Nanoporous Zeolite Research Articles

Preparation of Ethyl 4-Nitrobenzoate Using Ultradispersed Natural Zeolite Catalysts, Ultrasound and Microwave Irradiation

The new possibilities of preparing the ethyl 4-nitrobenzoate by esterification of 4-nitrobenzoic acid (4-NBA) with ethanol under argon at 80°C are shown; particularly, over catalysts: on micrometric (4.8 - 7.0 μm) or ultradispersed crystallites (290 - 480 nm) of hydrogen forms of nanoporous natural zeolites H-CL, H-MOR, H-HEU-M, H-PHI and under irradiation of the reaction mixture with ultrasound (US, 37 kHz, 330 W, 2 h) or microwaves (MW, 2450 MHz, 300 W, 2 h). Ultradispersed crystallites of zeolite catalysts were prepared from hydrogen forms of parent natural zeolites by their treatment with US or MW. In the esterification, the synergism of the actions of catalysts and MW or US was revealed; wherein on the ultradispersed best catalysts H-HEU-M and H-MOR conversion of 4-NBA and yield of ethyl 4-nitrobenzoate reached up to 70% and 67%, respectively. GC/MS, FTIR, NMR methods were used in the study.

Novel anticancer drug delivery system based on zeolite encapsulating Hamelia patens leaf and flower extracts

Nanotechnology had placed an impact in improving the antiproliferative activity of crude leaf (CL) and flower (CF) extracts of Hamelia patens on the liver (HEPG2) and breast (MCF7) carcinoma cell lines, after their encapsulation onto zeolite (ZSM-5) nanopores, which acts as a drug delivery system (DDS). The cytotoxicity of the new formulas showed remarkable improvement in the activities on HEPG2. CL had low activity on HEPG2, at the tested concentrations, but the ZSM-5 loaded one (CLZ) showed enhanced action with IC50=42 μg/mL. Also, the cytotoxicity of CF improved after Zeolite incorporation, where the IC50 has been changed from 48 μg/mL for CF to 25 μg/mL for CFZ. Moreover, the polar fraction of leaves extracted by methanol (Me.L) showed improvement on the cytotoxicity on MCF7 for zeolite loaded formula (Me.Z) (IC50 had changed from 65 to 44.4 μg/mL). Quantitative estimations for polyphenolic contents as well as the phenolic profiles for CF and CL extracts were inspected using HPLC-DAD to explore the bioactive phytochemical compounds. Acute toxicity test showed that LD50 was 1500 and 2333 mg/kg b.wt. for CL and CF, respectively. The cytogenetic study was also done to detect the chromosome aberrations in somatic and germ cells after CL and CF administration to mice. DPPH antioxidant capacity assay revealed that CL has high redox-active effect than CF. This study is a contribution to the development of a creative new DDS that help in cancer treatment.

Production of Nanoporous Zeolites Modified by Silver Ions with Antibacterial Properties

We study the effect of activation of clinoptilolite specimens by the solutions of HCl, H2SO4 , NaOH, and NH4Cl with their subsequent thermal treatment for the sorption capacity in silver ions. It is shown that the highest sorption capacity is observed for the clinoptilolite activated by a sodium-hydroxide solution. It was established that, in all cases, the increment of sorption capacity observed upon attainment of a temperature of 200°С is insignificant. The rate of sorption of silver ions by clinoptilolite preliminarily activated by reagents is higher than the initial rate (without activation) by an order of magnitude. We also established the influence of the temperature of treatment of chemically activated clinoptilolite on the sorption rate of silver ions. It was shown that their absorption by clinoptilolite occurs according to the mechanisms of ion exchange and sorption.

