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Microporous and mesoporous materials
Elsevier Science BV
Microporous and mesoporous materials

Elsevier Science BV

1387-1811

Microporous and mesoporous materials/Journal Microporous and mesoporous materialsISTPCCREISCI
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    Bimetallic RhIn/ZIF-8 for the catalyic chemoselective hydrogenation of nitrostyrene: Exploration of natural selectivity of hydrogen sources and enhancing intrinsic selectivity

    Ding, KelongHu, Ze-NanZhang, WenhuiLiang, Jiaxing...
    9页
    查看更多>>摘要：Chemoselective hydrogenation of nitrostyrene to aminostyrene still faces the trouble of low selectivity and poor activity. The bimetallic catalysts, which adjust the activity of noble metal nanoparticles through the doping of non-noble metals, are promising for selectively catalytic transfer hydrogenation (CTH). For another aspect, the hydrogen source also plays a vital role in selective CTH. Based on this, we prepared activity-inhibited bimetallic RhIn/ZIF-8 catalyst to study the catalytic performance towards different hydrogen sources (N2H4 center dot H2O, NaBH4, NH3 center dot BH3 and H-2) and to explore the natural selectivity of these hydrogen sources. We found that the hydrazine hydrate was the most selective H-donor for the nitro group, while the H-2 had the highest natural selectivity to olefins. The H-2 produced from hydrazine hydrate is responsible for the formation of completely reduced products. The potential reduction by the intermediate imine did not occur to C = C double bonds, this indicates controlling the decomposition of N2H4 will enhance the selectivity of nitroarenes. Based on this, the reaction system with the catalyst bimetallic RhIn/ZIF-8 and N2H4 center dot H2O as the hydrogen source is established, which can fully reduce many nitrostyrenes with >98% selectivity to corresponding aminostyrenes.
      原文链接:
    • NSTL
    • Elsevier

    Effect of solvents coexistence on the intracrystalline diffusivity of toluene and phenol within Y-type zeolite in the liquid phase

    Su, XinluonaNakasaka, YutaMoriwaki, RenYoshikawa, Takuya...
    7页
    查看更多>>摘要：The intracrystalline diffusivities of phenol and toluene within H-Y-type zeolite (Si/Al = 2.8) in the mesitylene, cyclohexane and 2-propanol in the temperature range from 313 to 353 K were measured using the constant volumetric method. The activation energy for the intracrystalline diffusivity of toluene within H-Y in the liquid phase was larger than that in the gas phase, indicating that the solvent coexisting within the H-Y pores affected the diffusion mechanism of toluene. The intracrystalline diffusivity of phenol within H-Y in mesitylene was smaller than that of toluene. Moreover, the intracrystalline diffusivity of phenol within dealuminated H-Y was higher than those within H-Y, which further indicated that the phenol molecule was more strongly adsorbed on the Bronsted acid sites of H-Y, and this affected the residence time of phenol on the acid sites leading to a decrease in the diffusivity. The intracrystalline diffusivities of phenol within H-Y for the three solvents were in the following order: 2-propanol > cyclohexane > mesitylene. The amount of adsorbed phenol on H-Y in 2-propanol was smallest relative to the amounts of phenol adsorbed on H-Y in the other solvents. The results indicated that the adsorption of phenol on H-Y in the different solvents affected the intracrystalline diffusivity of phenol and its activation energy.
      原文链接:
    • NSTL
    • Elsevier

    ZIF-8 derived ZnO-calcium silicate mesoporous structures: Synthesis and photocatalytic activity

