Exfoliation of Layered double hydroxides to develop high temperature CO2 capture solid sorbents

Layered double hydroxides (LDHs) are also called as anionic clays, they derive their structure from mineral brucite, Mg(OH)2. Brucite comprises a close packing of hydroxyl ions in which Mg2+ ions occupy alternate layers of octahedral sites, leading to stacking of charge-neutral metal hydroxide slabs of composition [Mg(OH)2]. When a fraction, x, of the divalent metal ion M2+ is substituted by a trivalent ion such as Al3+ or Fe3+, the metal hydroxide layers acquire a positive charge. The metal hydroxide layers have the composition [MII1-xM'IIIx(OH)2]x+. To restore charge neutrality, anions along with water molecules are incorporated into the interlayer region to give a layered double hydroxide (LDH).LDH derived mixed metal oxides (MMOs) are gaining importance as high temperature CO2 sorbents due to;
(1)High CO2 sorption capacity (2) fast CO2 sorption kinetics (3) suitable to employ at flue gas temperatures and composition (4) economical and environmentally benign.
The performance of MMOs in CO2 capture is promising but often encounter shortcomings like; (i) Low surface area (ii) poor thermal stability (iii) particle sintering during cycling and (iv) capacity fading during cycling.

Exfoliation of layered solids is known to increase the surface area of the materials. In this project, we aim to exfoliate LDHs by employing various strategies to increase the surface area of the resultant MMOs. This method will also utilized to enhance the thermal stability and regenerability of the resultant MMOs by compositing exfoliated LDHs with thermally stable supports like, clays and silica.

Supervisor name: 
Dr Susana Garcia
Supervisor email addresses: 

MSc programme:

Deputy name: 
Prof Mercedes Maroto-Valer