Characterization of phase transformation from low grade kaolin to zeolite LTA in fusion technique: Focus on quartz melting and crystallization in presence of NaAlO2

The presence of clay and non-clay impurities, mainly quartz, in the processed kaolin is the inherent problem in the formation of zeolite LTA due to scarcity of aluminum. Therefore; in the current investigation the phase transformation from low-grade kaolin to LTA structure was studied in the fusion technique to achieve the appropriate frame. The quartz reaction with alkali solution and zeolite crystallization were related to starting material composition, temperature, NaOH/kaolin, NaAlO2/kaolin, and ageing time. The obtained products were characterized via X-ray diffraction, scanning electron microscopy, and Brunauer–Emmett–Teller textural measurements. The quartz reaction was accompanied by partial crystallization of hydrosodalite in the hydrothermal stage. The conversion of hydrosodalite to LTA frame was governed by aluminum ion content in which the relative crystallinity depends on starting kaolin composition. The presence of illite and pyrophyllite in the starting material composition results in the formation of amorphous phase while the absence of illite and pyrophyllite is the most efficient in the crystallization of nano-porous zeolite LTA, 10–12 nm, with the highest relative crystallinity, 100%, in comparison to reference manufactured commercially. Furthermore, the ageing time should be controlled within 24 h otherwise, the more extended ageing leads to lower relative crystallinity. A simplified method based on methylene blue adsorption was suggested for evaluating the change in the textural characteristics of synthesized materials. Hydrosodalite represented superior adsorption behavior compared to zeolite LTA. According to the presented pathway, the well-crystallized zeolite LTA can be produced from low-grade kaolin.

Atomistic understanding of gas separation through nanoporous DDR-type zeolite membrane

Abstract Molecular dynamics simulations were applied to evaluate the Kr/Xe separation performance by a pure silica DDR type membrane. The external pressure was applied up to 50 MPa in order to transfer the gas atoms through the membrane. The process was also studied at temperatures ranging from 293 to 373 K. The membrane exhibited best Kr atoms permeation (177.25 × 10−5 mol/(m2∙s∙Pa)) and selectivity at P = 10 MPa and T = 373 K, which indicates that the best separation performance can be achieved by increasing the temperature without applying higher pressures. The potential of the mean force (PMF) of Kr and Xe confirmed the necessity of applying the driving force for penetration of Kr or Xe atoms through the DDR membrane. Furthermore, the PMF curve demonstrated the higher energy barrier for the passage of Xe through the DDR membrane compared with Kr, which was also verified by simulation outputs.

Hierarchically Nanoporous TS-1 Zeolites for Catalytic Oxidation Desulfurization of Liquid Fuels

Hierarchically nanoporous titanosilicate TS-1 zeolites, comprising micropores (0.55 nm), super-micropores (1.6 nm), and mesopores (30 nm), have been prepared by hydrothermal crystallization and sub...

Development of the reference material of nanoporous zeolite

The article is devoted to the development of a reference material of the sorption roperties of nanoporous zeolite, which ensures metrological traceability of measurement results to the State primary measurement standard of units for specific gas adsorption, specific surface area, specific pore volume, pore size, open porosity and gas permeability coefficient of solid substances and materials GET 210-2019.The paper presents the results of theoretical and experimental studies on optimizing the conditions of sample preparation (thermal training) of the reference material using the thermogravimetric method and differential scanning calorimetry, coupled with mass spectrometric detection of the evolved gases (TG-DSC–MS analysis). The results of establishing the metrological characteristics of the reference material are described, including standard uncertainty due to the method of determining the certified value, as well as standard uncertainties from heterogeneity and instability. The GSO 10734–2015 reference material of the sorption properties of nanoporous zeolite (Zeolite SO UNIIM) has certified metrological characteristics: specific surface area (500–1200) m2/g; specific pore volume (0.10.5) cm3/g; the predominant pore diameter (0.4–0.9) nm; specific argon adsorption (0.001–20.0) mol/kg.The reference material is designed to calibrate measuring instruments and to control accuracy of results of sorption characteristics of nanoporous materials measurements; it can be used to certify appropriate measurement procedures, to test measuring instruments and reference materials for type approval and other types of metrological control.

