Synthesis Of ZSM-5 Zeolite Research Articles

Synthesis of ZSM-5 zeolite and silicalite from rice husk ash

Local rice husk was precleaned and properly heat treated to produce high purity amorphous SiO2 for use in the synthesis of ZSM-5 zeolite and silicalite by hydrothermal treatment (150°C) of the precursor gels (pH 11) under autogenous pressure in a short reaction time (4–24h). A wide range of SiO2/Al2O3 molar ratios (30–2075) and a small template content were employed to fully exploit the potential of rice husk ash (RHA). The mineralogical phases, morphology, specific surface area and pore volume of the synthesized products were investigated by XRD, FT-IR, SEM and BET analyses, respectively. Under the employed conditions, it was found that the gels with a low range of SiO2/Al2O3 molar ratios (<80) produced an amorphous phase to poorly crystalline ZSM-5 zeolite; those with a medium range (80–200) favored well crystalline ZSM-5 zeolite production with a large surface area; whilst those with a high range of SiO2/Al2O3 molar ratios (>200) yielded silicalite. The increase in Na2O content, which was derived from the addition of NaAlO2 to attain the desired SiO2/Al2O3 molar ratio of the gel, did not significantly enhance the crystallization rate, crystallinity, or yield of products. On the contrary, these properties were greatly affected by the increase in the SiO2/Al2O3 molar ratio.

Application of fractional factorial design to ZSM-5 synthesis using ethanol as template

A 2 IV 4 - 1 fractional factorial design of experiments was applied to synthesis of ZSM-5 zeolite using ethanol as template. With only 16 experiments, two runs for each of the eight experiments, the following results were obtained in this study. Analysis of variance showed that the most important main effect was SiO 2/Al 2O 3 molar ratio, and the most important two-way interaction variable was the interaction of H 2O/SiO 2 and SiO 2/Al 2O 3 molar ratio. A mathematical model for ZSM-5 synthesis was derived from the experimental data and validated by residual plot analysis. An optimum gel composition, H 2O/SiO 2 = 40, SiO 2/Al 2O 3 = 60, OH −/SiO 2 = 0.15 and C 2H 5OH/SiO 2 = 1.5, was found from surface plots.

Synthesis of ZSM-5 on kaolin microspheres in the absence of an organic amine template

AbstractZeolite ZSM-5 was synthesized successfully, in situ, on pyrokaolin microspheres (PKM) under hydrothermal conditions, without the use of an organic amine template. The utility of alkali-modified pyrokaolin microspheres (AMKM) was also evaluated. The resulting products were characterized using X-ray diffraction, scanning electron microscopy (SEM) and N2-adsorption isotherm data. The material containing ZSM-5 synthesized from the system PKM-additional silica-water had a large surface area and pore volume with significant enhancements in the micropore surface area and micropore volume. The SEM images show that the synthesis of zeolite ZSM-5 from pyrokaolin microspheres (PKM) led to the formation of polycrystalline aggregates &lt;2 μm in size. The purity of the zeolite ZSM-5 produced was affected by both the pH value of the reactant system and the reaction temperature. In the system containing AMKM-additional silica-water, very little of the synthesized zeolite resided on the kaolin microspheres.

Synthesis of ZSM-5 zeolite of improved bulk and surface properties via mixed templates

