Synthesis of Nd2O3 nanopowders by sol–gel auto-combustion and their catalytic esterification activity

Nd2O3 nanopowders were prepared by a novel sol–gel auto-combustion method using additive agent polyvinyl alcohol. The gel transformed from the aqueous solutions of metal nitrate, citric acid and small quality of polyvinyl alcohol underwent a self-propagation combustion process when ignited and yielded voluminous ashes. These ashes were single phase Nd2O3 powders with a particle size of 20–30 nm. The influences of preparation conditions such as the molar ratio of Nd3+ to citric acid, the amount of additive agent polyvinyl alcohol, the pH value of the reaction system on the formation of the particles have been studied in detail. X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM) were used for the sample characterization. It was found that the optimum molar ratio of Nd3+ to citric acid was 1:2, the optimum amount of polyvinyl alcohol was 10% of Nd(NO3)3. In addition, we also studied the catalytic activity of nanometer Nd2O3 and super solid acid SO42−/Nd2O3 in the synthesis of isobutyl acetate.