Abstract: The present invention relates to a process for production of pure terephthalic acid comprising: a) removing a mother liquor from a terephthalic acid through a filter with a gas, wherein the gas comprises steam at a concentration of least about 50% by volume; b) purifying the gas; and c) recycling the gas purified in step (b) back to step (a).

Abstract: The invention relates to a process for producing terephthalic acid and for purifying the mother liquor resulting from said process. Useful compounds can be extracted from the mother liquor and the purified mother liquor can be returned for use in the process. Advantageously, certain parameters of the mother liquor purification method are selected such that the purification provides an economic benefit as compared with other purification methods.

Abstract: The invention relates to a process for producing terephthalic acid and for purifying the mother liquor resulting from said process. Useful compounds can be extracted from the mother liquor and the purified mother liquor can be returned for use in the process. Advantageously, certain parameters of the mother liquor purification method are selected such that the purification provides an economic benefit as compared with other purification methods.

Abstract: A reactor for the oxidation of a precursor to an aromatic carboxylic acid or ester thereof in a liquid phase reaction mixture is disclosed. The reactor comprises an elongate vessel, substantially vertical in use, having an upper mixing element and a lower mixing element, characterised in that the upper mixing element is an axial pumping impeller and the lower mixing element is a radial pumping impeller. A process of producing a carboxylic acid or ester thereof in a reactor of the invention is also disclosed. In use, the configuration of mixing elements leads to three highly turbulent mixing zones. In a preferred embodiment of the process of the present invention oxidant, from one inlet, and solvent, precursor and catalyst, are introduced directly into a mixing zone. The highly turbulent mixing zones lead to rapid mass transfer suppressing the formation of unwanted, coloured by-products and reduced reactor fouling.

Abstract: An improved process for recycling unspent diol removed from a polyester manufacturing process wherein the diol is captured, hydrogenated, and recycled so that the final polyester product has improved color over polyesters produced using other recycled diols.

Abstract: A reactor for the oxidation of a precursor to an aromatic carboxylic acid or ester thereof in a liquid phase reaction mixture is disclosed. The reactor comprises an elongate vessel, substantially vertical in use, having an upper mixing element and a lower mixing element, characterised in that the upper mixing element is an axial pumping impeller and the lower mixing element is a radial pumping impeller. A process of producing a carboxylic acid or ester thereof in a reactor of the invention is also disclosed. In use, the configuration of mixing elements leads to three highly turbulent mixing zones. In a preferred embodiment of the process of the present invention oxidant, from one inlet, and solvent, precursor and catalyst, are introduced directly into a mixing zone. The highly turbulent mixing zones lead to rapid mass transfer suppressing the formation of unwanted, coloured by-products and reduced reactor fouling.