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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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    Gas sorption and selectivity study of N,N,N ',N '-tetraphenyl-1,4-phenylenediamine based microporous hyper-crosslinked polymers

    Cucu, EvrenDalkilic, ErdinAltundas, RamazanSadak, Ali Enis...
    12页
    查看更多>>摘要：One of the most important parameters to design porous polymeric materials for gas storage and separation is to discover appropriate linker. Determining the effect of linker, in fixed core, over the selectivity and adsorption has been great challenge. Here, three different N,N,N',N'-tetraphenyl-1,4-phenylenediamines (TPPA) based microporous hyper-crosslinked polymers synthesized by the Friedel-Craft reactions. Hypercrosslinked polymer, TPPA-DMM, was obtained from dimethoxymethane (DMM) and hypercrosslinked-covalent polymer, TPPA-DMB, from dimethoxybenzene (DMB) in presence of FeCl3. TPPA-CC, covalent triazine polymer was synthesized from cyanuric chloride (CC) via AlCl3 as the catalyst. After the careful characterization of these microporous structures with different analytical and spectral analyses, the gas uptake (for CO2, CH4, O-2, CO, and H-2) and selectivity properties (for CO2/N-2, CO2/O-2, for CO2/CO and CO2/CH4) were comparatively investigated at pipe gas temperatures and up to 1 bar. The high BET specific surface areas ranging from 742 to 883 m(2)/g with ultramicropore characters (0.53-0.58 nm), high chemical stability in different solvents even in concentrated acid and thermal stability (up to 450 degrees C) promised that these materials can be used in pipe gas processes. By changing the linkers on the core, materials have high gas uptake properties reaching 12.98 wt% for CO2 uptake, 1.57 wt% for CH4 uptake, 1.06 wt% for CO uptake at 1 bar/273 K and also reaching 1.28 wt% for H-2 uptake at 1 bar/77 K. In addition, the unusual N-2 phobic character down to 0.2 wt% and O-2 phobic character down to 0.3 wt% were observed. The selectivity was calculated by using the ideal adsorbed solution theory (IAST). The selectivities were found reaching 80.4 for CO2/N-2, 8.5 for CO2/CH4, 30.1 for CO2/CO and 39.1 for CO2/O-2. These calculations show that the obtained polymers can be used in post combustion processes which needs high pressures and temperatures. The selectivities of the synthesized materials for the gas sorptions changed drastically by switching the linkers in all three materials. Interestingly, IAST calculations from single to dual gas, in the different ratios, showed that selectivities were almost the same for each polymer within itself at same temperature. To date, these are the first reported discoveries for the porous organic polymers in the literature.
      原文链接:
    • NSTL
    • Elsevier

    Designed synthesis of single-crystalline silicoaluminophosphate zeolite via interzeolite transformation for n-dodecane hydroisomerization

    Ge, LixiaLi, WantingLi, ShenggangYu, Gan...
    10页
    查看更多>>摘要：Single-crystalline zeolites are highly desirable in this field owing to their high hydrothermal stability and high mass transfer efficiency. However, the preparation of single-crystalline silicoaluminophosphate SAPO-11 zeolite remains a significant challenge due to its complex synthesis process. Herein, we firstly report a facile and direct approach to synthesize single-crystalline SAPO-11 by interzeolite transformation via a kinetic-modulated process. The crystallization process of single-crystalline SAPO-11 was monitored by the time-dependent characterizations. A panel of characterizations by XRD, SEM, N-2-adsorption and solid-state NMR provided evidence that the formation mechanism of single-crystalline SAPO-11 involved fast interzeolite transition process between two different topologies from AlPO4-8 (AET) to SAPO-11(AEL), thus it avoids the aggregation of small nanocrystals during the conventional polycrystalline SAPO-11 synthesis. In addition, the Bronsted acid sites of the prepared samples could be precisely regulated. The resulting single-crystalline catalyst exhibits superior isomer selectivity (92.3% vs. 70.6%) and yield (77.9% vs. 62.3%) in the n-dodecane hydroisomerization compared with the conventional polycrystalline sample due to the unique morphology and suitable acidity. This synthetic strategy provides a new orientation to design other single-crystalline zeolite catalysts.
      原文链接:
    • NSTL
    • Elsevier

    Elastic and plastic mechanical properties of nanoparticle-based silica aerogels and xerogels

