[Chemical Knowledge]：Production and manufacturing method and process flow of phthalic anhydride

The manufacturing method
of phthalic anhydride
phthalic anhydride, also known as phthalic anhydride, is an important organic chemical raw material, widely used in plastics, fibers, dyes, pharmaceuticals and pesticides. Phthalic anhydride can be produced by a variety of methods, including a gas phase oxidation method, a liquid phase oxidation method, a solid phase oxidation method, and the like. This article will introduce the manufacturing method of phthalic anhydride in detail.

1. gas phase oxidation method

gas phase oxidation method is the gaseous benzene in the presence of a catalyst, into the air or oxygen oxidation reaction, the generation of phthalic anhydride and water vapor process. This method has the advantages of high reaction temperature, fast reaction speed and high yield, so it is widely used in industrial production.

1. The reaction principle of

gas phase oxidation is that benzene vapor and oxygen are passed into a reactor equipped with a catalyst. Under the action of the catalyst, benzene is oxidized to generate phthalic anhydride and water vapor. The reaction equation is as follows:

C6H6 3/2O2 → C6H4O3 H2O

2. Process flow
The process flow of
gas phase oxidation method includes the steps of raw material preparation, oxidation reaction, product cooling, separation and purification. The specific process is as follows:

(1) raw material preparation: benzene vapor and oxygen are mixed according to a certain proportion and introduced into the reactor.

(2) oxidation reaction: under the action of the catalyst, benzene is oxidized to produce phthalic anhydride and water vapor.

(3) Product cooling: The reaction product was cooled to room temperature and allowed to condense into a solid.

(4) Separation: Solid phthalic anhydride is separated from water vapor.

(5) Purification: Phthalic anhydride is purified to remove impurities.

3. equipment and operation

gas phase oxidation method requires the use of high temperature and high pressure reactor, as well as catalyst and control system and other equipment. During the operation, attention should be paid to controlling the reaction temperature and pressure to ensure the smooth progress of the reaction and the quality of the product.

2. liquid phase oxidation method

liquid phase oxidation method is a process of mixing benzene and solvent, adding catalyst and oxidant for oxidation reaction, generating phthalic anhydride and water. Compared with the gas phase oxidation method, the liquid phase oxidation method has the advantages of lower reaction temperature and slower reaction rate, but it has the advantages of simple equipment and convenient operation.

1. reaction principle

liquid phase oxidation reaction principle is under the action of a catalyst, oxidation-reduction reaction of benzene and oxidant, generating phthalic anhydride and water. The reaction equation is as follows:

C6H6 3/2O2 → C6H4O3 H2O

2. Process flow
The process flow of
liquid phase oxidation method includes the steps of raw material preparation, oxidation reaction, separation and purification. The specific process is as follows:

(1) Raw material preparation: After mixing benzene with a solvent, a catalyst and an oxidant are added.

(2) oxidation reaction: under the action of the catalyst, benzene is oxidized to produce phthalic anhydride and water.

(3) Separation: The reaction solution was separated to obtain phthalic anhydride and water.

(4) Purification: Phthalic anhydride was purified to remove impurities.

3. equipment and operation

liquid phase oxidation method needs to use the reactor, stirrer, separation equipment and other equipment. During the operation, attention should be paid to controlling the reaction temperature and pH value to ensure the smooth progress of the reaction and the quality of the product.

3. solid phase oxidation method

solid phase oxidation method is a new type of phthalic anhydride manufacturing method, the method is benzene and solid acid catalyst contact, at room temperature and pressure under the oxidation reaction, the generation of phthalic anhydride process. The solid-phase oxidation method has the advantages of mild reaction conditions, simple equipment and convenient operation, and is one of the hotspots of current research.

1. reaction principle

solid phase oxidation reaction principle is under the action of solid acid catalyst, benzene is oxidized to produce phthalic anhydride. The reaction equation is as follows:

C6H6 3/2O2 → C6H4O3

2. Process flow
The process flow of
solid phase oxidation method includes the steps of raw material preparation, oxidation reaction, product separation and purification. The specific process is as follows:

(1) Raw material preparation: Benzene and solid acid catalyst are mixed.

(2) oxidation reaction: at room temperature and pressure, benzene and solid acid catalyst contact, oxidation reaction to produce phthalic anhydride.

(3) Product isolation: The reaction product is isolated to obtain phthalic anhydride.

(4) Purification: Phthalic anhydride was purified to remove impurities.

3. equipment and operation

solid phase oxidation method needs to use fixed bed reactor or fluidized bed reactor and other equipment. During the operation, attention should be paid to controlling the reaction temperature, space velocity and catalyst activity to ensure the smooth progress of the reaction and the quality of the product.

In short, there are many manufacturing methods of phthalic anhydride, and the process flow and equipment operation of different methods are different. When choosing a manufacturing method, it is necessary to choose according to the actual situation and product requirements to ensure the smooth progress of production and product quality.