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Eimer, Griselda A.; Pierella, Liliana B.; Monti, Gustavo A.; Anunziata, Oscar A.

doi:10.1023/a:1014924332500

Cited by 70 publications

(53 citation statements)

References 39 publications

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“…The absorption associated with silanol groups in Si-C is more intense than that in both Si-A and Si-B, indicating that there are more abundant silanol groups on the surface of the former. Thus, the surface of Si-C might be more hydrophilic due to the polar character of the silanol groups, which is proved by the more intensive deformational vibrations of adsorbed water molecules at ca.1,630 cm -1 [13,14] in the sample Si-C than in both Si-A and Si-B. In the preparation of the sample Si-C, apart from TEOS, organosiloxane APTMS was added as part of the silica sources, it would be intercalated into the silica wall during the ageing procedure, the organic moieties decomposed after calcination, leading to a larger amount of uncondensed Si-O units exposed [15], forming lots of silanol groups.…”

Section: Catalytic Activity Evaluationmentioning

confidence: 99%

Mesoporous silica supported cobalt oxide catalysts for catalytic removal of benzene

Hao

et al. 2007

J Porous Mater

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Two types of mesoporous silica SBA-15 with different pore diameter were synthesized with an ageing temperature of 373 K and an ageing temperature of 308 K, respectively; in addition, mesoporous silica with amorphous structure was synthesized by adding organosiloxane as part of the silica source during the synthesis procedure. Mesoporous silica and conventional alumina supported cobalt oxide catalysts were prepared by incipient wetness impregnation method. These materials were characterized by FT-IR, nitrogen adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM) and Temperature programmed reduction (TPR) techniques, and the activity of the supported cobalt oxide catalysts for deep oxidation of benzene were evaluated in a fixed-bed reactor. It seems that the pore diameter of the silica increase with the elevation of the ageing temperature. Mesoporous silica supported cobalt oxide catalysts are more active than conventional alumina supported ones. Cobalt oxide can be relatively better dispersed on the surface of mesoporous silica which has larger pore diameter and surface areas. Meanwhile, more silanol groups exist on the surface of amorphous silica, which could induce a strong interaction with the supported cobalt oxide species, leading to poor activity for benzene oxidation.

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Section: Catalytic Activity Evaluationmentioning

confidence: 99%

Mesoporous silica supported cobalt oxide catalysts for catalytic removal of benzene

Hao

et al. 2007

J Porous Mater

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“…[14][15][16] Although several reports have discussed the study of hydroxy groups, [17][18][19][20][21] none of them considered the problem of mesoporous hybrid organic-inorganic materials. Only recently was the study of periodic mesoporous organosilicas (PMOs) by vibrational spectroscopy addressed by Hoffmann and co-workers, [22] who compared experimental data with results of DFT calculations to probe the nSiC modes of several organic building blocks.…”

Section: Introductionmentioning

confidence: 99%

Vibrational Study on the Local Structure of Post‐Synthesis and Hybrid Mesoporous Materials: Are There Fundamental Distinctions?

Vaz

Nunes

Vasconcellos-Dias

et al. 2007

Chemistry A European J

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Organic-inorganic mesoporous materials of the MCM-41 type are important materials that can be prepared by either post-synthesis or one-pot synthesis procedures. A complete control of the characteristics at a local level is of the utmost importance in view of the applications of such materials. However, there are not many studies relating such features with synthetic approaches. In this work, we prepared samples by post-synthesis derivatization of materials from Si-based MCM-41, with bidentate nitrogen ligands bearing one or two silylated arms, and by one-pot synthesis of organic-inorganic hybrid materials. The bulk properties of the two kinds of materials were comparable. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and Raman spectroscopy were used to investigate the local environment, namely, the number of OH groups and distribution of SiO(4) units (large and small ring units). Hydrophilicity correlates with both the type of organic moiety used (mono- or disilylated), as well as with the synthetic procedure. The same vibrational studies showed how the structure in the channels changes as a function of pressure, reflecting the low mechanical stability of the mesoporous materials.

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“…32 The signal at 1653 cm -1 is due to the presence of adsorbed water. 28 Signal at 969 cm -1 and 962 cm -1 for S-NaF and S hosts, respectively, are assigned to asymmetric stretching of Si-O neighboring to Si-OH. 25 Martinez et al 25 attributed the absence of these signals to the interaction of surface silanol groups with Al species forming Si-O-Al bonds.…”

Section: Resultsmentioning

confidence: 99%

Polymerization of Aniline in Different Sba-16 Silica Hosts

Giraldo¹,

Vélez²,

Mesa³

2016

Química Nova

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publicado na web em 06/06/2016Polyaniline-silica composites made with mesoporous silica have been reported to improve the mechanical properties of the free polymer. However, there are not many studies about the effect of the chemical and physical properties of the inorganic material used as hosts over the final properties of polyaniline and the composites. Here, polyaniline-silica composites, exhibiting electrical conductivity, were synthesized using different types of SBA-16 mesoporous silica as hosts. The effects of the characteristics of the hosts in the polymerization kinetic, molecular weight and electrical conductivity of the final polymer were studied. The composites showed higher electrical conductivity in comparison with polyaniline synthesized under similar conditions of this work but in the absence of silica. The use of silica allowed to obtain composites with defined morphology, which did not occur in the absence of these hosts. From the results of this work, it can be concluded that SBA-16 mesoporous silica hosts have a bifunctional role in the formation of polyaniline-silica composites: the hosts behaved like nucleation sites, which favors polymerization of high molecular weight polyaniline and they catalyzed the polymerization reaction, especially when aluminum is present in the structure of the host.

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Untitled

Cited by 70 publications

References 39 publications

Mesoporous silica supported cobalt oxide catalysts for catalytic removal of benzene

Mesoporous silica supported cobalt oxide catalysts for catalytic removal of benzene

Vibrational Study on the Local Structure of Post‐Synthesis and Hybrid Mesoporous Materials: Are There Fundamental Distinctions?

Polymerization of Aniline in Different Sba-16 Silica Hosts

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