| 词条 | MCM-41 |
| 释义 |
StructureMCM-41 consists of a regular arrangement of cylindrical mesopores that form a one-dimensional pore system.[2] 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.[3] The mesopores have a diameter of 2 nm to 6.5 nm. PropertiesContrary 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.[3] MCM-41 is not hydrothermally stable because of the slight wall thickness and the low degree of cross-linking of the silicate units.[2] SynthesisTo achieve a defined pore diameter surfactants are used that form micelles in the synthesis solution. These micelles form templates that help build up the mesoporous framework. For MCM-41 mostly cetyltrimethylammonium bromide (CTAB) is used. 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. UsesMCM-41, as the zeolites, are widely used as catalytic cracking.[4] They are also used for separations. References{{Commons category}}1. ^{{Cite journal | doi = 10.1088/1468-6996/15/3/035005| pmid = 27877681| title = Amperometric catechol biosensor based on laccase immobilized on nitrogen-doped ordered mesoporous carbon (N-OMC)/PVA matrix| journal = Science and Technology of Advanced Materials| volume = 15| issue = 3| pages = 035005| year = 2014| last1 = Guo | first1 = M. | last2 = Wang | first2 = H. | last3 = Huang | first3 = D. | last4 = Han | first4 = Z. | last5 = Li | first5 = Q. | last6 = Wang | first6 = X. | last7 = Chen | first7 = J. |pmc=5090526}} 2. ^1 2 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) 3. ^1 {{cite journal|author=Silaghi, M.-C., Chizallet, C., Raybaud, P.|title=Challenges on molecular aspects of dealumination and desilication of zeolites|journal=Microporous and Mesoporous Materials|volume=191|pages=82|doi=10.1016/j.micromeso.2014.02.040|year=2014}} 4. ^{{cite journal|title=Catalysis by Crystalline Mesoporous Molecular Sieves|author=Sayari, Abdelhamid|journal= Chemistry of Materials|year=1996|volume=8|pages=1840-1852|doi=10.1021/cm950585+}} 1 : Mesoporous material |
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