Patent ID: 8034980

Claim:
A process for preparing polyether polyols by reaction of the following starting materials: a) one or more alkylene oxides and, optionally, carbon dioxide and also b) one or more H-functional starter substances, in the presence of a catalyst, in a reaction unit having a plurality of parallel layers A, B which are microstructured so that each layer has a multiplicity of channels which are arranged parallel to one another and form a continuous flow path from one side of the plate to the opposite side of this, in which part of the starting materials or all starting materials and, optionally, the catalyst are premixed at a temperature below the temperature of the reaction in a mixer outside the reactor and the mixture is subsequently fed into the channels in the layers A on one side of this and the reaction mixture is taken off on the other side of this and a heat transfer medium is fed into the channels of layers B arranged alternately to the layers A on one side of these and is taken off again on the other side of these, wherein a distribution device for introduction of the starting materials and the catalyst is provided at one end of the channels of the layers A and a collection device for the reaction mixture is provided at the other end of these, wherein the pressure in the channels of the layers A is in the range from 10 to 200 bar absolute, the temperature is in the range from 60 to 200° C. and the residence time of the reaction mixture is in the range from 1 to 600 seconds, and wherein the distribution and collection devices are configured as chambers having a geometric shape for creating flow and pressure drop conditions different from the channels each arranged within the stack of the layers A, B by the parallel channels of each layer A having a transverse channel connecting the parallel channels arranged in the region of each of the two ends of these and all transverse channels within the stack of the layers A, B being connected by a collection channel arranged essentially perpendicular to the plane of the layers A, B.