Zeolite Synthesis Method Research Articles

Facile synthesis of zeolites under an atmospheric reflux system

Traditionally zeolites are produced under long aging processes and high autogenous pressure reactions associated with a lot of safety concerns and explosion risks. Herein, a facile zeolite synthesis method under atmospheric pressure using a reflux system is reported. The zeolite gel crystallizes rapidly under the synthesis conditions of heating, stirring, and reflux in an oil bath. We have successfully synthesized LTA, FAU, MFI, and BEA zeolites. This technique not only eliminates the potential risks associated with pressure vessels but also greatly improves the synthesis rate and speeds up the production cycle. This synthesis strategy provides a new, safe and rapid way of synthesizing zeolites. • Safe synthesis of various zeolite by reflux system. • The synthesis of zeolite under atmospheric reflux system is faster than the conventional method. • Different synthesis methods of zeolite in reflux system are introduced in detail.

Optimization of the Beta Zeolite Synthesis Method

Optimization of the Beta Zeolite Synthesis Method

Synthesis of Fly Ash-Based Zeolite and its Research Progress in Wastewater Treatment

Fly ash is the most common solid waste in the industry, and its high value-added utilization has become a hot issue of study. Carrying out the green synthesis route of zeolite as the raw material of fly ash has become an extremely important scientific significance and practical value. In this paper, the research progress of fly ash-based zeolite was introduced from three aspects, including fly ash activation method, fly ash-based zeolite synthesis method and fly ash-based zeolite in the wastewater treatment sector. The relevant applications of fly ash-based zeolite as an adsorbent material in the treatment of wastewater pollution were summarized, and the development trend has prospected.

Novel Composites of Multifunctional NaP Zeolite/Graphene Oxide for Highly Efficient Removal of Fe(III) from Aqueous Solution

Composites of graphene oxide (GO, 1–5 wt%) loaded into the inter pores of the hollow NaP zeolite at 100 °C were successfully prepared via the zeolite synthesis method (ZSM). These NaP/GO composites were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy and N2 physisorption analysis. The structural properties of NaP/GO (1–3 wt%) indicated that GO moieties can be accommodated in the voids of the NaP zeolite without modifying its framework or structure. The FE-SEM image of NaP/GO (3 wt%) showed the tendency of GO to form significantly smaller individual particles of NaP zeolite than corresponding of NaP/GO (1 and 2 wt%). The FTIR band due to asymmetric stretching T–O lattice vibration (~ 1000 cm−1) was shifted towards higher frequencies with increasing content of GO (1–3 wt%), reflecting the involvement of GO adducts in the intracrystalline structure of NaP zeolite. The produced composites were used for the removal of Fe(III) ions from aqueous solution and such process took place via a surface uptake and intra-particle diffusion which operate simultaneously through the interaction between Fe(III) ions and NaP/GO (3 wt%). The dielectric constant (er) values as a function of frequency were increased after adsorbing Fe(III) onto NaP/GO (3 wt%) which may be attributed to cations hopping diffusion along zeolite structure.

Photocatalytic Degradation of Dye Pollutant Over FeTPP/NaY Zeolite Nanocomposite

This study aimed to determine the photocatalytic activity of photo-Fenton reagent in the photodegradation of 4-Nitrophenol. For this purpose, Fe(III) tetraphenyl porphyrin encapsulated NaY zeolite (FeTPP/NaY) was successfully synthesised via the zeolite synthesis method. The effects of catalyst amount, H2O2 and UV illumination, concentration of 4-Nitrophenol and pH value on the photodegradation process were examined. Ultraviolet–Visible spectroscopy studies revealed that catechol, benzoquinone, and nitrate as the key intermediate species for photodegradation of 4-Nitrophenol. The chemical oxygen demand analysis indicated mineralisation of pollutant which exhibits 85% conversion of 4-Nitrophenol after 120 min irradiation. Rational design of FeTPP/NaY Nanocomposite as Fenton reagent for efficient photodegradation of 4-Nitrophenol was reported, and the possible reaction pathways of the photocatalytic reaction were proposed.

