Fig. 6a, suggests a sigmoidal shape since it changes from completely concave (27 g min-1, 0.60 wt.%) to completely convex (9 g min-1, 1 wt.%). As the reaction kinetics at 60 C for 0.6 wt.% and 1 wt.% of NaOH are practically identical , the observed differences between curves at the same flow rate and different percentage of catalyst in