JPS62153260A - Production of p-phenylenediamine - Google Patents

Abstract

PURPOSE:To obtain a compound useful as a dye, rubber chemical, heat-resistant wholly aromatic polyamide raw material, etc., in good yield while suppressing formation of by-products, by subjecting p-aminoazobenzene to catelytic hydrogenolysis in an aniline solution using a catelyst-filled column type reactor. CONSTITUTION:Hydrogenolysis reaction is carried out at 80-180 deg.C under 4-25kg/cm<2>G, preferably 100-170 deg.C under 5-20kg/cm<2>G while containuously feeding a solution of p0-aminoazobenzene in aniline and hydrogen gas from the bottom of a vertical and cylindrical reactor filled with a reducing catalyst, e.g. Pd, Ni, etc., to continuously give the aimed substance as an aniline solution from the top of the above-mentioned reactor. The solution of the p- aminoazobenzene in aniline is obtained by diazo coupling aniline to give diazoaminobenzene and rearranging the resultant diazoaminobenzene.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a method for producing jLp-phenylenediamine (hereinafter referred to as pPDA) by catalytic hydrogenolysis of p-aminoazobenzene (hereinafter referred to as pAAB). Regarding. More specifically, using a catalyst-packed tower type reactor,
The present invention relates to a process for producing p-phenylenediamine by continuous catalytic hydrogenolysis of p-aminoazobenzene in the liquid phase in an aniline reaction medium.

pPDA, which is produced by the catalytic hydrogenation reaction of pAAB, has been used for a long time in the dye industry and rubber chemical industry, and has recently been used as a raw material for heat-resistant wholly aromatic polyamides, and has important industrial uses. .

(Prior art, problems to be solved by the invention) pPDA
Many methods have been introduced to produce 'i-, but one of the production methods that seems to be economically advantageous is to obtain diazoaminobenzene by diazotization coupling of aniline, and then rearrange it. There is a method of catalytic hydrogenolysis of pAAB obtained by

In this method, the hydrogenolysis reaction can also be carried out using a solvent other than aniline, such as alcohol, as a reaction medium. However, the synthesis of pAAB from aniline is usually carried out using an excess of aniline. Furthermore, as shown in the above reaction formula, by the hydrogenolysis reaction of pAAB,
Aniline is produced as a by-product along with pPDA. Therefore, in actual industrial large-scale processes, it is considered preferable to use aniline as a reaction medium in the hydrogenolysis reaction step.

The catalytic hydrogenolysis of pAAB using aniline as a reaction medium can be carried out in either a batch method or a continuous method. However, on an industrial scale, continuous mode is the preferred configuration.

When performing a liquid-phase hydrogenation reaction in a continuous manner, a catalyst-packed column type reactor is used to supply both the raw material liquid and hydrogen gas from the top of the reactor (hereinafter this method is referred to as the gas-liquid downward parallel flow method). ) is commonly used.

An example of a method for synthesizing pPDA' by hydrogenolyzing pAAB in a continuous manner using aniline as a reaction medium is shown in JP-A-57-122047. The reaction is carried out using a gas-liquid downward parallel flow system using a reactor. However, it is said that the higher the reaction pressure, the more advantageous the catalytic hydrogenolysis of aniline is. However, in the above publication, 207 (lK
It is stated that a pressure of Pa (approximately 22 Kg/d) or higher is required, and 5 to KPa (55,7 Ky/crl)
Although examples of reactions have been shown, good results have not always been obtained despite the reaction being carried out under high pressure.

As a result of intensive research into continuous hydrogenolysis reactions of pAAB in a gas-liquid descending parallel flow system using a commonly used catalyst-packed column type reactor, the present inventors discovered the following problems. Ta.

That is, pAAB is catalytically hydrogenolyzed using aniline as a reaction medium in the presence of a catalyst such as platinum, palladium, -dium, nickel, etc. at 80° C. to 200° C. under a pressure of 100 atmospheres or less to synthesize pPDA. The reaction is known.