    Shamsaei, Ezzatollahde Souza, Felipe BasquirotoSagoe-Crentsil, KwesiDuan, Wenhui...
    9页
    查看更多>>摘要：Nanoscale metal-organic frameworks (MOFs) show potential as catalysts or catalyst precursors, but they suffer from difficult separation and weak stability and do not conform to practical application conventions. Herein, we demonstrate the application of nanostructured calcium silicate hydrate (C-S-H), the building block of Portland cement concrete, to fabricate hierarchically porous zeolitic-imidazolate-framework-8 (ZIF-8)-derived ZnO nanocomposites. The dispersing and stabilizing effects of the C-S-H nanoplate structure effectively suppressed the agglomeration of ZIF-8 nanocrystals during high-temperature treatment. After calcination at 450 degrees C, ZnO nanocomposites with high specific surface area (579 m2 g-1) and hierarchical porosity were obtained. The nanocomposites were used as photocatalysts for degradation of rhodamine B and exhibited degradation efficiency as high as 95.5% within 45 min of UV light illumination with high photocatalytic stability and excellent reusability. This study demonstrated a facile way of using economic and versatile C-S-H nanostructures to fabricate MOF and MOF-derived nanocomposites with enhanced stability and functionality.
      原文链接:
    • NSTL
    • Elsevier

    Composites of porous materials with ionic liquids: Synthesis, characterization, applications, and beyond

    Zeeshan, MuhammadHabib, NitashaGulbalkan, Hasan CanAlsuhile, Ala Abdulalem Abdo Moqbel...
    29页
    查看更多>>摘要：Modification of the physicochemical properties of porous materials by using ionic liquids (ILs) has been widely studied for various applications. The combined advantages of ILs and porous materials provide great potential in gas adsorption and separation, catalysis, liquid-phase adsorption and separation, and ionic conductivity owing to the superior performances of the hybrid composites. In this review, we aimed to provide a perspective on the evolution of IL/porous material composites as a research field by discussing several different types of porous materials, including metal organic frameworks (MOFs), covalent organic frameworks (COFs), zeolites, and carbonaceous-materials. The main challenges and opportunities in synthesis methods, characterization techniques, applications, and future opportunities of IL/porous materials are discussed in detail to create a road map for the area. Future advances of the field addressed in this review will provide in-depth insights into the design and development of these novel hybrid materials and their replacement with conventional materials.
      原文链接:
    • NSTL
    • Elsevier

    Influence of adding a modified zeolite-Y onto the NiMo/Al2O3 catalyst utilized to produce a diesel fuel with highly reduced sulfur content

    Karami, HamidKazemeini, MohammadSoltanali, SaeedRashidzadeh, Mehdi...
    12页
    查看更多>>摘要：In order to make a Na-Y zeolite with Si/Al ratio of 2.27 more acidic with a higher volume of mesopores, a combination of different and consecutive methods including; chemical (i.e.; utilizing different compounds, such as NH4F and EDTA) and thermal/hydrothermal (i.e.; implementing calcination/steaming) methods, were employed for modification and dealumination. The combination of acidic-hydrothermal dealumination method led to a further structural collapse compared to that of the acidic calcination. In comparison with the other dealumination methods, the fluorination strategy (i.e.; utilizing NH4F) resulted in a zeolite with higher crys-tallinity, acidity, and specific surface area. The modified and dealuminated zeolites were employed to prepare the catalyst support of FAU + Al2O3 for the HDS process. The sulfidation and performance evaluation of the prepared catalysts were carried out in a fixed bed microreactor. Then after, the effects of zeolite modification during the dealumination process, especially acidity and Si/Al ratio variations, upon the activity of NiMo/FAU + Al2O3 catalyst were understudied. Results indicated that, the enhanced performance of the catalysts containing the modified zeolites in removing of the sulfur containing aromatic compounds, as well as their longer observed lifetime in terms of lower coke deposition levels were obtained. The removal of the sulfur containing compounds increased with acidity so that the maximum removal (i.e.; of conversion = 93%) was determined using Cat-F-AT-Cal catalyst containing the zeolite modified by acid treatment-calcination together with fluorination. In addition, the highest performances in terms of removal of aromatic compounds and catalyst lifetime (i.e.; due to lower coke deposition) were shown by the Cat-AT-St and Cat-AT-Cal catalysts, respectively. These species contained the zeolite modified through the acid treatment-steaming and acid treatment-calcination methods, respectively.
      原文链接:
    • NSTL
    • Elsevier

    Enhanced surface capacitive sodium storage by pores regulation in carbon/carbon composite nanofibers

