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Expanded Graphite (EG) has been widely used for treating oil-polluted water. Removal of dye pigments from oily wastewater is the biggest challenge for paint industries. So, the present work focuses on treating simultaneously oil and dye-contaminated water by introducing TiO2/EG composite. EG samples with the highest exfoliation volume have been prepared by microwave irradiation by optimizing time and tested through an oil adsorption study with different oils. TiO2 NPs have been synthesized by the sol–gel method. A novel EG/TiO2 composite has been synthesized by mixing TiO2 NPs in graphite intercalation compound (precursor) and exfoliating the mixture for the optimized irradiation time. A comparative study of the effect of EG, TiO2 NPs, and EG3/TiO2 composite on oil and dye-polluted water has been performed in direct sunlight. Results of UV–visible spectroscopy showed that the addition of TiO2 NPs with EG accomplished the dye degradation along with the adsorption of oil from polluted water. [ABSTRACT FROM AUTHOR]

The effect of different acids on the pore structure and fractal characteristics of micropores and mesopores was determined with the help of low-temperature liquid nitrogen adsorption, X-ray diffraction, and the Frenkel–Halsey–Hill (FHH) model by using Yuwu coal as a sample and placing it in acidic environments, such as HF, HCl, HNO3, and CH3COOH. The results show that the acidization effects of HF and CH3COOH are separately dominated by the micropore and mesopore formation effects, while HCl and HNO3 mainly play their roles in expanding mesopores. After acidization, the surface fractal dimensions D1 and D1′ of micropores and mesopores in coal are always negatively correlated with the total specific surface area SBET, specific surface area Smic of micropores, and specific surface area Smes of mesopores. After being acidized by HF, D2 is negatively correlated with the total volume Vtot and the corresponding micropore volume Vmic, while acidization with HCl and HNO3 leads to the opposite result. After being acidized by CH3COOH, D2 has a negative correlation with Vtot and a positive correlation with Vmic. The structural fractal dimensions D2′ of mesopores in samples acidized by HF and CH3COOH are positively correlated with both the volume Vtot and mesopore volume Vmes, while it is the opposite for samples acidized by HNO3. D2′ of coal samples acidized by HCl is negatively correlated with Vtot while positively correlated with Vmes. [ABSTRACT FROM AUTHOR]

This work reports the synthesis of a mixed crystal phase mesoporous metal–organic framework (MOF) through a new synthesis route. The Hexagonal Centred Planar/Face Centred Cubic mixed phase UiO-67(Zr) product was microfluidically synthesised using benzoic acid as the acid modulator. This phase ratio can be altered through changing the concentration of water present in the reaction solution. This product shows increased mesoporosity and uptake of N2 at 77 K and 1 bar of 1083 cm3/g, as compared to 615 cm3/g for the product made via the traditional batch approach. This leads to an increase working capacity due to the change in isotherm type, from type I to type IV, with the uptake occurring more gradually overall as pressure increases. An increased working capacity allows for a greater range of control for the volume of N2 stored in/released from the material. This product has only been successful in microfluidic conditions, highlighting the potential importance of this method for future synthesis of this MOF. [ABSTRACT FROM AUTHOR]

Summary: The scientific community is actively testing new materials to enhance the electrochemical properties of supercapacitors (SCs) and the porous nanomaterials/composites have emerged as promising candidates for such purposes. In this review, we summarize the most recent strategies to enhance the capacitance and cycling stability of electrode materials/SCs using micro‐, meso‐ and macroporous structures. We described the morphology and surface properties of the porous nanomaterials/composites (containing or not carbon materials) published in the literature. Later, we explained how the parameters of pore size, pore‐volume, surface area, orientation and morphology of the nanomaterials affect the electrochemical performance of the SCs. The type of pore (micro‐, meso‐ and macropore) or the presence of various types of pores (meso‐/micro‐, macro‐/meso‐, etc) not only increased/decreased the capacitance of the materials/devices but also was critical to determine which mechanism (electric double layer or redox) was dominant for the charge storage. This review is useful to understand the main phenomena that affect the performance of SCs based on porous materials as well as to design new types of porous nanostructures with new physical and chemical properties, which in turn, would improve the lifetime and the charge storage capabilities of SCs. [ABSTRACT FROM AUTHOR]

Nanoporous solids are ubiquitous in chemical, energy, and environmental processes, where controlled transport of molecules through the pores plays a crucial role. They are used as sorbents, chromatographic or membrane materials for separations, and as catalysts and catalyst supports. Defined as materials where confinement effects lead to substantial deviations from bulk diffusion, nanoporous materials include crystalline microporous zeotypes and metal–organic frameworks (MOFs), and a number of semi-crystalline and amorphous mesoporous solids, as well as hierarchically structured materials, containing both nanopores and wider meso- or macropores to facilitate transport over macroscopic distances. The ranges of pore sizes, shapes, and topologies spanned by these materials represent a considerable challenge for predicting molecular diffusivities, but fundamental understanding also provides an opportunity to guide the design of new nanoporous materials to increase the performance of transport limited processes. Remarkable progress in synthesis increasingly allows these designs to be put into practice. Molecular simulation techniques have been used in conjunction with experimental measurements to examine in detail the fundamental diffusion processes within nanoporous solids, to provide insight into the free energy landscape navigated by adsorbates, and to better understand nano-confinement effects. Pore network models, discrete particle models and synthesis-mimicking atomistic models allow to tackle diffusion in mesoporous and hierarchically structured porous materials, where multiscale approaches benefit from ever cheaper parallel computing and higher resolution imaging. Here, we discuss synergistic combinations of simulation and experiment to showcase theoretical progress and computational techniques that have been successful in predicting guest diffusion and providing insights. We also outline where new fundamental developments and experimental techniques are needed to enable more accurate predictions for complex systems. [ABSTRACT FROM AUTHOR]