    Marszewski, MichalDashti, AliMcNeil, Patricia E.Fox, Maggie...
    7页
    查看更多>>摘要：This paper reports and analyzes, for the first time, the effective Young's modulus and hardness of nanoparticle-based silica aerogels and xerogels with porosity ranging from 46 to 81%. Pure silica aerogel and xerogel monoliths were synthesized by (i) gelation of aqueous suspensions of silica nanoparticles on omniphobic sub-strates (PTFE or perfluorocarbon liquids), (ii) aging, (iii) drying at ambient temperature and pressure, and (iv) calcination. The aging and calcination conditions were varied to elucidate their effect on the mechanical properties of the monoliths. Both the effective Young's modulus and the hardness of the mesoporous slabs were measured by nanoindentation and were found to obey a power law as a function of the effective density. No effect of the synthetic conditions or structural parameters other than porosity were observed. Interestingly, the effective hardness was linearly proportional to the effective Young's modulus. The elastic properties of the present nanoparticle-based materials were compared with those of the molecular precursor-based silica aerogels and xerogels reported in the literature. A single relationship was proposed that can be used to estimate the effective Young's modulus of nanoparticle-based and molecular precursor-based silica aerogels and xerogels with porosity between 0 and 98% and Young's modulus between similar to 10(-4) and 70 GPa. Deposition of an alumina coating was also demonstrated as a way to increase the hardness of these mesoporous monoliths by a factor 2-13 for porosity of 40-73%. The experimental results and the accompanying analysis broaden the understanding of structure-property relationships in mesoporous silica and will help in the design and fabrication of mesoporous silica components.
      原文链接:
    • NSTL
    • Elsevier

    Graphene oxide/hollow mesoporous silica composite for selective adsorption of methylene blue

    Yilmaz, Muge Sari
    13页
    查看更多>>摘要：In this study, graphene oxide/hollow mesoporous silica composite was synthesized to apply selective adsorption of methylene blue from methyl orange and methylene blue mixture for the first time. In addition, layered double hydroxide/hollow mesoporous silica composite was also synthesized for comparison purpose. The effect of pH, contact time, and initial concentration on the adsorption were investigated. Changing the pH of the dye solution is effective in the adsorption behavior of the composite. The maximum adsorption capacities for the uptake of methyl orange at pH 3 and methylene blue at pH 9 from graphene oxide/hollow mesoporous silica were 270.27 and 476.19 mg g-1, respectively. On the other hand, this value for the uptake of methyl orange at pH 3 and methylene blue at pH 10 from layered double hydroxide/hollow mesoporous silica was found as 344.83 and 416.67 mg g-1, respectively. The kinetics and equilibrium data for adsorption of dyes using both composites fit the pseudo-second-order and Langmuir model, respectively. At pH 9, graphene oxide/hollow mesoporous silica showed remarkable selectivity for adsorption of methylene blue from the binary mixture, while at pH 10, layered double hydroxide/hollow mesoporous silica showed similar selectivity trend. The plausible adsorption mechanisms for methylene blue onto composite surfaces were examined Fourier transforms infrared, X-ray photoelectron spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy. The electrostatic attraction and 7C-7C stacking interaction were the main adsorption mechanisms for the adsorption of methylene blue onto graphene oxide/hollow mesoporous silica. The regeneration experiments demonstrated the methylene blue adsorption/desorption efficiencies of graphene oxide/hollow mesoporous silica were more steady and higher than layered double hydroxide/hollow mesoporous silica.
      原文链接:
    • NSTL
    • Elsevier

