RU2136654C1 - Aniline production process - Google Patents

Abstract

FIELD: industrial organic synthesis. SUBSTANCE: vapor-phase hydrogenation of nitrobenzene into aniline is carried out at 180-280 C and atmosphere pressure on industrial cement-containing copper-zinc and copper-zinc-manganese oxide catalysts for low-temperature carbon monoxide conversion and gas emission treatment. Conversion of nitrobenzene is close to 100% and yield of aniline up to 99.6%. EFFECT: avoided requirement of specially prepared catalysts and reduced process temperature. 3 cl, 7 ex

Description

 The invention relates to methods for the production of aromatic amines, in particular aniline, by hydrogenation of nitrobenzene in the vapor phase.

 Aniline is widely used in industry as a raw material in the manufacture of dyes, pharmaceuticals, diisocyanates, additives to motor fuels and oils, chemicals for rubbers and other organic synthesis products.

A known method of producing aniline by hydrogenation of nitrobenzene in the vapor phase on a catalyst containing: (wt.%) Nickel 30-52; kieselguhr 23.4-38.6; tin oxide, antimony oxide, bismuth oxide (or a mixture thereof) - the rest, at a temperature of 300-350 ^o C and atmospheric pressure (USSR AS 551861/1 /). Under these conditions (after a special redox activation - stabilization of the catalyst at 350 ^o C) at a volumetric rate of nitrobenzene supply of 0.4 h ^-1 , nitrobenzene is hydrogenated in two reactor operation modes: in the initial period (144-250 hours), the molar ratio hydrogen: nitrobenzene 10-12, at the second stage, the molar ratio of the reactants is reduced to 4. The content of nitrobenzene in the catalyst does not exceed 0.06 wt.%; the interregeneration period of the catalyst is 400 hours.

The disadvantage of this method is: high hydrogenation temperature, which contributes to the formation of a significant amount of by-products, deterioration in the quality of the resulting catalysis and a decrease in the yield of aniline, the difficulty of implementing a dual mode of operation of the reactor, as well as the need to synthesize a special catalyst followed by redox activation (stabilization) in synthesis reactor at a temperature of 350 ^o C.

There is also known a method for producing aniline by reduction of nitrobenzene with hydrogen in the vapor phase on a catalyst containing, wt.%: Nickel 8.5-13.5; copper 1.2-1.7; tin (IV) oxide 3.8-15; the rest is aluminum oxide (Al ₂ O ₃ - calcined at 1100 ^o C); the hydrogenation process is carried out at a temperature of 260-430 ^o C, atmospheric pressure, with a volumetric feed rate of liquid nitrobenzene 0.5 h ^-1 and a molar ratio of hydrogen: nitrobenzene 10 (a. USSR 950718). Under these conditions, the inter-regeneration period of the catalyst reaches 215 hours, while the residual content of nitrobenzene in the catalyst does not exceed 0.01% / 2 /.

 The disadvantage of this method is the short inter-regeneration period of the catalyst, as well as high temperatures in the reaction zone, leading to a rapid loss of catalyst activity due to its tarring and coking, the formation of significant quantities of by-products and to the complication of the hardware design of the process associated with heat removal and the use of heat-resistant high temperature coolant.

 There is also known a method for producing aniline by high-temperature vapor-phase hydrogenation of nitrobenzene in the presence of nickel-copper-aluminum-vanadium catalyst B-3 (A.S. USSR 302333/3 /). This method is implemented in all plants of the Russian Federation producing aniline.

The hydrogenation process is carried out in a tubular reactor at a temperature in the catalyst layer of from 300 ^o C to 430-450 ^o C, atmospheric pressure, a volumetric feed rate of nitrobenzene of 0.2-0.5 hours ^-1 in excess of hydrogen. Under these conditions, almost complete conversion of nitrobenzene is achieved, the yield of aniline is about 96%, and a large number of by-products are formed. The catalyst operates continuously for 50-150 hours, after which it is regenerated by burning coke and resins with atmospheric oxygen and subsequent reduction (activation) of it with hydrogen.

 An explosive nitrite-nitrate mixture is fed into the annulus of the reactors at all of the above plants as a coolant.

 The disadvantages of this method are: the high temperature of the hydrogenation process, leading to a rapid loss of catalyst activity due to its coking and gumming; relatively low activity, productivity and selectivity of the used catalyst; short inter-regeneration cycle of his work; the need to use for heating the raw materials and removing heat the reaction of a high-temperature, explosive coolant (nitrite mixture), which in case of accidental contact with the raw materials or reaction products leads to explosive emergencies at the industrial plant for the synthesis of aniline.

