JP2000281595A - Highly selective production of ethylbenzene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly selectively obtain ethylbenzene while reducing the quantity produced of polyethylbenzene such as diethylbenzene by reacting benzene with ethylene in the presence of a zeolite catalyst in a continuous reaction system. SOLUTION: Ethylbenzene is obtained by reacting benzene with ethylene in the presence of a zeolite catalyst in a continuous reaction system partially retaining a liquid phase in a coexisted state with preferably a 5-7C paraffin or a naphthene in raw material oil at preferably 170-270 deg.C and 10-50 kg/cm2 while reducing the quantity produced of polyethylbenzene such as diethylbenzene down to the quantity as little as possible. The reaction system is an upflow one and preferably employs the fixed bed filled with a zeolite catalyst. The content of the paraffin or naphthene made to coexist in raw material oil is preferably 10-70 wt.% and the mol ratio of benzene in raw material oil to ethylene in supply gas is preferably 2-5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing industrially useful ethylbenzene using ethylene and benzene.

[0002]

2. Description of the Related Art Ethylbenzene is a raw material for styrene monomers and is an industrially useful reaction intermediate. Although various methods for producing ethylbenzene are known, industrially, ethylbenzene is generally produced from benzene and ethylene. The alkylation reaction of benzene with ethylene is known as a Friedel-Crafts type reaction and can be carried out using a catalyst represented by aluminum chloride or solid phosphoric acid. By the way, it is known that several side reactions occur simultaneously in the Friedel-Crafts type reaction, one of which is a polysubstituted alkylation reaction. That is, under normal reaction conditions, the polysubstitution reaction of ethylene onto the benzene ring cannot be suppressed, and the selectivity of the monoalkylated product is reduced due to an increase in by-products. In addition, the reaction using the above catalyst requires a purification step such as neutralization and washing of the reaction product, and there is a problem of wastewater treatment in this step. Further, when carried out on an industrial scale, corrosion of the reactor by a catalyst is also a major problem. Therefore, in recent years, in order to solve these problems, alternative processes using catalysts represented by zeolites such as Y-type and MFI-type have been developed and are being industrially implemented.

[0003] The advantages of a process using a zeolite catalyst are that neutralization and washing steps during purification can be omitted and that corrosion of the reactor can be solved. Further, since the alkylation reaction is subject to steric restrictions derived from the zeolite structure, there is a feature that the production of bulky polyethylbenzene such as triethylbenzene and tetraethylbenzene is reduced. However, even if a zeolite catalyst is used, the diethyl form is still formed, and in order to improve the yield of ethylbenzene, transethylation is performed by further reacting diethylbenzene with benzene to produce ethylbenzene after the alkylation reaction with ethylene. And a secondary device such as a distillation column for separating diethylbenzene from heavy aromatics having a higher boiling point.

As an example of a process for producing ethylbenzene using a zeolite catalyst, Mobil / Ba
The dger process is known. In this process, an MFI type zeolite is used to react in a gas phase at a high temperature. However, in a gas phase reaction at a high temperature, xylene which is a compound in the vicinity of the boiling point of ethylbenzene is generated, so that there is a problem that the purity of ethylbenzene is reduced. For this reason, for the production of ethylbenzene, a reaction that maintains the alkylation activity under milder liquid phase conditions is desirable. Recently, studies for maintaining the liquid phase conditions have been actively conducted.

Among such studies, there is a report of a highly active catalyst, such as a zeolite having a 12-membered ring structure such as MCM-22 or β type. US Patent 5,334,795
An example using MCM-22 is also disclosed in
No. 37 reports an example using β-form.

Although these zeolites exhibit high alkylation activity even under mild liquid phase conditions, the amount of diethylbenzene produced may be larger than that of the MFI type. This is MCM-2
It is considered that the pore structure of the zeolite of 2 or β type is larger than that of the 10-membered ring structure of MFI type.

As described above, even under milder liquid phase conditions, the problem of by-produced diethylbenzene is not solved. In an industrial apparatus, to increase the yield of ethylbenzene,
Equipment for transethylation is still required after the alkylation reaction with ethylene. As described above, the equipment configuration for producing ethylbenzene is complicated, and the production cost is high.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a method for producing ethylbenzene using benzene and ethylene, by minimizing the amount of polyethylated product such as diethylbenzene produced, thereby reducing the ethylbenzene selectivity in the product. There is a feature in enhancing the This allows
Inexpensive production of ethylbenzene is achieved with a simple apparatus configuration that does not require a transethylation reaction after the present alkylation reaction, which is performed in a normal reaction.

