Abstract: The present invention pertains to an improved method of oxidizing substituted aromatic compounds (such as p xylene) to their corresponding aromatic acids (such as terephthalic acid). The improvement involves carrying out the oxidation reaction in an aqueous medium, wherein the aqueous medium contains at least 30 percent water, preferably up to 30 percent surfactant and preferably a low molecular weight material containing a hydrophilic end group as a co-surfactant. The reaction is carried out at a pH of less than 3.0.

Abstract: A process for the preparation of purified terephthalic acid which comprises first introducing a liquid slurry containing crystalized terephthalic acid with impurities into a high pressure rotary filter, then filtering the slurry with the high pressure rotary filter and collecting at least some of the solid portion. The filter typically consists of a case, pressurized at process pressure, and a drum covered by a filtering device such as, for example, a cloth or equivalent filtering device, pressurized at a pressure suitably lower than the case. The drum is ideally divided into three zones: first zone, where the mother liquor is removed; second zone, where the solid is washed; third zone, where the excess of washing liquor is removed and the solid is discharged. The solid portion is washed, onto the filter drum, with additional amounts of water. The washed solid portion is then transferred to a letdown zone, which is at a pressure less than the zone in which the solid portion was collected.

Abstract: The present invention relates to a process for the preparation of crude terephthalic acid which comprises first introducing a slurry containing crystallized terephthalic acid with impurities in an aliphatic carboxylic acid mother liquor into a rotary filter comprising a case and a rotating drum, wherein the rotating drum is subjected to a uniform pressure differential over the entire drum, and the inside of the drum is at a pressure approximately equal to atmospheric pressure or greater, then filtering said slurry; and finally collecting at least some of the solid portion. Other aspects of the invention include continuously adding the original slurry to the rotary filter and washing the solid portion with additional aliphatic carboxylic acid, water or a combination of the two. The solid portion can then be transferred to a reslurry tank which is at the same pressure as the pressure at the point where the solid portion was collected.

Abstract: A process for the preparation of purified terephthalic acid which comprises first introducing a liquid slurry containing crystalized terephthalic acid with impurities into a high pressure rotary filter, then filtering the slurry with the high pressure rotary filter and collecting at least some of the solid portion. The filter typically consists of a case, pressurized at process pressure, and a drum covered by a filtering device such as, for example, a cloth or equivalent filtering device, pressurized at a pressure suitably lower than the case. The drum is ideally divided into three zones: first zone, where the mother liquor is removed; second zone, where the solid is washed; third zone, where the excess of washing liquor is removed and the solid is discharged. The solid portion is washed, onto the filter drum, with additional amounts of water.