Adsorption - Introduction to Carbon Capture and Sequestration - page 261

Figure 6.5.1 The zeolite LTA
Part of the LTA structure; the red spheres are oxygen atoms and the blue spheres
silica atoms. The grey surface illustrates the cavity and the pore openings. Graphic
by Richard Martin. This animation can be viewed at : http://www.worldscientifi c.com/
worldscibooks/10.1142/p911#t=suppl
to regenerate. In Figure 6.5.1 part of the LTA zeolite is shown, and more
examples of structures were given in Figure 6.1.2 .
Activated carbon
As we have mentioned, activated carbon is one of the oldest known
adsorbents. More recent variants of carbon include carbon nanotubes
[6.14] and carbon molecular sieves [6.15]. These carbon materials show
a good selectivity toward CO 2 , but as with the cationic zeolites, the active
sites also preferentially adsorb water.
Clays
Clays are very common materials, and we will see in Section 9.2 that they
play an important role in the geological sequestration of CO 2 . For carbon
capture, we are interested in a particular form seen in hydrotalcite-like