[0009]

Means for Solving the Problems According to the present invention, as a result of intensive studies on a method for producing ethylbenzene from benzene and ethylene using a zeolite catalyst, paraffin or naphthene is coexisted in addition to benzene in a feedstock oil. It has been found that by using a fixed bed upflow reaction type, the production of polyethylbenzene such as diethylbenzene is as small as possible and ethylbenzene is produced with high selectivity.

That is, the present invention provides: In the method of producing ethylbenzene by reacting benzene and ethylene, using a continuous reaction method using a zeolite catalyst and maintaining a partial liquid phase, and coexisting paraffin or naphthene in addition to benzene in the feedstock oil 1. A method for highly selective production of ethylbenzene, characterized by minimizing the amount of polyethylbenzene such as diethylbenzene produced by the method. 2. The method for highly selective production of ethylbenzene according to 1 above, wherein the continuous reaction system in which a part of the liquid phase is maintained is an upflow system. 3. The method for highly selective production of ethylbenzene according to 1 above, wherein the continuous reaction system in which a partial liquid phase is maintained is a system using a fixed bed filled with a zeolite catalyst; 4. The method for highly selective production of ethylbenzene according to the above 1, 2, or 3, wherein the carbon number of paraffin or naphthene coexisting in the feedstock is 5 to 7, 5. The method for highly selective production of ethylbenzene according to any one of the above items 1 to 4, wherein the proportion of paraffin or naphthene coexisting in the feedstock is in the range of 10 to 70 wt%. The molar ratio of benzene in the feedstock to ethylene in the feed gas is in the range of 2 to 5,
6. A method for highly selective production of ethylbenzene according to any one of the above, Reaction temperature 170-270 ° C, reaction pressure 10-5
7. The highly selective method for producing ethylbenzene according to any one of the above items 1 to 6, wherein the method is 0 kg / cm ² . 8. The method for highly selective production of ethylbenzene according to the above 1 or 3, wherein the zeolite is of β type. 9. The method for highly selective production of ethylbenzene according to 8 above, wherein the β-type SiO ₂ / Al ₂ O ₃ ratio is 16 to 50.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The catalyst used in the present invention is a medium having excellent thermal stability and a large pore zeolite such as Y type, USY type, ZS
M-5,12 type, mordenite type, β type, MCM-2
2, 42, 59, etc. can be used. Among them, zeolite in which the entrance of the pore is constituted by a 12-membered oxygen ring, for example, USY type, mordenite type, β type, MCM-22 and the like are preferably used. β-type zeolite is particularly preferably used in the present invention because of its high ability to alkylate benzene with olefins.

[0013] Representative examples of β-type zeolites include those synthesized by the method shown in US Patent No. 3,308,069, for example. This corresponds to 2θ = 20 in X-ray diffraction.
It has a unique peak at ~ 32 °.

Also, naturally occurring Tschernichite is said to be a mineral similar to β-type zeolite, and is known to exhibit similar X-ray diffraction (J. Catal., Vol. 148, p.
91-99 (1994)).

Many other synthesis methods for β-zeolite have been proposed, and any of these methods can be used in this reaction.

The properties of β-type zeolite are characterized by its tetravalent silicon and trivalent metal. As the trivalent metal, aluminum, titanium, vanadium, iron, gallium and the like can be used alone or in combination. The properties of the zeolite vary depending on the trivalent metal element, but aluminum which has a strong acid property is most suitable for this reaction. The acid properties of β-zeolite are characterized by the ratio of silicon to aluminum oxide (hereinafter abbreviated as SiO ₂ / Al ₂ O ₃ ratio). When the ratio of SiO ₂ / Al ₂ O ₃ is small, the amount of acid increases, and the alkylation reaction shows high activity, but also has a large amount of by-products, which lowers the selectivity of ethylbenzene. When the ratio of SiO ₂ / Al ₂ O ₃ is large, the amount of acid is small and the activity of the alkylation reaction is low. The decrease in activity can be compensated for by increasing the reaction temperature, but it becomes difficult to maintain the liquid phase in the reaction state.
Furthermore, by increasing the temperature, by-products are easily generated, and the selectivity of ethylbenzene is reduced.