Hydrothermally synthesized ZSM-5 zeolites using tetrapropyl-ammonium bromide (TPA-Br), Xylitol (Xy) and tetrapropyl-ammonium bromide + Xylitol templates; those compared with that of the parent having the same Si/Al molar ratio (64) and purchased from Mobil, were characterized with several physicochemical techniques including N2 adsorption, XRD, TG/DSC, FTIR and pyridine-FTIR. The effect of various templates on the crystallinity, crystallites size, surface properties and thermal stabilities of the produced ZSM-5 were investigated. ZSM-5 synthesized using TPA-Br + Xy; of S BET = 393 m2 g−1, exhibited a crystallinity percentage comprises of 142% when compared with that of the parent (taken at 100% crystallinity) and measured as well a crystallites size of 61 nm exceeding that derived from Xy (41 nm) that measured the lowest crystallinity percentages (71%), lowest S BET (303 m2 g−1) and highest yield (65%) between all samples. The former sample showed high thermal stability (till 1,000 °C) when compared with that derived from TPA-Br, as illustrated from TG/DSC thermograms that provided a criteria on decreasing the pore radius as a result of enclosing appreciable amounts of TPA+ and Xy inside narrow pores of ZSM-5. This sample also indicated a hydrophobic tendency when compared with that devoted from TPA-Br. Pyridine adsorption measurements showed that addition of Xy to TPA-Br stimulate the existence of basic sites in addition to acidic ones (mainly Bronsted ones) that was in the middle between that derived from Xy and TPA-Br templates. More infomations on the textural properties, morphologies, vibrational tetrahedral co-ordination T(Si or Al)–O modes and acidity were evaluated and discussed.

Synthesis of ZSM-5 zeolite from expanded perlite and its catalytic performance in FCC gasoline aromatization

A hydrothermal synthesis method for ZSM-5 preparation was investigated by using expanded perlite as the only alumina source. The effect of crystallization conditions on ZSM-5 zeolite formation, such as temperature, time, pH, chemical composition of the reaction mixture, were studied. The samples were characterized by XRD, IR, SEM, XRF and BET surface area measurements. The ZSM-5 zeolite from expanded perlite showed better catalytic activity for the FCC gasoline aromatization reaction compared to ZSM-5 prepared by the standard method.

Synthesis of ZSM-5 zeolite from rice husk ash: Characterization and implications for photocatalytic degradation catalysts

Silica synthesized from raw rise husks (white particles) through submission to consecutive chemical treatment using NaOH and HCl solutions was well incorporated with other components forming zeolites; under hydrothermal conditions, to synthesize two series of ZSM-5 (Z) of different Si/Al ratios, namely Z40 and Z80. Transition metal oxides (V, Co) were incorporated with Z samples by in situ synthesis and by impregnation. Various techniques were employed for samples characterization including XRD, FTIR, SEM, N 2 adsorption and pyridine-FTIR. The photocatalytic activity of V and Co incorporated Z zeolites in addition to neat ZSM-5 samples towards degradation of acid green (AG) dye were well investigated and compared under similar conditions. The characterization results of the catalysts indicated that Z80 measured higher surface area (616 m 2/g) and crystallites size (44.4 nm) than Z40 (536 m 2/g and 35.8 nm) besides, Z40 signifies the presence of distinct phase of silica capable of decreasing the pore radius and volume of this particular sample (22.9 Å, 0.49 cm 3/g) when compared with the former (25.3 Å, 0.623 cm 3/g). The degradation rate of Z40 was 16 times higher than Z80 in presence of UV irradiation reflecting the importance of absorbability of silica phase present on Z40 as well as acidity and decreased crystallites size. V and Co impregnated Z (VZ imp, CoZ imp) samples were found to exhibit higher and unique photocatalytic activities for AG degradation than in situ incorporated ones. CoZ80 imp exhibited the highest activity (0.14 min −1) among all samples exceeding CoZ40 imp (0.11 min −1) and VZ40 imp (0.043 min −1). The enhanced photocatalytic activity of CoZ80 imp is attributed to charge transfer excited complex between Co in Z along with AG ligand in addition to increasing the percentages of Co 3O 4 and cobalt silicate moieties over those in CoZ40 imp and to the higher surface area of CoZ80 imp, comparatively. More informations on local structures of metal oxides inside zeolites and their photocatalytic activities towards AG were deduced, correlated and discussed.