The achievement of hierarchical zeolite templated carbons (ZTCs) is firstly reported through the use of mesoporous zeolites as sacrificial scaffolds. The achieved hierarchical ZTCs feature both tailored microporosity and high degree of mesoporosity and allow hence to bridge the gap between classical ZTCs and CMK-like materials. Mesoporosity from steamed zeolites was meticulously transcribed to the ZTC particles. The use of zeolites featuring surfactant-templated mesoporosity allowed for achieving a ZTC with a very high mesopore volume (0.85 cm3 g−1). The rearrangement of surfactant-templated mesoporosity could be evidenced through nitrogen physisorption and transmission electron microscopy on ultramicrotomed samples. The rearrangement of mesoporosity during ZTC formation has been found to impact coherent crystal size and the lattice strain of the zeolite template. The combination of data from X-ray diffraction and nitrogen physisorption allowed further to reveal that the thickness of the ZTC skeleton is impacted by the degree of intracrystalline mesoporosity in the template zeolite. Through comparing the textural characteristics of the zeolite templates and of the achieved hierarchical ZTCs, important evidence was found that the surfactant-templating of USY zeolite leads to the development of a secondary amorphous phase and that the reduction of the microporous volume during this process is merely apparent.

• Activated carbon nanofiber was synthesized from coconut shell charcoal and poly(vinyl alcohol). • Electrospinning followed by carbonization generated activated carbon nanofiber. • Activated carbon nanofiber synthesized by iodine treatment had the highest dye adsorption capacity. • The highest theoretical maximum monolayer adsorption capacity was 166.67 mg/g. • The dye adsorption capacity was maintained constant at 96% at the third cycle. Activated carbon nanofibers (ACNF) have been successfully prepared using an electrospinning method with coconut shell charcoal (CSC) as a carbon source and poly(vinyl alcohol) (PVA) as a spinning polymer agent. The high voltage of 10 kV was applied for the electrospinning system. The positive electrode of the high voltage power supply was connected to the needle tip, and the grounded electrode was connected to the metallic collector wrapped with an aluminum foil. The dry fibers in the form of a fibrous mat were collected in the aluminum foil. The average pore diameters of the generated fibers for all variables ranging from 2.23 to 3.73 nm corresponding to mesoporous carbon nanofibers. The total pore volumes were ranging from 0.50 to 0.92 cm3/g. IACNF-60 had the largest surface area of 1,277 m2/g obtained from the use of PVA 12 w/v %, 60 wt% CSC, and the use of iodine treatment before thermal stabilization, carbonization, and activation stages. Methylene blue solution was used as a model for the dye adsorption capacity that followed the Langmuir adsorption model. IACNF-60 also indicated the highest theoretical maximum monolayer adsorption capacity in the amount of 166.7 mg/g. Furthermore, the methylene blue removal ability of IACNF-60 for the third cycle was maintained relatively constant at 96%. [ABSTRACT FROM AUTHOR]

A solvent-free synthesis of hierarchical porous carbons is conducted by a facile and fast mechanochemical reaction in a ball mill. By means of a mechanochemical ball-milling approach, we obtained titanium(IV) citrate-based polymers, which have been processed via high temperature chlorine treatment to hierarchical porous carbons with a high specific surface area of up to 1814 m2 g−1 and well-defined pore structures. The carbons are applied as electrode materials in electric double-layer capacitors showing high specific capacitances with 98 F g−1 in organic and 138 F g−1 in an ionic liquid electrolyte as well as good rate capabilities, maintaining 87% of the initial capacitance with 1 M TEA-BF4 in acetonitrile (ACN) and 81% at 10 A g−1 in EMIM-BF4.

Advances in material science and nanotechnology permits combination of new materials with tuned physical, chemical and optical properties with high effectiveness. These multifunctional materials has wide areas of application in gas sensors/separators, membranes, catalysis etc. Air and water quality monitoring, food-safety, medicine, defense are the important fields require a novel technology for fabricating a device having desirable characteristics such as low power requirements, selectivity, sensitivity and stability. Metal-Organic Framework (MOF) is a widely studied porous nanomaterial due to its exceptional degree of flexibility for both organic/inorganic ligands in the structure, which differentiate it from other organic nanostructure. The known strategies used in MOF synthesis, includes different synthesis routes, precursor concentration, temperature and pressure plays a precious role in view of the above required applications. This review article compiles and recounts the extending traits and behavior of MOF, synthetic route, nucleation and growth corresponding with applications, introduction to its structure and various results analysis in comprehensive way. The detailed discussion of MOF nanomaterial as chemical sensor and the historical background of porous nanomaterial in solid state chemistry is presented. Image 1 [ABSTRACT FROM AUTHOR]

• A high surface area and hierarchical pore structure composite was prepared from SBA-15 and ACF. • The pore size distribution and hysteretic loop indicated the micro-mesoporous structure of the composite. • The composite shows excellent potential in CO 2 capture application. SBA-15/ACF with a hierarchical pore structure was produced by the modified hydrothermal synthesis method using SBA-15 and activated carbon fiber (ACF). As the factors related to the pore structures, the optimized temperature of removing template at 300 °C and materials ratio of 1:50 made the SBA-15/ACF with a high specific surface area of 1468 m2 g−1 and total pore volume of 0.7519 cm3 g−1. Compared with the existing adsorbents, the hierarchical pore structure of the composite resulted a good CO 2 adsorption capacity of 4.49 mmol g−1. The excellent CO 2 adsorption capacity demonstrated that the SBA-15/ACF composite could be a promising adsorbent in the CO 2 capture field. [ABSTRACT FROM AUTHOR]

