| 摘要 |
Prepn. of terephthalic acid comprises oxidising p-xylene with O2 or O2-contg. gas with a cobalt-manganese-bromine catalyst in acetic acid, in a liq. phase while the moisture content in the reaction on system is maintained at 3-9 pref. 5-7 wt. %. The catalyst consists >0.01-0.5 wt. % of cobalt metal based on the amt. of the acetic acid >35 wt. % of manganese metal, pref. manganese acetate, based on the amt. of cobalt metal, pref. cobalt acetate, and HBr converted into 0.10 wt. % of bromine atom based on the amt. of the acetic acid. This method provides terephthalic acids which contain less impurities, e.g. 4-carboxybenzaldehyde, and colouring agent with relatively low-priced and low-concn. catalyst system. Oxdn. of the solvent is suppressed. By maintaining low moisture content, the catalyst activity is improved. Pref. the acetic acid is used in a concn. of 1-20 pts. wt. pref. 3-10 pts. wt. per 1 pts. wt. of paraxylene and the oxidn. reaction is effected at 170-200 degrees C and at 15-25 atm. The prod. may be polymerised directly. |
