JPH0910595A - Method for recovering activity of solid catalyst for 1-methylnaphthalene isomerization - Google Patents

Abstract

(57) Abstract: A method for producing 2-methylnaphthalene from a feedstock oil containing 1-methylnaphthalene by an economically advantageous method utilizing an isomerization reaction. SOLUTION: 1-Methyl, which is used in an isomerization reaction of a feed oil containing 1-methylnaphthalene, and which comprises contacting a solid catalyst having reduced activity with at least one compound selected from tetralin and alkyltetralin Method for recovering activity of solid catalyst for isomerization of naphthalene.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to isomerization of 1-methylnaphthalene (α-methylnaphthalene, hereinafter abbreviated as 1-MN) -containing oil to 2-methylnaphthalene (β-methylnaphthalene, hereinafter abbreviated as 2-MN). The present invention relates to a method of recovering the activity of a catalyst used in the case of

[0002]

2. Description of the Related Art 2-MN is useful as a synthetic intermediate for dyes, pharmaceutical vitamin K and the like.
It is also an important compound as a synthetic intermediate of 2,6-naphthalenedicarboxylic acid, which is a raw material of a polyester-based synthetic resin having high tensile strength. Since 2-MN is contained in a methylnaphthalene fraction obtained by distilling a tar component produced by dry distillation of coal, conventionally, a basic substance is extracted from the methylnaphthalene fraction and then crystallized. Or it was recovered by distillation. The methylnaphthalene fraction after removal of the basic substance, which is a crystallization or distillation raw material, contains a large amount of 1-MN together with 2-MN. A large amount of 1-MN is also present in the residual liquid. Although 1-MN has a use as a dye or the like, it has less industrial demand than 2-MN.

On the other hand, the isomerization reaction of 1-MN to 2-MN has been reported by V. Solinas et al. (Ap.
plied Catalysis 9, 1984, PP.109-117, the same 5, 1938, 17
1-17), in which various zeolites are used as isomerization catalysts, and their activities, lifetimes and regeneration methods are described.

In Japanese Patent Publication No. 55-21018, isomerization of alkylbenzene, specifically mixed xylene, is carried out using a silica / alumina catalyst. In this case, cyclic hydrocarbons exemplified by tetralin, decalin, cyclohexane and the like are used. It is described that its presence improves the selectivity to para-xylene in the isomerization of mixed xylene and reduces carbon deposition on the catalyst.

[0005]

SUMMARY OF THE INVENTION The present inventors have proposed 1-M
A feed oil containing N was subjected to an isomerization reaction in the presence of a solid catalyst to obtain an equilibrium composition of 1-MN and 2-MN, and after earnestly studying a method for obtaining 2-MN from it, isomerization There is a problem that the activity of the solid catalyst used in the isomerization reaction decreases in an extremely short period of time, and it is necessary to find a method for obtaining 2-MN while keeping the life of the solid catalyst in the isomerization reaction long. 2-M from feedstock oil containing MN
The present inventors have found that this is a very important issue in producing N economically advantageously.

The object of the present invention is thus to economically advantageously produce 2-MN from an oil containing 1-MN, ie by isomerizing 1-MN contained in an oil containing 1-MN to 2-MN. In order to obtain 2-MN from 1-MN-containing oil in a high yield and economically, it is to provide a method for recovering the activity of the catalyst used for isomerizing 1-MN.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a catalyst containing a solid catalyst can be prepared by supplying a raw material containing alkyltetralins onto a catalyst whose activity has once decreased. The inventors have found that the activity is restored and have completed the present invention.

That is, according to the present invention, a solid catalyst used in the isomerization reaction of a feed oil containing 1-MN and having reduced activity is contacted with at least one compound selected from tetralin and alkyltetralin. A method for recovering the activity of a solid catalyst for 1-MN isomerization is provided.

The aspects of the present invention will be described below. The aforementioned Japanese Examined Patent Publication No. 55-21018 is mainly concerned with the isomerization of mixed xylenes (consisting of p-xylene, m-xylene, o-xylene and ethylbenzene).
-The reaction is completely different from the isomerization of MN. Moreover, in the isomerization of mixed xylene, there is no mention of the relationship between the presence of cyclic hydrocarbons such as tetralin and the life of catalytic activity,
Since the amount added is large, it is rather judged that the product purity is lowered. Therefore, the fact that the catalytic activity is restored when the feed oil containing 1-MN is subjected to isomerization in the presence of a small amount of tetralin or alkyltetralin was a surprising and unexpected thing.