Two types of silica particles were synthesized by the sol-gel process. The first type of silica particles was synthesized by neutralization of a highly basic sodium silicate solution. The obtained particles were polydispersed with irregular shapes and a mesoporous structure. The second type of silica particles was prepared by hydrolysis and condensation of tetraethylortosilicate (TEOS). The obtained particles were spherical and monodispersed with a microporous structure. Multimodal size distribution was characteristic of the silica particles obtained from the sodium silicate solution with a particle size distribution between 0.2 and 6 μm. On the other hand, the silica particles obtained from TEOS had a unimodal size distribution with an average particle size of about 0.5 μm. The physical adsorption of Candida rugosa lipase onto the obtained silica particles was investigated at pH=7. The silica particles prepared from TEOS had the lowest adsorption efficiency (2%) while those prepared from the highly basic sodium silicate solution had the highest adsorption efficiency (50%). The isoelectric point of silica particles and Candida rugosa lipase was 2.5 and 2.4, respectively, which suggests that van der Waals' forces probably play the major role in the process of binding lipase into mesoporous silica when physical adsorption was involved at pH 7.

Abstract Herein, we report the synthesis of hierarchical AlPO 4 -5 and SAPO-5 molecular sieves that exhibit varying degrees of mesoporous interconnectivity by controlling the amount of triethylamine (TEA) (used as the structure directing agent) and the Si-to-Al ratio (Si/Al); the gel mixture had a composition of (1 − y) Al 2 O 3 :y SiO 2 :1.3 P 2 O 5 :x TEA:200 H 2 O. The molecular sieves were characterized by X-Ray powder Diffraction (XRD) and Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM/EDX), and their sorption properties were studied by N 2 adsorption-desorption at 77 K and water adsorption at 316 K. In the synthesis gel with x = 1.6 ((1 − y) Al 2 O 3 :y SiO 2 :1.3 P 2 O 5 :1.6 TEA:200 H 2 O), SAPO-5 and AlPO 4 -5 exhibit high Brunauer-Emmett-Teller specific surface areas of ~380 m2 g−1 and 325 m2 g−1, respectively. SAPO-5, having a composition of Si 0.46 Al 0.6 P 0.804 , exhibits significant water uptake at low relative pressures (3.4 mmol/g at P/P 0 = 0.03 vs. 0.2 mmol/g for pure AlPO 4 -5) attributed to the contribution of hydrophilic Brønsted acid sites, arising from the charge imbalance created by the isomorphic substitution of Si into the aluminophosphate structure predominantly via the SM2 mechanism. Furthermore, SAPO-5 exhibited a hierarchical pore structure having distinct pore size distributions centred on 0.7 nm and 15.8 nm, attributed to the AFI framework and the induced mesoporosity, respectively. At higher relative pressures, SAPO-5 exhibited the highest total water adsorption capacity of 14.1 mmol/g at a relative pressure of 0.38, compared to 11 mmol/g for AlPO 4 -5. The higher overall capacity of SAPO-5 is attributed to capillary condensation into the relatively large mesopore volume. Highlights • Hierarchical AlPO 4 -5 and SAPO-5 are made using hydrothermal method. • AlPO 4 -5 mesoporosity is introduced by control of the structural directing agent. • Mesoporosity is further increased in SAPO-5 by silicon introduction. • SAPO-5 possesses an unprecedented water adsorption capacity of 14.1 mmol/g. [ABSTRACT FROM AUTHOR]

The use of atrane complexes as hydrolytic precursors enables the homogeneous incorporation of manganese (25 ≤ Si/Mn ≤ 48) throughout the porous walls of the nanoparticles of a surfactant-templated bimodal mesoporous silica (UVM-7). The subsequent leaching of the manganese nanodomains allows adding controlled microporosity to the host silica framework. The resulting final silica material presents three pore systems structured at different length scales: interparticle textural-type macroporosity (ca. 43.2 nm), ordered intraparticle mesoporosity (ca. 2.63 nm; after template removal), and well-dispersed microporosity (< 2 nm; as consequence of the lixiviation of the Mn-rich domains). The good dispersion of the guest element (Mn) in the silica intermediate provided by the atrane route is responsible for the disordered but regular microporosity achieved. [ABSTRACT FROM AUTHOR]

Raman and FTIR spectroscopy are powerful techniques used to characterize or observe alterations in the structure or properties of Keggin type heteropoly acids, microporous/mesoporous materials, as well as their composites. These methods were applied in this study for investigation of 12-tungstophosphoric acid (WPA) supported as active phase on zeolites (H-BEA and NaY-zeolite) and mesoporous molecular sieves (TiO 2 , MCM-41, SBA-15). It has been shown that important information on interaction of heteropoly acid and the support can be obtained by the applied vibrational spectroscopic methods. Obtained results show how interaction of WPA with different supports depends on the nature and properties of both, active phase and the support. In the case of microporous supports such as BEA or NaY zeolites, the basicity of the support, i.e., ratio of Si/Al, strongly determines interaction between WPA species and surface of the support. In the case of mesoporous silica supports, WPA is well dispersed over the support without strong interaction. However, TiO 2 causes strong and complex interaction with WPA. [ABSTRACT FROM AUTHOR]

