Zeolite Products Research Articles

Charge distribution and conformational stability effects of organic structure-directing agents on zeolite synthesis.

While the use of the so-called organic structure-directing agents (OSDAs) is no stranger to zeolite synthesis at all, the effects of their charge distribution and conformational stability on the phase selectivity of the crystallization remain elusive. To systematically investigate these effects, we have prepared a series of imidazolium and pyrazolium derivatives with the same geometric shape but different positions of nitrogen atoms in the five-membered heterocyclic aromatic ring and used them as OSDAs for the synthesis of zeolites with pure-silica composition. Meaningful differences in the zeolite product were observed.

Microwave digestion and alkali fusion assisted hydrothermal synthesis of zeolite from coal fly ash for enhanced adsorption of Cd(II) in aqueous solution

A novel microwave digestion and alkali fusion assisted hydrothermal method was proposed to synthesize zeolite from coal fly ash and the zeolite product was studied for removal of Cd(II) from aqueous solution through batch experiments. The adsorbent was characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, surface area analyzer and zeta potential measurement. The results show that the synthetic zeolite was identified as faujasite. The optimum conditions for removal of Cd(II) are found to be: adsorbent dose of 0.5 g/L, pH 6, contact time of 90 min and initial concentration of 20 mg/L, the removal rate of Cd(II) is 98.55%. The experimental kinetic data agree well with the pseudo second-order equation; the Langmuir isotherm model is found to be more suitable to explicate the experimental equilibrium isotherm results than Freundlich, Dubinin-Radushkevich and Temkin models, and the maximum adsorption capacity of Cd(II) is found to be 86.96 mg/g. The thermodynamic parameters such as ΔGΘ, ΔHΘ and ΔSΘ were evaluated and the results show that the adsorption of Cd(II) onto the as-synthesized zeolite is spontaneous, endothermic and feasible under studied conditions.

VARIABLE FACTORS CONTROLLING AMORPHOUS-ZEOLITE PHASE TRANSFORMATION IN METAKAOLIN BASED GEOPOLYMER

Metakaolin based geopolymer binder was synthesized using variable factors such as Na2O/SiO2, Na2O/Al2O3 and H2O/Na2O molar ratios as well as curing time. Metakaolin was used as an alumino silicate source incorporating with strong alkali activators; sodium hydroxide solution to undergo polycondenation and hence a formation of hardened geopolymeric binder. This work was aimed to investigate the effect of Na2O/SiO2, Na2O/Al2O3 and H2O/Na2O ratios, as well as curing time on phase transformation. The chemical composition, phase development and microstructure of reaction products were examined by X-ray fluorescence, X-ray diffraction analysis and scanning electron microscopy with respect to their final compressive strength. Increasing the molar ratios of Na2O/Al2O3 and H2O/Na2O tended to favour the transformation of amorphous gel to various types of crystalline zeolite. Sodalite (pseudo-phase zeolite) and zeolite belonging to the Faujasite group, as well as zeolite X and A were identified in these mixtures. Based on this study, systems that favoured the formation of zeolitic products tended to possess lower strengths.

Fly ash-derived MCM-41 as a low-cost silica support for polyethyleneimine in post-combustion CO2 capture

The mesoporous silicate molecular sieve, MCM-41, has been synthesized from pulverized coal fly ash (PFA), where the silicate filtrate used is a by-product from hydrothermal zeolite production. Rice husk ash was also used for comparison but fusion with sodium hydroxide was used to prepare the silicate filtrate, along similar lines to earlier reports of using PFA as a precursor for MCM-41 synthesis. The MCM-41 samples are chemically and mineralogically similar to a commercially available sample, but with higher pore volumes dominated by mesopores (0.92–1.13 cf. 0.88 cm3 g−1). After polyethyleneimine (PEI) impregnation for CO2 capture, the ash derived MCM-41 samples displayed higher uptakes than the commercial sample with the maximum achievable PEI loading of 60 Wt.% PEI (dry basis) before particle agglomeration occurs, approximately 13 compared to 11 Wt.%, respectively, the latter being comparable to earlier reports in the literature. The PFA sample that displays the fastest kinetics to achieve 90% of the equilibrium uptake had the largest mesopore volume of 1.13 cm3 g−1. Given the PFA-derived MCM-41 uses a waste silicate solution for hydrothermal preparation and no prior preparation is needed, production costs are estimated to be considerable lower where silicate solutions need to be prepared by base treatment, even if ash is used, as for the RHA derived MCM-41 used here.

