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Title: Surface heterogeneity analysis of MCM-41 metallosilicates by using nitrogen adsorption data

Abstract

MCM-41 silicas with framework-incorporated aluminum and boron heteroatoms were studied using nitrogen adsorption at 77K over a wide range of relative pressures. It was shown that despite significant differences in surface area, pore sizes, and widths of pore size distributions, the framework-substituted MCM-41 materials studied exhibited very similar low-pressure relative adsorption curves and adsorption energy distributions. This indicates that the presence of heteroatoms does not lead to significant changes in the surface properties with respect to nitrogen molecules. However, small but detectable and systematic changes in the low-pressure adsorption were observed for two series of samples with different contents of heteroatoms prepared under similar conditions. It was concluded that low-pressure nitrogen adsorption exhibits rather low sensitivity toward framework-incorporated aluminum and boron heteroatoms, but it may provide some information about contents of heteroatoms for samples prepared under the same conditions. Because of the similarity of nitrogen adsorption processes on surfaces of siliceous ordered mesoporous materials with and without framework-substituted heteroatoms, the methods of micropore analysis (e.g., the comparative plot method) and mesopore size analysis developed and/or calibrated for pure-silica materials are expected to be fully applicable for samples with different kinds of incorporated heteroatoms.

Authors:
; ;
Publication Date:
Research Org.:
Kent State Univ., OH (US)
OSTI Identifier:
20000512
Report Number(s):
CONF-9808111-
Journal ID: ISSN 0743-7463; LANGD5
Resource Type:
Journal Article
Journal Name:
Langmuir
Additional Journal Information:
Journal Volume: 15; Journal Issue: 18; Conference: Third international symposium on effects of surface heterogeneity in adsorption and catalysis on solids, Torun (PL), 08/09/1998--08/16/1998; Other Information: PBD: 31 Aug 1999; Journal ID: ISSN 0743-7463
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; 36 MATERIALS SCIENCE; MOLECULAR SIEVES; SURFACE AREA; PORE STRUCTURE; POROSITY; SORPTIVE PROPERTIES; ALUMINIUM; BORON; DOPED MATERIALS

Citation Formats

Kruk, M., Jaroniec, M., and Sayari, A. Surface heterogeneity analysis of MCM-41 metallosilicates by using nitrogen adsorption data. United States: N. p., 1999. Web. doi:10.1021/la981258u.
Kruk, M., Jaroniec, M., & Sayari, A. Surface heterogeneity analysis of MCM-41 metallosilicates by using nitrogen adsorption data. United States. doi:10.1021/la981258u.
Kruk, M., Jaroniec, M., and Sayari, A. Tue . "Surface heterogeneity analysis of MCM-41 metallosilicates by using nitrogen adsorption data". United States. doi:10.1021/la981258u.
@article{osti_20000512,
title = {Surface heterogeneity analysis of MCM-41 metallosilicates by using nitrogen adsorption data},
author = {Kruk, M. and Jaroniec, M. and Sayari, A.},
abstractNote = {MCM-41 silicas with framework-incorporated aluminum and boron heteroatoms were studied using nitrogen adsorption at 77K over a wide range of relative pressures. It was shown that despite significant differences in surface area, pore sizes, and widths of pore size distributions, the framework-substituted MCM-41 materials studied exhibited very similar low-pressure relative adsorption curves and adsorption energy distributions. This indicates that the presence of heteroatoms does not lead to significant changes in the surface properties with respect to nitrogen molecules. However, small but detectable and systematic changes in the low-pressure adsorption were observed for two series of samples with different contents of heteroatoms prepared under similar conditions. It was concluded that low-pressure nitrogen adsorption exhibits rather low sensitivity toward framework-incorporated aluminum and boron heteroatoms, but it may provide some information about contents of heteroatoms for samples prepared under the same conditions. Because of the similarity of nitrogen adsorption processes on surfaces of siliceous ordered mesoporous materials with and without framework-substituted heteroatoms, the methods of micropore analysis (e.g., the comparative plot method) and mesopore size analysis developed and/or calibrated for pure-silica materials are expected to be fully applicable for samples with different kinds of incorporated heteroatoms.},
doi = {10.1021/la981258u},
journal = {Langmuir},
issn = {0743-7463},
number = 18,
volume = 15,
place = {United States},
year = {1999},
month = {8}
}