Ten Years of Aberration Corrected Electron Microscopy for Ordered Nanoporous Materials

AbstractOrdered nanoporous materials including zeolites, zeotypes, and metal‐organic frameworks (MOFs) are widely used in the fields of heterogeneous catalysis, ion exchange and gas storage/separation. In addition, due to their particular structural features new applications are continuously being explored as a consequence of their well‐defined porous network, thermal stability, acidity and guest‐species confinement. All physicochemical properties are directly structure related and therefore characterization at atomic level is highly desired. In the current work, we have aimed to review the recent progress of electron microscopy science applied to the characterization of different nanoporous materials since the first work that made use of spherical aberration (Cs) corrected electron microscopy in 2010. All difficulties encountered for the application of this technique will be presented, together with the excellent degree of information that can be extracted and the scientific responses that only Cs‐corrected electron microscopy can provide in the area of nanoporous materials, zeolites, zeotypes and MOFs.

ВИСОКОПРОДУКТИВНІ ОБЧИСЛЮВАЛЬНІ МЕТОДИ І ТЕХНОЛОГІЇ МОДЕЛЮВАННЯ НАНОПОРИСТИХ СИСТЕМ ЗІ ЗВОРОТНИМИ ЗВ'ЯЗКАМИ ДЛЯ АДСОРБЦІЙНОГО ОЧИЩЕННЯ ГАЗІВ

Розглядається задача моделювання неізотермічної адсорбції та десорбції в нанопористих цеоліт-системах для нелінійної адсорбційної рівноваги типу Ленґмюра. Пропонуються висопродуктивні методи операційного числення Гевісайда та перетворення Лапласа звикористанням схем лінеаризації на основі підходу Ландау щодорозкладу в ряд функції рівноваги Ленґмюра в околі точки температури фазового переходу та малого параметру, що дозволяють ефективне розпаралелювання обчислень. Подані результати обчислювальних експериментів.

Antireflection Enhancement by Composite Nanoporous Zeolite 3A-Carbon Thin Film.

A straightforward and effective spin-coating technique at 120 °C was investigated for the deposition of a thin nanoporous layer with antireflection properties onto glass and indium tin oxide (ITO) coated glass. A mixture of zeolite 3A powder and high iodine value vegetable oil was deposited, creating a carbonic paste with embedded nanoporous grains. Experimental results evidenced excellent broadband antireflection over the visible-near-infrared wavelength range (450–850 nm), with a diffuse reflectance value of 1.67% and 1.79%. Structural and optical characteristics stabilized over time. The results are promising for the accessible and cost-effective fabrication of an antireflective surface for optoelectronic devices.

A Brief Overview on the Anticorrosion Performances of Sol-Gel Zeolite Coatings

Research activity concerning nanoporous zeolites has grown considerably in recent decades. The structural porosity of zeolites provides versatile functional properties such as molecular selectivity, ion and molecule storage capacity, high surface area, and pore volume which combined with excellent thermal and chemical stability can extend its application fields in several industrial sectors. In such a context, anti-corrosion zeolite coatings are an emerging technology able to offer a reliable high performing and environmental friendly alternative to conventional chromate-based protective coatings. In this article, a focused overview on anti-corrosion performances of sol-gel composite zeolite coatings is provided. The topic of this review is addressed to assess the barrier and self-healing properties of composite zeolite coating. Based on results available in the literature, a property–structure relationship of this class of composites is proposed summarizing, furthermore, the competing anti-corrosion active and passive protective mechanisms involved during coating degradation. Eventually, a brief summary and a future trend evaluation is also reported.

Utilization of Various Analogy of Synthetic Nanoporous Zeolites and Composite of Zeolites for Decontamination/Detoxification of CWA Simulants—An Updated Review

In this review, we summaries the past few year work on the chemistry of CWA’s and their simulants on various heterogeneous surfaces of zeolites, composites of zeolites and doped zeolite with transition metal oxides. This review elaborates an updated literature overview on the degradation of CWA’s and its simulants. The data written in this review were collected from the peer-reviewed national and international literature.

Hydrogen Isotope Separation in Confined Nanospaces: Carbons, Zeolites, Metal-Organic Frameworks, and Covalent Organic Frameworks.