Therefore, the SiO ₂ / Al ₂ O ₃ ratio has an appropriate range, preferably from 12 to 100, and more preferably from 16 to 50. The β-type zeolite thus synthesized usually has a cation such as sodium, and this cation can be exchanged with another cation by a well-known ion exchange method. As such a cation, a multivalent cation such as magnesium or calcium, or a monovalent cation such as proton or cesium can be used. In the present invention, it is preferable to be activated by protonation using a mineral acid such as hydrochloric acid or nitric acid or an ammonium salt ion exchange method.

The raw material oil used in the present invention is a liquid that shows a liquid state at normal temperature and normal pressure, and is a mixture of benzene and paraffin or naphthene. As the paraffin or naphthene to be mixed, a hydrocarbon compound having 5 to 7 carbon atoms is used. The paraffin may be a linear compound or a branched compound as long as it has 5 to 7 carbon atoms. As long as the naphthene has 5 to 7 carbon atoms, its cyclic structure is not limited as long as the total carbon number does not exceed 7 even if an alkyl group is attached. Paraffin or naphthene having more than 7 carbon atoms easily causes a decomposition reaction during the present reaction, which causes a reduction in catalyst life. In addition, a paraffin or naphthenic hydrocarbon compound having 8 to 10 carbon atoms is not preferable because it is near the boiling point of ethylbenzene, which is a main product, so that the number of steps for separation and purification from ethylbenzene increases.

The mixing amount of paraffin and naphthene is not particularly limited. However, if the amount is too small, the selectivity of ethylbenzene is reduced. If the amount is too large, the efficiency of productivity of ethylbenzene decreases. From the above, it is possible to apply the ratio of paraffin or naphthene in the feed oil in the range of 10 to 70 wt%.

As a feedstock, a light catalytic reforming oil can also be used. The light catalytic reforming oil contains 20 to 70% by weight of paraffin and naphthene having 5 to 7 carbon atoms and 30 to 80% by weight of benzene, and is within the applicable range of the present invention. However, since the light catalytic reforming oil may contain unsaturated hydrocarbons having 5 or more carbon atoms, a composition in which unsaturated hydrocarbon compounds having 5 or more carbon atoms are not present as much as possible by a method such as hydrotreating in advance. It is preferable to keep it. Because
If unsaturated hydrocarbon compounds having 5 or more carbon atoms are mixed as impurities, the alkylation of benzene by these unsaturated hydrocarbon compounds proceeds, thereby reducing the selectivity of ethylbenzene in the product. This is because impurities cause acid point poisoning and shorten the catalyst life.

As ethylene supplied to the reaction system of the present invention, ethylene produced by the thermal decomposition of naphtha, ethylene contained in off-gas of FCC, and the like can be used.
However, ethylene obtained through these steps includes:
Since it contains unsaturated components such as propylene, it is preferable to use ethylbenzene separately to increase the selectivity of ethylbenzene.

The supply gas may be supplied by ethylene alone or diluted with a component inert to the reaction, for example, a component such as methane, ethane, propane, nitrogen, helium, argon and carbon monoxide.

The amount of ethylene supplied to the reaction system is determined by the amount of benzene in the feedstock. In an ordinary reaction of producing benzene with ethylene from benzene, an excess of benzene is used relative to the amount of ethylene. This is mainly because of the following purposes.

One is to suppress the formation of polyethylbenzene and increase the selectivity of ethylbenzene, and the other is to remove the reaction heat by treating benzene as a reaction solvent.

From such a background, the molar ratio of benzene to ethylene in the reaction system is more than 5, and usually, the molar ratio is usually about 7 to 10. However, in the present invention, the selectivity of ethylbenzene can be increased by mixing paraffin or naphthene into the feedstock oil, so that it is not necessary to suppress the production of polyethylbenzene by increasing the molar ratio of benzene to ethylene. In the reaction of the present invention, a part of the liquid phase is maintained, and the non-benzene component of paraffin and naphthene in the feedstock oil can absorb the heat of reaction. You don't have to. From such a viewpoint, the molar ratio of benzene to ethylene is preferably 2 or more and 5 or less.

In carrying out the present invention, the reaction system may be a batch system or a continuous system. However, in carrying out the present invention, a continuous reaction system is preferable in order to suppress a decrease in the selectivity of the reaction. As the continuous method, various reaction methods such as a fixed bed flow reactor, a fluidized bed reactor, a continuous tank reactor, a fixed bed reactive distillation reactor, a boiling bed reactor, and the like can be considered. Although the above reaction system can be applied, an upflow reaction system that is easy to maintain the liquid phase reaction is preferable. In particular, the fixed bed upflow reaction system is preferably used because the operation of the reaction is easy.

