Kinetics and intensification of tertiary amine N-oxidation: Towards a solventless, continuous and sustainable process

The N-oxidation of tertiary amines is an industrially important reaction, with the product having applications as surfactants, biocides, and emulsifiers. Currently, most processes for the production of fatty amine N-oxides are carried out in a batch or semi-batch manner using organic solvents such as n-propanol. Our analysis of the kinetics of both the N-oxidation reaction as well its thermal degradation in an aqueous system illustrated the possibility of intensifying the reaction through the use of a continuous flow reactor. In this paper, we have proposed the use of the rotor–stator spinning disc reactor as a solventless, continuous system, where mass transfer limitations can be overcome using high shear forces. The reactor could be safely operated at high reactant concentrations and temperatures. A specific productivity of 1960 kg could be achieved in four minutes of reaction time in flow. In comparison, batch reactions are usually performed in the time scale of hours. The results obtained here illustrate that the rotor–stator spinning disc reactor can be used to produce amine N-oxides in a more sustainable and intensified manner.