Closest to the proposed is a method for producing aniline by hydrogenation of nitrobenzene in the vapor phase in the presence of a catalyst having the following composition, wt.%: Nickel 5-10; copper 1-3, chromium oxide (III) 1-3; titanium oxide 84-93; the process is carried out at a temperature of 240-300 ^o C, a molar ratio of hydrogen: nitrobenzene 10 and a volumetric feed rate of nitrobenzene 0.35 hour ^-1 . The catalyst is preliminarily reduced in a stream of hydrogen at a temperature of 350 ^° C. Under the indicated conditions, 98% selectivity for the formation of aniline is achieved, while the inter-regeneration period of the catalyst is at least 200 hours (AS USSR 525304/4 /).

 The disadvantage of this method are: high temperatures for the hydrogenation of nitrobenzene and reduction of the catalyst, the need to synthesize a special catalyst, its low activity and productivity, as well as the small inter-regeneration cycle of its operation.

 Common disadvantages of the methods for producing aniline described above are: low activity of the used catalysts, high temperatures of the nitrobenzene hydrogenation process, leading to rapid coking and gumming of the catalysts, a low inter-regeneration cycle of their operation, the need for frequent regeneration of catalysts with the replacement of hydrogen in hydrogenation plants with nitrogen and then air or a vapor-air mixture, which reduces the performance of these aniline synthesis plants, the safety of their operation and But it worsens their economic and environmental performance.

 The aim of the invention is to simplify the technology for producing aniline by using a ready-made more active industrial catalyst, lowering the reaction temperature, and increasing the active life of the catalyst.

The goals are achieved by hydrogenation of nitrobenzene on industrial oxide copper-zinc cement-containing catalysts for low-temperature conversion of carbon monoxide, for example, NTK-10 series, for example: NTK-10, NTK-10-1, NTK-10-2, NTK-10-2l, NTK-10 10-2 fm or oxide copper-zinc manganese cement-containing catalysts for the purification of gas emissions, for example, NTK-10-7 at a temperature of 180-280 ^o C and atmospheric pressure.

Used oxide copper-zinc cement-containing catalysts NTK-10, NTK-10-1, NTK-10-2, NTK-10-2l, NTK-10-2fm have the following composition, wt.%: CuO 27.0 - 51.0; ZnO 22.1-40.3; NiO 0.0-2.0; CaO 7.1-10.0; Al ₂ O ₃ 17.2-24.6 (Chemical industry, N 4, 1994, S. 29-35. TU 113-03-00209510-68-92, TU 113-03-00209510-44-89).

The oxide copper-zinc-manganese cement-containing catalysts of the NTK-10-7 series have the following composition, wt.%: CuO 32.0 - 42.4; ZnO 23.2-27.4; Mn ₃ O ₄ 0.5-14.0; CaO 7.6-10.3; Al ₂ O ₃ 17-22.1 (Specifications for the catalyst for purification of gas emissions TU 113-03-00209510-75-95).

 The desired product, aniline, is isolated from the catalyst by distillation.

 Under these conditions, almost complete conversion of nitrobenzene is achieved, the yield of aniline is up to 99.6%, the catalysts are tested for a duration of 310-430 hours and have not lost their activity.

Salient features of the proposed method for producing aniline are: the use of a finished industrial oxide copper-zinc cement-containing, thermostable catalyst for low-temperature conversion of carbon monoxide, for example, the NTK-10 series or oxide copper-zinc manganese cement-containing catalyst for cleaning gas emissions, for example, the NTK-10-7 series, and the process lower temperature 180 - 280 ^o C, which simplifies the technology of producing aniline by eliminating the stage of the production of a special catalyst, the recovery of a special catalyst and the process of hydrogenation of nitrobenzene at lower temperatures, as well as an increase in the period of active operation of the catalyst without regeneration.

 The use of cement-containing oxide copper-zinc and copper-zinc-manganese catalysts of the NTK-10 and NTK-10-7 series for the hydrogenation of nitrobenzene to aniline is not known, which allows us to consider this feature as new.

 The industrial applicability of the proposed method is confirmed by the following examples.

Example 1. In a tubular reactor made of stainless steel, load 50 ml of industrial catalyst NTK-10 of the following composition, wt.%: CuO 41.2; ZnO 30.8; CaO 7.3; Al ₂ O ₃ 20,7 and restore in a stream of hydrogen at a temperature of 240 ^o C.