The reaction temperature is preferably a low temperature in order to partially maintain the liquid phase, but at least a temperature for alkylating ethylene at a sufficient rate with the catalyst used in the present invention is required. From such a viewpoint, the reaction temperature is 170 to 270.
C is a preferred temperature range.

As the reaction pressure, a pressure for maintaining a partial liquid phase at the above reaction temperature is used. From the viewpoint of promoting the selectivity of the present invention, a pressure range of 10 to 50 kg / cm ² is preferable.

[0029]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Example 1 (1) Preparation of β-type zeolite β-type zeolite was synthesized as follows. 40% aqueous solution of tetraethylammonium hydroxide in ion exchange water 27
0 g and sodium aluminate 26.4 g were added and stirred. 300 g of colloidal silica (Snowtex 40, manufactured by Nissan Chemical Industries, Ltd.) was added to this aqueous solution, and the mixture was vigorously stirred.
Here, the SiO ₂ / Al ₂ O ₃ ratio of the β-type zeolite was 16 at the time of charging.

This mixture was placed in a 1-liter titanium autoclave and reacted at 160 ° C. for 48 hours. After the reaction, the product was separated by filtration and washed with ion-exchanged water. After washing, it was dried at 110 ° C. for 16 hours and calcined at 530 ° C. for 3 hours. 20 g of the calcined β-type zeolite was immersed in 300 ml of a 1N ammonium nitrate aqueous solution in order to make it into a proton type, kept at 90 ° C. for 8 hours, exchanged the same solution, and repeated four times. The solution was filtered, dried at 110 ° C. for 16 hours, and calcined at 550 ° C. for 3 hours in an air atmosphere.

The β-zeolite thus prepared is hereinafter referred to as catalyst A. (2) Reaction example A 16/28 mesh quartz chip was filled in a stainless steel reactor having an inner diameter of 10 mm and a preheated portion as a fixed bed flow type reactor, and then tableted and then sized to 40/60 mesh. 4.00 g of the prepared catalyst A was charged, and 16 /
A 28-mesh quartz chip was filled to fix the catalyst layer. After the reactor was pressurized to 20 kg / cm ² while flowing argon gas at room temperature, the temperature of the catalyst layer was reduced to 2 kg / cm 2.
The temperature was raised to and kept at 00 ° C. Next, the feed oil and the feed gas whose feed pressure and feed rate were respectively adjusted were mixed at room temperature, and sent into the reactor from the lower part of the reactor. The feedstock used was a mixture of benzene and cyclohexane in a weight ratio of 40:60, and the feed gas used was a mixture of argon and ethylene in a volume ratio of 90:10 in advance.

At this time, the weight hourly space velocity (WHSV) of benzene in the feedstock oil per unit weight of the catalyst is:
1.0 h ^-1 and the molar ratio of benzene to ethylene is 2.
It was 5.

After starting the oil passing, it was confirmed that the feed oil and the supply gas reached the catalyst and the reaction temperature was increased.
The temperature was adjusted to 25 ° C.

The reaction product was extracted from the upper part of the reactor, and once separated into a gas component and a liquid component by a gas-liquid separator, and each was quantitatively analyzed by gas chromatography.

Table 1 shows the amounts of the feedstock oil, the supply gas, the reaction conditions, and the reaction results.

[0036]

[Table 1]

Comparative Example 1 (1) Reaction Example A fixed-bed flow reactor was charged with 4.00 g of the catalyst A, and the reaction was carried out in the same manner as in Example 1 except that the feed oil composition was 100% benzene. Table 2 shows the feedstock oil amount, the supply gas amount, the reaction conditions, and the reaction results.

[0038]

[Table 2]

Comparative Example 2 (1) Reaction Example Example 1 was repeated except that 4.00 g of the catalyst A was charged into a fixed bed flow type reactor, and feed oil and gas were supplied from the upper part of the reactor.
The reaction was carried out in the same manner as described above. Table 3 shows the feedstock oil amount, the supply gas amount, the reaction conditions, and the reaction results.

[0040]

[Table 3]

From Example 1 and Comparative Examples 1 and 2, when the reaction was carried out in a fixed-bed ascending flow system and naphthene (cyclohexane) having 6 carbon atoms coexisted in the feedstock, the molar ratio of benzene to ethylene supplied was It can be seen that even when the ratio is as high as 2.5, the amount of by-product diethylbenzene produced was as small as possible, and the selectivity for ethylbenzene in the reaction product was extremely high. Example 2 (1) Reaction Example Same as Example 1 except that 2.00 g of Catalyst A was charged into a fixed bed flow type reactor and the feedstock oil composition was a mixture of benzene and cyclohexane at a weight ratio of 80:20. Was performed. At this time, the weight hourly space velocity of benzene in the feedstock oil was WHSV = 2.0 h ⁻¹ , and the molar ratio of benzene to ethylene at the time of supply was 5.0. Table 4 shows the feedstock oil amount, the supply gas amount, the reaction conditions, and the reaction results.

