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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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    A nanocaged cadmium-organic framework with high catalytic activity on the chemical fixation of CO2 and deacetalization-knoevenagel condensation

    Zhengguo ZhangLiming FanHongxiao Lv
    9页
    查看更多>>摘要：Heterogeneous MOFs catalysts have attracted great attention due to the efficient combination of heterogeneity (easy post-reaction separation and recyclability) and homogeneity (active sites and porosity), which inspire us to explore functional MOFs materials with higher catalytic activity on the chemical fixation of CO2 and deacetalization-Knoevenagel condensation. Herein, the self-assembly of Cd~(2+) and H6TDP under acidic sol-vothermal condition generated one cadmium-organic framework of {[(CH3)2NH2]2 [Cd2 (TDP) (H2O)2]· 3DMF·2H2O}n (NUC-29, H6TDP = 2,4,6-tris(2,4-dicarboxyphenyl)pyridine) with nano-caged voids and hierarchical microporous channels, which were built on the combination of two kinds of mononuclear units of [Cd (1) (COO)3(H2O)] and [Cd (2) (COO)3(H2O)]. After the removal of solvent molecules by activation, NUC-29 possesses the coexistence of Lewis acid-base sites on the inner surface of channels including all exposed Cd~(2+) sites and N_(pyridine) sites, which render it an excellent recyclable heterogeneous catalyst to facilitate the cycloaddition reaction of epoxides with CO2 and deacetalization-Knoevenagel condensation under mild conditions.
      原文链接:
    • NSTL

    Solvent-free, efficient synthesis of methyl phenyl carbonate over an SBA-15 loaded Pb-Bi bimetallic catalyst

    Songlin WangNan JiangQiying Zhang
    9页
    查看更多>>摘要：Methyl phenyl carbonate (MPC) is one of the versatile carbonates; in particular, it is an important component in lithium-ion batteries. In recent years, the catalytic synthesis of MPC has become an important topic, but the development of highly active catalysts is still challenging. In this study, SBA-15-loaded nano-sized Pb-Bi catalysts with different Pb/Bi molar ratios were prepared by deposition-precipitation to improve the efficiency and selectivity. To investigate the relationship between the structure and performance of the catalysts, XRD, BET, SEM-EDS, HRTEM, H2-TPR, and XPS characterization, as well as catalytic activity and stability tests, were conducted. Results revealed that Pb-Bi/SBA-15 can efficiently catalyze the synthesis of MPC under solvent-free conditions, with the highest catalytic activity obtained over 6 Pb-lBi/SBA-15. SBA-15 with a large pore size and a high specific surface area was suitable as catalyst carrier, and the average diameter of Pb-Bi oxide particles was -3.57 nm. The addition of Bi led to the improved dispersion of active components, which were highly and evenly dispersed on the SBA-15 surface. Furthermore, an appropriate proportion of Pb and Bi on SBA-15 was conducive to the considerable enhancement of the catalytic activity. Besides, Pb-Bi/SBA-15 also exhibited good durability and recyclability, making it a promising catalytic material for the synthesis of various carbonates.
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    • NSTL

    Turning rice husks to a valuable boron and nitrogen co-doped porous C/ SiOx composite for high performance lithium-ion battery anodes

    Yehong DuNing ZhangHaibang Zhang
    10页
    查看更多>>摘要：For the exploitation of green biomass waste, boron (B) and nitrogen (N) co-doped porous C/SiOx composites (BN@C/SiOx) have been successfully synthesized applying rice husks (RHs) as both C and Si sources and NH4HB4O7 as the porogen reagent and heteroatom source via a one-step calcination route. The volume fluctuation of SiOx can be effectively relieved and the electronic conductivity can be substantially enhanced with the homogeneous distribution of SiOx particles in the B, N co-doped porous C matrix. Specially, B, N co-doping effectively reduces the transmission barrier of Li~+ in C skeleton of C/SiOx. The unique porous architecture, large specific surface area and B, N co-doping endow BN@C/SiOx with the large reversible capacity, exceptional rate property and superior cycling stability. As lithium-ion batteries (LIBs) anodes, the optimized BN@C/SiOx exhibits the cycling capacity of 1165 mAh/g at 100 mA/g and ameliorated initial coulombic efficiency (CE) of 74.3%. Even at 1.0 A/g, a stable cycling capacity of 650 mAh/g still can be obtained after 1200 cycles. This research offers a potential, relatively effective, cheap and environmental design of heteroatom doped biomass materials with enhanced Li~+ storage performance.
      原文链接:
    • NSTL