Seed-Assisted, OSDA-Free, Solvent-Free Synthesis of ZSM-5 Zeolite from Iron Ore Tailings

Comprehensive utilization of iron ore tailings (IOT) not only solves environmental problems but also creates huge economic benefits. Our approach is focused on reutilization of IOT by converting it to ZSM-5 zeolite. The solvent and organic structure-directing agents (OSDA) used in the hydrothermal synthesis of ZSM-5 zeolite are major obstacles to achieve the sustainable synthesis routes. Therefore, the development of environmentally friendly ZSM-5 zeolite synthesis method is strongly desired. Here, ZSM-5 zeolite is synthesized successfully from IOT via a seed-assisted, solvent-free method without using the organic template or solvent. In addition, the influences of Na2CO3·10H2O/SiO2 molar ratio, amount of seeds, and crystallization process of ZSM-5 are systematically investigated. The raw materials and as-synthesized products are characterized by XRD, XRF, SEM, 27Al MAS NMR, and BET analysis; and the ZSM-5 zeolite synthesized by seed-assisted, OSDA-free, solvent-free method has the same mesoporous and microporous structure as the seed crystal. The synthetic route proposed in this work provides a novel green alternative for the synthesis of ZSM-5 from IOT. Figure schematic illustration of the seed-assisted, OSDA-free, solvent-free synthesis of ZSM-5 .

The use of mathematical models for modelling sulphur dioxide sorption on materials produced from fly ashes

Fly ash-derived zeolites may become an attractive alternative for natural zeolites as well as for zeolites produced out of pure chemicals. A growing awareness of the need to protect the environment is an incentive for the use of waste materials as raw materials for production of microporous, multi-application materials – zeolites. Additionally, environmentally friendly actions undertaken in order to reduce air pollution intensify needs to search for new options for capturing hazardous air pollutants out of flue gases. Zeolites can be used as air pollutants sorbents. In this work there are presented results of sulphur dioxide, one of flue gases components, sorption experiments. The adsorbent used was zeolite synthesized form fly ash from a selected Polish power plant. For the purpose of investigation there were chosen fly ash zeolite samples synthesised with the use of different methods. Parameters were selected in such a way that one type of zeolite material was received. For the purpose of description of received results the mathematical model was used. As a result of experiments carried out it was found that the synthesized materials may be used as sulphur dioxide sorbent. It was found that the sorption capacity is highly connected with the zeolite synthesis method. Despite the fact that the same type of zeolite was received, samples presented differentiated values for capture, due to different conversion factors of fly ash into zeolite materials.

Synthesis, structural configuration and DFT molecular orbital studies of [Mn-2[benzo[b]oxazole] acetonitrile] complexes encapsulated in ZSM-5: Direct synthesis of phenol by benzene hydroxylation

In situ synthesis of Mn-BOA [BOA = 2[benzo[b]oxazole] acetonitrile] complexes with loadings from 7.8 to 12.3 wt% in the microporous structure of zeolite ZSM-5 (Si/Al = 38) by the zeolite synthesis method was reported. The structure and characterization of the prepared samples have been identified by elemental analyses, XRD, XPS, EPR, FT-IR, UV-vis, TGA/DTGA, mass spectroscopy and pore structure analysis by nitrogen adsorption at −196 °C. A monotonic increase in crystallinity up to Mn-BOA(10.3%)/Z was shown and hence must be attributed to templating effect of manganese complex. Concurrently, the surface areas and pore volumes were decreased, suggesting that the complex remained intact within the zeolite walls. The XPS analysis of Mn-BOA(9.3%)/Z and Mn-BOA(12.3%)/Z confirm that manganese exists in the +2 oxidation state, though the latter only has a satellite feature around 646 eV which could be a result of the presence of Mn2O3. The EPR of neat complex in solution exhibited broad spectra corresponding to nearest neighbor spin-spin interactions, whereas Mn-BOA(9.1%)/Z showed well resolved metal hyperfine features as in case of the spectra in dilute frozen solutions. Theoretically bond lengths, bond angles, energies of the highest occupied (HOMO), lowest unoccupied (LUMO) molecular orbital levels, reactivity parameters and the molecular electrostatic potential (ESP) have been calculated for all samples. The catalytic activity of the synthesized samples towards benzene hydroxylation to phenol using H2O2 as a green oxidant at room temperature was evaluated. The effects of contact time, catalyst amount, and concentration of benzene and H2O2 on the conversion rate were investigated. The encapsulated complexes showed higher activities compared to that of the neat complex.

