Synthesis of Hierarchically Porous Hydrogen Silsesquioxane Monoliths and Embedding of Metal Nanoparticles by On‐Site Reduction

Moitra, Nirmalya; Kanamori, Kazuyoshi; Shimada, Toyoshi; Takeda, Kazuyuki; Ikuhara, Yumi H.; Gao, Xiang; Nakanishi, Koji

doi:10.1002/adfm.201202558

Cited by 47 publications

(46 citation statements)

References 72 publications

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“…Hierarchical porous monoliths possessing well‐defined macropores, interconnected mesopores, and micropores have attracted significant attention due to the rapid mass transport driven by convection through the pores . The internal connecting pores and hierarchical structure provide improved accessibility and transport to active sites for energy and environmental applications . As templates for preparing macroporous monolith materials, high internal phase emulsion (HIPE) has received increasing attention due to the ease of synthesizing porous monoliths with controllable structures and physical properties .…”

Section: Introductionmentioning

confidence: 99%

Hierarchical Porous Polystyrene Monoliths from PolyHIPE

Yang

Tan

Xia

et al. 2015

Macromol. Rapid Commun.

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Hierarchical porous polystyrene monoliths (HCP-PolyHIPE) are obtained by hypercrosslinking poly(styrene-divinylbenzene) monoliths prepared by polymerization of high internal phase emulsions (PolyHIPEs). The hypercrosslinking is achieved using an approach known as knitting which employs formaldehyde dimethyl acetal (FDA) as an external crosslinker. Scanning electron microscopy (SEM) confirms that the macroporous structure in the original monolith is retained during the knitting process. By increasing the amount of divinylbenzene (DVB) in PolyHIPE, the BET surface area and pore volume of the HCP-PolyHIPE decrease, while the micropore size increases. BET surface areas of 196-595 m(2) g(-1) are obtained. The presence of micropores, mesopores, and macropores is confirmed from the pore size distribution. With a hierarchical porous structure, the monoliths reveal comparable gas sorption properties and potential applications in oil spill clean-up.

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Section: Introductionmentioning

confidence: 99%

Hierarchical Porous Polystyrene Monoliths from PolyHIPE

Yang

Tan

Xia

et al. 2015

Macromol. Rapid Commun.

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“…The presence of as low as 2wt% niobium resulted in the highest furfural yield at 140 8Cu nder continuous-flowc onditions, by using H 2 O/g-valerolactone as as afe monophasic solvent system.T he interception of at ransient 2,5-anhydroxylose species suggested the dehydration process occurs via ac yclic intermediates mechanism. [35,36] One reason for this is the hard to reproduce preparation of monoliths with 2-15 mm diameter to perform microsynthesis, [37,38] owing to the extreme structure sensitivity from the phase system composition. issues typicalo fp acked-bed systems, such as high backpressure evolution, low contacting efficiency,b road distribution of residence times, formation of hot-spots or stagnation zones, which result in uncontrolled fluid dynamics, hence in unsatisfactory performance.…”

Section: Introductionmentioning

confidence: 99%

“…[34] Despite their advantages, use of hierarchically porous inorganic monoliths in flow catalysis hasb een scarcely investigated so far,b eing essentially exploredf or HPLC applications. [35,36] One reason for this is the hard to reproduce preparation of monoliths with 2-15 mm diameter to perform microsynthesis, [37,38] owing to the extreme structure sensitivity from the phase system composition. [39] Specific functionalization of the monolithic material may also be required for catalytic applications.…”

Section: Introductionmentioning

confidence: 99%

Low‐Temperature Continuous‐Flow Dehydration of Xylose Over Water‐Tolerant Niobia–Titania Heterogeneous Catalysts

et al. 2018

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The sustainable conversion of vegetable biomass-derived feeds to useful chemicals requires innovative routes meeting environmental and economical criteria. The approach herein pursued is the synthesis of water-tolerant, unconventional solid acid monolithic catalysts based on a mixed niobia-titania skeleton building up a hierarchical open-cell network of meso- and macropores, and tailored for use under continuous-flow conditions. The materials were characterized by spectroscopic, microscopy, and diffraction techniques, showing a reproducible isotropic structure and an increasing Lewis/Brønsted acid sites ratio with increasing Nb content. The catalytic dehydration reaction of xylose to furfural was investigated as a representative application. The efficiency of the catalyst was found to be dramatically affected by the niobia content in the titania lattice. The presence of as low as 2 wt % niobium resulted in the highest furfural yield at 140 °C under continuous-flow conditions, by using H O/γ-valerolactone as a safe monophasic solvent system. The interception of a transient 2,5-anhydroxylose species suggested the dehydration process occurs via a cyclic intermediates mechanism. The catalytic activity and the formation of the anhydro intermediate were related to the Lewis acid sites (LAS)/Brønsted acid sites (BAS) ratio and indicated a significant contribution of xylose-xylulose isomerization. No significant catalyst deactivation was observed over 4 days usage.

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“…[1][2][3][4] Porous noble metal structures are expected to provide intriguing properties to generate enormously promising potential for various important applications, such as catalysis, actuators, sensing, surface enhanced Raman scattering, etc. [14][15][16][17][18][19][20][21] The regular morphology with better ligament connectivity endows nanoporous platelet structures with rather high permeability and remarkable catalytic properties relative to their monolithic foams. [14][15][16][17][18][19][20][21] The regular morphology with better ligament connectivity endows nanoporous platelet structures with rather high permeability and remarkable catalytic properties relative to their monolithic foams.…”

Section: Introductionmentioning

confidence: 99%

Design of porous Ag platelet structures with tunable porosity and high catalytic activity

Sui

Wang

et al. 2015

J. Mater. Chem. A

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Porous Ag structures have recently attracted great interest due to their unique characteristics, relatively low cost and good biocompatibility. Shape-, size-, porosity-, and crystallinity-controlled and surface defect tailored synthesis of porous metal materials is of scientific significance yet greatly underdeveloped because of the lack of rational design strategies. Here, a low cost and facile synthetic route is presented to produce regular porous Ag platelet structures with controlled size, porosity, crystallinity and surface defects by a two-step process. Initially, size-tailored regular Ag platelet precursors from 2.5 mm to 36 mm are obtained by merely adjusting the solution pH value; meanwhile D-glucose is introduced as a structure-directing agent. Subsequently, thermal treatment is performed to afford the porous Ag platelet structures. Simply by optimizing the annealing time, temperature and heating rate, porous Ag platelets with effectively tunable porosity, crystallinity and surface defects can be achieved. The porous Ag platelet structures could catalyze the reduction of p-nitrophenol and dyes quite effectively at room temperature, which is attributed to their regular morphologies, porosity, high surface-to-volume ratio, short diffusion length and good permeability. Moreover, these porous Ag platelet structures because of their unique morphology and network characteristics will exhibit excellent electrochemical catalytic activity, or act as outstanding electrodes, sensors, actuators, etc.

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Synthesis of Hierarchically Porous Hydrogen Silsesquioxane Monoliths and Embedding of Metal Nanoparticles by On‐Site Reduction

Cited by 47 publications

References 72 publications

Hierarchical Porous Polystyrene Monoliths from PolyHIPE

Hierarchical Porous Polystyrene Monoliths from PolyHIPE

Low‐Temperature Continuous‐Flow Dehydration of Xylose Over Water‐Tolerant Niobia–Titania Heterogeneous Catalysts

Design of porous Ag platelet structures with tunable porosity and high catalytic activity

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