A novel non-hydrolytic sol-gel synthesis of hybrid organosilicates is reported allowing control of micro/mesoporous character of the xerogels by variation of the silicon precursor. The polycondensation reaction of silicon(IV) acetate, Si(OAc) 4 , with 1,3,5-trihydroxybenzene (THB) in dry dioxane at 100 °C produces acetic acid and highly porous amorphous aromatic organosilicate xerogels. Their apparent BET surface areas are as high as 990 m 2 g −1 and the total pore volume is 0.843 cm 3 g −1 . These materials are mostly microporous with a low abundance of mesopores and an average pore size of 3.5 nm. The reaction of HSi(OAc) 3 with THB produced a novel mesoporous material with properties superior to xerogels obtained from Si(OAc) 4 . The BET surface area of 933 m 2 g −1 is retained upon heating and average pore size reached 6.0 nm. The total pore volume of 1.36 cm 3 g −1 is the highest value achieved in porous aromatic organosilicates so far and is comparable to values typical for 3D covalent organic networks (COFs). The materials are stable up to 400–500 °C but they are sensitive to hydrolysis in moist air. The reactions of other silicon precursors (MeSi(OAc) 3 and t BuSi(OAc) 3 ) and larger polyphenol connectors, 1,3,5-tris(4′-hydroxyphenyl)benzene (THPB), 2,4,6-tris(4′-hydroxyphenyl)-1,3,5-triazine (THPTA), and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP), produced materials with less satisfactory properties. [ABSTRACT FROM AUTHOR]

Worsening global warming and the proposition of carbon neutrality brings new challenge to the utilization of carbon dioxide. Dry reforming of methane draws much attention among various utilization routes due to its high efficiency. In this work, mesoporous silica support SBA-15 and microporous silica support beta were applied to the Ni catalysts for the dry reforming of methane. Compared with the impregnated catalyst Ni/SBA-15, highly-dispersed Ni nanoparticles were obtained on Ni-SBA-15 and Ni-beta catalysts prepared by ammonia evaporation method, and they performed excellent catalytic activity, with a CO 2 conversion of ca. 89 % and a CH 4 conversion of ca. 84 % at 700 °C and nearly 100 % conversions at 800 °C. Benefited from the confinement of the mesopores, Ni nanoparticles were well embedded in the pores of Ni-SBA-15 and exhibited distinguished resistance to Ni sintering and carbon deposition. Ni-beta suffered relatively more intensive Ni sintering and carbon deposition because the pore size of beta was much smaller so that it was difficult to introduce Ni into its micropores by ammonia evaporation method. [Display omitted] • Highly dispersed Ni particles were loaded on mesoporous silica support SBA-15 and mesoporous silica support beta via ammonia evaporation method. • Ni-SBA-15 exhibited distinguished Ni sintering and coke resistance in the dry reforming of methane on account of the confinement effect. • The pore size of beta was too small to hold most of the Ni particles, those located on the external surface of the support were easy to sinter without the confinement effect. [ABSTRACT FROM AUTHOR]

Integrated nanocatalysts (INCs) with multicomponent and hierarchically complex structures have recently drawn extensive research attention in terms of their fundamental sciences and industrial applications. To date, many innovative strategies have been established for the synthesis of INCs by thoughtful design. The aim of this review is to highlight the state-of-the-art of INCs with different porous materials for catalyst technology and heterogeneous catalysis. In the first part of this review, we briefly introduce catalytic active components (mainly metal, metal oxide, and hybrid nanoparticles) that are commonly used in INCs. Combining such active components with various porous materials provides us a huge array of architectural designs for INCs that can be used in chemical reactions. In choosing host materials for INCs, we focus on the mesoporous siliceous materials ( viz. , silica and metal silicates) and microporous metal-organic frameworks (MOFs), since they represent the two most attractive classes of porous materials known today. In the latter parts of this article, therefore, we review the recent developments of INCs which comprise these mesoporous and microporous solids with special emphasis on their roles as supports, encapsulating shells, and metal sources. Examples described here are drawn from our group and others; future research directions are also discussed. [ABSTRACT FROM AUTHOR]

Titanium containing mesoporous silicoaluminophosphate (MESO-TSAPO-37) molecular sieves were assembled from microporous titanium silicoaluminophosphate-37 (TSAPO-37) precursor possessing structural building units of SAPO-37. FT-IR studies and N sorption analysis supported the presence of microporosity on the walls of the mesoporous surface. The composite MESO-TSAPO-37 material showed promising catalytic activity in oxidation of cyclohexene. The catalyst showed complete conversion (100 %) of olefin with selective formation of allylic products (80 %). The catalytic activity persisted for several runs. Graphical Abstract: Titanium substituted MESO-TSAPO-37 materials was assembled in presence of surfactant from microporous precursors of TSAPO-37 by a two step procedure. Thoroughly characterized MESO-TSAPO-37 was used for allylic oxidation of cyclohexene which resulted in 100 % conversion and 80 % selectivity towards allylic product.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Spherical porous polymer particles with high surface area were synthesized using the water-in-oil-inwater (W/O/W) emulsion polymerization and Friedel-Crafts reaction. After the preparation of W/O emulsions, spherical porous polymer particles were synthesized by suspension polymerization. Spherical porous polymer precursor particles were subjected to Friedel-Crafts reaction using a Lewis acid catalyst. The properties of the final products synthesized with different porogen contents in the water-in-oil (W/O) emulsion were explored. The Friedel-Crafts reaction was used to increase the Brunauer-Emmett-Teller (BET) surface area. In order to identify the effects of the porogen levels and of the Friedel-Crafts reaction, the synthesized porous particles were analyzed by particle size analyzer (PSA), Hg porosimetry, and the BET surface area method. In addition, the morphology of the particles was investigated by FE-SEM. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