    Ibuprofen and diclofenac sodium adsorption onto functionalized minerals: Equilibrium, kinetic and thermodynamic studies

    Milena ObradovicAleksandra DakovicDanijela Smiljanic
    11页
    查看更多>>摘要：Cationic surfactant - octadecyldimethylbenzyl ammonium chloride (ODMBA) was used for modification of the three natural raw materials - bentonite, kaolin and zeolite. Adsorption of ODMBA by minerals occurred via ion exchange of inorganic cations on minerals with surfactant. Organomodified minerals - organobentonite (OB), organokaolin (OK) and organozeolite (OZ) were studied as adsorbents for removal of two non-steroidal antiinflammatory drugs - ibuprofen (IBU) and diclofenac sodium (DS) at pH 7. For all systems, the pseudo-second order model showed the best correlation to kinetic experimental data. In all cases, the positive values of AH° indicated that the adsorption of both IBU and DS by organomodified minerals was endothermic in nature. Equilibrium data were better described by the Freundlich isotherm model, pointing to adsorbent heterogeneous active sites for adsorption. Under applied experimental conditions, the highest adsorption of both drugs was achieved by OB, while much lower capacities were observed for OK and OZ. Nonlinear isotherms and physi-cochemical characterization of organomodified minerals after drugs adsorption suggested complex mechanism consisting of hydrophobic interactions between hydrophobic part of the drugs and surfactants alkyl chains, electrostatic interactions of anionic forms of IBU and DS with the cationic "head" of ODMBA, as well as anion exchange of counterion ions from ODMBA micelle and anionic forms of both drugs. Adsorption of both IBU and DS was strongly dependent on the amount of ODMBA ions in the minerals.
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    • NSTL

    The high efficiency of ZnAl2O4/ZSM-5 in the removal of carbon monoxide contaminants during photocatalytic oxidation process

    Soodabeh Gharibeh
    7页
    查看更多>>摘要：In this research, ZnAl2O4 nanocomposite was developed using the sol-gel method. Using the inoculation method, it was loaded on a ZSM-5 zeolite with variable molar ratios. The properties of the studied catalysts were determined by XRD, SEM, FT-IR, TEM, and BET methods. The photocatalytic activities of ZnAl2O4 and ZnAl2O4/ ZSM-5 nanocatalysts in the photocatalytic oxidation removal of carbon monoxide (CO) were studied under UV radiation in a discontinuous photocatalytic reactor. A gas chromatograph (GC) was applied for investigating the amount of CO removal in the photoreactor. The results indicated that ZnAl2O4/ZSM-5 nanoparticles (NPs) eliminate more CO in less time than pure ZnAl2O4 NPs under the same conditions. The results of the kinetics of the photocatalytic oxidation process of CO show that the reaction kinetics to CO is of the first order, and the rate constants for different molar ratios of zeolite to zinc aluminate (0%-20%) range from 99 × 10~(-4) to 14 × 10~(-2), respectively. Therefore, spinel/zeolite compounds can be a suitable option for oxidative removal of CO pollutants using the photocatalytic method due to the easy preparation method, low price, and high efficiency of these catalysts.
      原文链接:
    • NSTL

    In situ encapsulated molybdovanaphosphodic acid on modified nanosized TS-1 zeolite catalyst for deep oxidative desulfurization

