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A method for preparing maleic anhydride through continuous dehydration of maleic acid

A technology of maleic acid and maleic anhydride, applied in the direction of organic chemistry, can solve problems such as product quality reduction, pipeline and equipment blockage, energy consumption safety, environmental protection, etc., and achieve the effects of improving efficiency, reducing production costs, and reducing energy consumption

Active Publication Date: 2020-04-24
TIANJIN CLEANTECH TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] However, the use of xylene azeotropic physical dehydration has serious disadvantages that are difficult to overcome: the maleic anhydride produced is converted into maleic acid in contact with water, and maleic acid is repeatedly mixed with water in the high temperature zone of the stripping section of the tower. Contact with fumaric acid (acid reflux) with a high melting point (287°C) in heterogeneous formation will lead to serious blockage of pipelines and equipment, and it is easy to cause parking. It must be cleaned regularly with a large amount of water, and it cannot be produced stably for a long period. Cause serious energy consumption, safety, environmental protection problems; At the same time, due to the generation of acid reflux, the quality of the product is reduced, and the output of maleic anhydride is also affected

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Adopt the glass rectifying tower of diameter 30mm as dehydration equipment, tower height 1.5m, be the citric acid aqueous solution feeding place apart from tower still 1.2m place, be xylene and acetic anhydride feeding place (xylene and acetic anhydride feed place apart from tower still 0.3m place) The feed inlet of acetic anhydride is different);

[0029] Add 200ml of xylene and 10ml of acetic anhydride to the tower kettle, and heat it to reflux at normal pressure. At this time, the temperature of the kettle is 142°C, and the top temperature is 136°C. Start to continuously pump in an aqueous solution containing 30% of citric acid, xylene and acetic anhydride. The feed rate of acid aqueous solution is 60ml / hr, the feed rate of xylene is 180ml / hr, and the feed rate of acetic anhydride is 20ml / hr. At the same time, the reflux ratio at the top of the tower is 8, and the oil-water ratio is 2.5:1. The top temperature is 94.5°C, and after 6 hours of experimentation, there is ...

Embodiment 2

[0032] A glass rectification tower with a diameter of 30mm is used as the dehydration equipment. The height of the tower is 1.5m. The place 1.2m away from the tower kettle is the feeding place of the citric acid aqueous solution, the place 0.3m away from the tower kettle is the feeding place of xylene, and the place 0.2m away from the tower kettle It is the feeding place of acetic anhydride;

[0033] Add 200ml of xylene and 20ml of acetic anhydride to the tower kettle, and heat it to reflux at normal pressure. At this time, the temperature of the kettle is 142°C, and the top temperature is 136°C. Start to continuously pump in the aqueous solution containing 30% citric acid, xylene and acetic anhydride, and the cis The feed rate of acid aqueous solution is 60ml / hr, the feed rate of xylene is 180ml / hr, and the feed rate of acetic anhydride is 20ml / hr. At the same time, the reflux ratio at the top of the tower is 8, and the oil-water ratio is 2.5:1. The top temperature is 94.5°C,...

Embodiment 3

[0036] A glass rectification tower with a diameter of 30mm is used as the dehydration equipment. The height of the tower is 1.5m. The place 1.2m away from the tower kettle is the feeding place of the citric acid aqueous solution, the place 0.3m away from the tower kettle is the feeding place of xylene, and the place 0.2m away from the tower kettle It is the feeding place of acetic anhydride;

[0037] Add 200ml of xylene and 20ml of acetic anhydride to the tower kettle, and heat it to reflux at normal pressure. At this time, the temperature of the kettle is 142°C, and the top temperature is 136°C. Start to continuously pump in an aqueous solution containing 30% of citric acid, xylene and acetic anhydride to Feed rate is 60ml / hr, xylene feed rate is 180ml / hr, acetic anhydride feed rate is 20ml / hr, while the tower top adopts a reflux ratio of 1, and the production oil-water ratio is a cut of 2.5:1. At this time, the tower top temperature The temperature was 94.5°C, and after 6 ho...

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Abstract

The invention provides a method for the preparation of maleic anhydride by continuously dehydrating maleic acid. The acid anhydride is added as a chemical dehydration agent during azeotropic dehydration using a physical dehydration agent; and the chemical dehydration agent enters a dehydration system from a having a same or lower height with a physical dehydration agent inlet, and the pressure in the dehydration system is controlled to be normal pressure. The physical dehydration agent is used to remove most of water, the acid anhydride is added as the chemical dehydration agent, the acid anhydride rapidly reacts with the water removed from the maleic acid to produce a corresponding organic acid with a low boiling point and a low melting point organic acid, and the corresponding organic acid is discharged from the top of a tower, so obstruction of a pipeline and a device, caused by fumaric acid having a very high melting point, isomerized from the maleic acid in repeated contact with the separated water in the high temperature area of a stripping section is avoided, and the long-cycle, stable, continuous and efficient production of the maleic anhydride is realized.

Description

technical field [0001] The invention belongs to the technical field of chemical separation, and in particular relates to a method for preparing maleic anhydride through continuous dehydration of maleic acid. Background technique [0002] Maleic anhydride (MA), also known as maleic anhydride or dehydrated malic anhydride, referred to as maleic anhydride, is an extremely important organic chemical raw material. The development of processes such as catalytic hydrogenation of maleic anhydride to produce 1,4-butanediol (BDO), which is recognized as the most economical and promising in the world, has made maleic anhydride the third largest organic acid anhydride after phthalic anhydride and acetic anhydride, and its application fields are rapid Expansion, mainly used in the production of unsaturated polyester resins, pesticides, coatings, inks, lubricating oil additives, papermaking, textiles and surfactants, alkyd resins, fumaric acid, paper treatment agents and other fields. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D307/60
CPCC07D307/60
Inventor 张学岗刘通
Owner TIANJIN CLEANTECH TECH
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