Emulsion polymerisation in a pulsed packed column stability, reactor performance and scale-up

Emulsion polymerisations are frequently carried out in (semi-) batch proces ses. Demands for improved process control and narrow product specifications make that continuous operation may become an interesting alternative. For emulsion polymerisation in continuous flow reactors, product properties, su ch as conversion, particle concentration and particle size (distribution), are strongly dependent on the residence time distribution. Additionally, th ere is a risk for sustained oscillations in conversion and particle concent ration in reactors with a broad residence time distribution. Application of a plug flow reactor leads to products with the properties of a batch produ ct. The product properties of a batch process can be closely approximated i n reactors with a very small residence time distribution. The pulsed packed column combines low net flow rates, little axial mixing and intensive radi al mixing. Proper combinations of the net flow rate and the pulsation veloc ity make residence time distributions possible as narrow as that of a serie s of considerably more than 50 equally sized CSTRs. Sustained oscillations occurring in a single CSTR are suppressed. Conversions of a batch process a re possible. Particle concentrations for vinyl acetate homopolymerisations in the pulsed packed column are very sensitive to the pulsation velocity. S cale-up is limited by the removal of the heat of polymerisation. Isothermal operation is possible for column diameters up to 0.25 m.