    Preparation and properties study of F-SiO2@MPDA-AuNPs drug nanocarriers

    Su, SisiLin, LanlanLi, HaiyangWen, Xinyu...
    11页
    查看更多>>摘要：Photothermal material was one of the hot topics in nanomedicine in recent years, which had aroused widespread attention of scholars. In this paper, a kind of core-shell drug nanocarriers with good photothermal properties were prepared, and its photothermal therapeutic effect on tumor cells in vitro was studied. First, fluorescein isothiocyanate (FITC) was encapsulated in silica nanoparticles to form silica fluorescent (F-SiO2) nanoparticles. Then mesoporous dopamine (MPDA) layer were built on the F-SiO2 nanoparticles, the core-shell nanoparticles (F-SiO2@MPDA) with mesoporous shell structure were obtained. Finally, Au nanoparticles (AuNPs) were wrapped on the surface of the layer of MPDA shell by the citrate reduction method, and the F-SiO2@MPDA-AuNPs composite nanoparticles were formed. Then, the fluorescence property, adsorption performance, sustained release property, photothermal property and cytotoxicity of the F-SiO2@MPDA-AuNPs nanoparticles were researched. It was found that F-SiO2@MPDA-AuNPs nanoparticles had good fluorescence performance, high adsorption capacity (DOX, 111.275 mg/g) and pH responsive release performance. When pH = 5.2, the DOX release rate was 39.5% within 7 h under the action of near-infrared light (NIR). In addition, it also had a high photothermal conversion rate (36.95%), and the DOX loaded F-SiO2@MPDA-AuNPs nanoparticles had obvious inhibitory effect on tumor cells in vitro. As a kind of mesoporous drug nanocarriers with photothermal properties, it has potential application value.
      原文链接:
    • NSTL
    • Elsevier

    Separation of ethane/ethylene gas mixture by ethane-selective CAU-3-NDCA adsorbent

    Cho, Kyung HoYoon, Ji WoongLee, Jeong HyeonKim, Jin Chul...
    10页
    查看更多>>摘要：Ethane-selective adsorbents for separating ethane (C2H6)/ethylene (C2H4) gas mixtures have attracted considerable interest as promising alternatives to conventional cryogenic distillation because of the possibility of directly producing high-purity C2H4 (>99.95%). Herein, CAU-3-NDCA built by the coordination bond between [Al-12(OCH3)(24)](12+) and 2,6-naphthalenedicarboxylic acid (NDCA) was evaluated for use as a C2H6-selective adsorbent for separating a C2H6/C2H4 gas mixture. The separation performance of the adsorbents was investigated using single-component gas isotherms, ideal adsorbed solution theory calculations, dynamic breakthrough experiments for gas mixture, and molecular simulations, such as Monte Carlo simulation and density functional theory calculation. CAU-3-NDCA displayed exceptional adsorption capacity (9.2-10.2 mmol g(-1) at 15 bar) and good C2H6/C2H4 selectivity (1.44-1.56) in the temperature range 293-313 K. In the breakthrough experiments, the C2H6/C2H4 separation performance of CAU-3-NDCA exhibited high-purity C2H4 productivity of 6.6 and 25.7 L-STP kg(-1) under a 50/50 (v/v) and 10/90 (v/v) C2H6/C2H4 gas mixture, respectively, at 298 K and 7 bar. Recyclability was evaluated by a multi-cyclic breakthrough test for five cycles with a 10/90 (v/v) C2H6/C2H4 gas mixture. Molecular simulations indicated that the preferential adsorption of C2H6 originates from the higher affinity strength of multiple C-H center dot center dot center dot pi interactions of C2H6 with NDCA linkers, in addition to the stronger methyl group-gas interaction of the methanolate group than those of C2H4. Moreover, it is characterised by thermal and moisture stability. Therefore, CAU-3-NDCA is a promising candidate for pressure swing adsorption operation as a C2H6-selective adsorbent.
      原文链接:
    • NSTL
    • Elsevier

    Synthesis of mesoporous SiO2 nanoparticles and toxicity assessment in early life stages of zebrafish

    Krishnan, VigneshPrakash, Joy SebastianManigandan, VenkatesanVenkatasubbu, G. Devanand...
    9页
    查看更多>>摘要：Mesopomus nanoparticles (MNPs) have attracted great interest in the biomedical applications as reliable drug carriers for cancer treatment. They have significant advantages over the traditional drug carriers due to high surface area, controllable pore size, large pore volume, easy adjustment of the inner and outer surfaces, and also, high drug loading capacity. This work has focused on the synthesis of mesoporous silicon dioxide nanoparticles (MNPs) with different pore volumes and their toxicity effects on zebrafish. The structural and morphological analyses of MNPs were carried out through XRD and HRTEM, functional groups have been identified by FTIR and N2 adsorption/desorption isotherm and the pore size distribution was determined by BET analysis. The maximum pore volume of 1.5 cm(3)/g and a pore size of 8.0 nm, were reported. Survival percentage of zebrafish was reported to be above 85%.
      原文链接:
    • NSTL
    • Elsevier