Removal of Ammonia from Aqueous Solutions, Ground Water, and Wastewater Using Mechanically Activated Clinoptilolite and Synthetic Zeolite-A: Kinetic and Equilibrium Studies

Natural zeolite clinoptilolite and synthetic zeolite Na-A were characterized using XRD and SEM to be used as adsorbents for ammonia from aqueous solutions, ground water, and sewage water. Clinoptilolite was mechanically activated for 2, 4, 6, and 8 h to study the effect of activation in enhancing the adsorption capacity. The adsorption by activated natural zeolite and synthetic zeolite is high pH dependent and achieve the best values at pH = 7. The adsorption capacity of activated natural zeolite increases with increasing the activation from 2 to 8 h achieving removal percentage close to that obtained using synthetic zeolite. The equilibrium was obtained after 60 min for synthetic zeolite and all the activated natural zeolite (except 2-h-activated product, the equilibrium was achieved after 30 min). The kinetic studies reflected the high fitness of the adsorption results of activated natural zeolite products and synthetic zeolite with pseudo-second-order model rather than the other kinetic models. The obtained isotherms reflected the formation of S-type isotherm curve for the adsorption using mechanically activated clinoptilolite and L-type curve for the uptake using synthetic zeolite. The results represented well with Langmuir model followed by Temkin and Freundlich model for adsorption using synthetic zeolite. The uptake using mechanically activated clinoptilolite can be represented by Temkin model rather than both Langmuir and Freundlich models. Thermodynamic parameters indicate spontaneous endothermic adsorption of ammonia using all the zeolitic products under investigation. Finally, the mechanically activated natural zeolite and synthetic zeolite exhibit high efficiency in the removal of ammonia and other water pollutants from ground water and sewage water.

A facile synthesis of mordenite zeolite nanostructures for efficient bleaching of crude soybean oil and removal of methylene blue dye from aqueous media

In the current investigation, we have reported on the preparation of mordenite zeolite nanostructures using a low-cost hydrothermal treatment of silica gel, aluminum nitrate, and sodium hydroxide. The influence of organic templates such as ethylene glycol, glycerol, and polyethylene glycol 200 (PEG 200) on the zeolite products was studied. The crystallite sizes of the as-fabricated samples increased in the following order: (PEG 200)<(ethylene glycol)<(glycerol)<(without template). The PEG 200 organic template generated a mordenite product with 57.51nm crystallite size and 28.26m2/g BET surface area. The as-prepared products were identified using FE-SEM, FT-IR, XRD, HR-TEM, and BET analysis. The as-prepared mordenite product could be successfully applied to purify the crude soybean oil from the yellow and red colors. The mordenite product also showed good adsorption properties toward the removal of methylene blue (MB) dye from wastewater. Kinetic data exhibited that the dye adsorption process obeyed pseudo-first-order, intra-particle diffusion, liquid film diffusion, and pore diffusion models whereas the rate determining step of the adsorption is only controlled by the pore diffusion model. Adsorption data fitted well both Langmuir and Dubinin–Radushkevich (D–R) isotherm models. Moreover, the adsorption is a physisorption and exothermic process.