However, when the reaction is carried out in a fixed-bed continuous catalytic hydrogenation method using known catalysts, reaction temperatures, and reaction pressure conditions, in the gas-liquid downward parallel flow method, if the flow rates of raw material liquid and hydrogen gas are increased, There is a tendency for the pAAB reaction rate to decrease, and this tendency increases significantly when the reactor internal diameter and catalyst size increase. Industrial-scale production requires relatively large reactor internal diameters and catalyst sizes, and this trend is a major problem.

This reduction in the reaction rate of pAAB is achieved by adjusting the space velocity and reducing the flow rate of the raw material liquid and hydrogen gas.
This can be avoided, but on the other hand, the space-time yield will decrease.

Therefore, when increasing the scale of the apparatus, it is difficult to maintain both a high reaction rate and a high space-time yield of pAAB.

Furthermore, in the gas-liquid descending parallel flow method, the by-products N-cyclohexylaniline (hereinafter referred to as CHA) and N-fuclo-xyl-p-phenylenediamine (hereinafter referred to as CH
(denoted as PD) is likely to be produced, and this tendency is particularly noticeable when the inner diameter of the reactor becomes large and the catalyst size becomes large.

In other words, when attempting to produce pPDA by hydrogenolyzing pAAB using an industrial-scale gas-liquid descending parallel flow reactor, the space-time yield is low, and furthermore, many by-products are produced due to side reactions. There's a problem.

The present invention solves the problems in the prior art described above, maintains a high reaction rate, and improves the space-time yield in a method for producing pPDAt by subjecting a 7=yn solution of pAAB to a catalytic hydrogenolysis reaction. The object of the present invention is to provide a method for continuously producing p-phenylenediamine (pPDA') at a high yield, which is suitable for an industrial production method that simultaneously achieves improvement and suppression of by-product production.

(Means for solving the problem 'fc) The present inventors aimed to solve the above-mentioned drawbacks of the conventional method and develop an industrially advantageous method for producing pPDA from pAAB by continuous catalytic hydrogenolysis. As a result of intensive research, the above-mentioned knowledge was obtained, and the present invention was achieved based on this new knowledge.

That is, the present invention provides a method for producing p-phenylenediamine by subjecting an aniline solution of p-74-7-zobenzene to a catalytic hydrogenation reaction to hydrogenolyze p-7-7-7-zobenzene. From the bottom of the type cylindrical reactor.

A hydrogenolysis reaction is carried out while continuously supplying an aniline solution of p-7i-7zobenzene and hydrogen gas,
- A method for producing p-phenylenediamine, which is characterized in that phenylenedi7mine is continuously taken out from the upper part of the reactor as an aniline solution.

In the present invention, the continuous reaction method in which both the raw material liquid and gas are supplied from the lower part of the cylindrical reactor and the reaction product liquid and excess gas are taken out from the upper part is called the gas-liquid rising parallel flow method. write down

The 7=yin solution of pAAB used in the method of the present invention is not particularly limited, but may be a mixture of pAAB and aniyne prepared separately, or a diazotized solution of aniline in excess of aniline by a conventional method. ring to synthesize diazoaminobenzene, and then rearrange this diazo7minobenzene to obtain an aniline solution containing pAAB'. Of these, the latter is desirable industrially. In the latter case, O-aminoazobenzene (hereinafter referred to as oAAB), which is produced as a by-product during the reaction, coexists; however, in the case of the present invention, even if oAAB coexists, there is no adverse effect on the hydrogenolysis reaction. oAAB is similarly hydrogenolyzed to produce 0-phenylenediamine (hereinafter referred to as oPDA).
) is obtained.

In the latter case, it is preferable to remove impurities such as acids in the raw material liquid in advance by pretreatment such as washing with water or washing with an alkaline aqueous solution.

The pAAB concentration in the raw material liquid supplied to the catalyst packed bed is as follows:
There is no particular restriction, and in practical equipment, pA
The concentration is determined in consideration of the solubility of AB and pPDA in aniline, the ability to remove reaction heat, and the like. In practice, the pAAB concentration is usually about 2 to 40 Wt96.

The countercurrent method, in which the catalyst layer is in the liquid continuous phase state, has the disadvantage of complicating the operation to maintain the liquid continuous phase state in the reactor, but good results can be obtained to some extent. However, the present invention does not include a countercurrent system.

