Alcohol; Phthalic anhydride

dioctyl phthalate

To produce dioctyl phthalate and other plasticizers from their alcohol and phthalic anhydride (PA) using an amphoteric catalyst in a batch esterifiction process.

Description: Alcohol and liquid PA are fed into the esterification reactor (1). Then the excess alcohol from the previous charge as well as catalyst are added and the reaction mixture is heated to the required esterification temperature. Evaporated reaction water and alcohol are condensed and separated (2), so that the alcohol can be recycled to the esterification reactor. After completion of the rection, traces of unreacted monoester are neutrlized (3) with soda ash, followed by steam stripping of the excess alcohol. The overhead vapor mixture is condensed, the alcoholic phase being separated (4) from water and collected in the excess alcohol tank (5). The condenste is worked up internally to avoid environmental problems. After drying the ester with nitrogen, filter aid is added and the ester is cooled and filtered (6). The pure product is then transferred to storage.

Yield: Typical specifications for dioctyl phthalate:

Purity, via saponification number, min         
Color, APHA
Acid number
Hydroxyl number

99.2
20
0.03-0.04
0.6

Raw materials and utility consumption: Per metric ton dioctyl phthalate:

Phthalic anhydride, kg
2-Ethylhexanol, kg
Catalyst, kg
Cooling water (Δt = 10℃), m ³
Electrical energy, kWh

382
672
1
60
20