Embedding MIL-100(Fe) with magnetically recyclable Fe3O4 nanoparticles for highly efficient esterification of diterpene resin acids and the associated kinetics

MIL-100(Fe) embedded with magnetic Fe3O4 nanoparticles (Fe3O4/MIL-100(Fe) composite) is directly used as an effective and recyclable heterogeneous catalyst for the rosin esterification. The Fe3O4/MIL-100(Fe) composite shows unexpectedly high rosin conversion of 94.8% at 240 degrees C within 2.5 h, which is higher than that obtained using a homogenous ZnO catalyst. Characterizations reveals that the Fe3O4/MIL-100(Fe) composite exhibits apparent catalytic activity due to the interaction of MIL-100(Fe) with Fe3O4. The kinetics of rosin esterification using Fe3O4/MIL-100(Fe) composite and ZnO is studied. The effect of glycerol can be considered as constant due to the excess supplies. For Fe3O4/MIL-100(Fe) composite, a first order kinetic model is obtained, but for ZnO catalyst, a second order kinetic model is obtained, affording the activation energies of 25.794-28.808 and 33.048-34.358 kJ mol(-1), respectively, indicating that the presence of Fe3O4/MIL-100(Fe) composite reduces the energy barier that is required in the esterification, thus making it easier to perform. Further, the Fe3O4/MIL-100(Fe) composite shows acceptable stability and reusability for six cycles.