After cooling the catalyst to 180 ^o C, hydrogenation of nitrobenzene at atmospheric pressure, a volumetric feed rate of liquid nitrobenzene of 0.5 hour ^-1 and a molar ratio of nitrobenzene: hydrogen = 1: 10 are carried out at this temperature, controlling the temperature in the “hot” spot of the catalyst is not above 250 ^o C.

 The raw material in this process is technical nitrobenzene, corresponding to TU 6-36-0204208-107-89, used in the industry for synthesis and containing a small amount of trace elements of benzene, nitrotoluenes, dinitrobenzene, nitrophenol and water.

 The resulting catalyzate contains 72.08 aniline, 27.60 water, 0.01 benzene, 0.03 toluidines, 0.27 high boiling point by-products (WFP) and 0.007 nitrobenzene.

 Toluidines and runways are formed in this process due to the hydrogenation of impurities contained in nitrobenzene - isomers of nitrotoluene, dinitrobenzene and nitrophenol, as well as due to other adverse reactions.

 The conversion of nitrobenzene is almost complete, the yield of aniline is 96.6%.

 The catalyst was tested for a duration of 430 hours and did not lose its activity.

Example 2. In a tubular reactor load 50 ml of industrial catalyst NTK-10-1 of the following composition, wt.%: CuO 42.1; ZnO 31.0; NiO 2.0; CaO 7.1; Al ₂ O ₃ 17.8.

The catalyst is reduced in a stream of hydrogen at a temperature of 240 ^o C.

Hydrogenation of nitrobenzene at a molar ratio of nitrobenzene: hydrogen = 1:10 and a volumetric feed rate of liquid nitrobenzene of 0.5 h ^-1 are carried out above the catalyst at a temperature of 180 ^o C, while the maximum temperature in the "hot" point of the catalyst does not exceed 250 ^o C.

 Under these conditions, catalysis is obtained containing 72.05% aniline, 27.45% water, 0.01% benzene, 0.02% toluidines, 0.46% runway and 0.005% nitrobenzene.

 The conversion of nitrobenzene is almost complete, the yield of aniline is 99.4%.

 The catalyst worked for 365 hours and did not change its activity.

Example 3. In a tubular reactor load 50 ml of industrial catalyst NTK-10-2l of the following composition, wt. %: CuO 27.0; ZnO 40.3; CaO 8.1; Al ₂ O ₃ 24.6.

The catalyst is reduced in a stream of hydrogen at a temperature of 240 ^o C.

The process of hydrogenation of nitrobenzene is carried out at a temperature of 200 ^o C, the volumetric feed rate of nitrobenzene 0.3 hour ^-1 and a molar ratio of nitrobenzene: hydrogen = 1:10.

In the hydrogenation process, the maximum temperature in the "hot" point of the catalyst is controlled, which does not exceed 250 ^o C.

 The resulting catalyzate contains, wt.%: 72.03% aniline, 27.56% water, 0.01% benzene, 0.02% toluidines, 0.35% runway and 0.007% nitrobenzene.

 The conversion of nitrobenzene is almost complete, the yield of aniline is 99.5%, the catalyst was tested for a duration of 372 hours and did not lose activity.

Example 4. In a tubular reactor load 50 ml of industrial catalyst NTK-10-2 of the following composition, wt.%: CuO 44,0; ZnO 31.8; CaO 7.0; Al ₂ O ₃ 17.2.

The catalyst is reduced in a stream of hydrogen at a temperature of 240 ^o C.

Hydrogenation of nitrobenzene over this catalyst is carried out at a temperature of 180 ^o C, a volumetric feed rate of nitrobenzene of 0.8 hour ^-1 and a molar ratio of nitrobenzene: hydrogen = 1:10.

In the process of hydrogenation, the temperature in the "hot" point of the catalyst reaches 280 ^o C due to the exothermicity of the reaction.

 The resulting catalyzate contains, wt.%: 72.0% aniline, 27.7% water, 0.01% benzene, 0.03% toluidines, 0.25% runway and 0.006% nitrobenzene.

 The conversion of nitrobenzene is almost complete, the yield of aniline is 99.6%.

 The catalyst was tested for a duration of 324 hours and did not lose its activity.

Example 5. In a tubular reactor load 50 ml of industrial catalyst NTK-10-2fm of the following composition, wt. %: CuO 51.0; ZnO 22.1; CaO 7.2; Al ₂ O ₃ 19.7.

The catalyst is reduced in a stream of hydrogen at a temperature of 240 ^o C.