[0042]

[Table 4]

Example 3 (1) Example of Reaction Example 1 was prepared by charging 2.00 g of Catalyst A into a fixed bed flow-type reactor and mixing benzene and cyclohexane in a feed oil composition at a weight ratio of 60:40. The same reaction as in Example 1 was performed. At this time, the weight hourly space velocity of benzene in the feedstock oil was WHSV = 2.0 h ⁻¹ , and the molar ratio of benzene to ethylene at the time of supply was 5.0. Table 5 shows the feedstock oil amount, the supply gas amount, the reaction conditions, and the reaction results.

[0044]

[Table 5]

Example 4 (1) Reaction Example 2.00 g of Catalyst A was charged into a fixed bed flow reactor, and benzene, normal hexane and normal heptane were mixed in a feed oil composition in a weight ratio of 80:10 to 10:10. The reaction was carried out in the same manner as in Example 1. At this time, the weight hourly space velocity of benzene in the feedstock oil is WHSV = 2.
0 h ⁻¹ , and the molar ratio of benzene to ethylene at the time of supply was 5.0. Table 6 shows the feedstock oil amount, the supply gas amount, the reaction conditions, and the reaction results.

[0046]

[Table 6]

Comparative Example 3 (1) Reaction Example 2.00 g of Catalyst A was charged into a fixed bed flow reactor, and the same reaction as in Example 1 was carried out using 100% benzene as a feed oil composition. At this time, the weight hourly space velocity of benzene in the feedstock oil was WHSV = 2.0 h ⁻¹ , and the molar ratio of benzene to ethylene at the time of supply was 5.0. Table 7 shows the feedstock oil amount, supply gas amount, reaction conditions and reaction results.
Shown in

[0048]

[Table 7]

[0049]

According to the method of the present invention, in the production of ethylbenzene using ethylene and benzene, polyethylbenzenes such as diethylbenzene can be suppressed as much as possible in the reaction product, so that the selectivity of the produced ethylbenzene is extremely high. Inexpensive production of ethylbenzene can be achieved with a simple apparatus configuration that does not require a transethylation reaction after the present alkylation reaction, which is performed in a normal reaction.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4H006 AA02 AC23 BA71 BC10 BC11 BC31 BC35 BD80 BJ50 DA12 DA25 FC52 4H039 CA12 CF10

Claims (9)

[Claims] 1. A method for producing ethylbenzene by reacting benzene and ethylene, wherein a continuous reaction system using a zeolite catalyst and maintaining a partial liquid phase is used, and paraffin or paraffin or benzene is used as a raw material oil in addition to benzene. A highly selective method for producing ethylbenzene, characterized in that the production of polyethylbenzene such as diethylbenzene is minimized by coexisting naphthene. 2. A continuous reaction system in which a partial liquid phase is maintained,
2. The method for highly selective production of ethylbenzene according to claim 1, wherein the method is an upflow method. 3. A continuous reaction system in which a partial liquid phase is maintained,
2. The method for highly selective production of ethylbenzene according to claim 1, wherein the method uses a fixed bed filled with a zeolite catalyst. 4. The process for highly selective production of ethylbenzene according to claim 1, wherein the carbon number of paraffin or naphthene coexisting in the feedstock is 5 to 7. 5. The method for highly selective production of ethylbenzene according to claim 1, wherein the ratio of paraffin or naphthene coexisting in the feed oil is in the range of 10 to 70% by weight. 6. The highly selective production of ethylbenzene according to claim 1, wherein the molar ratio of benzene in the feed oil to ethylene in the feed gas is in the range of 2 to 5. Method. 7. A reaction temperature of 170 to 270 ° C. and a reaction pressure of
10-50kg / cm ^TwoClaims characterized in that
Highly selective production of ethylbenzene according to any one of 1 to 6
Construction method. 8. The method for highly selective production of ethylbenzene according to claim 1, wherein the zeolite is of the β type. 9. A β-type SiO ₂ / Al ₂ O ₃ ratio of 16 to 50.
The method for highly selective production of ethylbenzene according to claim 8, wherein: