Buhler Ag

Claudemiro Ferreira

Andreas Christel

Camille Borer

Urs Georg Naef

The invention relates to a method for producing a high-molecular polyester from a solidified polyester prepolymer by solid phase polycondensation. The polycondensation cleavage products of the solid phase polycondensation reaction are extracted from the product by means of a process gas, and the process gas is then cleaned and essentially recycled. According to the invention, the process gas is cleaned by means of an aqueous washing liquid. The invention also relates to an installation for carrying out the inventive method, said installation containing a crystallisation appliance () and a reaction appliance (). A gas outlet () of the reaction appliance () is directly or indirectly connected to a gas inlet () in a gas cleaning system (), and a gas outlet () of the gas cleaning system () is connected to a gas inlet () of the reaction appliance (). Furthermore, the gas cleaning system () comprises a gas washing appliance to which an aqueous washing liquid is supplied, and a gas drying appliance () which is mounted downstream.

Solid-phase polycondensation of polyester with process gas purification

The invention relates to a method for producing a high-molecular polycondensate from a solidified polycondensate prepolymer by solid phase polycondensation. According to said method, the polycondensation cleavage products of the solid phase polycondensation reaction are extracted from the product by means of a process gas, and the process gas is then cleaned of the polycondensation cleavage products and essentially recycled. According to the invention, the specific energy input is less than 120 kWh/t, preferably less than 110 kWh/t and especially between 70 and 100 kWh/t. The invention also relates to an installation for producing a high-molecular polycondensate, said installation comprising a heating appliance (), followed by a crystallisation appliance (), a reaction appliance (), and a cooling appliance (). A gas outlet () of the cooling appliance () is connected to a gas inlet () of the heating appliance (), a gas outlet () of the reaction appliance () is connected to a gas inlet () in a gas cleaning system (), and a gas outlet () of the gas cleaning system () is connected to a gas inlet () of the reaction appliance ().

Production of a high-molecular polycondensate

The invention relates to a method for purifying a gas stream containing impurities composed of organic compounds, said gas stream flowing out of a reactor ( ) designed for solid phase condensation, preferably for aromatic polyesters and polyamides. According to said method, a gas containing at least oxygen is fed to the gas stream containing the impurities. The combined gas stream is then conveyed, at a high temperature, especially from 280&deg; C. to 380&deg; C., onto a catalyst ( ) containing rhodium or a rhodium alloy on an inert porous support. It was found advantageous that the amount of oxygen used be hypo stoichiometric, in relation to the organic impurities, and/or that the ratio of oxygen to impurities be controlled by means of a lambda probe (A). Such a lambda probe (A) is used in a facility according to the invention.

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Poços de Caldas, Brazil

Claudemiro Ferreira