A series of heteropolyacid (HPA) salts as catalysts were prepared and characterized. Transesterifications of trimethylolpropane (TMP) were carried out using these catalysts. The influence of organic cations and heteropolyanions on the reaction, optimization of reaction conditions, and catalytic reusability were investigated. The results show that the heteropolyacid (HPA) salts present a self-separation performance after reaction, which ...