JPH03240740A - Method for purifying dicyclopentadiene - Google Patents

Abstract

PURPOSE:To readily purify crude dicyclopentadiene at a low cost by bringing the crude dicyclopentadiene into contact with activated clay having a specified silica/alumina ratio, specific surface area and solid acid content, distilling the resultant substance and removing a heavy fraction. CONSTITUTION:Crude dicyclopentadiene is brought into contact with specific activated clay at about 30 deg.C and then distilled to remove a heavy fraction. Thereby, high-purity dicyclopentadiene useful as a raw material for a reaction injection molding method using a metathetic catalyst is obtained. Activated clay having 7-15 silica/alumina weight ratio, >=300m<2>/g specific surface area, >=0.5mmol/g solid acid content expressed in terms of the total acid points having a Hammett acidity function (H0) of <=+4.8 and <=0.2mmol/g solid acid content expressed in terms of strong acid points having an H0 of <=-5. 6 is preferred as the activated clay. The distillation is preferably carried out in an atmosphere of an inert gas under reduced pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for purifying dicyclopentadiene (hereinafter referred to as rDCPD).

DCPD purified by the method of the present invention can be produced by reaction injection molding using a metathesis catalyst.
Injection Molding, hereinafter referred to as rRIM
It is suitable as a raw material for

[Prior art] Conventionally, the RIM method has been used to produce polyurethane resins, but in recent years, DCPD has been used as a raw material to polymerize and crosslink by the RIM method using a metathesis catalyst consisting of a tungsten compound, a molybdenum compound, and an organoaluminum compound.
The method of obtaining molded products is attracting attention.

The raw material DCPD used in this case needs to be of high purity, and normally commercially available DCPD has an insufficient degree of purification and does not allow the polymerization and crosslinking reaction to proceed smoothly. Furthermore, in extreme cases, no reaction may occur.

For example, U.S. Pat.
, 748,216, it is said that even the commercially available highest purity 97% DCPD is still insufficiently purified as a raw material for the RIM method. This is thought to be because trace amounts of impurities contained in DCPD inhibit polymerization, and it is necessary to remove these impurities that inhibit polymerization in advance for purification.

As a purification method for this purpose, for example, there is a method of distilling DCPD and then adsorbing it with an adsorbent such as molecular sieve or alumina (US Pat. No. 4,584.425 and US Pat. No. 4,748,216). .

This method uses DCP with a purity of about 95%, which can be easily done manually.
When D is used, there are problems in terms of purity, such as low distillation yield and heavy components generated in the adsorption treatment remaining in the purified product.

Further, there is a purification method in which DCPD is brought into contact with an alkaline substance such as an aqueous sodium hydroxide solution, washed with water, and then dehydrated by distillation or molecular sieve or synthetic zeolite. This method generates a large amount of alkaline waste water, is expensive to treat, and achieves a low purity of about 96%.

[Problems to be Solved by the Invention] As a result of earnestly searching for a method to industrially easily obtain high-purity DCPD, the present inventor treated crude DCPD with activated clay, and then removed heavy components by distillation. The present invention was completed based on the discovery that this method is extremely effective.

[Means for Solving the Problems] The present invention provides a method for purifying DCPD, which comprises bringing crude DCPD containing impurities into contact with activated clay, and then removing a heavy fraction by distillation. It is.

That is, the features of the present invention consist of two requirements: bringing crude DCPD into contact with activated clay and distilling it after the contact treatment.

The crude DCPD used in the method of the present invention is usually
DCPD obtained by thermal cracking of hydrocarbons, for example naphtha for the production of ethylene-based lower olefins
Alternatively, it is obtained by trimerizing cyclopentadiene (hereinafter referred to as rCPDJ) contained in a fraction having 5 carbon atoms obtained by thermal decomposition thereof, and separating it by distillation. The DCPD thus obtained is usually a mixture of endo and exo isomers, and the purity of both is around 95% in total.

In the present invention, crude DCPD is first brought into contact with activated clay.

The activated clay to be used has silica and alumina as its main components, and the acid clay, which is a montmorillonite clay mineral containing iron, magnesium, etc., is treated with mineral acids such as sulfuric acid to form alumina, iron, magnesium, etc. A portion of it is eluted, and the composition ratio of silica and alumina and specific surface area (surface area per Ig) vary depending on the processing conditions.
Alternatively, one with surface acidity can be obtained. Any of these activated clays can be used as the activated clay used in the method of the present invention, but those whose content ratio of silica as a main component to alumina is in the range of 7 to 15 by weight, 1
The specific surface area per gram is 300012 or more, or the amount of solid acid is 0.5 mmo 17 g or more at total acid points of Hammett acid function (■.) + 4.8 or less, and -5,
Particularly effective are those having strong acid points of 6 or less and 0.2 mmol/g or less.