    Shengjie SongMingli BiZhixin Li
    13页
    查看更多>>摘要：In order to solve air pollution caused by SOx, oxidative deep desulfurization of diesel, has become a hotspot all over the world. In this paper, molybdovanaphosphodic acid (HPV2Mo_(10)), a typical polyoxometalate (POM), was in-situ impregnated on TS-1-TAPOH@SiO2 which originated from TS-1 modified by tetrapropylammonium hydroxide (TPAOH) and tetraethyl orthosilicate (TEOS). The catalysts were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Ultraviolet-Visible Diffuse Reflectance (UV-vis), Raman Spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), N2-physisorption, X-ray Photoelectron Spectroscopy (XPS), Inductively Coupled Plasma Spectroscopy (ICP), ~(31)P and ~(29)Si Magic Angle Spinning-Nuclear Magnetic Resonance (MAS-NMR). The characterization results of XRD, FT-IR, UV-vis, Raman and MAS-NMR showed that HPV2Mo_(10) was successfully loaded on TS-1-TPAOH@SiO2, while the structure of support and Keggin-type of HPV2Moio remained unchanged. The catalysts were applied to the oxidative desulfurization (ODS) and adsorption desulfurization of thiophene (TH), benzothiophene (BT), and dibenzothiophene (DBT). The results show that HPV2Mo_(10)/TS-l-TPAOH@SiO2 catalyst prepared by in-situ method has the best oxidation activity when the structure of both the POM and modified zeolite are retained. Under the selected reaction condition: T = 70 °C, n(H2O2)/n(Sulfur) = 13, m_(oil): m _(catalyst) = 35:1. The conversion rates of TH, BT and DBT over HPV2Mo_(10)/TS-1-TPAOH@SiO2-in situ after 3 h were 99.3%, 45.9% and 84.1%, respectively. The function of two part in the investigated HPV2Mo_(10)/TS-1-TPAOH@SiO2 catalyst, known as the modified nanosized TS-1 zeolite and HPV2Mo_(10), for the oxidative desulfurization activity are demonstrated.
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    • NSTL

    Synthesis and characterization of lanthanum-modified pseudoboehmite -The precursor of alumina supports and catalysts

    V.V. DanilevichK.A. NadeinaE. Yu. Gerasimov
    11页
    查看更多>>摘要：The present work shows that the introduction of 0.25-1.25 wt% lanthanum to the composition of aluminum hydroxide at the stage of its hydrothermal synthesis allows increasing the content of the pseudoboehmite phase in the product up to 95 wt% and, as a consequence, reduces the content of the "amorphous" component. Lanthanum uniformly distributes over the surface of aluminum hydroxide as isolated cations with a surface density of 10-15 cations per 10 nm~2. During plasticizing of lanthanum-modified pseudoboehmite followed by granulation and heat treatment, the formation of the oxide form of La is not observed, and the cations retain their isolated state. The specific surface area of La-modified alumina increases by 18-26 m~2/g compared to the unmodified sample, while the pore volume remains the same and the average pore diameter slightly reduces. It was found that when the content of La in pseudoboehmite was 1 wt%, the temperature of reaching a residual sulfur content of 10 ppm in the hydrotreated diesel fuel was 5 °C lower comparing to the unmodified sample.
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    • NSTL

    Facile synthesis of flower-like carbon microspheres for carbon dioxide capture

    Megha SharmaMark A. Snyder
    9页
    查看更多>>摘要：Among classes of porous sorbents with promise for use in mitigating carbon dioxide (CO2) emissions, carbons remain attractive due to their economical synthesis, high CO2 capacity, attractive CO2/N2 selectivity, and ease of regeneration. Here, we report a facile and scalable strategy to synthesize carbon microspheres (~6 μm) bearing a unique, hierarchically structured flower-like morphology. These flowery carbons have specific surface areas as large as 2064 m~2/g and total pore volumes ranging as high as 1 cm~3/g, achieved through activation by CO2 at 900 °C. Detailed study of the textural properties and surface chemistry of these materials as a function of the activation time, primarily, and temperature, secondarily, reveals that CO2 capacity is strongly correlated to the volume of the ultra-micropores (diameters <1 nm) rather than to surface area, total pore volume, or specific N or O functionality. Ultra-micropore volume increases as a function of activation until devolving into larger micro-and meso-pores, with the optimal materials in this study showing high CO2 uptake at 1 bar spanning 4.5 mmol/g (25 °C) to 6.44 mmol/g (0 °C) and competitive CO2/N2 selectivity, as estimated by the Ideal Adsorbed Solution Theory (IAST), without any specific heteroatom doping. These carbons, derived from the simple processing of cheap precursors, also offer low isosteric heats of adsorption (20-30 kJ/mol), thereby, enabling facile temperature and pressure-swing-based cyclic regeneration. Taken together with their hierarchical structure, these materials show promise as efficient and cost-effective CO2 sorbents.
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    • NSTL