Estudo da síntese da zeólita ZSM-5 a partir de argilas naturais

The synthesis of ZSM-5 zeolite was studied by three synthesis methods: standard synthesis, three day synthesis and synthesis employing clays (kaolin and montmorillonite). The raw materials and prepared materials were characterized by Chemical Analysis by X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD). The results show that it is possible to synthesized ZSM-5 zeolite using clays as raw materials. Kaolin gives phases of higher crystalinity than montmorillonite.

Synthesis of ZSM-5 zeolite from expanded perlite/kaolin and its catalytic performance for FCC naphtha aromatization

Abstract A hydrothermal synthesis method for ZSM-5 preparation was investigated by using expanded perlite (or kaolin) as the only alumina source. The ZSM-5 zeolites from the expanded perlite (or kaolin) have a distinctive pore systems which were a combination of a medium pore ZSM-5 zeolite and a large pore matrix perlite (or kaolin). The ZSM-5 zeolites from the expanded perlite (or kaolin) showed a better catalytic activity in the FCC naphtha aromatization reaction compared with ZSM-5 obtained by a ordinary method.

05/00084 Synthesis of ZSM-5 zeolite from lignite fly ash and rice husk ash: Chareonpanich, M. et al. Fuel Processing Technology, 2004, 85, (15), 1623–1634

05/00084 Synthesis of ZSM-5 zeolite from lignite fly ash and rice husk ash: Chareonpanich, M. et al. Fuel Processing Technology, 2004, 85, (15), 1623–1634

Synthesis of ZSM-5 zeolite in fluoride media: an innovative approach to tailor both crystal size and acidity

ZSM-5 zeolites were prepared at neutral pH by fluoride-mediated synthesis. The degree of crystallinity, the specific surface area and the crystal size are higher than those of the zeolites prepared under alkaline conditions. Moreover, by varying the F/Si ratio from 0.3 to 1.6, the H–[F]–ZSM-5 zeolites with crystal size ranging from 10 to 75 μm and the specific surface areas from 60 up to 350 m 2/g were obtained. Temperature programmed desorption of pyridine was applied to characterize the zeolite acidity. A decrease of the number of Brönsted acid sites with a higher F/Si ratio in the starting synthesis solution was observed. Based on the Hammett acidity function H 0, a model has been developed to correlate the Brönsted acidity of the resulting zeolitic material with the amount of fluoride anions introduced. Thus, ZSM-5 zeolites with tailored properties both at the molecular and microscopic levels are obtained.

Synthesis of ZSM-5 zeolite from lignite fly ash and rice husk ash

The lignite fly ash from the Mae-Moh power plant, Thailand, and rice husk ash were used as raw materials for ZSM-5 zeolite synthesis. Factors affecting the yield of ZSM-5 zeolite synthesized from fly ash, i.e., the SiO 2/Al 2O 3 mole ratio, the presence of tetrapropyl ammonium bromide (TPABr, the structure-directing material for ZSM-5 zeolite synthesis), the holding temperature and time, and the initial pressure were investigated. It was found that without TPABr only zeolite P could be synthesized at SiO 2/Al 2O 3 mole ratios of 2.8–200. In order to synthesize ZSM-5 zeolite, sodium silicate solution was added to adjust the SiO 2/Al 2O 3 mole ratio in raw ash. The yield of ZSM-5 zeolite was as high as 59 wt.% when following conditions were used: SiO 2/Al 2O 3 mole ratio, 40; the holding temperature, 210 °C; the holding time, 4 h and the initial pressure, 4 bar. The catalytic performance for CO 2 hydrogenation reaction of the ZSM-5 zeolite was preliminary tested and compared with that of commercial one. It was observed that there was no significant difference in the catalytic performance between these two catalysts.