The reactor may be of a commonly used fixed bed catalyst packed column type, and is not particularly limited, but since the reaction is exothermic, it is preferably of a type that can remove the generated heat. Further, the shape of the reactor may be cylindrical, but it is preferable that the cross section perpendicular to the long axis direction is substantially circular, but it may be oval or elliptical close to a circle. Moreover, a large number of tubes may be provided in the reactor.

A normal reduction catalyst is used as the catalyst.

A palladium catalyst and/or a nickel catalyst is preferably used, but metal group catalysts such as platinum and rhodium, cobalt catalysts, copper chromite catalysts, etc. may also be used. These catalysts are prepared by supporting a metal component such as a palladium component or a nickel component on a support inert to the reaction, such as carbon, silica, alumina, and diatomaceous material. Note that each metal component and each metal compound are used as each metal component. Typical examples of commercially available catalysts include o, 5wtc) 5 palladium-supported silica, 0.5wt96 palladium-supported alumina, o, 5wt
96 Palladium-supported carbon (both manufactured by Nippon Engelnord Co., Ltd.) and nickel catalyst N-111 (8
(manufactured by Volki Kagakusha).

The shape and size of the catalyst are appropriately selected depending on the size of the reactor. Generally, the catalyst used is shaped into a pellet shape, a spherical shape, a hollow cylindrical shape, or the like. The size is normal size, usually 1 to 10.
It is about 1 silk, preferably about 2.5 to 6 silk.

The reaction conditions are the same as in conventional methods, but the catalyst used is selected so that it exhibits high activity. For example, when a palladium catalyst or a nickel catalyst is used, the reaction temperature is 80°C to 180°C, preferably 100°C to
It is assumed to be 170℃. The reaction is carried out at a temperature within this range, taking into consideration the heat generated by the reaction and removing heat as necessary. If the temperature is lower than this, the reaction progresses slowly, and if it is higher, the amount of by-products increases.

The reaction pressure is 4 to 25 KII/ff1G, preferably 5
~20Kf/adG. At a pressure lower than this, the reaction progresses slowly, and although it is possible to carry out the reaction at a pressure higher than this, it is not particularly advantageous in terms of effectiveness and economy.

The space velocity of the raw material liquid and hydrogen gas supplied to the catalyst bed is appropriately selected depending on the inner diameter of the reactor, the size of the catalyst, the height of the catalyst packed bed, etc.

The reaction can be carried out in a single pass or in multiple passes, although the space velocities of the feed liquid and hydrogen gas will vary depending on such embodiments.

As described above, the space velocity can be varied within a wide range, but in practice, the LH3V (liquid hourly space velocity) is 0.5 to 10 Hr.

The amount of hydrogen gas supplied to the catalyst bed varies depending on the height of the catalyst packed bed, but the amount of hydrogen gas supplied to the catalyst bed varies depending on the height of the catalyst packed bed.
The amount of hydrogen is in excess of the theoretical amount of hydrogen required for hydrogenolysis, and is usually 1.1 to 5 times the amount. As the height of the catalyst packed bed increases, the required supply amount of hydrogen gas becomes relatively smaller, but if an excess amount of gas is supplied, the pAA
The reaction rate of B can be increased.

The gas exhausted from the top of the reactor is excess hydrogen gas, which can be reused if necessary.

(Example) The present invention will be explained in more detail with reference to Examples. However, it goes without saying that the present invention is not limited to the examples.

Example 1 (A) Synthesis of pAAB Glass-lined product equipped with stirrer and thermometer +7) 50
01 Aniline 283 and oK4 were charged in a reactor with a jacket, and 3596 hydrochloric acid 48.7Kf was added while stirring and cooling.
added.

After adding hydrochloric acid, continue adding sodium nitrite 26. 2Kg
An aqueous solution of 4F in 50% water was added over about 2 hours while maintaining the temperature in the reactor below 20°C by cooling.

After the addition of sodium nitrite was completed, stirring was continued for 15 minutes at a liquid temperature of 20°C to obtain a reddish yellow slurry containing diazoaminobenzene.

Next, this slurry was heated to 50'C over 30 minutes, and a rearrangement reaction was carried out at 48-50C for 45 minutes. The reaction solution became a reddish-brown homogeneous solution. In order to complete the reaction, the temperature was raised to 70°C over an additional 30 minutes, and stirring was continued at 70°C for 15 minutes to complete the reaction.

