RU2408573C1 - Method of producing dicyclohexylamine from cyclohexylamine - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a novel improved method of producing dicyclohexylamine, which is used in production of atmospheric corrosion inhibitors, general purpose rubber-based efficient rubber vulcanisation accelerators from cyclohexylamine, involving catalytic disproportionation of cyclohexylamine in the presence of hydrogen at 160-200°C in gaseous phase in a flow reactor on a hydrogen-reduced copper-zinc-chromium-aluminium catalyst.

EFFECT: method simplifies the process and increases output of the end product.

1 cl, 9 ex

Description

The invention relates to a method for producing dicyclohexylamine from cyclohexylamine in the gas phase at atmospheric pressure in a stream of hydrogen on a heterogeneous copper-zinc-chromium-aluminum catalyst. Dicyclohexylamine is used in the production of atmospheric corrosion inhibitors, effective rubber vulcanization accelerators based on general-purpose rubbers.

A known method of producing dicyclohexylamine from nitrobenzene, phenol and hydrogen gas on a palladium catalyst at temperatures up to 150 ° C and a pressure of 1-6.9 atm (UK Patent No. 1235443, publ. June 16, 1971).

The disadvantages include the fact that this method requires the use of an expensive catalyst and high pressure, and the process time is 35 hours or more.

A known method of producing dicyclohexylamine by hydrogenation of aniline in the presence of nitrobenzene (0.01-1 wt.%) And a catalyst - Nickel and palladium deposited on asbestos at a temperature of 180 ° C and atmospheric pressure. The product yield is 85% (Aut. St. USSR No. 420616, IPC S07C 87/36, publ. 10.11.1974).

The disadvantage of this method is the use of an expensive catalyst and the presence in the products of impurities - benzene, cyclohexane, aniline - in significant quantities.

In another method, the hydrogenation of aniline is proposed to be carried out in the liquid phase in the presence of a catalyst — Ru-Pt-Pd, supported on Al ₂ O ₃ at temperatures of 80-240 ° C and a pressure of 50-500 atm. The product yield is 55% (US Patent No. 5023226, IPC B01J 23/00, 25/58; C07C 85/24, 87/36; publ. June 11, 1991).

This method requires the use of an expensive catalyst and high pressure, and is also characterized by a relatively low yield.

Thus, in none of the described methods can one obtain dicyclohexylamine from cyclohexylamine in the gas phase using oxide catalysts in a flow reactor at atmospheric pressure.

The technical result of the proposed method is the development of a technological method for producing dicyclohexylamine from cyclohexylamine with a yield of 50-72.7%.

The technical result achieved is achieved by the catalytic disproportionation of cyclohexylamine in the presence of hydrogen, carried out at 160-200 ° C in the gas phase in a flow reactor using a copper-zinc-chromium-aluminum catalyst pre-reduced with hydrogen.

In this case, dicyclohexylamine is obtained with a yield of 50-72.7%. The process is characterized by high selectivity - 99%. The reaction time is 8-30 s.

The advantages of this method include the following:

- the process is carried out in the gas phase in a flow reactor on a heterogeneous catalyst, which can significantly simplify the technology;

- the process is carried out at atmospheric pressure and low temperatures;

- the reaction time is 8-30 s;

- An available industrial oxide copper-zinc-chromium-aluminum catalyst is used.

The inventive method is as follows.

An NTK-type copper-zinc-chromium-aluminum catalyst is placed in the reactor — a catalyst for low-temperature conversion of carbon monoxide, which, when heated, is reduced with hydrogen until the moisture evolution ceases, controlling the temperature increase along the height of the catalyst layer. The recovery of the catalyst is carried out only once after its replacement. Then, cyclohexylamine is fed to the reactor at atmospheric pressure. The process is carried out at temperatures of 160-200 ° C. The reaction mass exiting the reactor is cooled in a refrigerator and collected in a collector. The catalyst contains dicyclohexylamine, cyclohexanol and cyclohexylamine. The yield of dicyclohexylamine is 50-72.7%.

The choice of the specified temperature range in the reaction zone is due to the following:

- a decrease in temperature in the reactor below 160 ° C leads to a sharp decrease in the conversion of cyclohexylamine and a decrease in the yield of dicyclohexylamine;

- an increase in temperature in the reactor above 200 ° C leads to a sharp decrease in the yield of dicyclohexylamine due to a decrease in the selectivity of the process.

The method for producing dicyclohexylamine from cyclohexylamine is illustrated by the following examples.

Example 1. 4 g of copper-zinc-chromium-aluminum catalyst is loaded into a laboratory reactor, which is a quartz tube 0.25 m long, 0.009 m in diameter.

The catalyst is heated to 160-180 ° C and restored with hydrogen for 2-3 hours at a flow rate of hydrogen of 0.3 l / h until the evolution of water. Then, cyclohexylamine is started to be fed into the reactor at atmospheric pressure at a feed rate of 0.0064 mol (0.732 ml) per hour (1.6 mol / hour * kg of catalyst). The reaction temperature is 200 ° C. The reaction mass exiting the reactor is cooled in a refrigerator and collected in a collector. The output of dicyclohexylamine is 72.7%.

Examples 2-9 are performed analogously to example 1 with varying the temperature in the reaction zone and the specific feed rate of cyclohexylamine. The results are shown in the table.

Table. Experience number The temperature in the reactor, ° C The specific load on cyclohexylamine, mol / (hour * kg of catalyst) The output of dicyclohexylamine,% one 200 1,6 72.71 2 160 0.3 65.47 3 160 0.4 57.90 four 160 0.5 50.61 5 180 0.3 72.21 6 180 0.4 71.70 7 200 2,4 71.10 8 200 3.2 68.17 9 200 four 63.79

Thus, a technological method has been developed that allows dicyclohexylamine to be prepared from cyclohexylamine in the gas phase at atmospheric pressure on a heterogeneous catalyst, which simplifies the technology. The duration of the process is 8-30 s. An available industrial oxide catalyst is used.

Claims (1)

A method of producing dicyclohexylamine from cyclohexylamine, comprising the catalytic disproportionation of cyclohexylamine in the presence of hydrogen, carried out at a gas phase of 160-200 ° C in a flow reactor using a copper-zinc-chromium-aluminum catalyst pre-reduced with hydrogen.