Page 222 - Academic Press Encyclopedia of Physical Science and Technology 3rd InOrganic Chemistry

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Encyclopedia of Physical Science and Technology EN009I-420 July 10, 2001 15:8

Mesoporous Materials,

Synthesis and Properties

Robert Mokaya

University of Nottingham

I. Introduction and Background
II. Synthesis
III. Compositions
IV. Pore Geometry
V. Pore Size Control
VI. Characterization Techniques and Properties
VII. Potential Applications

GLOSSARY here. Although there is a large variety of materials that
can loosely be described as mesoporous, this report con-
Liquid crystal An array of highly ordered molecules in centrates on mesoporous molecular sieves, which possess
solution. a regular arrangement of uniform (mesopore) channels in
Mesophase Pertaining to the morphology of a meso- a solid inorganic framework. The main distinguishing fea-
structure. ture of mesoporous molecular sieves, compared to other
Mesoporous Having pores of size 2–50 nm in diameter. molecular sieves, is the size of pores they possess and the
Mesostructure Pertaining to the structure of a mesopo- way in which the pores are arranged. In terms of their
rous material. structure, they offer highly unusual textural characteris-
Micelle A number of surfactant molecules forming a sph- tics such as uniform pore sizes greater than 2 nm, surface
2
ere, rod, or other shape to minimize repulsive inter- areas in excess of 1000 m /g, and long-range order in
actions between their hydrophobic tails and aqueous the packing of pores. These physical characteristics of-
solution. fer exciting properties that may find applications in (het-
Microporous Having pores less than 2 nm in diameter. erogeneous) catalysis, adsorption, molecular sieving, and
Supramolecular Pertaining to a large array of molecules. guest–host chemistry. In general, the mesoporous mate-
rials currently available can also be distinguished from
zeolites by the fact that their pore walls are amorphous
THE SYNTHESIS and properties of porous solids gen- rather than crystalline. Their ordering lies in the arrange-
erally referred to as mesoporous materials, is described ment of the pore channels rather than within the pore walls.

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