Synthesis and characterization of nano-sized zeolites

Synthesis of zeolite ZSM-5 and silicalite-1 by hydrothermal crystallization of clear supersaturated homogeneous synthesis mixture has been achieved. The influence of the templates, synthesis temperature, synthesis time and SiO2/Al2O3 ration on the properties of the nano-sized zeolite has been investigated. The properties of the samples were characterized by X-ray powder diffraction, N2 adsorption/desorption, scanning electron microscopy, and transmission electron microscopy. The results show that the temperature at 170℃ was favorable to synthesize the nano-size zeolites. The use of tetrapropylammonium hydroxide as the template in the hydrothermal synthesis conditions employed was favorable to form nanozeolite than tetramethylammonium hydroxide. The synthesis time also plan an important role. 1 day was required to obtain a fully crystallized product. The longer crystallization time would produce bigger particles. A decrease in Al2O3 content would decrease the crystallite size. The nanosize ZSM-5 and silicalite with crystallite size of 150 nm have been successfully synthesized.

Effect of aluminium source and content on the synthesis of zeolite ZSM-5 from kanemite via solid-state transformation

The effect of the incorporation of aluminium during the synthesis of zeolite ZSM-5 from kanemite via solid-state transformation was studied using X-ray powder diffraction, 29Si and 27Al NMR spectroscopy, thermal analysis and elemental analysis. During cation exchange, which takes place in highly basic media, silicate layers of kanemite give rise to the formation of silica colloids and shorter silicate layers. For Si/Al ratios ≥19, some aluminium is incorporated into the short silicate layers, however, most of the aluminium is incorporated into the Si–O–Si network during the condensation of the silica colloids in silica polymers when the pH is lowered to 8.5, independent of the aluminium source used (NaAlO2, Al2(SO4)3 or Al(NO3)3·9H2O). Mesoporous materials are synthesized from Al-containing kanemite, that is, aluminium is added during the synthesis of kanemite. The formation of silica colloids during cation exchange is the reason why, unlike the synthesis of mesoporous materials, aluminium could be added to the kanemite-template mixture during cation exchange. The highest amount of incorporated aluminium was obtained using NaAlO2 because it is the aluminium source for which the pH is highest during cation exchange and consequently it is the aluminium source which yields the highest amount of silica colloid precipitates during the adjustment of the pH to 8.5.

ZSM-5 zeolite synthesis in the presence of a copper-phthalocyanine complex characterization by ESR and 129Xe NMR

In the presence of a copper phthalocyanine complex (CuPc), it is possible to synthesize ZSM-5 zeolite containing the complex, and the crystallinity is good, provided that the amount of CuPc trapped is lower than the number of channel intersections where it can be located without too much distortion. The crystallinity is retained after decomposition of the CuPc in a stream of air at 500 °C. The copper-ZSM-5 system is characterized by the combined application of xenon adsorption, ESR and 129Xe NMR spectroscopy.

Aromatization ofn-butane over Ni-ZSM-5 and Cu-ZSM-5 zeolite catalysts prepared by using Ni and Cu impregnated silica, fiber

The reaction ofn-butane aromatization was carried out over Ni-ZSM-5 and Cu-ZSM-5 zeolite catalysts prepared by using Ni and Cu impregnated silica fiber during the process of ZSM-5 zeolite synthesis. The catalysts prepared were characterized by X-ray powder diffraction, nitrogen adsorption and X-ray fluorescency. The acidic properties of the catalysts were investigated by temperature-programmed desorption of ammonia using a mass spectrometer equipped with a QTMD detector. The effect of catalyst pretreatment, reaction temperature, and time on stream on the reaction ofn-butane to aromatic hydrocarbons were investigated. The modification of ZSM-5 by Ni and Cu increased the selectivity to aromatic hydrocarbons. The state of Ni and Cu and their stabilization in the ZSM-5 structure was highly influenced by the mode of catalyst pretreatments.

