Pyromellitic Dianhydride factory

    Pyromellitic dianhydride is an organic compound with the formula C6H2(C2O3)2. It is the double carboxylic acid 

anhydride that is used in the preparation of polyimide polymers such as Kapton. It is a white solid.It is prepared by 

gas-phase oxidation of 1,2,4,5-tetramethylbenzene (or related tetrasubstituted benzene derivatives).

    Pyromellitic Dianhydride,there can be multiple preparation methods. The raw materials used can be xylene, 

trimethylbenzene, tetramethylbenzene or anthracene. The oxidation methods include liquid phase method and gas 

phase method.

   1. The gas-phase oxidation of mesitylene is characterized by simple process, can omit the dehydration to 

anhydride process, no other oxidants except air (such as nitric acid, permanganic acid, chromic acid, etc.), and no 

catalyst necessary for liquid phase Separation of processes, continuous production, easy to realize automatic 

operation, is the main method of foreign development. The raw materials used can also start from 1,2,4-

trimethylbenzene, in the presence of a catalyst, it is alkylated with propylene to produce 1,2,4-trimethyl-5-

propylbenzene, and then obtained by catalytic oxidation with gas-phase air Pyromellitic dianhydride.

   2. Pyromellitic Dianhydride is obtained from xylene (p-xylene or meta-xylene) through chloromethylation, 

oxidation and cyclization. The industrial product pyromellitic dianhydride is white to light yellow-green crystals. The 

melting point of the first grade product is 284-287℃, and the melting point of the second grade product is 283.5-

287℃. When 1,2,4-trimethylbenzene is produced by oxidation method, 3000kg of 1,2,4-trimethylbenzene and 

1200kg of propylene are consumed per ton of product.

   3. Carbon monoxide method The high-purity intermediate aromatic aldehyde 2,4,5-trimethylbenzaldehyde is 

prepared by the reaction of trimethylbenzene and carbon monoxide, and then oxidized to obtain pyromellitic acid, 

and finally dehydrated to produce PM-DA. The method adopts a new carbonylation process, with few side reactions, 

high product purity, high yield, strong selectivity, low corrosiveness to equipment, and meets environmental

protection requirements, and a set of equipment can be used to switch to produce two products, trimellitic 

anhydride and PMDA. The production cost is lower.

    Pyromellitic Dianhydride is one of the best-selling products of Chemwill Asia co.,Ltd. Their factory produces a 

large number of high-quality and good-priced products. Welcome to buy.

Pyromellitic Dianhydride 89-32-7 manufacturer (chemwillchina.com)