Influence of the Bronsted and Lewis acid sites on the catalytic activity and selectivity of Fe/MCM-41 system

被引:42
作者
Fellenz, N. A. [2 ]
Bengoa, J. F. [1 ]
Marchetti, S. G. [1 ]
Gervasini, A. [3 ,4 ]
机构
[1] UNLP, Fac Ciencias Exactas, CICPBA, CONICET,CINDECA, RA-1900 La Plata, Buenos Aires, Argentina
[2] Univ Nacl Rio Negro, RA-8500 Viedma, Rio Negro, Argentina
[3] Univ Milan, DCFE, I-20133 Milan, Italy
[4] Univ Milan, Ctr Interdipartimentale Mat & Interfacce Nanostru, I-20133 Milan, Italy
关键词
POX isomerization; Lewis acid sites; MCM-41; Mossbauer spectroscopy; VAPOR-PHASE SILYLATION; ALPHA-PINENE OXIDE; TI-MCM-41; SILICA; MCM-41; ISOMERIZATION; MOSSBAUER;
D O I
10.1016/j.apcata.2012.06.003
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
The system Fe2O3/MCM-41, with high iron dispersion, was synthesized in order to introduce Lewis acid sites into the MCM-41 structure. Two calcination atmospheres (inert and oxidant) were used to produce iron nanoclusters with different structural properties. Besides, a silylation treatment was realized on both solids with the aim of neutralizing the Bronsted acidity associated with the MCM-41 silanol groups. The samples were characterized by atomic absorption spectroscopy, X-ray diffraction at low angles, N-2 adsorption, temperature-programmed reduction, Fourier transform infrared spectroscopy, nuclear magnetic resonance of Si-29, and Mossbauer spectroscopy. The influence of the structural changes of the nanoclusters and the effect of the simultaneous presence of Lewis and Bronsted acid sites were evaluated studying the product distribution from the alpha-pinene oxide isomerization reaction. It was determined that the Bronsted acidity of the Fe/MCM-41 system has not the sufficient acid strength to modify the product distribution which is mainly governed by the Lewis sites. (c) 2012 Elsevier B.V. All rights reserved.
引用
收藏
页码:187 / 196
页数:10
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