Above the catalyst at a temperature of 180 ^o C, a volumetric feed rate of nitrobenzene of 0.8 hour ^-1 and a molar ratio of nitrobenzene: hydrogen = 1:10, the process of hydrogenation of nitrobenzene is started, and due to the exothermicity of the process, the temperature in the "hot" point of the catalyst reaches 280 ^o C The catalyst contains 72.04% aniline, 27.48% water, 0.01% benzene, 0.02% toluidines, 0.44% runway and 0.005% nitrobenzene.

 The conversion of nitrobenzene is almost complete, the yield of aniline is 99.4%.

 The catalyst worked in this process for 320 hours and did not lose its activity.

Example 6. In a tubular reactor load 50 ml of industrial catalyst NTK-10-7 of the following composition, wt. %: CuO 32.0; ZnO 23.2; Mn ₃ O ₄ 14.0; CaO 10.3; Al ₂ O ₃ 20.5.

The catalyst is reduced in a stream of hydrogen at a temperature of 240 ^o C.

Hydrogenation of nitrobenzene is carried out above the catalyst at a temperature of 180 ^° C. The volumetric feed rate of nitrobenzene is 0.3 hour ^-1 , the molar ratio of nitrobenzene: hydrogen = 1:10. In the process of hydrogenation control the temperature in the "hot" point of the catalyst, which should not exceed 240 ^o C.

 The resulting catalyzate contains, wt.%: 72.0% aniline, 27.80% water, 0.01% benzene, 0.02% toluidines, 0.15% runway, 0.02% nitrobenzene, nitrobenzene conversion 99.99% aniline yield of 99.8%.

 The catalyst was tested for a duration of 350 hours and did not change its activity.

Example 7. The catalyst of the NTK-10-7 series of the following composition, wt.%: CuO 42.4, ZnO 27.4; Mn ₃ O ₄ 0.5; CaO 7.6; Al ₂ O ₃ 22.1.

 The catalyst is reduced in a stream of hydrogen at a temperature of 240.

The process of hydrogenation of nitrobenzene begins at a temperature of 180 ^o C, a volumetric feed rate of nitrobenzene of 0.8 hour ^-1 and a molar ratio of nitrobenzene: hydrogen = 1:10, while due to the exothermicity of this reaction, the temperature in the "hot" point of the catalyst reaches 280 ^o C.

 The resulting catalyzate contains 72.01% aniline, 27.62% water, 0.1% benzene, 0.02% toluidines, 0.34% runway and 0.008% nitrobenzene.

 The conversion of nitrobenzene is about 100%, the yield of aniline is 99.5%.

 The catalyst was tested for a duration of 310 hours and did not lose its activity.

Sources of information
1. USSR author's certificate N 551861, 1977

 2. Copyright certificate N 950718 B.I. 1982, No. 30, MKI C 07 C 87/52, B 01 J 23/74 (RLC 12H158P, 1983).

 3. Copyright certificate of the USSR N 302333, MKI C 07 C 211/46.

 4. Copyright certificate of the USSR N 525304, B.I. 1984, No. 15, MKI C 07 87/52.

 5. Chemical industry. N 4, 1994, p. 29-35.

6. Specifications for the catalyst for the conversion of carbon monoxide NTK-10 series
TU 113-03-00209510-68-92
TU 113-03-00209510-44-89
7. Specifications for the catalyst for purification of gas emissions TU 113-03-00209510-75-95.

Claims (2)

1. The method of producing aniline by hydrogenation of nitrobenzene in the vapor phase at an elevated temperature on a copper-containing catalyst, followed by separation of the target product from the catalysis by distillation, characterized in that the copper-containing catalyst is a copper-zinc oxide catalyst for low-temperature conversion of carbon monoxide or oxide catalyst-gas-zinc-carbon catalyst and the process is carried out at 180 - 280 ^o C. 2. The method according to claim 1, characterized in that as the oxide of copper-zinc cement-containing catalyst using a catalyst composition, wt.%:
CuO - 27.0 - 51.0
ZnO - 22.1 - 40.3
NiO - 0 - 2.0
CaO - 7.1 - 10.0
Al ₂ O ₃ - 17.2 - 24.6
3. The method according to p. 1, characterized in that as the oxide of copper-zinc manganese cement-containing catalyst using a catalyst composition, wt.%:
CuO - 32.0 - 42.4
ZnO - 23.2 - 27.4
Mn ₃ O ₄ - 0.5 - 14.0
CaO - 7.6 - 10.3
Al ₂ O ₃ - 17 - 22.1