Furthermore, the content ratio of silica to alumina is in the range of 7 to 15 by weight, and at the same time the specific surface area per gram is 3.
0On+2 or more, or in addition to this, solid acid content is Hammett acid function (H,) +4.8 or less, total acid points are 0.5 ma+ol/g or more, and -5,6 or less strong acid points It is even more effective to have an O of 12 mmol/g or less.

The treatment method of the present invention may be a method (batch method) in which activated clay is charged together with crude DCPD into a suitable tank, stirred, and then filtered.
It may be processed using a flow method (continuous method). When carrying out the batch method, 1% or more by weight, preferably 5 to 20% by weight, of activated clay that has been dehydrated in advance is added to DCPD, and the mixture is heated at normal pressure.
1 to 10, preferably in an atmosphere of an inert gas such as nitrogen.
Stir for an hour. Dehydration of activated clay is, for example, 120~
It is sufficient to heat the mixture at a temperature of Zoo°C for 2 hours.

The treatment temperature needs to be higher than the melting point of crude DCPD since it is handled in a liquid phase. The melting point of pure CPD is 34°C, but since commercially available crude DCPD contains impurities, it is usually in the 20°C range. On the other hand, if the treatment temperature exceeds 50° C., depolymerization or unnecessary polymerization of some DCPD may occur, which is not preferable. Therefore, it is preferable to perform the treatment at a temperature between 20°C and 50°C, particularly around 30°C.

As a result of activated clay treatment, impurities that inhibit polymerization (hereinafter referred to as "polymerization inhibitors") are not necessarily removed by adsorption. Many of the polymerization inhibitors undergo chemical changes such as polymerization due to the catalytic action of activated clay and become heavier, resulting in DC
Exists in PD. For this reason, activated clay treatment alone is insufficiently effective, and it is necessary to remove heavy components by distillation after treatment.

This will be explained in detail in the Examples below, but as shown in Figure 1, the heavy fraction and hollow fraction of DCPD treated with activated clay are more rapidly absorbed than the untreated fraction. This shows that the amount of polymerization inhibitors is significantly reduced. On the other hand, it is clear that the heavy fraction did not polymerize even if it was diluted 10 times, and the amount of polymerization inhibitors increased significantly.

As can be seen from FIG. 1, polymerization inhibitors are partially contained in the light fraction, so if a high degree of purification is required, it is preferable to distill off the light fraction as well.

Although the chemical structure of the polymerization inhibitor has not been confirmed, activated clay treatment also has the effect of making hydrocarbon impurities heavier. For example, as shown in Table 3, which will be explained in Examples below, the purity of DCPD does not change much before and after activated clay treatment, but the boiling point of C9 to C11 hydrocarbons is lower than DCP.
This can be seen from the fact that hydrocarbon impurities near D are selectively reduced, and heavy impurities are increased instead. Although these C9-C0 hydrocarbon impurities do not necessarily inhibit polymerization, their boiling point is close to DCPD, so they usually
It is difficult to break down by distillation.

However, as a result of the activated clay treatment, some parts become heavier,
They can be easily separated by distillation.

With other solid acids, such as alumina, such changes in hydrocarbon composition do not occur, as shown in Table 4.

As mentioned above, it is essential to carry out the distillation after the activated clay treatment, and the objective cannot be achieved by carrying out the distillation first, as is done in the prior art.

Regarding the distillation conditions, it is preferable to carry out the distillation under an atmosphere of an inert gas such as nitrogen and under reduced pressure in order to prevent decomposition reactions and oxidation reactions caused by heating during distillation. During the distillation, antioxidants, such as 2,6-di-tert-butylphenol (
It is also possible to add 100 to 10,000 ppa+ of BHT) or the like. For example, when distilling with a packed rectification column equivalent to 20 plates in a nitrogen atmosphere with a reflux ratio of 2 to 50 and a pressure of 20 mdg, with the addition of 11,000 pp of B) IT,
By removing 10% each of the heavy fraction and the heavy fraction, high purity DCPD of 99% or more can be obtained with a distillation yield of about 80%. The reason for excluding heavy components is as shown in Figure 1.
This is because this fraction also contains some polymerization inhibitors.

[Effects of the Invention] According to the method of the present invention, highly purified DCPD suitable for RIMJ1 can be obtained industrially, easily, and at low cost. That is, since the polymerization-inhibiting substance is made heavier by the activated clay treatment, the subsequent distillation increases the purification effect of the distillation, making it possible to easily obtain highly purified DCPD.