In this article, we describe a novel strategy for synthesizing hierarchical ZSM-5 zeolites via the nanoscale depolymerization–reorganization of natural aluminosilicate minerals. This strategy involves two important steps: the first is the top-down depolymerization of one aluminum-rich aluminosilicate mineral via a novel submolten salt system and one silicon-rich aluminosilicate mineral via conventional thermal treatment into nanoscale building blocks, and the second is the bottom-up rearrangement and reorganization of nanoscale building blocks in the synthesis system into hierarchical ZSM-5 zeolites. When used as a fluid catalytic cracking catalyst additive, the resulting ZSM-5 zeolite with hierarchical micro–mesoporous structure exhibited high activity and selectivity for valuable products in preliminary oil refining tests. The salient features of the strategy lie in that it neither involves any inorganic aluminum and silicon salts as precursors nor uses any secondary mesoscale template and post-treatment to create mesopores, thus demonstrating itself to be a green route to synthesizing hierarchical zeolites. [ABSTRACT FROM AUTHOR]

Highlights: [•] The importance of furfural and hydroxymethylfurfural increased in the past years. [•] Heterogeneous acid-catalysts were widely reported for furan-derivative production. [•] This review focuses on the yields of different microporous and mesoporous materials. [Copyright &y& Elsevier]

Highlights: [•] Simple nonionic polymer (PEG) is able to control the pore size of amorphous silica. [•] PEG with low molecular weight leads to the mesoporous silica. [•] PEG with molecular weight 3000 and more is able to form meso- and microporous silica. [•] Texture of the produced silica is strongly correlated with polymer solution rheology. [•] We propose a rapid and simple synthesis of microporous silica. [Copyright &y& Elsevier]

In the past years, porous media have become a major focus of materials science, due to their versatile properties, such as high surface area, low specific weight, high surface functionality, and the ability to customize their surface properties. Applications of porous media range from catalysis to separation media to gas storage. All of the mentioned applications involve the introduction of guest molecules into the pores. For efficient application of the materials, it is essential to know the behavior of these introduced molecules in the confined state. Solid state (ss) NMR gives a unique insight into the dynamics, the guest-host interactions, and the binding sites of porous materials and is probably the most powerful characterization method for probing a huge variety of real-life systems. Recent results in research of microporous zeolites and periodically mesoporous silica (PMS) materials using NMR will be highlighted. [ABSTRACT FROM AUTHOR]

The formation of micro/mesoporous zeolites by treating zeolite crystals with alkaline hydroxides has received a lot of interest, but fundamental understanding is still lacking. Here, we study the reactivity of a crystalline zeolitic material with various alkaline hydroxides, to close this knowledge gap. The use of ex situ and in situ small-angle X-ray scattering has allowed us to determine the reactivity of faujasite (FAU) type zeolite Y at different pH and Si/Al ratio (SAR), with a variety of different organic ammonium hydroxides. Supplemented with ex situ XRD and BET isotherm measurements, we show that the pH of the starting mixture and SAR of the zeolite significantly influence the stability of the microporous structure and the extent of formation of mesoporous material. [Display omitted] • Synchrotron based in situ SAXS. • Dependence of Reactivity of H-Zeolite Y on Silica-Alumina ratio (SAR). • Mesopore formation from H-Zeolite Y. • Effect of the pH of the starting reaction mixture. • Effect of the hydroxide system used on the reactivity of H-Zeolite Y. [ABSTRACT FROM AUTHOR]

Herein, we report a general and straightforward synthesis method for gold supported on mesoporous and microporous metal oxides. Supported materials, in general, show higher crystallinity compare to unsupported systems as verified through powder X-ray diffraction (XRD). Also, through XRD, most of the metal is observed to be in its oxide form, whereas the gold support was found to be in its metallic state, which has been further confirmed from TEM. In terms of surface area, the catalyst was not found to follow any trend. Morphology wise, there are no changes observed after doping except in few cases. Combined results from XRD, X-ray fluorescence spectroscopy, Auger, and X-ray photoelectron spectroscopy suggest that gold is mainly in the bulk and very little (0.04% in case of gold doped calcium oxide) or non (in case of gold doped mixed manganese-cerium oxide) on the surface. The presence of Au (0) 4f peaks in XPS further confirms the metallic state of the gold. Oxides of indium, magnesium and calcium have been studied for the organic transformation reactions. An enhancement in activity and product selectivity was observed in the case of the gold supported catalysts. Indium serves as a great catalyst for C–C coupling and electrophilic aromatic substitution reactions and gives >99% conversion. Interestingly, 88% selectivity for C–C coupling and >99% selectivity for aromatic substitution have been achieved at 100 °C and room temperature respectively. Magnesium and calcium give Knoevenagel condensation products. At room temperature with very low catalyst loading, >99% conversion and selectivity were observed for the Knoevenagel reaction with as high as 35.30 TOF. A mechanism for the C–C coupling reaction has been proposed based on these results. The general and straightforward synthesis of gold promoted mesoporous and microporous metal oxides were templated using Pluronic P123 surfactant via inverse micelle formation. These catalysts were scanned for the various organic transformation reactions and enhanced activity was shown in the case of gold promoted catalysts. [Display omitted] • A general and straightforward synthesis method for gold support mesoporous and microporous metal oxides. • An improvement in metal oxide crystallinity as a result of gold doping. • An enhancement in activity and product selectivity due to the gold supported catalysts. • Indium based C–C coupling and electrophilic aromatic substitution reactions that give >99% conversion. • High selectivity and high conversion for Knoevenagel ester condensation with very low catalyst loading. [ABSTRACT FROM AUTHOR]

Abstract: This review presents the state-of-the-art of adsorption characterization of mesoporous and microporous materials by using the density functional theory (DFT) methods. The DFT methods have found numerous applications for calculating pore size distributions in traditional and newly discovered nanoporous solids. We discuss the foundations of the non-local (NLDFT) and quench solid (QSDFT) density functional theories applied for modeling adsorption and capillary condensation in pores of different geometry and surface chemistry. Special attention is paid to the limitations of the theoretical models and critical analysis of the obtained data. The methods are demonstrated on a wide variety of systems, including microporous and mesoporous carbons and silicas, zeolites, mesoporous crystals of MCM and SBA families, metal–organic frameworks, and other designer nanoporous materials. Illustrated with many typical examples and detailed discussions of the advantages and limitations of the NLDFT and QSDFT methods, this review provides guidance for the practitioners interested in getting a better understanding of the current capabilities and limitations of the adsorption methods for characterization of porous solids [Copyright &y& Elsevier]