    Improvement of PROX-CO catalytical performance by modulation of the pore structure of CeO2 nanorods decorated with Au nanoparticles

    Machado Silva, Raul Brunode Oliveira, Cristine SantosTeixeira-Neto, EricoSigoli, Fernando Aparecido...
    11页
    查看更多>>摘要：Au/CeO2-based materials are widely investigated catalytical systems used for the preferential oxidation of CO (PROX-CO). Recent research focused on their improvement via the development and optimization of nanostructures, where both metal and oxide may be individually tailored to provide the best combination of catalytic performance, stability, and cost. In this work, we synthesized CeO2 porous nanorods using a facile hydrothermal synthesis and tailored their native porous structure using a simple acid lixiviation procedure to enlarge its pores and expose facets such as the {110} ones that are more susceptible to oxygen vacancy formation, one of the main requirements for PROX-CO. We decorated both lixiviated and as-synthesized CeO2 nanorods with Au nanoparticles using deposition-precipitation, and evaluated the effect of lixiviation over the morphology, structure, oxygen storage capacity and catalytic activity for PROX-CO. Through HRSTEM we observed an increase in the pore size while maintaining the morphology and structure of the nanorods. This increase was accompanied by the facilitation of oxygen vacancy formation, resulting in almost tripling the oxygen storage capacity (OSC). This impacted the performance of the CeO2/Au nanorods for PROX-CO, allowing a maximum of 88% CO conversion rate at 181 degrees C, compared to 27% and 238 degrees C for the non-lixiviated nanorods, under the same catalytical conditions.
      原文链接:
    • NSTL
    • Elsevier

    The influence of external acid strength of hierarchical ZSM-5 zeolites on n-heptane catalytic cracking

    Chen, FengqiuHao, JingYu, YueyangCheng, Dang-guo...
    9页
    查看更多>>摘要：The hierarchical ZSM-5 zeolite is expected to enhance mass transfer performance and accessibility of acid sites. The acid sites distributed in different locations (mesopore/outer surface and micropore) play different roles in catalytic reactions. In this work, a series of hierarchical ZSM-5 zeolites with similar porous structures but different external acid strength was successfully prepared through chemical vapor deposition (CVD) method by adjusting the reaction temperature and treatment time. Then the n-heptane (the model compound of naphtha) catalytic cracking was employed as a model to test the catalytic performance. The results show that the external environment is an important place for primary cracking reaction and bimolecular reaction. The weakening of the acid strength is conducive to suppress the bimolecular reactions of light olefins. At the same time, the change of selectivity of key products indicates that the microporous pores are the main place to generate ethylene compared with external environment which lacks the confinement effect.
      原文链接:
    • NSTL
    • Elsevier

    Role of amine-based fuel combination in conventional and microwave-assisted smoldering combustion for production of mesoporous hydroxyapatite with super adsorptive characteristics for separation of disperse dye

    Dastoorian, FarniaSalem, AminSalem, Shiva
    11页
    查看更多>>摘要：The effect of amine-based fuel combination, and smoldering combustion route on adsorptive characteristics of hydroxyapatite (HA) are the challenge of current study for separation of disperse dye. A systematic procedure, mixture design methodology, was used to determine the proper combination of urea-glycine-hexamine in the conventional (CSC), and microwave-assisted smoldering combustion (MSC) for one step fabrication of HA with maximal adsorption capacity. It was established that the ternary combination of used fuels, including the same proportions of glycine, and hexamine, 16.7 mol %, provided an adequate energy, > 7200 kJ mol(-1) for fabricating the poorly crystalline HA by CSC, allowed to achieve the maximal capacity, similar to 5000 mg g(-1). Glycine was identified as a proper fuel to produce spongy amorphous nanoparticles, 130 nm, predominantly containing HA, through MSC in which the microwave power should be controlled at 600 W. The product displayed the mesoporous structure with average pore diameter about 3.8 nm, due to releasing gaseous phase, 65.6 mol mol(-1) HA, providing a surface area around 72 m(2) g(-1) which is responsible for the surprised adsorptive properties. The microwave-assisted combustion facilitates the formation of HA with super adsorption properties because of operational simplicity which is completed within a shorter time due to uniform energy dissipation when is compared with the other methods.
      原文链接:
    • NSTL
    • Elsevier