Method for preparing diphenylamine by aniline liquid phase condensation and denitrification coupling

A deamination coupling, aniline liquid technology, applied in the condensation/addition reaction to prepare amino compounds, organic chemistry, etc., can solve the problems of affecting the reaction equilibrium conversion rate, prolonging the residence time, decreasing the selectivity, etc. The production capacity of the device is improved, the energy consumption of separation is reduced, and the operation and control are convenient.

Inactive Publication Date: 2008-05-14
NANJING TECH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

[0006] In industry, the reaction pressure is controlled at 2.0-2.5MPa, and the reaction temperature is 320-350°C. Due to the limitation of chemical balance, the single-pass conversion rate of aniline can generally only be below 25%, which is equivalent to the aniline raw material needs of 3-4 times the amount of diphenylamine products. After rectification, separation and recycling, the burden on the subsequent separation process is very heavy, and the energy consumption is very high.
[0007] Although increasing the temperature and prolonging the residence time are effective ways to increase the conversion rate, for reversible exothermic reactions, too high a temperature will affect the reaction equilibrium conversion rate, and the selectivity will also decrease. At the same time, in order to maintain the pressure of the liquid phase condensation system, it must increase; the residence time is prolonged, while the conversion rate is increased, the production capacity of the catalyst will decrease. Due to the high price of the catalyst, the service life is only one year, and it needs to be regenerated once in about three months, and the production capacity of the catalyst will decrease. It is bound to increase the cost occupied by the catalyst

Method used

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  • Method for preparing diphenylamine by aniline liquid phase condensation and denitrification coupling
  • Method for preparing diphenylamine by aniline liquid phase condensation and denitrification coupling
  • Method for preparing diphenylamine by aniline liquid phase condensation and denitrification coupling

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0021] Four fixed-bed reactors numbered 1, 2, 3, and 4 were connected in series successively, and 6 grams, 12 grams, 24 grams and 48 grams of beta zeolite molecular sieve catalysts were loaded respectively, and the total loading amount of the catalyst was 90 grams. Control the pressure of each reactor to be 2.0MPa and the temperature to be 330°C. After the raw material aniline is pressurized and heated, it is added to the bottom of the first reactor at a speed of 36 g / hour (the space velocity is 0.4 g / g catalyst·hour), followed by Passing through the catalyst beds of the four reactors and exiting from the top of the fourth reactor, samples were taken for analysis of the composition of the reaction mixture. The tops of No. 1, No. 2 and No. 3 reactors are respectively equipped with reflux condensers and valves. When the valves are opened to a certain degree, the deamination can be stabilized while the aniline condensation reaction is carried out. The conversion rates of aniline ...

example 2

[0023] Adopt the same device as example one, catalyst loading, reaction pressure and temperature are also identical with example one. Raw material aniline joins in the reaction system with the speed of 54 grams / hour (space velocity is 0.6 gram / gram catalyst hour), and the aniline conversion rate obtained under deamination and not deamination two kinds of operation forms is respectively 23.8% and 18.4%, it can be seen that the conversion rate of aniline has increased by 5.4% because of the coupled deamination and condensation reaction.

[0024] Comparing the results of Example 1 and Example 2, it can be seen that, when the aniline conversion rate is low, deamination is more beneficial to the improvement of the conversion rate.

example 3

[0026] Two fixed-bed reactors filled with 5250 kg of beta zeolite molecular sieve catalysts are connected in series, and the top of each reactor is equipped with a gas-liquid separator, a reflux condenser and a liquid level control system. Control the operating pressure and temperature in the reactor to be 2.0MPa and 320°C respectively. After pressurized and heated, the raw material aniline is added to the first reactor at a rate of 2950 kg / hour (the space velocity is 0.28 g / g catalyst·hour). The bottom, after passing through the catalyst beds of the two reactors, leaves the reaction system from the top of the second reactor. According to the analysis and measurement, the aniline conversion rates under deamination and non-deamination operation conditions are 26.6% and 24.5% respectively, and the coupling of deamination and condensation makes the aniline conversion rate increase by 2.1%.

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Abstract

The invention provides a process for preparing diphenylamine by the coupling of condensation reaction and diphenylamine for increasing phenylamine once-through conversion ratio, wherein the condensation reaction and diphenylamine coupling apparatus employs 2-N fixed bed reactors through cascade connection, each reactor is filled with beta-zeolite molecular sieve catalyst, the reactor is equipped with a gas-liquid separator and a direct condenser on the top, the gas-liquid separator is equipped with liquid level display and control system, the operating pressure for each reactor is controlled between 1.5-3.0 MPa, the reaction temperature is controlled between 260-400 deg. C.

Description

technical field [0001] The invention relates to the synthesis of organic compounds, in particular to a method for producing diphenylamine using the coupled technology of aniline liquid phase condensation and deamination. Background technique [0002] Diphenylamine, also known as N-phenylaniline, has the molecular formula C 12 h 11 N. It is an important fine organic chemical raw material with a wide range of uses, mainly used in rubber additives, explosive stabilizers, medicine, dyes and other industries. As rubber additives, diphenylamine anti-aging agents have good anti-thermal oxygen and anti-bending effects, and also have certain protective effects on metal aging and ozone cracking; as explosive stabilizers, diphenylamine itself and its degradation products It is a good stabilizer and propellant for explosives; in the dye industry, it is mainly used to synthesize acid yellow G, acid IV, sulfur brilliant blue and other dyes; in the pharmaceutical industry, it is mainly ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C211/55C07C209/60
Inventor 乔旭张进平崔咪芬汤吉海
Owner NANJING TECH UNIV
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