects can be obtained. (1) Since the selectivity for adsorbing β-methylnaphthalene from a mixture containing α- and β-methylnaphthalene is excellent, it can be efficiently separated. (2) Compared to distillation or crystallization methods, less energy is required for separation, and highly pure β-methylnaphthalene can be obtained.

Claims (1)

[Scope of Claims] 1. 20 Å from the outer surface of the zeolite obtained by modifying phasiasite type zeolite with a SiO ₂ layer forming agent and obtained by X-ray photoelectron spectroscopy.
Based on the measured value of the Si/Al _atomic ratio at the depth of
] However, (Si/Al): Si/Al atomic ratio obtained from X-ray photoelectron spectroscopy of modified zeolite (): Si/Al atomic ratio obtained from X-ray photoelectron spectroscopy of untreated zeolite An adsorbent for separating β-methylnaphthalene made of zeolite with a calculated degree of SiO ₂ layer formation of 12.5 or more. 2. The adsorbent according to claim 1, which has a degree of _SiO2 layer formation of 12.5 to 17. 3 Modification treatment with SiO ₂ layer forming agent is performed by adding 10 to 250 SiO ₂ layer forming agent to faujasite type zeolite.
After contacting in liquid phase or gas-liquid mixed phase at a temperature of 300 °C, unreacted SiO ₂ layer forming agent is removed, and then 300 °C
The adsorbent according to claim 1 or 2, which is calcined at a temperature of 600°C. 4 Modification treatment with SiO ₂ layer forming agent is performed by adding 10 to 250 SiO ₂ layer forming agent to faujasite type zeolite.
After contact in the gas phase at a temperature of 300-600 °C
The adsorbent according to claim 1 or 2, which is calcined at a temperature of °C.