1. Pillaring of Clays and Colloids by Sahil Inamdar Sap ID: 60011115017

2. Definition: Pillaring is a commonly used procedure to transform a layered crystalline inorganic compound into a material with microporosity and mesoporosity.

3. Important Points to discuss: Layered Compound Intercalation Pillaring Pillaring Agent Interlayer Region

4. Layered Compounds: It is a crystalline material wherein the atoms in the layers are cross-linked by chemical bonds. The atoms of adjacent layers interact with each other with physical forces. A single layer is called a slab, sheet or lamella.

5. Intercalation: It is the insertion of a guest species in the interlayer regional of a layered solid with a preservation of the layered structure. It is called as a intercalation compound.

6. Pillaring: It is the process by which a layered compound is transformed into a thermally stable micro- and/or mesoporous material with retention of the layer structure. The material obtained is pillared compound or a pillared layered solid.

7. A pillared derivative is distinguished from an ordinary intercalate by virtue of intercrystalline porosity made possible by the lateral separation of the intercalated guest.

8. Pillaring Agent: Any compound which can be intercalated between adjacent layers of a layered compound. It maintains the spacing between the adjacent layers on removal of the solvent It induces an experimentally observable pore structure between the layers.

9. Interlayer Region: It is the space between the adjacent layers of a layered compound. It is also called as “gallery”.

11. Characteristics: The layers are propped apart vertically and do not collapse on removal of the solvent. The minimum increase in basal spacing is the diameter of N 2 molecule: 0.315-0.353 nm.

12. The pillaring agent has molecular dimensions and is laterally spaced in the interlamellar space on a molecular length scale. The interlamellar space is porous and at least accessible to molecules as large as N 2 ; there is no upper limit to the size of the pores.

13. Criteria for a material to be called pillared: Chemical and thermal stability. The lamellae of the layered compound must be ordered so as to give an X-Ray Diffraction (XRD) pattern which allows the determination of the d 001 spacing. Accessibility of the interlayer region by molecules as large as N 2.

14. Advantages: Pore sizes can be controlled. Increased surface area. Thermally and Chemically stable. Selective reactivity towards compounds.

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