Sharif Digital Repository

This mini review article, intends to provide the essential information about microemulsion technique as a reliable approach toward the synthesis of zeolitic nano crystallites. The strategy discussed here provides a unique, effective, and potentially general methodology to the preparation of uniform and high purity nano crystallites of template-free zeolitic materials including LTA, faujasite type and other zeolitic-like materials (i.e. zeotype materials). Microemulsion is a reliable approach for controlled synthesis of uniform nano sized zeolitic particulates. On the other hand, the microwave assisted microemulsion technique has the advantages of short reaction time, producing smaller and... 

LTA Zeolite nanoparticles was successfully synthesized from clear solution under controlled conditions using hydrothermal method using tetramethyl ammonium hydroxide as a structural directing agent. The as-synthesized LTA zeolite particles were characterized by powder X-ray Diffraction (XRD) analysis, Scanning Electron Microscopy (SEM), Fourier Transform InfraRed (FT-IR) spectroscopy, Energy Dispersive X-ray (EDX) analysis and surface area measuring technique of Brunauer, Emmett and Teller (BET). XRD patterns and FT-IR spectra were ascertained the formation of pure crystalline phase of 4A (i.e. LTA) zeolite. SEM micrograph was shown particles size in the range of 60 -170 nm with uniform... 

A heterogeneous catalyst for epoxidation of alkenes has been synthesized by introducing polyoxomolybdate into a natural zeolite as a solid and green support. The prepared catalyst was characterized by FT-IR, inductively coupled plasma optical emission spectrometry (ICP-OES), powder X-ray diffraction (XRD), N2 absorption–desorption, field emission scanning electron micrograph (FE-SEM) and transmission electron microscopy (TEM). The catalytic investigations disclosed that nanocluster polyoxomolybdate supported on the surface is an active and recyclable catalyst in liquid phase alkene epoxidation in dichloroethane at 80 °C. © 2017 Informa UK Limited, trading as Taylor & Francis Group  

The effects of varying operating conditions on metals removal from aqueous solution using a novel platinum nanopartcles/Zeolite-4A adsorbent are reported in this paper. Characterization of the adsorbent showed successful production of platinum nanopartcles on Zeolite-4A using 3 Wt% platinum. The effects of operation conditions on metals removal using this adsorbent were investigated. The optimal metals adsorption was observed at pH 7, 0.1 g/10 mL dosage and 30 min contact time. Sorption data have been interpreted in terms of Langmuir and Freundlich isotherms  

Zeolite-based photocatalysts were prepared by the sol-gel and deposition methods. The photocatalysts were characterised by X-ray diffraction, nitrogen adsorption-desorption isotherms, FTIR spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectrometry. The activity of the prepared photocatalysts was evaluated by the UV-induced degradation of acid blue 92, a textile dye in common use. The effect of various parameters, such as catalyst concentration, initial dye concentration, thiosulphate concentration and pH, on the rate and efficiency of the photocatalytic degradation of acid blue 92 was investigated. The results showed that each parameter influenced the degradation... 

ZnO and Mordenite zeolite (MOR) nanoparticles were prepared by precipitation process using ultrasonic irradiation and hydrothermal method, respectively. Supported ZnO catalysts were prepared and the effect of different supports on the photocatalytic activity of ZnO nanoparticles was investigated. All prepared samples were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform-Infra Red Spectroscopy (FTIR), UV–vis spectroscopy (UV–vis) and BET surface area technique. The photocatalytic activity of the synthesized catalysts was elucidated using the photo-oxidation of Acid Blue 92 (AB92) as a hazardous pollutant under UV light. The effect of different... 

Functionalized magnetic core–zeolitic shell nanocomposites were prepared via hydrothermal and precipitation methods. The products were characterized by vibrating sample magnetometer, X-ray powder diffraction, Fourier transform infrared spectroscopy, nitrogen adsorption–desorption isotherms, and transmission electron microscopy analysis. The growth of mordenite nanocrystals on the outer surface of silica-coated magnetic nanoparticles at the presence of organic templates was well approved. The removal performance and the selectivity of mixed metal ions (Pb2+ and Cd2+) in aqueous solution were investigated via the sorption process. The batch method was employed to study the sorption kinetic,... 

Zeolite-based Ag/AgBr and Ag/AgBr/TiO2 photocatalysts were prepared by sol–gel and deposition methods and were characterized. Their photocatalytic activities were evaluated by inactivation of Escherichia (E.) coli and the photodegradation of Acid Blue 92 and potassium permanganate. The composites containing Ag/AgBr showed the antibacterial activity in the dark by releasing Ag+ ions into the medium. The results for inactivation of E. coli indicated that Ag/AgBr/TiO2 modified photocatalyst had better antibacterial activity than Ag/AgBr/zeolite, while zeolite and TiO2/zeolite did not show any antibacterial activity under visible light and dark conditions. Photodecolarization rate was affected... 

A number of HZSM-5 catalysts modified with 5 wt% Mg, Na, Zr, and Al as well as others modified with 5-60 wt% Zn prepared by wet impregnation. These materials were characterized by the NH3-TPD, XRF, and XRD analyses and tested in a slurry reactor to determine their activities in dehydration of methanol solution in kerosene. Reactions were carried out at 230°C and 19 bar for 4 h of residence time in the reactor. Results showed that in the first series, the catalyst modified with Zr and in the second series, the one modified with 10 wt% Zn led to the highest methanol conversion. It was deduced that elimination of strong acid sites and partial replacement of active cations in the HZSM-5 zeolite... 

