Gas-liquid contactor reactors

Equation 4.20 shows that mass transfer is a determining factor in anionic polymerisation of PO, a high surface area of the liquid reaction mass giving high rates of PO consumption. On the other hand, due to the very high efficiency of stirring, the gas-liquid contactor reactor type assures a very narrow MW distribution of the resulting polyether. For the ethoxylation of intermediate propoxylated polyethers (in block copolymers PO-EO... 

After the addition of the calculated quantity of monomer, a very important step is the consumption of the unreacted monomer, by maintaining the reaction mass at the polymerisation temperature (100-125 °C), under continuous stirring or/and recirculation of the reaction mass. Because the PO addition was stopped, the pressure decreases from 0.35-0.45 MPa to less than 0.1 MPa, in 1.5-2 hours. This step is very important for the improvement of polyether yields and for the loss of a minimum quantity of monomer. The very intensive gas-liquid contactor reactors are extremely efficient in this step of digestion, because the remaining quantity of unreacted monomer decreases very much, in a short digestion time. 

---