Synthesis of stable suspensions of discrete colloidal zeolite (Na, TPA)ZSM-5 crystals

Synthesis of zeolite ZSM-5 in the form of stable suspensions of colloidal crystals from clear homogeneous solutions has been achieved from synthesis mixtures with low sodium and high TPAOH concentrations. The ultimate size of the discrete crystals is in the range 130–230 nm with a narrow particle size distribution. The crystal growth was monitored by the direct method of dynamic light scattering. An increasing alumina concentration was found to decrease the crystal growth rate, the number of crystals produced, and the ZSM-5 yield. The final crystal size was found to increase with increasing alumina concentration in the synthesis solution. The number of crystals produced decreased with an increased alkalinity in contradiction to what has been found for colloidal TPA-silicalite-1. This together with the presence of the two competing processes, crystal growth and crystal dissolution, which are both catalyzed by hydroxide ions, suggests the presence of an optimum alkalinity (depending on the alumina concentration).

Synthesis of ZSM-5 zeolite with small crystal size and its catalytic performance for ethylene oligomerization

ZSM-5 zeolites of SiO2Al2O3 = 25 with a small crystal size were synthesized under various conditions in order to clarify a relationship between external surface area and catalytic performance, especially lifetime, for the oligomerization of ethylene to higher hydrocarbons of the gasoline range. The measurement of the external surface area, XRD patterns, and FTi.r. spectra of the resulting ZSM-5 zeolites suggested that their crystal grains were very fine. The shapes and sizes of the primary grains of the ZSM-5 zeolites were observed by means of a scanning electron microscopy with a magnification of 300,000. The crystal sizes were in the range of 30–50 nm. In the oligomerization of ethylene, a proton-type zeolite that was synthesized under a high molar ratio of OHSiO2 showed both high ethylene conversion and high gasoline range selectivity for three times longer on-stream time than those of other zeolites. The external surface area of the zeolite was also three times greater than those of other zeolites, which indicated that the lifetime of ZSM-5 zeolite in the oligomerization of ethylene depended on the external surface area or crystal size.

The investigations on the synthesis of zeolite ZSM-5 with the use of ethylenediamine as a templating agent

The effect of the chemical composition of the reacting mixture (RM),aswell as of time and temperature of crystallization, on the synthesis of zeolite ZSM-5 was investigated. Ethylenediamine (ED) served as a templating agent. The crystallization was conducted at 180-120°C for 1–20 d. The quantitative estimation of the phase composition was made on the ground of X-ray diffraction measurements. Zeolite ZSM-5 (max. purity 96%), contaminated with quartz, mordenite, and an amorphous phase, was obtained.

Synthesis of ZSM-5 zeolite from very dense systems: Formation of pelleted ZSM-5 zeolite from (Na, Li, TPA, Si, Al) hydrogels

(Li,Na)-, Na-, and (Na,K)ZSM-5 zeolites are readily prepared in hydrothermal conditions at 170 + 2 °C from highly dense gels of compositions aM2O bNa2O 2bTPABr bAl2O3 150 SiO2 490 H2O with M = Li, Na, or K; 0.9 ⩽ a ⩽ 8.82 and 1.66 ⩽ b 15. In a quite narrow domain of composition, (Li,Na)ZSM-5 self-bonded pellets are formed from the same hydrogel with 8 ⩽ a ⩽ 9 and 14 ⩽ b ⩽ 16. The ca. 4 μm ZSM-5 crystallites are embedded in the remaining amorphous gel formed essentially by LiAlO2. The self-bonded pellets are also tested for attrition, pore-size distribution, and catalytic activity.

Synthesis of highly siliceous ZSM-5 using diaminoalkanes as templates

A series of α,ω-diaminoalkanes, in which the alkane chain contained from 2 to 8 carbon atoms, was investigated regarding the suitability of these organic directing compounds in the synthesis of zeolite ZSM-5 having a silica-to-alumina mole ratio of around 250:1. For ZSM-5 with this composition, 1,6-diaminohexane was found to be the most satisfactory compound. Unfortunately, the product obtained is prone to include some unwanted zeolite ZSM-48, and synthesis conditions to minimise the formation of this material were identified. Nevertheless, from the conversion of methanol, the resulting ZSM-5 catalyst was still found to be capable of producing good light alkene selectivities of around 65%.