Oxidative dehydrogenation of n-butane was tested using carbon dioxide as a mild oxidant over bimetallic Cr-V supported catalysts (MCM-41, ZSM-5, MCM-22 and mesoZSM-5). The textural properties of the catalysts were measured by means of XRD, N adsorption, SEM-EDX, Raman, H-TPR, pyridine FT-IR, NH and CO-TPD techniques. The metal content of Cr and V was maintained around 1.2 and 2.8 wt% for the catalytic test in packed bed reactor at different temperatures (525-600 °C) for 180 min. 1.2Cr2.8 V/MCM-41 and 1.2Cr2.8 V/ZSM-5 exhibited maximum conversion of 14 and 13.1 %, respectively at 10 min and 600 °C. Significantly, high butenes selectivity was observed over MCM-41 (86.27 %) than ZSM-5 support (58.1 %). The mesoporosity in ZSM-5 had a negative impact on conversion level (7.1 %) but improved the butenes selectivity slightly. 1.2Cr2.8 V/M-22 showed the highest cracking ability leading to overall reduced butenes selectivity (57.9 %). The study shows that over all catalysts, n-butane conversion is independent of CO conversion. 1.2Cr2.8 V/M-22 showed highest CO conversion in the range 2.35-2.2 % between 525 and 550 °C. The apparent activation energies of dehydrogenation and cracking reaction over the four catalysts were evaluated. The ratio of conversion to coke weight per cent over the four catalysts are observed in the following order: 1.2Cr2.8 V/M-41 > 1.2Cr2.8 V/Z-5 > 1.2Cr2.8 V/mesoZ-5 > 1.2Cr2.8 V/M-22. [ABSTRACT FROM AUTHOR]

Kanemite belongs to the group of naturally occurring sodium silicate minerals that was first found in Kanem, at the edge of the Lake Chad, and has been synthesized in different ways from NaOH-SiO2 mixtures and used as precursor for the design of microporous and mesoporous materials. The fluoride route to the synthesis of microporous materials is based on the substitution of OH- anions by fluoride anions, which may subsequently also play a mineralizing role, and gives rise to materials with higher hydrophobicity and thermal and hydrothermal stability. Moreover, F- plays an important role in the incorporation of framework heteroatoms, thereby affecting the activity of the final material. The aim of this study was to synthesize fluorokanemite using different synthetic routes and different F- source. The final product was characterized by a combination of methods that provided information regarding the incorporation of fluorine into the framework and the short- and long-range structural order of the fluorosilicate. Kanemite with water content close to ideal was obtained in all cases. The washing process was found to have no effect in the long- or short-range structural order of the layer framework, although it did affect the structure of the cation in the interlayer space of kanemite. The mineralizing agent therefore appears to be the key to the synthesis. Furthermore, it governs the resulting kanemite structure by controlling the formation of hydrogen bonds in the framework, and therefore the degree of lamellar structure condensation. [ABSTRACT FROM AUTHOR]

Abstract: Mesoporous HZSM-5 was compared with microporous HZSM-5 as catalyst for Friedel–Crafts acylation of 2-methylindole with acetic anhydride. Nitrogen sorption (BET and BJH methods) was used to determine the surface area, pore size and porosity of the materials. The adsorption isotherms showed presence of pores in the size range 6–7nm for the mesoporous HZSM-5 and X-ray diffraction displayed a typical crystalline diffraction pattern corresponding to ZSM-5 for both the microporous and the mesoporous material. Dynamic light scattering was used to determine the particle size of the zeolites, which was shown to be approximately the same for the two materials. The mesoporous and the microporous ZSM-5 zeolites were prepared with the same Si/Al molar ratio and diffuse reflection infrared spectroscopy was used to confirm that the acidity of the materials was the same. Reaction over the microporous zeolite was regiospecific, giving acetylation only in the 3-position of 2-methylindole. Reaction over the mesoporous zeolite resulted in a mixture of two isomers, the N-acetylated product and the product with acetylation in 3-position, obtained in a 3:2 ratio. A kinetic model was constructed for the Friedel–Crafts acylation reaction, which correlated well with an Eley–Rideal reaction mechanism. The kinetic model allowed determination of rate constants, adsorption energy and activation energy for the reaction. It was found that the microporous HZSM-5 zeolite gave higher rate constants and lower activation energy compared to the mesoporous HZSM-5 zeolite. However, the mesoporous HZSM-5 zeolite gave lower adsorption energy and a considerably higher yield at the highest reaction temperature used, 89%, compared to 65% for the microporous HZSM-5 zeolite. Consequently, the catalytic material with the larger pore size gave a lower reaction rate but better resistance to poisoning and deactivation of the catalyst compared to its microporous counterpart. [Copyright &y& Elsevier]

Abstract: A fractal permeability model for hydrogen diffusion across porous inorganic membranes is presented. The model accounts for the actual microstructures in terms of two fractal dimensions, one relating to the capillary flow pathways described by the pore area fractal dimension, Df and tortuosity of the capillary pathways described by tortuosity fractal dimension, Dt. From this, meso-porous titania membrane was found to contain less large pores (Df=1.83) and less tortuous capillary pathways (Dt=1.47) than titania–alumina (Dt=1.51, Df=1.76). The model was found to be consistent with the famous Kozeny–Carman equation for meso and micro porosity region, making the quantitative analysis of the gas diffusion into the media possible. [Copyright &y& Elsevier]