The current study aimed at application of the plain and supported platinum nanoparticles as a heterogenous catalyst for the reduction of aromatic nitro compounds. Monodispersed platinum nanoparticles were synthesized by reduction of H2PtCl6 by ethanol in the presence of polyvinyl pyrrolidone as a stabilizer, and then were immobilized on four types of zeolites. The obtained catalyst granules were characterized by X-ray diffractometry and transmission electron microscopy. The study then focused on elaboration of the catalytic activity of the nano catalysts under different operational conditions. It was found that reaction is adequately rapid at ambient temperature, and by utilizing a... 

The Mn-hydrazone Schiff base has been prepared, characterized, and encapsulated into NaY to prepare a new heterogeneous catalyst. Elemental analysis, UV-Vis, infrared spectroscopic analysis, diffuse reflectance spectroscopy, thermal analysis, small angle X-ray diffraction, and N2 sorption indicate the presence of Mn-hydrazone Schiff base within the nanocavity pores of zeolite-Y. The catalysts showed excellent catalytic efficiency in epoxidation with various olefinic compounds including cyclooctene, using tert-BuOOH as oxidant. Cyclooctene showed high conversion (97%) as well as epoxide selectivity (89%) with tert-BuOOH. Moreover, the encapsulated complex showed good recoverability without... 

MFI zeolite membranes were prepared on porous α-alumina substrates, using secondary growth of nano-seeded layers. The resulting membranes were characterized by means of Scanning Electron Microscopy (SEM), X-Ray Diffractometry (XRD), and pervaporation performance tests for separation of Benzene, Toluene and Xylene (BTX) mixture from contaminated water. The morphology, thickness, homogeneity, crystal preferential orientation and permeation properties of these membranes have been studied in relation to the seed layers. Successful separation of BTX mixture from water was performed by using the manufactured MFI zeolite membrane. The influence of temperature, feed concentration on the membrane... 

In this work, we synthesized two types of zeolite nano-adsorbents termed HZ1 and HZ2. For further improving the effluent quality and reduction of membrane fouling, these two synthesized zeolite nano-adsorbents were used in a membrane bioreactor (MBR). Particle size distribution (PSD), soluble microbial products (SMP), and extracellular polymeric substance (EPS) for sludge were measured. In addition Fourier-transform infrared spectroscopy (FTIR), excitation-emission matrix (EEM) fluorescence spectroscopy, gel permission chromatography (GPC), and EPS analysis were performed for characterization the properties of the formed cake. The results showed that both HZ1 and HZ2 had better function in... 

Calcined Na-ZSM-5 zeolite was directly reacted with the chloroauric acid solution in different concentrations and pH for gold loading process. The synthesized Au/ZSM-5 catalyst was then characterized using XRD, BET, SEM, TEM and EDS techniques. In order to evaluate its catalytic activity, effect of temperature on CO conversion was investigated. © 2008 World Scientific Publishing Company  

The liquid-phase dehydration of methanol to dimethyl ether was investigated over various materials including synthetic zeolites, namely, ZSM-5, Y, Mordenite, Ferrierite and Beta as well as silica and alumina. The key characters investigated were the Si/Al ratio and cation exchange. The results showed that the Mordenite zeolite exchanged with H+ exhibited the highest activity in dehydration of methanol. After finding the most active catalyst, the Mordenite zeolite was modified with Cu, Zn, Ni, Al, Zr, Mg and Na via wet-impregnation method to further improve its selectivity, and characterized by AAS, XRD, NH3-TPD, NH3-FT-IR and BET surface area techniques. It was found that these materials... 

2D minerals are among key elements of advanced systems, but the need for understanding their interactions/reactions with materials and systems in which they are involved necessitates tracking their molecular and atomic monitoring. Zeolitic structures are microporous materials formed in the nature through volcanic activities or synthesis. Because of their outstanding physicochemical properties like cation exchange capacity and excellent adsorption properties, zeolites have found application in diverse chemical processes, e.g., gas adsorption, water purification, and wastewater treatment. Prediction of zeolite performance for a targeted application saves time and expense as such projection... 

The adsorption of nickel ions in an aqueous solution system was measured using zeolitic imidazolate framework-8 (ZIF-8) nanoadsorbent. ZIF-8 crystals were synthesized using the hydrothermal method. Nanoadsorbent was characterized by FTIR, XRD, SEM and N2 adsorption analysis. ZIF-8 crystals showed a high surface area of 1303 m2/g and particle size 100–150 nm. The Langmuir and Freundlich isotherms model were used to analyze the data. The sufficiently high R2 value of 0.996 resulted from the Langmuir isotherm model demonstrated the perfect performance of this model. The kinetic data were analyzed using the pseudo-first-order and pseudo-second-order models of types 1–4. Kinetic studies of the... 

In the present work, Tetrahydrofuran was produced from 1,4-butanediol by catalytically dehydration of 1,4-butanediol in contact with a catalyst. Material used as catalyst were Synthesized and natural zeolites as well as alumina and silica. Synthesized zeolites were investigated in different aspect such as pore size, cation and Si/Al ratio. Results indicated that with increasing the Si/Al ratio, the activity of the zeolite used for 1, 4-butanediol dehydration step was reduced. Furthermore, it was observed that, upon the replacement of sodium with hydrogen and ammonium cations, the conversion of the 1, 4-butanediol into tetrahydrofuran was increased. It was shown zeolites possessing smaller... 

Polymeric membrane technology has received extensive attention in the field of gas separation, recently. However, the tradeoff between permeability and selectivity is one of the biggest problems faced by pure polymer membranes, which greatly limits their further application in the chemical and petrochemical industries. To enhance gas separation performances, recent works have focused on improving polymeric membranes selectivity and permeability by fabricating mixed matrix membranes (MMMs). Inorganic zeolite materials distributed in the organic polymer matrix enhance the separation performance of the membranes well beyond the intrinsic properties of the polymer matrix. This concept combines...