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Новости Nature

Three-dimensional ordered porous electrode materials for electrochemical energy storage

Mesoporous Platinum Prepared by Electrodeposition for Ultralow Loading Proton Exchange Membrane Fuel Cells

Structural dynamics of a metal–organic framework induced by CO2 migration in its non-uniform porous structure

Boron-neutron Capture on Activated Carbon for Hydrogen Storage

Block copolymer derived uniform mesopores enable ultrafast electron and ion transport at high mass loadings

Porous hypercrosslinked polymer-TiO2-graphene composite photocatalysts for visible-light-driven CO2 conversion

Permanent porous hydrogen-bonded frameworks with two types of Brønsted acid sites for heterogeneous asymmetric catalysis

Development of High-Performance Supercapacitor based on a Novel Controllable Green Synthesis for 3D Nitrogen Doped Graphene

Porous supraparticle assembly through self-lubricating evaporating colloidal ouzo drops

Confinement of poly(allylamine) in Preyssler-type polyoxometalate and potassium ion framework for enhanced proton conductivity

3D printing of sacrificial templates into hierarchical porous materials

Three-dimensional printing of piezoelectric materials with designed anisotropy and directional response

Лента новостей (Journal of Porous Materials)

Effective adsorptive performance of Fe 3 O 4 @SiO 2 core shell spheres for methylene blue: kinetics, isotherm and mechanism

Abstract

In this study, Fe3O4 nanoparticles (NPs) as a core surrounded with thick and tunable SiO2 shells were successfully synthesized and characterized by means of N2-isotherm, scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared (FT-IR) and UV–Vis diffuse reflection spectroscopy (UV–Vis DRS) techniques. The characterization results revealed that well-structured SiO2 shell of 105 nm thick is uniformly formed around Fe3O4 (NPs size of 500 nm) surface. The application of the synthesized core–shell structures was investigated for methylene blue (MB), rhodamine B (Rh B) and methyl orange (MO) toxic dyes adsorptive removal from water by batch adsorption methods and different adsorption parameters such as time, pH, material dosage, concentration of solution and different dyes were optimized. The highest adsorption capacity (123 mg g−1) of MB dye was achieved on Fe3O4@SiO2. The isotherms and kinetic models exhibited that MB adsorption values are well described by Freundlich isotherm and pseudo-first-order kinetics models. The adsorptive binding of MB with Fe3O4@SiO2 was directed through electrostatic interaction and size filter effect. After regeneration, approximately 100% MB dye adsorption capacity was recovered. Thus, we can say that the Fe3O4@SiO2 is an outstanding material for dyes removal from water.

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Evaluation of silanization of Fe-silicalite-1, Na-Fe-ZSM-5 and solvent concentration on the oxidation of n -octane to C8 oxygenates

Abstract

The synthesis of Na-Fe-Silicalite-1(80), Na-Fe-Silicalite-1(128), Na-Fe-ZSM-5(78) and Na-Fe-ZSM-5(126) was conducted using the isomorphic substitution method. These catalysts were further modified by the process of silanisation to yield Na-Fe-Silicalite-1(80:Sil), Na-Fe-Silicalite-1(128:Sil), Na-Fe-ZSM-5(78:Sil), and Na-Fe-ZSM-5(126:Sil) (The numbers in brackets represent the Si/Fe molar ratio and Sil represents silanization). The XRD analyses show that only the ZSM-5 phase was present in all the catalysts. These catalysts were tested in the oxidation of n-octane in MeCN using H2O2 as an oxidant. It was found that the selectivity to terminal products increased with increasing the volume of MeCN. Thus, e.g. terminal C8 selectivities could be improved from 17 to 28% using the Na-Fe-Silicalite-1(80) catalyst by increasing the volume of solvent. Furthermore, the Na-Fe-Silicalite-1(80), Na-Fe-Silicalite-1(80:Sil), Na-Fe-Silicalite-1(128) and Na-Fe-Silicalite-1(128:Sil) show terminal selectivities of 28.1, 14.3, 17.6 and 12.3% respectively. In contrast Na-Fe-ZSM-5(78), Na-Fe-ZSM-5(126), Na-Fe-ZSM-5(78:Sil), and Na-Fe-ZSM-5(126:Sil) show terminal selectivities of 24.5, 25.7, 21.3 and 27.3% respectively. Results also showed that the Na-Fe-ZSM-5 catalyst has better selectivity to terminal products than Na-Fe-Silicalite-1.

