Method of hydrogenation for benzoic acid

A technology of benzoic acid and hydrogen, which is used in the preparation of carboxylic acid by ozone oxidation, organic chemistry, etc., can solve the problems of limiting and maintaining the reserves of Ru/C additives, so as to reduce production costs, increase processing capacity, and improve hydrogenation. active effect

Active Publication Date: 2009-08-05
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method still discharges the catalyst filter residue according to the original process, and the Ru / C additive with stable activity is also discharged from the device. It is necessary to regularly replenish fresh catalyst and a certain proportion of Ru / C additives

Method used

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  • Method of hydrogenation for benzoic acid
  • Method of hydrogenation for benzoic acid
  • Method of hydrogenation for benzoic acid

Examples

Experimental program
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Effect test

Embodiment 1

[0017] Such as Figure 2 Show, reactant benzoic acid, hydrogen and Pd / C catalyst, Ru / C auxiliary agent enter reactor system together and carry out benzoic acid hydrogenation reaction, wherein, the consumption of Ru / C auxiliary agent is 3% of Pd / C catalyst weight in the system %, the reaction temperature is 167±2°C, and the pressure is 1.35±0.05MPa. After passing through the four-stage reactor, more than 99% of benzoic acid is converted into products. After the reaction mixture leaves the reactor, it undergoes gas-liquid separation, and the liquid-solid mixture enters the suspension separator, and after hydrocyclone separation, the turbid liquid containing a relatively high concentration of catalysts and additives is circulated back to the reactor from the bottom, containing less solid phase. The supernatant liquid leaves the hydrocyclone from the top, enters the centrifugal separator for liquid-solid separation again, and the separated Pd / C catalyst and Ru / C auxiliary agent a...

Embodiment 2

[0019] Another embodiment of the present invention is as Figure 3 Show. Identical with embodiment 1, raw material benzoic acid, hydrogen and catalyzer, auxiliary agent enter reactor and carry out benzoic acid hydrogenation reaction, wherein, the consumption of Ru / C auxiliary agent is 8% of system Pd / C catalyst weight, temperature of reaction 165 ± 2°C, pressure 1.50±0.05MPa. After the reaction, the mixture is separated by hydrocyclone and centrifugal separation, and the turbid liquid with high solid phase concentration is separated and returned to the reactor system. The separated clear liquid enters the evaporator for evaporation, and the evaporated CCA product is discharged from the device and enters the next production process. Unlike Example 1, the effluent from the bottom of the evaporator containing high concentrations of catalyst and adjuvants is directly returned to the reactor system.

Embodiment 3

[0021] Laboratory Pd / C catalyst hydrogenation activity stability test.

[0022] Z for hydrogenation activity of Pd / C catalyst 0 Characterization, which represents the hydrogen consumption rate of the catalyst per unit time. Determination of Z 0 The best method is to use a oscillating high-pressure reactor, add 2 grams of Pd / C catalyst (dry basis) and 200 grams of benzoic acid, replace it with nitrogen three or four times, fill it with nitrogen to 2.0 MPa, heat to 150 ° C, and use high-purity hydrogen Replace three or four times, fill the hydrogen pressure to 11.0MPa, start stirring and start timing at the same time, when the reaction pressure drops from 11.0MPa to 9.0MPa, record the reaction time t (minutes), Z 0 =20 / 4t, recharge to 11.0MPa, carry out 7 consecutive times, and take the average value. Z 0 The larger the value, the higher the hydrogenation activity. Z 0 For the determination method, see (Shijiazhuang Chemical Fiber Co., Ltd.) "Compilation of Analytical Meth...

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Abstract

The invention provides a method for hydrogenation of benzoic acid. The process is as follows: in the presence of Pd / C catalyst and Ru / C auxiliary agent, molten benzoic acid and hydrogen carry out hydrogenation reaction in a reactor, and the reaction mixture passes through Cyclone separation and centrifugal separation, the turbid liquid containing high concentration of catalyst and additives is recycled back to the reactor, the separated clear liquid enters the evaporator for further separation, and the separated catalyst and additives are completely returned to the reactor system. The method saves the cost of repeatedly preparing the catalyst, reduces the processing cost of the benzoic acid hydrogenation, improves the activity of the Pd / C catalyst for the benzoic acid hydrogenation, and increases the processing capacity of the device.

Description

technical field [0001] The invention provides a method for hydrogenating benzoic acid, in particular a method for hydrogenating benzoic acid using a Pd / C catalyst and an anti-CO poisoning additive of the Pd / C catalyst. Background technique [0002] The hydrogenation of benzoic acid is an intermediate process in the production of caprolactam by the SNIA method. The reaction process takes benzoic acid and hydrogen as raw materials and uses Pd / C as a catalyst. The main product is cyclohexanecarboxylic acid (CCA for short), and the by-product is the reactant benzene CO and CO produced by the decarboxylation of formic acid and the reaction product CCA 2 . Because the side reaction product CO is strongly adsorbed on the Pd / C catalyst, the catalyst is poisoned and deactivated, which shortens the service life of the catalyst. In order to maintain normal catalyst activity, it is necessary to continuously add fresh catalyst to the system and discharge a part of the deactivated catal...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C61/08C07C51/36
Inventor 李志民曹志广赵承军
Owner CHINA PETROLEUM & CHEM CORP
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