| abstract |
1,250,222. Gas/liquid/solid contact; catalytic reactions. TEIJIN Ltd. 25 Oct., 1968, No. 50731/68. Heading B1F. [Also in Division C2] Terephthalic acid is prepared by reacting pdialkylbenzene or an intermediate oxidation product thereof with molecular oxygen in an aliphatic monocarboxylic acid solvent containing 2-4 carbon atoms in the presence of a heavy metal catalyst, the liquid level, and the pressure and temperature in the reactor being controlled between certain limits. In Fig. 1, the molecular oxygen is supplied from sparger 6, and is dispersed by draft tube 7 and distributor 8, and feed material comprising p-dialkyl benzene or intermediate oxidation product thereof, aliphatic monocarboxylic acid with 2-4 carbon atoms, and heavy metal oxidation catalyst is introduced via port 5, the ratio of supply of gas and feed material and withdrawl of product at 4 being such that the ratio 1/L is 1/4 to 1/3, where 1+L are measured as shown in Fig. 1 downwards from liquid level 11. Tubes 10a and jacket 10b are used to maintain the temperature of the reaction mixture between 80‹C and 150‹C, and the pressure in the reactor is maintained between atmospheric and 100 atmospheres. The starting material may comprise p-xylene, p-cymene, p-toluic acid, or 4 carboxy benzaldehyde. The acid solvent may be acetic, proprionic or butyric acid. The catalyst may comprise the acetates of Co, Mn, Ag, Mo, Nb, possibly containing minor amounts of compounds of Sc, Y, La, Nd, Gd, Th, Zr, Hf, NH 4 Br or O 3 may also be present. The oxygen gas may be mixed with N 2 , A, or CO 2 , e.g. as air. The distributor 8 may be of cross section shown in Fig. 4b, or may be used for introducing part of the molecular oxygen and be of cross-section as shown in Fig. 5c or 7b. |