2.2 | Experimental Setup and Procedure
BPA production reaction which results from the reaction of 2 moles of phenol with 1 mol of acetone. In practice, this reaction cannot be carried out efficiently using stoichiometric ratios. This is due to the formation of isomers and deriva-tives of BPA and the self-condensation of acetone in series and parallel reactions (Mcketta & Cunningham, 1977). In order to prevent this, practically high phenol:acetone ratios are preferred. This ensures that the acetone concentration is kept low in the reaction medium. But this will actually lead to an increase in energy costs as well. Based on this challenge, the operating conditions of the semi-batch reactor using stoichiometric phenol/acetone ratio were investigated.
In semi-batch experiments, 0.4 moles of acetone were fed into the reactor during the 6 hours reaction time that previously added 0.8 moles of phenol, at various flow modes (pulsed mode). In order to keep the concentration of acetone in the media to a low level, it was fed to the reaction medium in a semi-batch condition. The semi-batch feeding was performed in various modes (45-15, 50-10, 60-30, 75-15, 90-30, 120-60, 180-180, 360-0 and batch 1-359).
In these modes the first term indicates the feeding time as minute and the seconds referee the waiting time (stopping the feeding). In the experiments firstly, 37% HCl was used as catalyst and 5%, 15% and 25% of the total reactants by mole were added to the medium. The reactants were stirred at 800 rpm and reacted at 60 ° C and the reaction continued for 6 hours. Samples were taken at 4, 5 and 6th hours and analyzed. In addition, solid Amberlyst ion-exchange resin was also used as catalyst. Catalyst was added 10%(w/w) of the reactants to the reaction medium. In batch experiments, phenol and acetone were added to the reactor at a various molar ratios and the experiments were carried out under the above condi-tions. The results were compared with the experiments performed at 2:1, 3.5:1 and 5:1 etc. molar ratios of phenol-acetone. The semi-batch experiment system is shown in Figure 3.