    Evaluation and application of machine learning principles to Zeolite LTA synthesis

    Bethany ConroyRichi NayakAndrea Lucia Rocha Hidalgo
    11页
    查看更多>>摘要：A progressive machine learning methodology was utilised to not only identify the relationship between zeolite synthesis descriptors but also evaluate the potential for machine learning to predict the quantitative output of synthesis routes. The hypothesis was if statistics and machine learning principles are applied, then it may enable pre-evaluation and result in potential increases to zeolite yield and performance. Various machine learning algorithms were applied to zeolite LTA synthesis data; including linear regression, ridge regression, regression tree, random forest, XGBoost and artificial neural network models. Major findings included the use of input synthesis variables and the product yield for model training. Additionally, the use of both quantitative and qualitative X-ray diffraction (XRD) data was required to accurately determine product composition ("hybrid XRD" approach). Models, including linear regression, ridge regression and regression trees, returned R~2 values less than 0.5 indicating the complexity inherent with the problem. Embedded tree-based models, including random forest and XGBoost, resulted in testing accuracies equal to R~2 = 0.620 and R~2 = 0.700, respectively. An ANN model achieved the highest accuracy among all machine learning algorithms of R~2 = 0.84. Notably, this model was the most accurate because it exploited non-linear and complex relationships within a multidimensional and inter-correlated dataset such as that obtained from zeolite synthesis. Despite reaching an accuracy greater than 80%, the ANN model accuracy continued to increase by increasing the network size, indicating that advanced deep learning models should be considered as part of future work.
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    • NSTL

    Hierarchically nanostructured carbon nanotube/polyimide/mesoporous Fe2O3 nanocomposite for organic-inorganic lithium-ion battery anode

    Qingfu BanPeiyan LiuYuanyuan Liu
    9页
    查看更多>>摘要：Integrating organic multiple-carbonyl polymers and inorganic mesoporous metal oxides on highly conductive carbon nanotubes is a promising strategy to manufacture high-performance lithium-ion battery anodes; however, developing multicomponent nanocomposites with a hierarchical architecture still remain challenging. Herein, we design and produce hierarchically nanostructured carbon nanotube (CNT)/polyimide (PI)/mesoporous Fe2O3 (meso-Fe2O3/PI/CNT) ternary nanocomposite materials via a sequential assembly and high-temperature dehydration strategy, aiming to fabricate flexible Pi-supported meso-Fe2O3 stacked on a conductive CNT supporting skeleton. By controlling the linear PI mainchain through the comonomer composition, different PI assemblies can grow on the surface of CNT to anchor meso-Fe2O3 nanoparticles as well as alleviate the structural strain resulting from the volume expansion of meso-Fe2O3 in its phase conversion reaction. Considering the porosity and cavity, the mesoporous Fe2O3 architecture can not only buffer its volume expansion but also accommodate a large number of electrolytes to promote Li~ + transport. In addition, the hierarchical architecture endows the meso-Fe2O3/PI/CNT nanocomposite materials with a high structural stability during the electrochemical process. Benefiting from these structural advantages, Li-ion batteries assembled with meso-Fe2O3/PI-EDA/CNT electrodes deliver high capacities of 708.9, 608.2, and 454.5 mAh g~(-1) at 0.1, 0.3, and 0.5 A g~(-1), respectively. Even at a high current density of 1 A g~(-1), a discharge capacity of 95.6 mAh g~(-1) is still obtained after 3000 cycles. This work provides a promising route to integrate multiple-carbonyl polymers and mesoporous metal oxides with the aim of developing multicomponent organic-inorganic composite anode for Li-ion battery.
      原文链接:
    • NSTL