This reaction product liquid was cooled and added with 35Wt96NaOH.
Aqueous Solution 10.7 Nori was added and stirred, then allowed to stand, the aqueous layer was separated, and the acid content was removed.

Furthermore, 60 ml of water was added to this oil layer and mixed by stirring.
This mixture was passed through a column filled with glass wool, and then separated into an aqueous layer and an oil layer.

In this way, pAABt-containing aniline solution 29
3Ke was obtained.

When this aniline solution was analyzed by gas chromatography, the pAAB concentration was 25.2 wt%, and the oAA]311 degree was 2.0 wt96.

(B) Synthesis of pPDA by hydrogenolysis reaction of pAAB A system in which the entire aniline solution of pAAB obtained in the above figure is supplied from the bottom of the reactor using a packed column-type continuous catalytic reduction device with the raw material liquid and hydrogen gas. A hydrogenolysis reaction of pAAB was carried out by bringing it into contact with a catalyst (gas-liquid rising cocurrent flow system).

The reactor is 28 mm x 100100 with jacket.
This was filled with 0.5wt% palladium-supported silica catalyst (manufactured by Nippon Engelhard Co., Ltd.) 490- as a catalyst (filling height approximately 80 cIn).
).

While hydrogen is not supplied from the lower part of the reactor, the reactor is heated with a heating medium to bring the temperature of the catalyst layer to about 115°C, and the pressure inside the reactor to i7. The hydrogen gas supply amount was adjusted so that the outlet gas flow rate was 85 NJ/Hr while maintaining the hydrogen gas at OK4/dG. Next, the pAA obtained with the (N)
The aniline solution of B was fed from the bottom of the reactor at a rate of 1100.9/Hr to start the reaction.

The reaction generates heat, but the temperature of the catalyst layer is 120℃~1
Preheating of the hydrogenation raw material liquid and cooling of the catalyst layer were adjusted so that the temperature was 30° C., and the reaction was carried out while maintaining the pressure cuff, aKg/adG, and outlet gas amount at 85 Nl/Hr.

One hour after the start of supply of the raw material liquid, the reaction reached a steady state, but 5500 g of an aniline solution of pAAB was then supplied for another 5 hours, during which time 5510 g of the reaction product liquid was supplied.
9 was discharged from the top of the reactor.

Feed liquid volume was LH3V 2.24. Also,
The amount of hydrogen gas supplied is equivalent to 2.35 times the theoretical required 4 tons.

The gas discharged from the upper part of the reactor was discharged to the outside of the apparatus via a gas-liquid separator, a cooler, and an outlet gas flow meter.

When the obtained reaction product liquid was analyzed by gas chromatography, no residual pAAB and oAAB were observed, and the concentrations of pPDA and 0PDA were 12.44, respectively.
wt% and 1.06 wt%. C as a by-product
HA and CHPD were not observed.

pAAB and oAAB contained in the feedstock liquid
Standard yields are pPDA9B, 0% and oP, respectively.
DA 96,896. The space-time yield is 280. j
9-pPDA//-cat-Hr, 24g-oPDA/
1-cat・Hr, total 304. ! i+/)・c
at-Hr.

Comparative Example 1 An aniline solution of pAAB obtained in the same manner as in Example 1(A) was brought into contact with hydrogen and a palladium catalyst in a gas-liquid downward cocurrent flow system using a packed column type continuous catalytic reduction apparatus. A hydrogenolysis reaction of pAAB was carried out.

As the reactor, the reactor used in Example 1(B) was used, with the gas-liquid introduction line and the discharge line serving as the upper and lower parts, respectively.

The same amount of the same catalyst as in Example 1(B) was used as the catalyst.

The reaction operation was the same as in Example 1 (B) except that the gas-liquid inlet was changed to the upper part, and the temperature of the catalyst layer was 120'C to 120'C.
50℃, pressure cuff, OK9/cdG, supply liquid ff1110
0g/Hr, exit gas flow! All reactions were carried out with Kffi set to 85 Nl/I (r).

At steady state, p of 5X5[10,9 during 5 hours
An aniline solution of AAB is fed to the reactor during which 5
5027 reaction product liquids were obtained.