Abstract: Synthesis of solid base Ce–H-MCM-41, Ce–Si-MCM-41, Cs-MCM-41, K-MCM-41 mesoporous materials and Na-ZSM-12, Cs-ZSM-12 microporous zeolites were carried out by means of evaporation impregnation and ion-exchange methods. The solid base catalysts were characterized using X-ray powder diffraction, scanning electron microscope, nitrogen adsorption, FTIR of pyridine and temperature programmed desorption of CO2. The H-ZSM-12, Cs-ZSM-12 zeolite, H-MCM-41, Ce–H-MCM-41 and Ce–Si-MCM-41 mesoporous catalysts were studied for the synthesis of diethyl carbonate starting from ethanol and carbon dioxide, using butylene oxide as the dehydrating agent. Catalyst testing for the synthesis of diethyl carbonate was carried out at 170°C and 4.5MPa of initial CO2 pressure. 16wt.% Ce–H-MCM-41 mesoporous material exhibited higher amount of weak, medium and strong basic sites than that of 32wt.% Ce–Si-MCM-41. The presence of weak and strong basic sites was observed in the microporous 2wt.% Cs-ZSM-12 catalyst. Diethyl carbonate formation was observed over Ce–H-MCM-41 and Ce–Si-MCM-41 mesoporous materials. Amount of basic sites and its strength influenced the synthesis of diethyl carbonate over the mesoporous materials. [Copyright &y& Elsevier]

Abstract: The internal surface of micro and nanoporous substrates can be modified in terms of charge, functionality or even reactivity or stability by means of bifunctional organic molecules able to self-assembly. This work investigates the impregnation with trialkoxysilanes of porous systems using supercritical carbon dioxide (scCO2) as a solvent, which combines several advantages such as liquid-like density and high solvating power with gas-like transport properties. Moreover, scCO2 does not have specific interactions with the substrate and there is no competition for absorption between added reagents and solvent molecules. The work aims at describing a generic liquid-solventless impregnation method applicable to macro (perlite), meso (silica gels and agglomerated nanoparticles) and microporous (zeolite) silica-based substrates using scCO2. The hydrophobic octyltriethoxysilane was used to impregnate the internal surface of the chosen substrates with the objective of obtaining high capacity oil adsorbents. FTIR, TGA and N2 adsorption isotherms were used to determine the interactions between the substrate and the silane deposited monolayer. The acquired hydrophobic character was evaluated using the Karl Fischer method to measure the loss in water adsorption capacity after silane grafting. [Copyright &y& Elsevier]

Abstract: A simple one-step method to fabricate hierarchically porous TiO2/Pd composite hollow spheres without any template was developed by using solvothermal treatment. Pd nanoparticles (2–5nm) were well dispersed in the mesopores of the TiO2 hollow spheres via in-situ reduction. In our experiment, polyvinylpyrrolidone played an important role in the synthetic process as the reducing agent and the connective material between TiO2 and Pd nanoparticles. HF species generated from solvothermal reaction leaded to the formation of TiO2 hollow spheres and Ostwald ripening was another main factor that affected the size and structure of the hollow spheres. The as-prepared TiO2/Pd composite hollow spheres exhibited high electrocatalytic activity towards the reduction of H2O2. The sensitivity was about 226.72μAmM−1 cm−2 with a detection limit of 3.81μM at a signal-to-noise ratio of 3. These results made the hierarchically porous TiO2/Pd composite a promising platform for fabricating new nonenzymic biosensors. [ABSTRACT FROM AUTHOR]

Abstract: 2D arrayed Pt columns with 3D-nanoporous structure were fabricated by electroplating Pt in reverse micelle (L2) solution of a nonionic surfactant filled in 1D microchannels of alumina porous membrane. This thin film features a unique hybrid system consisting of nanoporous structure embedded in the secondary microstructure, which is increasingly of great importance in terms of maximal efficacy of the interfacial properties of nanoporous surface. The diameter of the 3D-nanoporous pillars was ∼300nm and the length was precisely controlled by the electroplating condition. This is the first report of the hybrid 3D-nanoporous micro-columnar metal film by one-step electrochemical deposition in a reverse micelle solution. [Copyright &y& Elsevier]

Abstract: On the basis of SEM, TEM, XRD and N2-adsorption/desorption characterizations, it is found that the microspheres of about 10–20μm in diameter obtained from a hydrothermal reaction system possess a hierarchical architecture and they contain microporous AlPO4-11 nanocrystals of about 50nm in size and a wide distribution mesopores centered around approximately 7nm. [Copyright &y& Elsevier]

The purpose of this review is to highlight developments in self-assembled nanostructured materials (i.e., mesoporous and nanoparticle-based materials) and their catalytic applications. Since there are many available reviews of metal-based nanoparticles as catalysts, this review will mainly focus on self-assembled oxide-based catalytic materials. The content includes: (1) design and synthetic strategies for self-assembled mesoporous catalysts, (2) polyoxometalate (POM)-based nanocatalysts, (3) dendrimer-based nanocatalysts, and (4) shaped nanomaterials and catalytic applications. We show that controlled assembly of molecules, crystalline seeds, and nano building blocks into organized mesoscopic structures or controlled morphologies is an effective approach for tailoring porosities of heterogeneous catalysts and controlling their catalytic activities. [ABSTRACT FROM AUTHOR]

Abstract: SiO2 hollow nanostructured fibers with hierarchical walls have been fabricated by the sol–gel combined two-capillary spinneret co-electrospinning technique using triblock copolymer as the porous directing agent. The as-prepared SiO2 hollow nanostructured fibers were as long as 10 cm with the outer diameter of 400–600 nm and shell thickness of 50–200 nm, and their walls contained the random mesopores with the size of 6.6 nm and the micropores with size of 0.6 nm based on the N2 absorption–desorption isotherm. [Copyright &y& Elsevier]

