Patent ID: 7309590

Claim:
A method for producing an aqueous acrylamide solution, comprising: forming a first mixture by mixing water and a biocatalyst in a reactor; circulating the first mixture through the reactor and a pumping circuit with a pump, wherein the pumping circuit has at least one heat exchanger and a circuit with which said heat exchanger may be bypassed; continuously adding acrylonitrile to the first mixture circulating through the pumping circuit and the reactor at a location after the heat exchanger and directly before the reactor to form a reaction mixture; allowing the formation of acrylamide in said reaction mixture by the biocatalyst that catalyzes the conversion of acrylonitrile and water into the aqueous acrylamide solution; cooling the reaction mixture by circulating the reaction mixture through the reactor and said pumping circuit; and monitoring the course of the reaction by on-line measuring at least one of the acrylonitrile and acrylamide concentration flowing through the pumping circuit at a location before the addition of the acrylonitrile to the pumping circuit.