[Example] The present invention will be described in more detail with reference to Examples below. Prior to this, the analytical method and method for evaluating the degree of purification used in the Example will be described.

<Purity measurement method using gas chromatography> OV-
Using a 101 capillary column (50 m), 90-2
The analysis was performed at 50°C.

Evaluation method of purity degree> Evaluation was made by polymerization delay time according to the method described in US Pat. No. 4,584,425.

Tungsten hexachloride (WCI6) 20 g/
A solution of 8.2 g of para-t-butylphenol/30 ml of toluene was added to a solution of 60 ml of toluene, and WCI was applied.

Hydrogen chloride (ICI) generated by the reaction between the reactant and para-t-butylphenol was removed with nitrogen to obtain a 0.1M tungsten catalyst solution. Add DCPD to 5 ml of this catalyst solution.
add loml and 0.07ml benzonitrile,
A 0.033M catalyst/DCPD solution (hereinafter referred to as "Liquid A")
). Separately, 0.1 ml of isopropyl ether and 0.36 ml of 1.0 M diethylaluminum chloride (Et2Al (1:l/D CP D solution) were mixed with 8.6 ml of DCPD to obtain an activator/DCPD solution (hereinafter referred to as "Liquid B"). ).

1 ml of Ail and 8.9 ml of solution B were mixed at 25° C. and stirred vigorously, resulting in a strong exotherm after a short induction period and a solid polymer. Time until the start of this polymerization (
seconds) was measured and defined as the polymerization delay time.

When the degree of purification of DCPD is high, polymerization occurs quickly and the polymerization delay time is short. Therefore, the shorter the polymerization delay time, the higher the degree of purification and the better the RIM raw material.

<Example 1> 500 g of crude DCPD (purity 94.4%) obtained by naphtha decomposition was placed in a glass flask with a volume of 11 Ji at 150°C.
Activated clay A (silica 79.5%,
Alumina 9.6%; silica to alumina weight ratio 8.3;
Specific surface area per Ig 305IT12; Hammett acid function (
H0) Amount of total acid points below +4.8 0, 87 mmol
/g, amount of strong acid points of the same 5.6 or less 0.17 mmol/
g) 50 g was added and stirred at 30°C for 3 hours. During this time, the temperature rose from 30°C to 36°C. After the treatment, activated clay A was separated by filtration to obtain 407 g of filtrate. B to the filtrate
Add HTloooppm as antioxidant and pressure 2
Simple distillation was carried out under a nitrogen atmosphere of 0 lllmHg to remove 20% and 30% of heavy fractions.
I got %. The polymerization delay time of the thus obtained purified DCPD (hollow fraction) was 21 seconds as shown in Table 1.

<Example 2> Activated clay B (silica 68.5
%, alumina 17.0%; weight ratio of silica and alumina 4
．． The same treatment as in Example 1 was repeated using 0; specific surface area per Ig of 100I02). The results are shown in Table 1. A solid polymer was obtained, and the polymerization delay time was 40 seconds.

<Example 3> Activated clay C (silica 76.7
%, alumina 11.2% Nijirica and alumina weight ratio 6
．． The same treatment as in Example 1 was repeated using a specific surface area of 8.1 g (240 m2). The results are shown in Table 1. A solid polymer was obtained, and the polymerization delay time was 64 seconds.

<Example 4> Activated clay D (silica 85.4
%, alumina 2.8%; weight ratio of silica and alumina 30
．． 5; Specific surface area per Ig: 220 m2) The same treatment as in Example 1 was repeated. The results are shown in Table 1. A solid polymer was obtained, and the polymerization delay time was 60 seconds.

<Example 5> Activated clay E was used instead of activated clay A (the amount of total acid sites with Hammett acid function (H0) + 4.8 or less was 0.95 mmol).
/g, the amount of strong acid points below -556 is 0.33 mmol
The same process as in Example 1 was repeated using 1/g).

The results are shown in Table 2. A solid polymer was obtained and the polymerization delay time was 52 seconds.

<Example 6> Activated clay F was used instead of activated clay A (the amount of total acid sites with Hammett acid function (■.) + 4.8 or less was 1.00 ma + o
l/g, the amount of strong acid points below -5,6 is 0.40 mmo
The same process as in Example 1 was repeated using 1/g).

The results are shown in Table 2. A solid polymer was obtained and the polymerization delay time was 64 seconds.

<Comparative Example 1> Either the polymerization delay time of the crude DCPD itself used in Example 1 was determined, or the crude DCPD did not polymerize and no polymerization delay time was obtained.

Comparative Example 2> In the treatment of Example 1, distillation was performed first, followed by activated clay treatment, and then no distillation was performed. Even with activated clay treatment, polymerization did not occur and no polymerization delay time was obtained.