The present invention will be further described below, but the objects, configurations and advantages of the present invention will become more apparent. The alkyltetralin in the present invention is 1 to 8
Is tetralin in which 1 to 8 alkyl groups having 1 to 4 carbon atoms are substituted at the position, and examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and an isopropyl group. Of the alkyltetralines, monomethyltetralin is most preferred. The reason is that the yield of methylnaphthalene increases when monomethyltetralin is dehydrogenated during the isomerization reaction and converted into methylnaphthalene, and methylnaphthalene is separated and recovered in a later step.

The isomerization raw material in the present invention, that is, 1-
The feedstock containing MN does not need to be pure, for example, in a mixed composition ratio of 1-MN and 2-MN,
It may contain 2-MN at an equilibrium concentration or less. In addition, hydrocarbons such as naphthalene may be mixed in the raw material as impurities. Specifically, coal tar fraction containing 1-MN, oil containing 1-MN such as petroleum fraction, and more specifically, methylnaphthalene after removal of basic substance containing 1-MN and 2-MN. Examples include fractions and residual liquids obtained by crystallization or distillation of 2-MN from the methylnaphthalene fraction, and these can be used as raw materials. In addition,
1-MN-containing oil used as a raw material is industrially
The content of MN is preferably 10% by weight or more, and 20
Those having a weight% or more are particularly preferable.

The content of the nitrogen-containing compound as an impurity in the 1-MN-containing oil used as the raw material is preferably 0.2% by weight or less, more preferably 0.1% by weight or less as nitrogen.

As the solid catalyst used in the present invention, any solid catalyst having 1-MN isomerization activity can be used. Specifically, a solid acid catalyst such as silica / alumina, alumina, zeolite and the like can be mentioned. In the case of a solid acid catalyst, it has the ability to dehydrogenate tetralins, and particularly when monomethyltetralin is added, the amount of 2-MN obtained from the product increases due to dehydrogenation and isomerization, and the decrease in product purity due to additives is minimized can do.

Further, Y-type zeolite is preferable, and dealuminated Y-type zeolite is particularly preferable because the catalyst activity can be maintained for a long period of time. In addition, when a dealuminated Y-type zeolite is used, the catalytic activity is maintained for a long time even if a small amount of tetralin is added.

The operation of regenerating the catalyst in the present invention may be carried out at a different place after taking out the deteriorated catalyst from the isomerization reactor, or may be carried out as it is in the isomerization reaction. Good. When the isomerization reaction operation is continued in the isomerization reactor as it is, the raw material supply may be continued or the raw material supply may be temporarily interrupted.

[0016] Various operating conditions in the case of carrying out the regeneration while continuing to supply the isomerization raw material must be such that the product yield and the like do not decrease and the catalyst is sufficiently regenerated. Such conditions include a temperature of 400 to 600 ° C., a pressure of 0 to 10 kg / cm ² G, WHSV (weight of 1-MN passing over a unit weight of catalyst per hour): 0.1 to 10 h ⁻¹ ,
The content of tetralin and / or alkyltetralins in the feed oil supplied to the reactor is 0.01% by weight or more,
Entrained gas (H ₂ is commonly used) / feedstock ratio 0.0
It may be in the range of 1 to 100 (vol / vol).

If the treatment temperature is too low with respect to the above range,
If the effect of the additive is not sufficient, and it is too high, the deterioration will be accelerated.
It is. The higher the pressure, the higher the reaction rate, but it is too high.
If so, factors such as an increase in power costs are disadvantageous to the economy.
If WHSV is too low, the volume of the reactor increases and it becomes uneconomical.
Not only the side reaction progresses but many by-products are generated.
However, if it is too high, a sufficient conversion cannot be obtained. Supply to reactor
Tetralin and / or alkyl teto in fed oil
If the content of larin is too low, the regeneration effect will be sufficient.
Absent. Hydrogen is a companion gas to prevent carbonaceous accumulation.
Most preferred. H _Two/ If the feedstock ratio is too low, carbonaceous material will accumulate
Deterioration due to
Increase and become economically disadvantageous.

