Preparation And Properties Characterization Of Rare Earth Oxide Nanostructured Fibers

This paper is focused on the fabrication and property investigation of rare earth oxide nanostructured-fibers via a sol-gel combined electrospinning technique. We discussed the preparation process, structure control of the fibers, the thermal property of the flexible La2Zr2O7 fibers and the water-gas-shift property of the Pt/CeO2 fibers. The aim is to investigate how to fabricate the functional nanostructured-fibers via electrospinning technique further, and relationship between the structure and property in order to find the better performance of applied nanostructured-fibers.1. Fabrication of flexible nanostructure La2Zr2O7 fibers and their thermal properties.Flexible nanostructured La2Zr2O7 fibers with pyrochlore phase were fabricated by electrospinning process using Zr(OAc)4,LaCl3·7H2O as reagent, silica sol as doping reagent and PVP as spinnable aids. The fibers had dense texture with uniform diameter of 2-3μm and smooth surface. And the basic grains was small which were about 50-100 nm. The transformation process from the xerogel fibers to La2Zr2O7 nanostructured fibers was tracked, and the thermal conductivity and flexibilility of the nanofibers affected by the additive silica and porosity were also discussed. The experimental results showed that the flexible La2Zr2O7 fibers with porosity close to 81% had lower thermal conductivity (0.05415 W/m·K) at room temperature and have potential value in thermal insulation at high temperatures.2. Fabrication of Pt/CeO2 nanofibers for use in water-gas shift reaction.The Pt/CeO2 nanofibers membrane with diameter of 80-120 nm were prepared by electrospinning method with Ce(NO3)3·6H2O as raw material and PVP as spinnable reagent. The process including the preparation of spinnable sol and electrospinning is both simple and low-cost, which is suitable for large-scale preparation. The Pt/CeO2 nanofibers calcined at 400℃were composed of nanoparticles of ca.20 nm. The analysis by XRD and pore structure also showed that with increase of the calcined temperatures the crystallization and particle size of nanofibers were increased, however the specific surface area was decreased. The water-gas shift experiments showed that the pure CeO2 nanofibers had no catalytic conversion and the lwt% Pt doped CeO2 nanofibers had better catalytic effect which indicated that the Pt dispersed well in the nanofibers with high activity. It also showed that the CO conversion were achieved 98% at 300℃with Pt/CeO2 nanofibers which were calcined at 400℃, and this high conversion rate maintained to the final texting temperature at 360℃. The results showed that the Pt/CeO2 nanofibers which assembled of monolithic catalyst achieve better catalytic conversion.