<Comparative Example 3> The same treatment as in Example 1 was repeated using Molecular Sieve 13X instead of the activated clay A. The results are shown in Table 1. The treated DCPD polymerized, but the polymerization delay time was 43 seconds.

Comparative Example 4> Instead of activated clay A, synthetic silica/alumina (Silica 8
%, alumina 90%) was repeated. The results are shown in Table 1. Although the treated DCPD polymerized, the polymerization delay time was 66 seconds.

Comparative Example 5> In Comparative Example 2, Molecular Sieve 1 was used instead of activated clay A.
3X was used. In this case, polymerization occurred, but the polymerization delay time was as long as 65 seconds.

<Example 7> The DCPD treated with activated clay A in Example 1 was processed in a packed rectification column with 20 plates at a reflux ratio of 10 and a pressure of 2.
BHT was heated at 11000p under a nitrogen atmosphere of 0 mmHg.
As a result of adding p1 and distilling to remove 10% of heavy components and heavy fraction groups, DCPD with a high purity of 99% or more was obtained with a distillation yield of 80% as shown in Table 3.

Comparative Example 6> The results of distilling DCPD without performing the activated clay treatment in Example 7 are also shown in Table 3.

In this case, the purity is lower and the polymerization delay time is longer than when activated clay treatment is performed.

Reference Example 1 DCPD before and after treatment with activated clay A in Example 1
The results of gas chromatography analysis (before distillation) were
Shown in the table. It can be seen that by the activated clay treatment, impurities whose boiling points are near DCPD and are difficult to separate by distillation are reduced, and instead, heavy components, which are easy to separate by distillation, are increased.

Reference Example 2> Alumina A (acidic alumina 90 manufactured by Merck & Co., Ltd., pH 4) was used instead of activated clay A in Example 1, and the DC before and after treatment was
Table 4 shows the results of gas chromatography analysis of PD (before distillation). Unlike the case of activated clay shown in Table 3, there is almost no change in composition.

<Reference Example 3> The same treatment as in Reference Example 2 was performed using alumina B (basic alumina manufactured by Merck & Co., pH 9). As shown in Table 4, there is almost no change in composition.

Reference Example 4> DCPD treated with activated clay A in Example 1 was distilled and divided into 10 fractions, and each fraction was distilled with the high purity DCPD obtained in Example 7 (polymerization delay time 20 seconds). It was diluted 10 times and the polymerization delay time of each was determined. The results are shown in FIG.

It can be seen that the polymerization delay time in light and middle distillates is shorter and the amount of polymerization inhibitors is reduced compared to the case where activated clay treatment is not performed. On the other hand, even though the heaviest fraction was diluted 10 times, it still did not polymerize and the amount of polymerization inhibitors increased significantly.

Reference Example 5 The same treatment as in Reference Example 4 was performed on the crude DCPD before the activated clay treatment. The results are also shown in Figure 1. Although there is little difference because the sample is diluted, it can be seen that the polymerization delay time is longer compared to the activated clay treated product except for heavy components.

Table 4 Composition change of DCPD due to alumina treatment

[Brief explanation of drawings]

FIG. 1 is a graph showing the distribution of polymerization inhibitors for each fraction explained in Reference Examples 4 and 5.

Claims (6)

[Claims] (1) A method for purifying dicyclopentadiene, which comprises bringing crude dicyclopentadiene containing impurities into contact with activated clay, and then removing a heavy fraction by distillation. (2) The method for purifying dicyclopentadiene according to claim 1, wherein the content ratio of silica to alumina in the activated clay is in the range of 7 to 15 by weight. (3) The specific surface area per gram of the activated clay is 300
The method for purifying dicyclopentadiene according to claim 1, wherein the area is at least square meter. (4) The amount of solid acid in the activated clay is determined by the Hammett acid function (H
_0) 0.5 mmol/g or more at total acid points below +4.8, and 0.2 mmol/g at strong acid points below -5.6
2. The method for purifying dicyclopentadiene according to claim 1, wherein the amount of dicyclopentadiene is less than g. (5) The content ratio of silica to alumina in the activated clay is in the range of 7 to 15 by weight, and the specific surface area per gram is 300 square meters or more.
The described method for purifying dicyclopentadiene. (6) The content ratio of silica to alumina in the activated clay is in the range of 7 to 15 by weight, the specific surface area per gram is 300 square meters or more, and the amount of solid acid is Hammett acid function (H_0) 0.5 mmol/g or more at total acid points below +4.8, 0 at strong acid points below -5.6
．． The method for purifying dicyclopentadiene according to claim 1, wherein the concentration is 2 mmol/g or less.