MCM-41 (

Mobil Composition of Matter Mobil Composition of Matter (MCM) is the initial name given for a series of mesoporous materials that were first synthesized by Mobil's researchers in 1992. MCM-41 (Mobil Composition of Matter No. 41) and MCM-48 (Mobil Composition of Matter No. ...

No. 41) is a

mesoporous A mesoporous material (or super nanoporous ) is a nanoporous material containing pores with diameters between 2 and 50 nm, according to IUPAC nomenclature. For comparison, IUPAC defines microporous material as a material having pores smaller ...

material with a hierarchical structure from a family of silicate and alumosilicate solids that were first developed by researchers at

Mobil Oil Corporation Mobil is a petroleum brand owned and operated by American oil and gas corporation ExxonMobil. The brand was formerly owned and operated by an oil and gas corporation of the same name, which itself merged with Exxon to form ExxonMobil in 1999. ...

and that can be used as catalysts or catalyst supports.Reichinger, M. (2007) ''Poröse Silikate mit hierarchischer Porenstruktur: Synthese von mikro-/mesoporösem MCM-41 und MCM-48 Materialien aus zeolithischen Baueinheiten des MFI-Gerüststrukturtyps''
Dissertation Ruhr-Universität Bochum (in German)

Structure

MCM-41 consists of a regular arrangement of cylindrical mesopores that form a one-dimensional pore system. It is characterized by an independently adjustable pore diameter, a sharp pore distribution, a large surface and a large pore volume. The pores are larger than with zeolites and the pore distribution can easily be adjusted. The mesopores have a diameter of 2 nm to 6.5 nm.

Properties

Contrary to zeolites, the framework of MCM-41 has no bronsted acid centers because there is no aluminium contained in the lattice. The acidity of alumina-doped MCM-41 therefore is comparable to that of the amorphous alumosilicates. MCM-41 is not hydrothermally stable because of the slight wall thickness and the low degree of cross-linking of the silicate units.

Synthesis

To achieve a defined pore diameter

surfactants Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsion#Emulsifiers , ...

are used that form

micelles A micelle () or micella () (plural micelles or micellae, respectively) is an aggregate (or supramolecular assembly) of surfactant amphipathic lipid molecules dispersed in a liquid, forming a colloid, colloidal suspension (also known as associat ...

in the synthesis solution. These micelles form templates that help build up the mesoporous framework. For MCM-41 mostly

cetyltrimethylammonium bromide Cetrimonium bromide ( C16H33)N(CH3)3r; cetyltrimethylammonium bromide; hexadecyltrimethylammonium bromide; CTAB) is a quaternary ammonium surfactant. It is one of the components of the topical antiseptic cetrimide. The cetrimonium (hexadecyltrim ...

(CTAB) is used. MCM-41 Synthesis English 2014

The surfactant first forms rod-like micelles that subsequently align into hexagonal arrays. After adding silica species these cover the rods. Later, calcination leads to a condensation of the silanol groups so that the silicon atoms are bridged by oxygen atoms. The organic template is oxidized and disappears.

Uses

MCM-41, as the

zeolites Zeolites are microporous, crystalline aluminosilicate materials commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula ･y where is either a metal ion or H+. These pos ...

, are widely used as

catalytic Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

cracking. They are also used for separations.

References

{{Reflist Mesoporous material