Abstract: Process for the solid state polycondensation of polyester resins, where an inert gas is circulating in a moving bed of polymer at a temperature between 180.degree. and 230.degree. C., characterized by the fact that the ratio by weight between the gas rate of flow per hour and that one of the discharged polymer is lower than 0.6.

Abstract: Process for the purification of an inert gas recycled from a solid state polycondensation (SSP) reactor of aromatic polyester resins, comprising the step of adding the gas with oxygen or gas containing oxygen in stoichiometric quantity or in such an excess that the gas at the outlet of the catalytic bed contains no more than 250 ppm of oxygen, circulating the gas on a catalytic bed comprising Pt or Pt and Pd heated at temperatures from 250.degree. to 600.degree. C. and recycling the gas to SSP reactor with previous drying to eliminate the water formed in the oxidation stage.

Abstract: Process for the purification of inert gases containing impurities of organic nature particularly of gas (nitrogen) coming from solid state polycondensation reactors or polyester resins including the gas treatment with the stoichiometric quantity (or slightly higher) of oxygen as regards the present impurities at a temperature between 250.degree. and 600.degree. C. by using Pt or Pt/Pd catalysts supported on a porous solid and the gas recycling directly to the polycondensation reactor before drying to eliminate the water produced during the reaction of impurities oxidation.