Porous, mixed-phase aluminosilicate materials containing a microporous MFI phase and a mesoporous Al-MCM-48 phase were synthesized using a one-pot synthesis method. Initially, the gemini surfactant '18-12-18' was used to form Al-MCM-48, and then the MFI template tetrapropylammonium (TPA) was added to the reaction mixture at a later time. Subsequent crystallization at 150 °C led to the formation of a series of mixed-phase materials. These new materials, called 'Al-MMM-2' (microporous/mesoporous materials), were characterized using powder X-ray diffraction and Si MAS-NMR. Consistent with previous results, the amount of the microporous phase formed was dependent on the crystallization time; thus, a range of materials could be formed from a single reaction mixture. In the alkylation of toluene with benzyl alcohol, Al-MMM-2 materials showed greater structural stability, catalytic activity, and product selectivity during repeated reaction cycles, compared to either pure Al-MCM-48 or pure MFI. [ABSTRACT FROM AUTHOR]

Abstract: Thermally stable titanium-containing microporous/mesoporous composite (Ti, Al)-Beta/MCM-48 was synthesised hydrothermally in the presence of structure-directing agents cetyltrimethylammonium bromide (CTABr), polyoxyethylene(8) isooctylhexyl ether (Triton® X-114) and tetraethylammonium hydroxide (TEAOH) in the absence of sodium cations. The presence of both microporous and mesoporous phases was determined by XRD and HRTEM measurements and by the analysis of nitrogen adsorption isotherm based on the α-plot method. The mass percentage (μ) of the microporous material in the composite is approximately 6.5%. NMR investigations showed that acid sites related to framework aluminium were generated by calcination of the as-synthesised (Ti, Al)-Beta/MCM-48. Local environment of titanium incorporated into the microporous/mesoporous silicate material was investigated by X-ray absorption spectroscopy. XANES studies showed the presence of tetrahedrally-coordinated Ti4+ cations in the template-free sample. EXAFS analysis revealed that titanium cations were coordinated to four oxygens in the first coordination shell, to one oxygen at 1.73(1) Å and three oxygens at 1.86(1) Å. In the second coordination sphere three silicon atoms were found at distances 3.18(2) Å and 3.48(2) Å, respectively. These results indicated framework Ti and thus the presence of Ti oxidation centres within the composite material. [Copyright &y& Elsevier]

Abstract: Hydrothermally stable titanium containing microporous/mesoporous composite (Ti,Al)-Beta/MCM-41 was synthesized hydrothermally in the presence of structure-directing agents cetyltrimethylammonium bromide (CTABr) and tetraethyl ammonium hydroxide (TEAOH). XRD analysis and analysis of nitrogen adsorption isotherm confirmed the presence of micropores and mesopores in the composite. HRTEM microscopic studies revealed that micro- and mesoporosity of the composite was not due to the mechanical mixture of microporous (Ti,Al)-Beta and mesoporous (Ti,Al)-Beta/MCM-41. The local environment of titanium incorporated into the microporous/mesoporous silicate material was investigated by X-ray absorption spectroscopy. XANES studies showed the presence of tetrahedrally coordinated Ti4+ cations in the template-free sample. EXAFS analysis revealed that titanium cations were coordinated to four oxygens in the first coordination shell at a distance of 1.84Å. In the second coordination sphere one and two silicon atoms were found at the distances 3.12Å and 3.51Å, respectively. These results indicated framework Ti and thus the presence of Ti oxidation centers within the composite material. NMR investigations showed that Brønsted and Lewis acid sites related to framework aluminum were generated by the removal of potassium and sodium ions from the (Ti,Al)-Beta/MCM-41 pores. The new composite material was preliminarily tested in the oxidation reaction. Titanium leaching from the composite was not observed. [Copyright &y& Elsevier]

Abstract: Gallokanemites, with Si/Ga values between 31.5 and 19.4, have been synthesized and parameters such as gallium source, gel composition and crystallization time have been explored. The results, such as the expansion of the unit cell or the absence of the octahedral aluminum, demonstrate that almost all the gallium has been incorporated into the kanemite framework, even for the gel composition with the lowest Si/Ga ratio, rendering crystalline kanemite-type particles. Therefore, it is an effective method for synthesizing a kanemite with active centres to be used as an acidic catalyst and as a possible precursor of microporous and mesoporous materials with high gallium content. [Copyright &y& Elsevier]

This review discusses the preparation, characterization, and application of amorphous porous mixed oxides, a rapidly growing class of materials with wide applications and a huge potential for the tailoring of chemical composition, microstructure, porosity, and surface properties. In contrast to crystalline materials, these amorphous mixed oxides are prepared under mild reaction conditions in ambient atmosphere. An ever-increasing variety of precursors, additives, modifiers, solvents, catalysts, and posttreatment conditions provide ample fine-tuning options. These materials often display properties commonly associated with well-defined crystalline phases. The functional properties of such solids are largely unexplored and provide a tremendous opportunity for the development of new or alternative materials (solids with a function). Here, emphasis is paid to micro- and mesoporous mixed oxides and their catalytic properties. Easy access to these materials is offset by their much more problematic characterization. Microstructure, chemical structure, morphology, and pore sizes often show broad distributions, and materials description cannot compare with the precise data associated with crystalline phases. The facile preparation and accessibility of these materials make them ideally suited for the application of high-throughput technologies (HTT), which dramatically accelerate searches for new materials as well as fine tuning and optimization. HTT also allow investigators for the first time to access and optimize multinary mixed oxides on a realistic timescale. [ABSTRACT FROM AUTHOR]