When the reaction product solution was analyzed, the concentration in the solution was pAAB
7.42wt%%oAAB 0066wt%, p
PDA 8.23wt% and 0PDA 0.7
It was 0wt%. By-products CHA and CHPD
The concentrations of are 0;18 wt96 and 0.21W, respectively.
It was tg46.

The reaction rate was pAAB 6B96, oAAB 67%, and the pAAB and oAAB contained in the feed liquid were
The yield based on AAB was 64.7% for pPDA and 64.7% for oPDA.
65,896.

Space-time yield 185.9-pPDA/l・c, a
t-Hr 116g-oPDA/J-cat-Hr.

The total amount was 201 g/1-cat・LIr.

In Example 1 (B), the pAAB reaction rate was 100%, whereas in this comparative example, the pAAB reaction rate was 6.
The space-time yield was low at 8%, and the space-time yield was also low.

Example 2 2. SyRm
× 2.5 nickel catalyst (crushed N-111 catalyst made by Kiyoshi Kagaku Co., Ltd.) The same operation as in Example 1 (B) was carried out except that 490 d was filled.
Using the aniline solution of pAAB obtained in the same manner as in A) as a raw material liquid, a hydrogenolysis reaction of pAAB was carried out in a gas-liquid ascending parallel flow system.

First, a reactor was filled with a catalyst, and the catalyst was subjected to reduction activation treatment at 190° C. for 3 hours at normal pressure and a space velocity of about 50 Hr. Next, adjust the temperature of the catalyst layer to 160℃~17℃.
0℃, pressure 15/dG, exit hydrogen gas flow rate 8O
The raw material solution was supplied to the lower part of the reactor at a rate of 1000 g/Hr, and the reaction was carried out while adjusting the supply amount of hydrogen gas so that the ratio was Nl/Hr.

A raw material solution of sooog was supplied to the reactor in a steady state for 5 hours, and a reaction product solution of 5oosy was obtained.

The concentration in the reaction product solution is pPDA 12.26wt%
, oPDA was 1.04 wt%.

No residual pAAB or oAAB was observed in the reaction product solution, and almost no CHA and CHPD were detected. The pPDA yield relative to pAAB present in the raw material solution was 96.5%, relative to 0AAB. PDA yield was 94.
Chill at 8%.

The space-time yield is 250 g-p PDA/l-ca
t-Hr.

21,! Corresponds to i'-oPDA/1-cat-Hr.

Example 3 Except that the reactor was changed to a 50g1×1500mm one,
In the same manner as in Example 1 (B), a hydrogenolysis reaction of the aniline solution of pAAB obtained in the same manner as in Example 1 (AJ) was carried out.

As a catalyst, O, 5wt96 palladium-supported silica five-eyed spherical catalyst (manufactured by Nippon Engelnord Co., Ltd.) 2500
1117 was filled.

The pressure inside the reactor was 8, OKq/cr/IG, the outlet gas amount was 50ONl/Hr, and the temperature of the catalyst layer was '1201.
69009 in terms of raw material liquid supply amount while maintaining c ~ 135°C
/Hr.

In a steady state, a raw material liquid of 34.5 Kq was supplied to the reactor for 5 hours, and a reaction product liquid of 34.6 Kq was obtained.

The concentration in the reaction product solution is pPDA 12.45wt%
, oPDA was 1.05 wt%.

No residual pAAB or oAAB was observed, and almost no by-products of CHA and CHPD were observed.

The yields for pAAB and oAAB contained in the raw material solution were 98.2% for pPDA and 98.2% for oPDA, respectively.
It was 96,096.

Space-time yield is 545g-pPDA/1-cat・Hr
, 299-o PDA/J-cat-Hr.

Comparative Example 2 Reaction used in Example 3'! h'f: The gas-liquid supply and discharge lines were rearranged to adopt a gas-liquid descending parallel flow system, and the reaction was carried out using this.

The same catalyst and the same amount as in Example 3 were used, and the raw material solution obtained in the same manner as in Example 1 was used.

The raw material liquid supply jt is about 5000.9/Hr, the outlet gas amount ft55Nl/Hr, and the temperature of the catalyst layer is 120℃~1
The reaction was carried out at 35° C. and the pressure was adjusted to 8,000 kg/di G.