Encapsulation of ferro- and ferricyanide complexes inside ZSM-5 zeolite synthesized from rice straw: Implications for synthesis of Prussian blue pigment

Encapsulation of [Fe(CN)6]4− and [Fe(CN)6]3− complexes in the intracrystalline pores of ZSM-5 zeolite, FeIIL/Z and FeIIIL/Z respectively, by the zeolite synthesis method was reported. The modified zeolites were characterized by powder XRD, FT-IR and UV–vis spectroscopy. The nitrogen adsorption isotherms allow for the evaluation of pore structure of the complex-modified zeolites, whereas the thermal analysis (TGA/DTA) measurements provide insight into the decomposition products of the immobilized complexes. The modified zeolites exhibited smaller pore volumes and surface areas as compared with those of unpromoted ZSM-5, suggesting the inclusion of iron cyanides inside the interconnecting channels of ZSM-5. While the ferricyanide complex enhanced the formation of highly crystalline zeolite, the ferrocyanide one resulted in a lesser effect. The electronic spectra of the colloidal species developed when FeIIIL/Z brought in contact with an aqueous solution of [Fe(CN)6]3− exhibit absorptions attributed to CN− → iron charge-transfer. New bands at 294 and 319 nm due to d–d transitions of FeIII tetrahedral monomeric moieties were emitted concurrently under successive adsorption of [Fe(CN)6]aq3− over FeIIIL/Z, along with a broad band at 555 nm assigned to polymeric [FeII–C–N–FeIII] of Prussian blue (PB). The FT-IR spectra of FeIII/IIL/Z devoted to the adsorption of an aqueous solution of [Fe(CN)6]3− showed a band at 2092 cm−1 assigned to the C–N stretch in the FeII–CN–FeIII linkages. The vibrations attributable to Fe–O–Si bonding along with hydrocarbon and nitroprusside appeared only in the spectrum of FeIIIL/Z, thus was found to be strong evidence for the mutual interaction between [Fe(CN)6]3− and the latter sample.

Host (nanocavity of zeolite-Y or X)–guest (manganese (III) tetrakis[4- N-methylpyridinum]porphyrin) nanocomposite materials as efficient catalysts for biomimetic alkene epoxidation with sodium periodate: Shape-selective epoxidation of linear alkenes

Manganese (III) 5,10,15,20- tetrakis(4- N-methylpyridyl) porphyrin encapsulated into zeolite X, [Mn(TMPyP)-NaX], and zeolite Y, [Mn(TMPyP)-NaY] was synthesized through the zeolite synthesis method, in which NaX and NaY zeolites were synthesized around one cationic Mn porphyrin. The syntheses yielded pure MnP-NaX and MnP-NaY catalysts without any by-products blocking the zeolite nanopores. These heterogenized catalysts were characterized by FT-IR, UV–vis spectroscopic techniques, X-ray diffraction (XRD), neutron activation analysis (NAA) and thermal analysis. These catalysts were used for efficient and selective alkene epoxidation with NaIO 4 under mechanical stirring and under ultrasonic irradiation. These catalysts were also used for epoxidation of linear alkenes and good shape selectivity was observed.

A novel synthesis of NaA zeolite encapsulated iron(III) Schiff base complex: Photocatalytic oxidation of direct blue-1 dye with hydrogen peroxide

Abstract The complex of FeIII2[2-(hydroxy-benzeylidine)-amino]benzoic acid has been encapsulated in pores of NaA zeolite by two different synthesis procedures, namely a zeolite synthesis method in the presence of preformed iron complex (FeIIIL/Aen) and a solid–solid-type reaction (FeIIIL/Ass). The preparations were characterized by using powder XRD, mid-FTIR, Mossbauer spectroscopy, TGA/DTGA, sorption and surface texture measurements. These results have been compared with those obtained for neat complex. The carbon and iron percentages obtained by elemental analysis indicate a mononuclear structure of the complex with 1Fe:1L proportion. Analysis by Mossbauer confirmed that FeIII acquires distorted octahedral structure of the encapsulated complex, with a number of iron ions being formed as α-Fe2O3 in FeIIIL/Ass. The compatible physicochemical data of solids have indicated a better complex encapsulation for sample prepared by the zeolite synthesis method. The complex in FeIIIL/Aen serves to impart structural order to the inorganic NaA network where the integrity of the matrix was confirmed by FTIR, XRD and texture studies. The resulting host/guest compound including H2O2/UV is active system for the oxidative color removal of direct blue-1 in aqueous heterogeneous suspensions with very low catalyst/substrate ratio. The heterogenized complex especially FeIIIL/Aen is significantly more stable than the corresponding homogeneous complex over prolonged reaction time, and therefore a better catalyst than the homogeneous one.