One of the greatest challenges of modern separation technology is separating isotope mixtures in high purity. The separation of hydrogen isotopes can create immense economic value by producing valuable deuterium (D) and tritium (T), which are irreplaceable for various industrial and scientific applications. However, current separation methods suffer from low separation efficiency owing to the similar chemical properties of isotopes; thus, high-purity isotopes are not easily achieved. Recently, nanoporous materials have been proposed as promising candidates and are supported by a newly proposed separation mechanism, i.e., quantum effects. Herein, the fundamentals of the quantum sieving effect of hydrogen isotopes in nanoporous materials are discussed, which are mainly kinetic quantum sieving and chemical-affinity quantum sieving, including the recent advances in the analytical techniques. As examples of nanoporous materials, carbons, zeolites, metal-organic frameworks, and covalent organic frameworks are addressed from computational and experimental standpoints. Understanding the quantum sieving effect in nanospaces and the tailoring of porous materials based on it will open up new opportunities to develop a highly efficient and advanced isotope separation systems.

Combined Natural Gas Separation and Storage Based on in Silico Material Screening and Process Optimization

We propose an intensified process for combined separation and storage (CSS) of natural gas from various unconventional sources using a single multifunctional unit. The CSS process involves selectively storing methane in a column filled with an existing nanoporous zeolite material, while venting out the impurities. A multiscale model is used to optimize the methane storage and screen for the top zeolites under minimum purity requirements and loss constraints. Adsorption properties for different zeolites are obtained via Monte Carlo simulations. Zeolite SBN with a high storage capacity for pure methane is found to be most suitable for combined separation and storage over a range of feed compositions. A rank ordered list of top zeolites is also obtained along with the optimal process conditions. It is, however, observed that the effectiveness of the intensification of natural gas separation and storage is limited by the constraint on the loss of methane exiting the column.

Multifunctional Green Nanoporous Zeolites as Catalysts in Organic Synthesis

Multifunctional Green Nanoporous Zeolites as Catalysts in Organic Synthesis

Removal of mercury(II) from aqueous solutions via Box–Behnken experimental design by synthesized hierarchical nanoporous ZSM-5 zeolite

In this study, hierarchical nanoporous ZSM-5 zeolite is synthesized from bagasse ash as silica source (grows in the south of the Caspian Sea, Mazandaran province, Iran) and used as adsorbent for removal of the Hg(II) from aqueous solutions. Synthesized zeolite is characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electronic microscopy, and energy dispersive X-ray, Brunauer–Emmett–Teller and Barrett–Joyner–Halenda methods. Four important parameters in three levels including: adsorbent dosage (10, 25 and 50 mg), pH of solution (3, 7 and 10), contact time (20, 180 and 320 min), temperature (25, 55 and 75 °C), are optimized to obtain the best response of Hg(II) removal % using the Box–Behnken design. A second-order quadratic model suggested the optimum conditions to be as follows: adsorbent dosage 50 mg, pH of solution 7, contact time of 180 min and temperature 75 °C.

Computational comparison of the efficiency of nanoporous zeolite frameworks for separation of phenol from water

Abstract The adsorption through zeolite is an efficient way of phenol removal from water. The adsorption performance of all-silica zeolites including BEA (Beta), FAU (Faujasite), MFI (silicalite-1), and MOR (Mordenite) to adsorb phenol from phenol/water vapor mixture was predicted and compared through Grand Canonical Monte Carlo (GCMC) simulation. The results show that the adsorption of phenol on zeolites is a function of diameter of largest included sphere and largest free sphere dimensions at high loading (FAU > BEA > MFI > MOR). At low pressure, the phenol adsorption is a function of Framework Density, FDSi, as: MFI > MOR ∼ BEA > FAU due to dominant adsorbate–wall attractions compared to other interactions. The preferential siting of zeolite is suggested by both GCMC simulation and quantum mechanics approaches. Hydrogen bonding and dispersion can improve the formation of clusters of organic compounds in the intersection and middle channel of zeolite. In distribution function versus energy curve, FAU shows a clear peak at about −20 kcal mol−1 since it possesses supercages with one tetrahedral center. Our results show that both the difference between structures of the zeolites and the interactions can be taken into account to determine the adsorption capacity.