In steady state, 15.00 Kg of raw material liquid was supplied to the reactor in 5 hours, and 15,011 (9) reaction product liquid was obtained.

The concentration in the reaction product solution was pAAB 5.05 wt%,
oAAB 0.47wt96. pPDA 9゜55
wt96, oPDA o, 78wt%, (jlAo,
18 wt% and CHPD 0.23 wt%.

Reaction rate: pAAB 78.296, oAAB 76.4
%, pPD relative to pAAB present in the raw material solution
A yield is 73.6%, based on oAAB. PDA yield is 71,296.

The space-time yield is 112 &-pPDA/1-cat Hr%
Corresponds to 9g-o PDA/J-caiHr.

Although the amount of liquid and gas supplied to the reactor was increased,
The reaction rate tended to be low.

Comparative Example 5 Using exactly the same equipment as that used in Comparative Example 2, the raw material solution was supplied to the reactor: lk2000. ! pAAB7 obtained in the same manner as in Example 1(A) in the same manner as in Comparative Example 2, except that il/Hr and the outlet gas amount were set to 5 Nl/Hr.
two! All reactions were carried out using J.

In a steady state, 10.0 OK9 raw material liquid was supplied to the reactor in 5 hours, and 9 reaction product liquid was obtained in 10.01 hours.

The concentration in the reaction product solution is pAAB 1.11wt96
, oAAB 0.10wt96, pPDAl 1.0
4wt96, oPDA O, 94wt5%, CHA
0.21 wt% and CHP D 0 .

It was 78wt%.

The reaction rate was pAAB 95,296, o AA895.
0%, the yield relative to pAAB present in the reaction solution was 88.
9-pPDA/A'-cat-Hr, 89-o
Corresponds to PDA/l-cat-Hr. By lowering the space velocity, the reaction rate improved, but the space-time yield decreased.

Example 4 The same procedure as in Example 5 was carried out except that the reactor was changed to a 50 mg x 2000 yen reactor, and the hydrogenolysis reaction of the pA A B 7 = yine solution obtained in the same manner as in Example 1 (A) was carried out. I did it.

As a catalyst, 4ffill of 0.5wt% palladium-supported alumina! I X 41Xill Hellet-like M
A medium (manufactured by Nippon Engel Co., Ltd.) 3500- was filled.

The pressure of the reactor was 104/dG, and the outlet gas amount was 55ONl/
The reaction was carried out at a feed rate of 8.00 hr and 9/hr while adjusting the temperature of the catalyst layer to 120°C to 135°C.

In a steady state, 40.0 OK4 raw material liquid was supplied to the reactor in 5 hours, and 4 OK4 reaction product liquid was obtained in 40.15 hours.

The concentration in the reaction product solution is pPDA 12.43wt9
6, oPDA 1,07Wt96.

No residual pAAB or oAAB was observed, and CHA and CHP D by-products V! There were only traces.

The yield of pPDA relative to pAAB present in the raw material solution was 97,796, relative to oAAB. The yield of PDA is 97
,696. Space-time yield, 2s4g-pPDA/A
'-cat-Hr, 24. q-o PDA/ 1-
Corresponds to cat-Hr.

(Effects of the Invention) According to the method of the present invention, compared to the conventional continuous hydrogenolysis reaction of pAAB using a gas-liquid descending co-current method, the space-time yield is significantly higher, and the production of by-products is completely suppressed. However, in high yield, pAAB to pPDA? It can be manufactured.

This effect becomes more pronounced as the inner diameter of the reactor becomes larger and as the catalyst becomes larger.

Patent applicant: Mitsubishi Gas Chemical Co., Ltd. People's representative Kazuyoshi Nagano

Claims (1)

[Claims] In a method for producing p-phenylenediamine by hydrogenolyzing p-aminoazobenzene by subjecting an aniline solution of p-aminoazobenzene to a catalytic hydrogenation reaction, , a hydrogenolysis reaction is carried out while continuously supplying an aniline solution of p-aminoazobenzene and hydrogen gas, and p-phenylenediamine is continuously taken out from the upper part of the reactor as an aniline solution. -Production method of phenylenediamine