Production process and product use of maleic anhydride

5.
Main equipment

Fluidized bed reactor, metering pump, spray absorption tower, azeotropic dehydration tower, vacuum distillation tower, storage tank
.

6.
Production process

In a fluidized bed with a diameter of 1500mm and a total height of 17500mm, 2000kg of microspherical vanadium-molybdenum catalyst is loaded
.

Before driving, the catalyst layer in the fluidized bed was heated to 350°C with hot air and activated for several hours

The reaction gas is quenched by a water spray cooling pipe, and then enters a water circulation spray absorption tower with a diameter of 1400mm and a height of 7000mm.
The maleic anhydride vapor in the reaction gas is absorbed by water and becomes a maleic acid solution with a concentration of about 30%.

.

In the kettle of the azeotropic dehydration tower, 3000kg of mixed xylene is first added and heated until the temperature of the kettle is higher than 136°C, and the xylene in the gold boils

The fixed bed oxidation process can also be used, and the production process is as follows:

The raw material benzene is firstly gasified in the gasifier; the air is filtered, compressed (0.
2～0.
3MPa), and preheated
.

The two are mixed in the mixing chamber according to the proportion, and after heat exchange with the reacted gas, they enter the tubular reactor

The tube-and-tube fixed-bed reactor has a diameter of 5m and has 13,000 tubes.
The annual production capacity of a single reactor is between 1.
0 and 12 thousand tons
.

The reactor is heated with a molten salt bath, and the molten salt is circulated to remove the reaction heat and produce high-pressure steam

7.
Product Standard

8.

Quality inspection

1) Assay

Accurately weigh 1g sample and place it in a 250mL conical flask with stopper.
Use a burette to add 35mL 0.
5mol/L NaOH standard solution and 35mL freshly boiled and cooled water.
Heat slightly until the sample is completely dissolved
.

Add 2 drops of 10g/L phenolphthalein indicator at 20～30℃, and then continue to drip with NaOH standard solution until it is reddish.

Where: V——The volume of NaOH standard solution consumed, mL;

c——The molar concentration of NaOH standard solution, mol/L;

G——The mass of the sample, g
.

2) Melt color measurement

Take an appropriate amount of sample and place it in a 50mL colorimetric tube and heat it in a 65℃±2℃ water bath
.

After the sample is melted, immediately adjust the sample volume to the scale and visually check the axis

9.

Safety measures

(1) Oxidation reaction equipment should be sealed, ventilation should be strengthened in the workshop, and fire prevention should be paid attention to
.

(2) Packed in large iron drums lined with plastic bags
.

Pay attention to moisture-proof, sun-proof, rain-proof and fire-proof

10.
Product use

Mainly used in the manufacture of unsaturated polyester resins, alkyd resins, insulating paints, nylon-4, long-acting sulfonamides, plasticizers, paper treatment agents, pesticides; also used in the manufacture of fumaric acid, maleic rosin, PVC stabilizers
.
It is one of the important basic organic raw materials with a wide range of uses
.

Related Links: Production Principle and Process Flow of Maleic Anhydride