Oxidation of α-methylstyrene on an MCM-22 encapsulated (R, R)-(−)-N, N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminocobalt(II) catalyst

Abstract(R, R)-(−)-N, N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminocobalt(II) was encapsulated into MCM-22 using the zeolite synthesis method. The encapsulated catalyst proved to be active in the oxidation of α-methylstyrene with NaOCl with higher specific activity than the homogeneous catalyst. At the same time, this encapsulated catalyst was completely inactive in the hydrolytic kinetic resolution of racemic styrene oxide. This observation is in a good correlation with the assumption of the cooperative bimetallic mechanism proposed by Annis and Jacobsen.

Zeolite Synthesis Using Degradable Structure-Directing Agents and Pore-Filling Agents

Zeolites and molecular sieves are synthesized using organic structure-directing agents (SDAs) that have the potential to be degraded into fragments within the pore space so that they can be readily extracted at mild conditions. The zeolites and molecular sieves, VPI-8, ZSM-12, and ZSM-5, are synthesized using the ketal-containing SDA, 8,8-dimethyl-1,4-dioxa-8-azoniaspiro[4,5]decane (SDA-1). As expected, solids with unidimensional pore systems (VPI-8, ZSM-12) are much more difficult to process by this methodology than solids containing multidimensional pore systems (ZSM-5). Pore-filling agents (PFAs) such as isobutylamine and cyclopentylamine are used together with the ketal-containing SDA-1 to prepare ZSM-5. Extraction of the PFA is shown to be feasible, and its removal provides space for components to enter the zeolite micropores where they react with and cleave SDA-1. Removal of the cleavage fragments from SDA-1 gives ZSM-5 that has the appropriate pore volume, framework aluminum (measured by 27Al NMR), and catalytic behavior. Reasons for desiring this new type of zeolite synthesis method are enumerated.

Biomimetical catalytic activity of iron(III) porphyrins encapsulated in the zeolite X

The approach adopted for the obtention of zeolite-encapsulated FeP led to clean syntheses of biomimetical catalyst. The catalysts were obtained through the zeolite synthesis method, where NaX zeolite was synthesised around one of the cationic FePs: iron(III) 5,10,15,20-tetrakis(4- N-methylpyridyl)porphyrin (FeP 1) or iron(III) 5-mono(2,6-dichloro-phenyl)10,15,20-tris(4- N-methylpyridyl)porphyrin (FeP 2). The syntheses yielded pure FeP 1NaX and FeP 2NaX catalysts without any by-products blocking the zeolite nanopores. FeP 1NaX and FeP 2NaX efficiently catalysed the epoxidation of ( Z)-cyclooctene by iodosylbenzene (PhIO) in DCE, giving rise to cis-epoxycyclooctane yields of 85% and 95%, respectively. Hydroxylation of adamantane shows a preferable alkane oxidation at the tertiary CH bond, indicating a hydrogen abstraction through the Fe IV(O)P ·+species in the initial step. The total adamantanol yields were 52% and 45% for FeP 1NaX and FeP 2NaX, respectively. Concerning selectivity, FeP 1NaX and FeP 2NaX gave an 1-adamantanol (Ad-1-ol)/2-adamantanol (Ad-2-ol) ratio of 20:1 and 11:1, respectively (after statistical correction). Therefore, these results indicate a free radical activation of the CH bonds of adamantane as expected for P-450 models. In the cyclohexane oxidation catalysed by FeP 1NaX in DCE, a cyclohexanol (C 6-ol) yield of 50% and an alcohol/ketone ratio of 10 was obtained. The hydroxylation occurs according to the so-called oxygen rebound mechanism, as expected for a P-450 model system. FeP 2NaX is less selective (C 6-ol yield=25% and alcohol/ketone=1.2). One possible explanation is that a Russell-type mechanism involving O 2 imprisoned within the zeolite cages may be operating parallelly, generating both C 6-ol and cyclohexanone.

