Design and Preparation of Organic−Inorganic Hybrid Catalysts

Wight, Andrea P.; Davis, Mark E.

doi:10.1021/cr010334m

Cited by 1,235 publications

(666 citation statements)

References 108 publications

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“…Numerous reviews of silica functionalization exist in the literature. [12][13][14][15] In a direct synthesis (also known as a one-pot synthesis), a silica precursor is polymerized in the presence of functional organosilanes in a single step. Using this route to functionalized silica materials, higher loadings of functional groups can be achieved and those groups can be well distributed within the silica matrix.…”

Section: Choice Of Silica Supportmentioning

confidence: 99%

Cooperative catalysis by silica-supported organic functional groups

2008

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Hybrid inorganic-organic materials comprising organic functional groups tethered from silica surfaces are versatile, heterogeneous catalysts. Recent advances have led to the preparation of silica materials containing multiple, different functional groups that can show cooperative catalysis; that is, these functional groups can act together to provide catalytic activity and selectivity superior to what can be obtained from either monofunctional materials or homogeneous catalysts. This tutorial review discusses cooperative catalysis of silica-based catalytic materials, focusing on the cooperative action of acid-base, acid-thiol, amine-urea, and imidazole-alcohol-carboxylate groups. Particular attention is given to the effect of the spatial arrangement of these organic groups and recent developments in the spatial organization of multiple groups on the silica surface.

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Section: Choice Of Silica Supportmentioning

confidence: 99%

Cooperative catalysis by silica-supported organic functional groups

2008

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“…Membrane properties can be significantly improved when the reinforced functionalized MWCNTs on loading ranges from 1-5 wt % based on the Nafion polymer weight. 28 MWCNT-g-poly (aniline-co-DABSA)/Nafion nanocomposite membranes showed enhanced water uptake values up to 1-2 wt % loading of the fMWCNTs. Afterward, further loading of the f-MWCNTs on the Nafion membranes did not improved in the water uptake values.…”

Section: Scheme 1 Preparation Procedures Of Mwcnt-g-poly (Aniline-comentioning

confidence: 98%

Preparation and Characterization of MWCNT-g-Poly (Aniline-co-DABSA)/Nafion^®Nanocomposite Membranes for Direct Methanol Fuel Cells

Kim¹,

Kim²,

Gopalan³

et al. 2013

Bulletin of the Korean Chemical Society

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Multiwalled carbon nanotube (MWCNT)-g-poly (aniline-co-2,5-diaminobenzenesulfonic acid) (DABSA) reinforced Nafion ® nanocomposite membranes were prepared and characterized for direct methanol fuel cells (DMFCs). The nanocomposite membranes with approximately 90 µm thickness were prepared by the water assisted solution casting method. To evaluate the properties of nanocomposite membranes for DMFC applications, the nanocomposite membranes were characterized by methanol and water uptake, thermal stability, and ion exchange capacity (IEC). Furthermore, oxidative stability measurements in terms of the hydrogen peroxide decomposition rate that represent the oxidative stability of the membranes were examined. The methanol uptake values of the nanocomposite membranes were dramatically decreased compared to the cast Nafion ® membranes. The IEC values of the nanocomposite membranes were increased about 30% compared to the cast Nafion ® membrane.

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“…Both spectra show two overlapping signals in the region from -100 to -110 ppm, ascribable to the Q 3 (-100 ppm) and Q 4 (-110 ppm) bands of Si(OH)(OSi) 3 and Si(OSi) 4 silicate species. In addition to these low field signals, the samples show peaks at around -66 ppm, which can be assigned to T 3 groups [T 3 = RSi(OSi) 3 ], demonstrating that the organosiloxanes are condensed as a part of the silica framework.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

“…Organically functionalized mesoporous silicas, in particular, have received considerable attention because various organic functional groups enlarge their practical applications to catalysis, separation, sensor, and drug delivery. [3][4] Mesoporous silicas functionalized with acidic groups, such as sulfonic acid, Nafion, and carboxyl groups, show high activity and selectivity for classical acidpromoted organic reactions, such as esterification, FriedelCrafts acylation, and olefin polymerization. [5][6][7][8][9] Various Ngroup-modified mesoporous silicas have been used in some base-catalyzed reactions including the Heck reaction, Knoevenagel condensation, and Michael addition.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Catalytic Properties of Two Zwitterionic Hybrid SBA‐15 Mesoporous Silicas

