Metal–organic framework-derived nanoporous titanium dioxide–heteropoly acid composites and its application in esterification

MIL-125(Ti) metal–organic framework-derived nanoporous titanium dioxide–heteropoly acid (PW–TiO 2 ) have been synthesized by a facile hydrothermal approach and subsequent calcination, and the PW–TiO 2 catalysts were investigated using various characterization technologies including FTIR, XRD, SEM, TEM, N 2 -physisorption, and NH 3 -TPD. Further, we investigated the use of PW–TiO 2 composites as heterogeneous acid catalysts for the catalytic esterification of oleic acid. Among all series of catalysts, the calcined PW–TiO 2 at a temperature of 350°C showed excellent activity with a high conversion of 90.5% at 160°C for 4 h. More importantly, the catalyst could be simply separated via centrifugation and reused for six cycles and shows a relatively high conversion of 74.8%.