Artículos SCI

CaO-based materials have been identified as promising sorbents for highly efficient pre-combustion and post-combustion CO2 capture in fluidized beds operated at high temperatures by means of the Calcium Looping (CaL) process. However, Ca-based sorbents suffer from a decline of the capture capacity over multiple sorption/desorption cycles, mainly due to sintering, and from a markedly heterogeneous fluidization behavior due to the strength of interparticle attractive forces as compared to particle weight. The present study is focused on the development of novel synthetic CaO/Al2O3 sorbents for CO2capture with enhanced CaL performance and fluidizability by dry mixing with flow conditioner nanopowders. The influence of initial precursors on the sorbents multicycle activity at realistic CaL conditions has been investigated. The formation of a stable Ca9Al6O18 mixed-phase during the preparation of the sorbents promotes the multicycle capture capacity. The type of Ca and Al precursors, either soluble or insoluble, can significantly affect the dispersion of this stabilizer (Ca9Al6O18) in the sorbent matrix and, consequently, may affect the carbonation activity of the materials. The sorbent prepared from soluble aluminum nitrate and calcium nitrate precursors by sol-gel method exhibits a very stable multicycle capture capacity with a capture capacity around 0.2 g of CO2/g of sorbent after 21 cycles keeping a 72% of its initial capture capacity. The fluidizability of this promising sorbent was also investigated as affected by the addition of three different flow conditioners. Fluidization experiments confirmed the positive effect of using hydrophilic alumina and hydrophobic silica nanoparticles on improving the fluidizability of the synthesized sorbents.

This work describes the electric study of Lithium lanthanum titanate (La0.59Li0.24TiO3) ceramics performed by Complex Impedance Spectroscopy. The nanoparticle powders have been synthesized through high energy ball milling and sintered via Spark Plasma Sintering technique. The experimental impedance data have been analyzed using the equivalent circuit model, the Extended Jonscher universal law and the derivative method. From these models, we have determined the dielectric response as well as the grain and grain boundary conductivity. The samples show ionic conductivity values between 10(-5) to 10(-4) S cm(-1) in the studied temperature range, and activation energy values 0.24 eV and 0.48 eV for grain and grain boundary, respectively. These results confirm the Li+ ions mobility through the crystalline structure of the material.