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Porosity tuned NiO nanocrystallites by solution combustion synthesis for the development of a voltammetric sensor for dopamine

Abstract

Nickel oxide (NiO) nanocrystallites of porous structure were synthesised by solution combustion method. The influence of F/O ratio on the structural, morphological and electrochemical parameters was investigated. The sample synthesized at F/O ratio 0.4 had a crystallite size of 5 nm. This sample possesses greater surface area and high porosity whereas the sample synthesized at F/O 0.2 was not porous and had lower surface area. Porous NiO was used to modify the carbon paste electrode for the selective detection of dopamine (DA) in the presence of a lot of excess ascorbic acid and uric acid. Sodium dodecyl sulphate (SDS) casting onto the NiO modified electrode improves the performance towards DA. NiO/SDS/MCPE electrode is completely insensitive to ascorbic acid signals below 1.0 × 10−3 M and enables the accurate quantification of DA in presence of 1000 fold excess of UA (uric acid). The fabricated electrode shows good reproducibility, stability and linear dynamic range of 0.3–300 µM.

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Preparation and application of ordered mesoporous carbon-based solid acid catalysts for transesterification and epoxidation

Abstract

Ordered mesoporous carbon (OMC) was prepared via the inverse replication method using SBA-15 as a hard template and sucrose as a carbon precursor. OMC was sulfonated to obtain the solid acid catalysts, such as OMC-SS and OMC-DS, by heating with sulfuric acid or coupling with sulfanilic acid diazonium. TEM and small-angle X-ray diffraction (XRD) results showed that OMC, OMC-SS, and OMC-DS exhibited ordered porous structures. XPS and Raman analysis showed that OMC had graphite structure. N2-BET analysis indicated that OMC, OMC-SS, and OMC-DS had average pore diameters of 3.0–3.3 nm and exhibited bimodal mesopore size distributions. Moreover, N2-BET analysis revealed that OMC, OMC-SS, and OMC-DS had surface areas of 1411, 924 and 1001 m2/g, respectively. The surface acid contents of OMC-SS and OMC-DS were 3.9–4.0 mmol H+/ g and higher than those of OCM (2.8 mmol H+/g). FTIR results demonstrated that –SO3H was present on OMC-SS and OMC-DS. OMC-SS and OMC-DS were used to catalyze the transesterification and epoxidation of waste frying oil. The transesterification reactions catalyzed using OMC-SS and OMC-DS provided the maximum yields of fatty acid methyl esters of 90.3 ± 3.3% and 89.0 ± 2.1%, respectively. The double-bond conversion rates of epoxidation reactions catalyzed using OMC-SS and OMC-DS reached 77.2 ± 1.9% and 68.5 ± 2.6%, respectively. The epoxy yields of epoxidation reactions catalyzed using OMC-SS and OMC-DS were 70.3 ± 2.4% and 65.1 ± 1.8%, respectively.

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SBA-15-supported Cu (II)/Schiff-base complex as an efficient and recyclable catalyst for one-pot azide-alkyne cycloaddition reaction

Abstract

A new complex of copper (II) was synthesized through the reaction of a Schiff-base, 4-(((2-hydroxyethyl)imino)methyl)phenol, with CuCl2·2H2O and, then, immobilization on SBA-15 support. Both immobilized and free copper complexes were characterized using different techniques such as FT-IR, elemental analysis (CHN), SEM, XRD and TEM, and were utilized as catalysts in one-pot azide-alkyne cycloaddition (AAC) reaction. Both catalysts showed high activity in conversion of various substrates to corresponding triazole compounds. The reaction was performed in water under mild condition and without any extra additives. The prepared catalyst was recovered and reused in 5 runs without any significant loss of activity.

