The preparation of zirconia-stabilized calcium oxide nanoparticles using supercritical drying technique for calcium looping process

Abstract

The objective of this work is to examine the effect of calcium oxide (CaO) nanoparticles on the CO2 capacity during calcium looping (CaL) in a thermogravimetric analyzer (TGA). This work provides highly reactive nanosized CaO particles synthesized by sol-gel and subsequent supercritical drying techniques resulting in a high surface area of 190 m2/g. Also, stabilized sorbents comprised of two mixed metal oxides of calcium oxide and zirconium oxide (zirconia) nanoparticles are disclosed. The preparation methods for these materials and their applications as sorbents for the calcium looping (CaL) process are presented in this study. The sorbents’ performances were conducted using zirconia/ CaO nanoparticles according to our novel patented method. The TGA results exhibited that the zirconia stabilized sorbent had the highest activity with a maximum CO2 capacity of 15 mol/kg sorbent at a temperature range of 650–700 °C. The sorbents’ characterization was performed applying various methods, such as BET surface area and BJH pore size analyses, thermogravimetry analyzer (TGA), and particle size analysis. The experimental results demonstrate that the appropriate amount of zirconia may stabilize CaO nanoparticles structure, increase the CO2 capacity of sorbents at higher temperatures and intensify the CaO resistance to the sintering during multi-cyclic operations.