Polystyrene-based superacidic solid acid catalyst: synthesis and its application in biodiesel production

A polystyrene-supported superacidic fluoroalkyl sulfonic acid catalyst (sPS-S) was synthesized using a combination of iridium-catalyzed C-H borylation and Suzuki-Miyaura coupling reactions. Catalytic activity of the new solid acid catalyst was examined for esterification of fatty acids and transesterification of triglyceride with methanol. Significantly higher activity than those of commercial sulfonated ion-exchange resins (Amberlyst 15 and Nafion NR50) was achieved with a catalyst loading as low as 0.5 wt%. The solid catalyst could be easily recovered by filtration and reused. Consistently high activities were obtained from the esterification for up to ten consecutive runs.