    Zhang, ShujunZhao, HanqingGao, XinmeiZhao, Dan...
    9页
    查看更多>>摘要：Carbon materials have broad application prospects as an anode material in the field of sodium-ion batteries (SIBs). Optimizing the structure of carbon materials has a significant effect in obtaining high electrochemical performance. Herein, carbon/carbon composite nanofibers (C/CNFs) were fabricated by electrospinning and their microstructure, texture, and surface functional groups are adjusted through introducing nanocarbons. The results show the introduction of graphene will regulate pore structures and surface functional groups, exhibiting excellent sodium storage performance as SIBs anodes. The graphene/carbon composite nanofibers (G/CNFs) showed a good reversible capacity of 253.6 mA h g(-1) at 0.05 A g(-1) after 300 cycles, which is enhanced by 62.67% comparing to the CNFs. The G/CNFs also retained a capacity of 200.6 mA h g(-1) at 2 A g(-1) after 600 cycles The pseudo-capacitive contribution was 90.4% at 1.0 mV s(-1) for the G/CNFs. Regulating pore structure of carbon materials by other nanocarbons provided new reference for the application of energy storage but not limited to this.
      原文链接:
    • NSTL
    • Elsevier

    Inclusion of CO2, NH3, SO2, Cl-2 and H2S in porous N4O4-donor macrocyclic Schiff base

    Korica, MilenkoBalic, Ivanavan Wyk, Lisa M.van Heerden, Dewald P....
    9页
    查看更多>>摘要：The removal and detection of highly toxic and environmentally harmful gases such as SO2, H2S and CO2 is a hot topic of the scientific community. Porous organic compounds, in particular, imine-based macrocycles, are promising materials for this purpose. In this paper we have used porous N4O4-donor macrocyclic Schiff base (1,6,20,25-tetraaza-2,5:8,9:17,18:21,24:27,28:36,37-hexabenzo-10,16,29,35-tetraoxa-cyclooctatriakonta-1,6,20,25-tetraen) (1) for sorption of NH3, SO2, Cl-2, CO2 and H2S. Five novel inclusion compounds 1xNH(3), 1xSO(2), 1xCl(2), 1xCO(2) and 1xH(2)S were prepared by a single-crystal to single-crystal (SC-SC) transformation. Single-crystal X-ray diffraction (SCXRD) analysis of 1xCO(2) and 1xNH(3) inclusion compounds have shown that CO2 molecule resides in the plane of the macrocyclic ring connected by weak C-O center dot center dot center dot pi interactions to the host, and no host-guest interactions in 1xNH(3) were observed. The relative thermal stabilities of the host-guest systems (T-on - T-b parameter) is in the range from 93 (1xNH(3)) to 132 degrees C (1xH(2)S), indicating the formation of stable inclusion compounds. Although used gases are highly reactive and corrosive, FT-IR and powder diffraction studies indicate that the molecular and crystal structure of the host is constant upon gas sorption. The activated compound displays moderate uptake (0.35 mmol/g) of CO2 at 298 K. The relatively high thermal stability, constant molecular and crystal structure of inclusion compounds with interesting optical properties (determined by solid state UV-Vis) make this material potentially useful for the detection of toxic gases.
      原文链接:
    • NSTL
    • Elsevier

    Improvement of microporous silicoaluminophosphate properties by Fe and Ti insertion for photocatalytic hydrogen generation under visible light

    Larbaoui, S.Hentit, H.Bentouami, A.Belayachi, C....
    10页
    查看更多>>摘要：Iron- and/or titanium-containing microporous silicoaluminophosphate catalysts have been synthesized, under hydrothermal conditions, using triethylamine structure directing, to obtain the aluminophosphate five phase (AFI). These solids were characterized by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), nitrogen adsorption measurements, UV-visible diffuse reflectance spectroscopy (UV-Vis-DRS) and X-ray photoelectron spectroscopy (XPS). The physico-chemical analyses have revealed that Fe- and/or Ti-containing materials have significant photocatalytic properties. Thus, they have been valorized in the photocatalytic hydrogen production from water. The reaction has been conducted, under visible radiations, and the process has been followed by photo-electrochemical characterization (PEC). Hydrogen is the only produced gas and the reaction takes place in the conduction band where water is reduced to hydrogen while the holes are entrapped using hole scavengers. The results show that our catalysts exhibit a remarkably high hydrogen evolution rate and remain stable during reuse up to at least five cycles.
      原文链接:
    • NSTL
    • Elsevier