Yang

Wang

et al. 2012

Eur J Inorg Chem

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Zwitterionic hybrid SBA-15 mesoporous silica materials containing both amine and sulfonic acid groups have been synthesized through cocondensation from as-synthesized zwitterionic siloxane precursors (ZS) with tetraethoxysilane (TEOS). Characterization by XRD, TEM, and N 2 adsorptiondesorption measurements show that the as-synthesized materials have ordered mesostructures. Analysis with UV, 29 Si/ 13 C cross-polarization magic angle spinning (CP-MAS) NMR, and X-ray photelectron spectroscopy (XPS) and elemental analysis demonstrates that the zwitterionic parts have been IntroductionOrdered mesoporous silica materials, such as the representative MCM-41 [1] and SBA-15, [2] with stable mesostructures, large surface areas, and size-tailored mesopores on the nanometer scale have been widely investigated and employed in many fields. Organically functionalized mesoporous silicas, in particular, have received considerable attention because various organic functional groups enlarge their practical applications to catalysis, separation, sensor, and drug delivery. [3][4] Mesoporous silicas functionalized with acidic groups, such as sulfonic acid, Nafion, and carboxyl groups, show high activity and selectivity for classical acidpromoted organic reactions, such as esterification, FriedelCrafts acylation, and olefin polymerization. [5][6][7][8][9] Various Ngroup-modified mesoporous silicas have been used in some base-catalyzed reactions including the Heck reaction, Knoevenagel condensation, and Michael addition. [10][11][12] Recently, base-and acid-bifunctional mesoporous catalysts were developed and received great attention because a cooperative catalytic system constructed from general acid and base groups is desired for some carbon-carbon bondformation reactions. [13][14][15] Lin et al. demonstrated that a general acid group, the ureidopropyl group, can activate substrates in cooperation with a general base group, the 3-[2- [a] [19][20] Kan et al. synthesized acid-base bifunctional mesoporous materials by controlling steric hindrance to prevent interactions between acid and base. [13] Although much effort has been made, precise control of the molar ratio and distribution of the acid and base centers to avoid their neutralization is still a big challenge. Zwitterions are neutral molecules with a positive and a negative electrical charge at different locations within the molecule. Their latent acidity (or basicity) could be obtained by combining 1:1 molar quantities of zwitterions with acids (or bases) possessing sufficiently low pK a (or pK b ) to convert the acidic (or basic) groups into the corresponding acids (or bases). Examples are known, such as SO 3 H-functionalized ionic liquids, which were prepared through the acidification of zwitterions containing alkanesulfonic groups by various strong donor acids. [21][22] Furthermore, CO 2 -philic ionic liquid materials were prepared by alkalizing zwitterions with quaternary ammonium hydroxides. [23] Therefore, it is very interesting to introduce zwitterions into mesoporous ...

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Design and Preparation of Organic−Inorganic Hybrid Catalysts

Cited by 1,235 publications

References 108 publications

Cooperative catalysis by silica-supported organic functional groups

Cooperative catalysis by silica-supported organic functional groups

Preparation and Characterization of MWCNT-g-Poly (Aniline-co-DABSA)/Nafion^®Nanocomposite Membranes for Direct Methanol Fuel Cells

Synthesis, Characterization, and Catalytic Properties of Two Zwitterionic Hybrid SBA‐15 Mesoporous Silicas

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Design and Preparation of Organic−Inorganic Hybrid Catalysts

Cited by 1,235 publications

References 108 publications

Cooperative catalysis by silica-supported organic functional groups

Cooperative catalysis by silica-supported organic functional groups

Preparation and Characterization of MWCNT-g-Poly (Aniline-co-DABSA)/Nafion®Nanocomposite Membranes for Direct Methanol Fuel Cells

Synthesis, Characterization, and Catalytic Properties of Two Zwitterionic Hybrid SBA‐15 Mesoporous Silicas

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Preparation and Characterization of MWCNT-g-Poly (Aniline-co-DABSA)/Nafion^®Nanocomposite Membranes for Direct Methanol Fuel Cells