Synthesis of A-type zeolite membrane using a plate heater and its formation mechanism

The synthesis of zeolite membrane using a plate heater is described. Attempts have been made to synthesize zeolite membrane either by the static method, which is a typical zeolite synthesis method, or by the circulated solution system. In both methods, the zeolite membrane was selectively formed on the substrate that was heated with a plate heater. Liquid phase solution, which was separated from the hydrogel, was found to be suitable as the starting material. In the case of the static method, A-type zeolite was mainly formed as the membrane. However, by-products such as gmelinite, chabazite and faujasite were detected with increasing crystallization period, which might be due to the shortage of secondary building units with the progress of zeolite formation. In the case of the circulated solution system, using an excess amount of the liquid phase solution, zeolite membrane crystals were formed consisting of only A-type zeolite, spherical in shape. The formation mechanism of A-type membrane is discussed according to observations by means of scanning electron microscope and X-ray diffraction analyses.

Zeolite-encapsulated manganese(III)salen complexes

Manganese(III) complexes of [ N, N′-ethylenebis(salicylidene-aminato)] (salen), [ N, N′-ethylenebis(5-chloro-salicylidene-aminato)] (Cl 2Salen), [ N, N′-ethylenebis(5-bromo-salicylidene-aminato)] (Br 2Salen) and [ N, N′-ethylenebis(5-nitro-salicylidene-aminato)] [(NO 2) 2Salen] have been encapsulated in the supercages of zeolite X by the zeolite synthesis method. The catalysts have been characterized by FTIR, UV–Vis and EPR spectroscopic techniques, XRD, SEM, thermal and elemental analysis, as well as nitrogen adsorption and cyclic voltammetric studies. The extent of encapsulation of the Mn(III)Salen complexes in zeolite X varies with the nature of the substituent group on the aromatic ring. While bromo groups enhance encapsulation, substitution with –NO 2 groups decreases the amounts of Mn(III) complexes encapsulated in the cavities of the zeolites. Cyclic voltammetric data indicate that the zeolite matrix facilitates the reduction of Mn(III) to Mn(II), suggesting that it behaves like an electron-withdrawing substituent. The aerobic oxidation of styrene to benzaldehyde, styrene oxide and phenylacetaldehyde over these catalysts is also reported.

Preparation and separation properties of silicalite composite membranes

Silicalite-alumina composite membranes were prepared by an in situ zeolite synthesis method using an alumina membrane tube with a 5-nm pore diameter, γ-alumina layer as a substrate. Single gas permeances of H 2, Ar, n-C 4H 10, i-C 4H 10, and SF 6 were measured and mixtures of H 2 i- C 4H 10 and H 2 SF 6 were separated to characterize the silicalite membrane. These measurements were made from 300 to 737 K, and are compared to an alumina membrane without a silicalite layer. Permeances were lower in the silicalite membrane (a factor of 8 for Ar at 298 K). Permeances for the alumina membrane decreased as the temperature increased, and separation selectivities were lower than values expected for Knudsen diffusion. Transport through the alumina membrane was by Knudsen flow and surface diffusion. The silicalite membrane showed dramatically different behavior, and transport appeared to be controlled by molecular size and adsorption properties. Permeances of all components studied were activated in the silicalite membrane, and activation energies ranged from 8.5 to 16.2 kJ/mol. The ratio of single gas permeances was as high as 136 for H 2 to SF 6 and 1100 for H 2 to i-C 4H 10 at 298 K. Separation selectivities at elevated temperatures were significantly above Knudsen diffusion selectivity for the silicalite membrane and were larger than ratios of pure gas permeances at the same temperature. The largest permeance ratio for the separation of mixtures was 12.8 for H 2 SF 6 at 583 K. Separation selectivities for both membranes were higher when a pressure drop was maintained across the membrane than when an inert sweep gas was used because of counter diffusion of the sweep gas.