    Ionic conductivity of tetra-n-butylammonium tetrafluoroborate in the MIL-101(Cr) metal-organic framework

    Ulikhin, Artem S.Uvarov, Nikolai F.Kovalenko, Konstantin A.Fedin, Vladimir P....
    9页
    查看更多>>摘要：Nanocomposite solid electrolytes (C4H9)(4)NBF4-MIL-101(Cr) based on pure components without any other additives were prepared and their structure and electrical properties were investigated as a function of temperature and concentration of the metal-organic framework MIL-101(Cr). According to the data of thermal analysis, the heat effect due to the melting of the salt in the composites strongly decreases and tends to zero at a molar fraction of MIL-101(Cr) x >= 0.34. This effect is assumed to be caused by the amorphization of the salt in the composites which is practically complete at high content of MIL-101(Cr). The dependence of the melting enthalpy on the molar or mass fraction of MIL-101(Cr) may be explained by filling of MIL-101(Cr) pores with the salt, provided that the salt residing outside the pores is crystalline, whereas the salt located inside the pores is amorphous. In this case, at some fraction of the MIL-101(Cr), x = x(max), all the salt will be located inside the pores, and the concentration of the salt occurring in an amorphous state reaches a maximum. At x < x(max) there is a linear dependence between melting enthalpy and molar (or mass) fraction from which allows one can determine x(max) and w(max) values from experimental data. From these data, the volume of accessible pores was estimated as V-pore = 0.92 cm(3)/g corresponding to 73% of the total pore volume determined by BET adsorption method. The thermal properties fairly correlate with the X-ray diffraction data. Reflections on X-ray diffraction patterns of the composites attributed to (C4H9)(4)NBF4 strongly decrease with the concentration of MIL-101(Cr) and at the concentration x >= 0.283 practically no reflections of the salt are observed on the X-ray patterns. The electrical properties of the composites were investigated. It was shown that the concentration dependence of conductivity has a maximum at the concentration close to x(max) value determined from the thermal analysis data. At x > x(max) temperature dependences of conductivity are not linear in Arrhenius coordinates, no sudden conductivity change is observed due to the melting of the salt. Such conductivity behaviour is typical for amorphous electrolytes. Quantitative analysis of the concentration dependence of conductivity was done using the pore filling model and the mixing equations proposed earlier for two-phase composites. Theoretical curves obtained using the mixing equations satisfactorily fit the experimental data. The maximum value of ionic conductivity, 5.10(-4) S/cm at 135 degrees C, obtained for the composite 0.675(C4H9)(4)NBF4-0.325MIL-101(Cr) is rather high assuming that BF4- anions are the most probable charge carriers.
      原文链接:
    • NSTL
    • Elsevier

    BODIPY-linked conjugated porous polymers for dye wastewater treatment

    Du, Xing-HaoJiang, ZhiyongLiu, ZhipengXu, Chao...
    8页
    查看更多>>摘要：As a new family of functional porous materials, conjugated porous polymers (CPPs) with tuneable porosities and molecular architectures show great potentials in adsorption, light harvesting, and catalysis applications. This paper describes the incorporation of strong visible-light absorbing BODIPY molecules into the skeleton of CPPs via Sonogashira coupling reactions. The obtained CPPs displayed integrated properties of high surface area, hierarchical porous structures and strong visible-light absorption. As a result, the CPPs showed relatively high adsorption capacity and high photocatalytic degradation efficiency towards organic dyes. Mechanism studies revealed that the CPPs enabled the generation of singlet oxygen species under light irradiation, accounting for the main driving force for the dye degradation. This study provides a new route for the development of organic adsorbents and photocatalysts for water treatment and purification.
      原文链接:
    • NSTL
    • Elsevier