Surface properties of nano mesoporous lanthanum oxide synthesized by sol-gel method

This study investigates surface properties like surface acidity/basicity, surface reducibility, surface area, and porosity of nano mesoporous lanthanum oxide (La2O3) synthesized by the sol-gel method. X-ray diffraction (XRD) analysis confirms the formation of nanocrystalline hexagonal La2O3 at 800 degrees C. Fourier transform infrared spectra (FT-IR) shows the peaks corresponding to surface carbonate and surface water on La2O3. Morphology of La2O3 was studied by transmission electron microscopy (TEM). The surface acidity of La2O3 was measured by temperature-programmed desorption (TPD-NH3) analysis and surface basicity by TPD-CO2. TPD profiles show the presence of medium and strong acidic and basic sites on the surface of La2O3. La2O3 has more surface acidity compared to surface basicity. Temperature programmed reduction (H2-TPR) analysis indicates good stability of La2O3 towards reduction. The values of H2 consumption indicate a greater amount of reducible species on the surface. Surface area and porosity measurements were done using Braunauer-Emmet-Teller (BET) analysis. The pore size distribution curve is also determined from the Barrett-Joyner-Halenda (BJH) adsorption/ desorption isotherm. La2O3 is found to be mesoporous with pore diameter of 20.6 nm and has wide pore size distribution between 5 and 50 nm. Typical type IV isotherm with H3 type hysteresis loops at a high P/P0 value is observed for La2O3.Copyright (c) 2022 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of 2022 International Conference on Recent Advances in Engineering Materials.