Abstract: The invention provides a process for the purification of polymer polyols that ensures a reduction of acrylonitrile, styrene as well as the residual amounts of optionally used chain regulator, and of occurring recombination products of the initiator when azo initiators are used, to levels of <25 ppm of acrylonitrile, <50 ppm styrene, <50 ppm chain regulator and <280 ppm of recombination products by stripping using packed columns.

Abstract: The invention relates to a process for the purification of polymer polyols by stripping using packed columns.

Abstract: The present invention relates to a process for purifying low molecular weight isocyanates or isocyanate mixtures from chlorine compounds by extractively treating the low molecular weight isocyanates or isocyanate mixtures with an extraction agent containing near-critical and/or super-critical fluids or fluid mixtures at a temperature of 10° C. to 200° C., a pressure of 10 bar to 1,000 bar and a weight ratio of the extraction agent to the isocyanate or isocyanate mixture of 1 to 200, and separating the chlorine compounds from the extraction agent by reduction in pressure.

Abstract: The chemical reactor is based on a cylindrical vessel with a stirring device. The stirring device consists of a magnetic stirrer 3, 5, 11a, 11b, 12 with magnetic coils which are disposed around the outside of the cylindrical vessel 1 in the form of a star and produce a magnetic field and of a rotor 3 which is mounted in the region of the rotating field in the vessel 1 such that it can rotate about the cylinder axis. The rotor is provided with stirring blades 11a, 11b, 12 and comprises permanent magnets 5 co-operating with the rotating field.