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Novel hierarchical HZSM-5 zeolites prepared by combining desilication and steaming modification for converting methanol to propylene process

Abstract

The effect of mesoporosity formation and acidity modification have been investigated by desilication and combined desilication–dealumination treatments over highly siliceous zeolite HZSM-5 (Si/Al = 200) and its catalytic performance has been studied in the conversion of methanol to propylene (MTP) reaction. Desilication of a conventional microporous HZSM-5 catalyst was performed using NaOH, mixtures of NaOH and tetrapropylammonium hydroxide (TPAOH), and mixtures of NaOH and tetrabutylammonium hydroxide (TBAOH) with different ratios. Subsequent mild steaming treatment has been used to modify acidity of the selected samples. The physicochemical properties of all samples were characterized by XRD, FE-SEM, BET and NH3-TPD methods. Textural and acidity properties confirmed that TBAOH is more effective than TPAOH in the mesoporosity formation, micropore volume preservation, and acidity modification. Steaming treatment after desilication over the sample with TPAOH/(NaOH + TPAOH) ratio of 0.4, led to increase in selectivities to propylene from 38.4 to 41.3%, and total light olefins from 69.4 to 76.6%, while it led to decrease in C5+ components selectivity from 14.8 to 10.1%. The combined alkaline-steam treatment over the sample with TBAOH/(NaOH + TBAOH) ratio of 0.2 compared to the parent one led to considerable higher selectivities to propylene (44.8 vs. 30.7%), total light olefins (84.1 vs. 57.9%), as well as lower selectivities to C5+ components (7.4% vs. 27.1%). Moreover, this sample showed double lifetime (830 h) in MTP reaction compared to the conventional micropore ZSM-5 catalyst (425 h). The results showed that desilication led to a remarkable mesoporosity development, while steaming treatment generally influenced on the HZSM-5 acidity. Therefore, the combined alkaline-steam treatment leads to HZSM-5 zeolite formation with tailored pore architecture and surface acidic properties.

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Sulfamic acid well dispersed in the micropores of Al-pillared α-ZrP as efficient heterogeneous catalyst for synthesis of structurally diverse 1,4-dihydropyridines under mild conditions

Abstract

In this study, α-zirconium phosphate (α-ZrP) has been prepared via reflux method. The α-ZrP material was pillared with [Al13O4(OH)24(H2O)12]7+ polycations to improve its surface area and thermal stability. The aluminum oxyhydroxy clusters were synthesized by in situ partial base hydrolysis of the aluminum salt precursor using sodium hydroxide as base. The microporous inorganic matrix of Al-pillared α-ZrP (AZP) was used for molecular dispersion of sulfamic acid to prepare novel composite materials. The sulfamic acid modified AZP materials were characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) specific surface area analysis. XRD study indicated an expansion in the interlayer space as a result of bilayer intercalation of Al137+ pillaring species. The pillared interlayer space is retained in the composite material. FTIR study indicated the structural integrity of the sulfamic acid. The composite materials exhibited enhanced microporosity with surface area and pore volume in the range 80–120 m2/g and 0.1–0.2 cc/g. FESEM and HRTEM studies indicated morphological reorganization of α-ZrP particles as a result of pillaring and subsequent dispersion of sulfamic acid. Elemental mapping study suggested well dispersion of the sulfamic acid in the composite material without any sign of local agglomeration. The catalytic activity of sulfamic acid loaded AZP materials has been evaluated for the synthesis of 1,4-dihydropyridines by multi component condensation reaction of ethyl acetoacetate, arylaldehydes/chalones and ammonium acetate. The composite materials were highly active for synthesis of structurally diverse 1,4-dihydropyridines in high yield and purity under mild conditions.

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Fast microwave dried mechanical robust melamine sponge/methyltrimethoxysilane-based silica aerogel composites with bendability and superhydrophobicity

Abstract

In this work, melamine sponge (MS) reinforced methyltrimethoxysilane (MTMS)-based silica aerogels were fabricated via a sol–gel method followed by fast microwave drying. The aerogel composites with large size (20 × 20 × 2 cm) can be dried within 30 min. The MS/MTMS-based silica aerogel composites exhibit macro-pore structure, low density (95–178 kg m−3), excellent integrity and bending flexibility, together with high mechanical strength (Young’s modulus up to 4.787 MPa). Moreover, the superhydrophobicity with a contact angle as high as 164° and a low thermal conductivity of 0.033 W m−1 K−1 are demonstrated. Our work offers an effective method to fabricate high-quality aerogel composites as promising candidates for energy-saving applications.

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