Electro-elastoviscous response of polyaniline functionalized nano-porous zeolite based colloidal dispersions

The present article discusses the typical influence of grafted conducting polymers in the mesoscale pores of dielectric particles on the static and dynamic electrorheology and electro-viscoelastic behavior of corresponding colloids. Nanocrystalline meso-nanoporous zeolite has been prepared by chemical synthesis and subsequently polyaniline (PANI) coating has been implemented. Electrorheological (ER) suspensions have been formed by dispersing the nanoparticles in silicone oil and their viscoelastic behaviors are examined to understand the nature of such complex colloidal systems under electric fields. PANI-Zeolite ER fluids demonstrate higher static electroviscous effects and yield stress potential than untreated Zeolite, typically studied in literature. Transient electro-viscous characterizations show a stable and negligible hysteresis behavior when both the fluids are exposed to constant as well as time varying electric field intensities. Further oscillatory shear experiments of frequency and strain sweeps exhibit predominant elastic behavior in case of Zeolite based ER suspensions as compared to PANI systems. Detailed investigations reveal Zeolite based ER suspensions display enhanced relative yielding as well as electro-viscoelastic stability than the PANI-Zeolite. The steady state viscous behaviors are scaled against the non-dimensional Mason number to model the system behavior for both fluids. Experimental data of flow behaviors of both the ER fluids are compared with semi-classical models and it is found that the CCJ model possesses a closer proximity than traditional Bingham model, thereby revealing the fluids to be generic pseudo-linear fluids. The present article reveals that while the PANI based fluids are typically hailed superior in literature, it is only restricted to steady shear utilities. In case of dynamic and oscillatory systems, the traditional Zeolite based fluids exhibit superior ER caliber.

Single-component structural correlation and self-diffusion of N2 and O2 through nanopores of Li-LSX zeolite: The role of temperature, loading, and Li-III cations

Diffusion-selective N2/O2 separation and competitive adsorption by nanoporous Li-LSX zeolite, as the best commercially available adsorbent, is a scientifically interesting phenomenon with important technological applications. In a recent paper (J. Phys. Chem. C 121, 2017, 1770–1780), we reported the first molecular dynamics (MD) study of the adsorption of the binary N2/O2 mixtures within this zeolite. In the present paper, the microscopic structure and intracrystalline self-diffusion coefficient of N2 and O2 as single-component guest species in Li-LSX zeolite are determined at different temperatures and practical loadings. The simulation results are found to be in very good complementary agreement with experimental adsorption findings as well as with the recent predictions based on the binary air mixture simulations. The influences of the internal surface dynamics of extra-framework Li+ cation in site III (Li-III) on the guest static and dynamic processes within the zeolite are determined. O2 has no significant association with Li-III, while all structural analyses prove remarkable adsorption and hence localization of N2 around the Li-III in the supercages. The degree of localization and the residence time of N2 on Li-III in particular increases with decreasing temperature and also with fixing of Li-III cations during the simulation. As a guide for future design of N2/O2 separation by zeolite frameworks at ambient temperature, an excellent adsorption selectivity ratio can be achieved if it is practically possible to reduce the dynamics of accessible Li-III sorption sites up to extremely fixed situations. The calculated Arrhenius activation energy for N2 diffusion process through Li-LSX zeolite is several times higher than that of O2. These results are due to the larger quadrupole moment of N2 and stronger Coulombic attraction between N2 and Li-III that causes the translational motion of N2 to be significantly hindered. Overall, the intracrystalline self-diffusion coefficients of both N2 and O2 slightly decrease with loading. Current simulations also correctly approve that the Li+ cations in sites I′ and II are inaccessible to interact with guest molecules.

Synthesis, Evaluation, Modeling and Simulation of Nano-Pore NAA Zeolite Membranes

Synthesis, Evaluation, Modeling and Simulation of Nano-Pore NAA Zeolite Membranes