In the embodiment of the present invention, the catalyst whose activity has been restored by tetralin or alkyltetralin has a higher selectivity than the catalyst in the high activity state before deterioration, and is
The production of by-products other than is extremely reduced. It also has the advantage that the amount of additives used can be reduced.

[0019]

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1 SiO ₂ / Al ₂ O ₃ (molar ratio) = 1
8. Steam-treated dealuminated lattice constant = 24.30Å
0.5g of Y-type zeolite whose cation sites are exchanged with protons is packed in a stainless reaction tube and heated at 450 ° C.
Then, 20 Nml of hydrogen and 0.75 g of the raw material were supplied every hour, and the reaction was carried out under normal pressure. As a raw material, 1-MN containing no nitrogen compound was used. After continuing the reaction for 1450 hours, the raw material contains 1% by weight of monomethyltetralin.
-Switched to MN and continued. The results are shown in Table 1. Here, the 1-MN conversion rate is expressed by the formula [1- (1-MN)
/ X] × 100 (%) (where (1-MN) is the molar fraction of 1-MN in all products including tetralin, and x is the mole fraction of 1-MN in all raw materials including tetralin. It represents the fraction) and shows how much of the supplied 1-MN has changed to something other than 1-MN. Also,
The 2-MN selectivity is a mol% of 2-MN out of converted 1-MN.

[0021] (Note) Thermodynamic equilibrium composition of 2-MN: 2-MN / (1-MN + 2-MN) ≒ 65% 1-MN conversion rate = [1- (1-MN) / X] x 100 (% ) 2-MN yield = (2-MN) / X x 100 (%) Selectivity = yield / conversion rate x 100 (%) In the above formula, (1-MN): all products including monomethyltetralin Molar fraction of 1-MN in the mixture X: 1-MN in all raw materials including monomethyltetralin
Molar Fraction of (2-MN): Molar Fraction of 2-MN in All Products Including Monomethyltetralin

Example 2 The reaction was carried out under the same reaction conditions as in Example 1 except that a dealuminated Y-type zeolite having a cation site exchanged with protons and a lattice constant of 24.31Å was used as a catalyst. After the reaction was carried out for 1000 hours, the starting material was switched to 1-MN containing 1% by weight of monomethyltetralin, and a regeneration treatment was carried out while carrying out an isomerization reaction for 600 hours. Then, the raw material was switched to 1-MN again to continue the reaction. Table 2 shows changes in the 1-MN conversion rate and the 2-MN yield at that time.

[0023] * 1-MN containing 1% by weight of monomethyltetralin

As shown in the examples, the activity of the solid catalyst is recovered by bringing at least one compound selected from tetralin and alkyltetralin into contact with the solid catalyst for 1-MN isomerization whose catalytic activity is lowered, 2-M
It can be seen that the selectivity of N is improved.

[0025]

According to the present invention, a deteriorated catalyst can be regenerated by an industrially advantageous method.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Taka ▼ Yoshinori Ki, No. 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture, Technical Research Laboratory, Kawasaki Steel Co., Ltd. (72) Inventor Matsuura Aitoku, Chiba, Chiba 1 Kawasaki-cho, Ward Kawasaki Steel Corporation Technical Research Institute

Claims (6)

[Claims] 1. A method for recovering the activity of a catalyst used in an isomerization reaction of a feed oil containing 1-methylnaphthalene, the method comprising:
A method for recovering the activity of a solid catalyst for 1-methylnaphthalene isomerization, which comprises contacting a solid catalyst with reduced activity with at least one compound selected from tetralin and alkyltetralin. 2. The solid catalyst is a solid acid catalyst.
The method for recovering the activity of the solid catalyst for isomerizing 1-methylnaphthalene according to 1. 3. The method for recovering the activity of a solid catalyst for isomerizing 1-methylnaphthalene according to claim 2, wherein the solid acid catalyst is Y-type zeolite. 4. The method for recovering the activity of a solid catalyst for 1-methylnaphthalene isomerization according to claim 3, wherein the Y-type zeolite is dealuminated Y-type zeolite. 5. The method for recovering the activity of a solid catalyst for isomerizing 1-methylnaphthalene according to claim 1, wherein the alkyltetralin is monomethyltetralin. 6. The 1-methylnaphthalene isomerization according to claim 1, wherein the content of the nitrogen-containing compound as an impurity contained in the feed oil is 0.2% by weight or less in terms of nitrogen atom. Method for recovering activity of solid catalyst.