Synthesis, characterization and high temperature CO₂ capture capacity of nanoscale Ca-based layered double hydroxides via reverse microemulsion

In this study, we report a reverse microemulsion method to prepare stable homogeneous suspensions containing dispersed Ca-Al layered double hydroxide (LDH) nanoparticles. By changing the concentration, reaction time and temperature, the nano-particles with different structural morphology was developed from amorphous aggregation to platelet, regular hexagon and hydrangea-like hierarchical structure. The crystallization and growth of Ca-Al LDH nanoparticles were involved with a nucleation and growth process under nonaqueous polar solvent/surfactant system. After calcination at 700 C, the calcined nano-sized Cal-Al LDH powders synthesized from the reverse microemulsion display remarkable CO₂ capture behavior at 600 C, which is strongly dependent on the reaction conditions (concentration, time and temperature). The calcined powder synthesized at 80 C exhibits a faster rate of CO₂ absorption and higher CO₂ capture capacity of 44 wt% CO₂ without apparent degradation under multiple cycles of carbonation-calcination.