Optimization of Process Variables in the Synthesis of Tributyl Citrate Using a Polyvinylpolypyrrolidone-Supported Brønsted Acidic Ionic Liquid Catalyst

Figure 5

Response surface plots showing the predicted values of the TBC yield: effect of the (a) n-butanol-to-citric acid molar ratio and temperature, (b) n-butanol-to-citric acid molar ratio and amount of catalyst, (c) n-butanol-to-citric acid molar ratio and reaction time, (d) temperature and amount of catalyst, (e) temperature and reaction time, and (f) amount of catalyst and reaction time on the TBC yield. Other variables were kept at their central level.

(a)

(b)

(c)

(d)

(e)

(f)