Estimation of the fractions of different nuclear iron species in uniformly metal-exchanged Fe-ZSM-5 samples based on a Poisson distribution

被引：66
作者：
Brandenberger, Sandro [1 ]
Kroecher, Oliver [1 ]
Tissler, Arno [2 ]
Althoff, Roderik [2 ]
机构：
[1] Paul Scherrer Inst, CH-5232 Villigen, Switzerland
[2] Sud Chem AG, D-83052 Bruckmuhl, Germany
来源：
APPLIED CATALYSIS A-GENERAL | 2010年 / 373卷 / 1-2期
关键词：
Fe-ZSM-5; Zeolite; Calculation; Iron species; Poisson distribution; SELECTIVE CATALYTIC-REDUCTION; DENSITY-FUNCTIONAL THEORY; LOW FE CONTENT; ACTIVE-SITES; N2O DECOMPOSITION; NITROUS-OXIDE; ZEOLITE CATALYSTS; AL DISTRIBUTION; FEMFI ZEOLITES; ZSM-5; ZEOLITES;
D O I：
10.1016/j.apcata.2009.11.012
中图分类号：
O64 [物理化学（理论化学）、化学物理学];
学科分类号：
070304 ; 081704 ;
摘要：
A simple calculation method is presented which allows for estimation of the fractions of different iron species in Fe-ZSM-5 based on statistical considerations. Under the assumption of uniformly distributed iron, the probability with which Fe-O-Fe bridged and higher nuclear Fe-species are formed in a Fe-ZSM-5 sample may be calculated based on a simple Poisson distribution. The results of these calculations were compared with DR-UV/vis and DRIFT spectroscopy measurements on a variety of Fe-ZSM-5 samples with different Fe/Al ratios. Moreover, the calculated concentration profiles were checked with literature data from other studies. It is shown that the fractions of different iron species in Fe-ZSM-5 can be estimated by this calculation method with satisfactory accuracy, provided that the metal-exchange process resulted in a uniform distribution of iron in the zeolite. The method may be useful for verifying of analytical results, understanding of observed activity patterns and may facilitate the identification of activity-structure relationships. (C) 2009 Elsevier B.V. All rights reserved
引用
收藏
页码：168 / 175
页数：8
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