The invention discloses a method for preparing 3, 3 ', 4, 4'-biphenyltetracarboxylic dianhydride. The method comprises the following steps: 1)
coupling and acid
precipitation: reducing a chlorinated
phthalate monosodium salt mixture by a hydrazine
reducing agent under the
catalysis of a
palladium-
copper carbon supported catalyst by taking water as a
solvent, carrying out a dechlorination couplingreaction to obtain 3, 3 ', 4, 4'-biphenyltetracarboxylic acid, adding filtrate after the catalyst is filtered into dilute
sulfuric acid, and carrying out cooling
crystallization to obtain a 3, 3 ', 4,4'-biphenyltetracarboxylic acid crude product; 2) refining: refining with a
methanol aqueous solution to obtain a 3, 3 ', 4, 4'-biphenyltetracarboxylic acid refined product; and 3)
anhydrous treatment: heating and dehydrating the 3, 3 ', 4, 4'-biphenyltetracarboxylic acid fine product to obtain the 3, 3 ', 4, 4'-biphenyltetracarboxylic dianhydride. The raw materials are easy to obtain, the
palladium-
copper carbon supported catalyst is adopted, and a proper dechlorination
coupling reducing agent hydrazine sulfate is preferably selected, so that the conversion rate of the chlorinated
sodium phthalate mixture reaches 100%; a proper
solvent system is selected, a product is finally obtained, the content is larger than 99.7%, the yield is 81%-87%, and
metal ions are smaller than 2 ppM.