Synthesis of zeolite A using sewage sludge ash for application in warm mix asphalt

Conventional landfill disposal of Sewage Sludge Ash (SSA) generates increasing environmental and economic concerns. This study aims to develop an innovative measure to solve this waste disposal problem by means of synthesizing zeolite A from the SSA and using it as a Warm Mix Asphalt (WMA) additive, which can decrease the construction temperature of asphalt pavement, thus reducing the associated energy consumption and pollutant emission. Alkaline fusion followed by hydrothermal reaction was implemented to synthesize zeolite A from the SSA. The orthogonal experimental design was carried out to optimize the synthesis conditions. The synthetic products were characterized using a Thermogravimetry-Differential Thermal Analyzer (TG-DTA), an X-ray Diffractometer (XRD) and a Scanning Electron Microscope (SEM). The zeolite product synthesized under the optimized conditions showed a desirable thermal property of gradual release of crystalline water up to 18.5% when heated to 200 °C. Its XRD spectrum validated the presence of zeolite A with high purity. The SSA-derived zeolite A was then used as a WMA additive to produce asphalt mixture at lower construction temperatures, which proved to reduce the construction temperatures of asphalt mixture by 25 °C. The approach to use SSA-derived zeolite can decline the environmental and economic burden and it can be a cleaner production method of WMA additive for environmental benefits.

Conversion of Coal Fly Ash into Zeolite Materials: Synthesis and Characterizations, Process Design, and Its Cost-Benefit Analysis

In this work, coal fly ash (CFA) – a byproduct of coal combustion, has been successfully converted into a value-added product— zeolite. This study focuses on the production of the Na-A zeolite phase via the fusion method. The effects of fusion reaction temperature, hydrothermal reaction temperature, reaction time, and the concentration of alkaline were investigated. The synthesized products were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) and studied for their purity and yield. A fusion temperature of 550 °C, fusion duration of 1.5 h, and a subsequent hydrothermal temperature of 100 °C for a reaction of 12 h were found to be the optimal conditions. Based on the synthesis conditions found, an up-scale production process was designed and simulated with aid from the Aspen Plus program. It was found that zeolite production via the fusion method obtained high profitability. For a 5000 kg/h coal fly ash feed, a payback period of 7.1 years is feasible over a 20-year ope...

A Novel Synthesis Method of Zeolite X From Coal Fly Ash: Alkaline Fusion Followed by Ultrasonic-Assisted Synthesis Method

This study was focused on synthesis of zeolite X from coal fly ash using the alkaline fusion method coupled with a novel method which uses ultrasonic energy for aging step. Optimum conditions were investigated using the Taguchi experimental design method. Synthesized zeolitic products were characterized by X-ray diffractometry, scanning electron microscopy, surface area, and cation exchange capacity analysis. Aging time was reduced from 24 to 2 h with usage of ultrasonic energy. Due to high surface area and similar crystal and morphological properties of the final products, we propose that the synthesized zeolitic products can serve as commercially competitive available material.

Zeolite as Nanomaterial for Water Treatment in a Production Exploitation

A new technologies and materials stand at front of thescientific interest. Their development leads to technological potential increasing at various fields of industry.Progressive new materials are based on the development of nanotechnologies and nanomaterials, which have a widerange of the applications in manufacturing, medicine and the environment protection. There sult of the hugeefforts in the development of nanostructured materials, the amount of new material sthat are the building blocks of nanoparticles with defineds tructures and properties. Progress in the use of nanotechnologies and nanomaterials has been noticed in the area of water protection, because they develop a modern, economically viable and environmentally more acceptable sewage processes and materials. At this sphere new zeolite products are developing with modified external surface.

Insights into the Organotemplate-Free Synthesis of Zeolite Catalysts

Abstract As the most important nanoporous material, zeolites, which have intricate micropores, are essential heterogeneous catalysts in industrial processes. Zeolites are generally synthesized with organic templates under hydrothermal conditions; however, this method is environmentally unfriendly and costly due to the formation of harmful gases and polluted water. This article briefly summarizes the role of organic templates and describes designed routes for the organotemplate-free synthesis of zeolites, aided by zeolite seeds and zeolite seeds solution. Furthermore, this review explicates that the micropore volume decreases with an increase of the Si/Al ratios in the organotemplate-free synthesis of zeolite products, where Na + exists as an alkali cation. This feature is very important in directing the synthesis of zeolite catalysts with controllable Si/Al ratios under organotemplate-free conditions, and is thus important for the efficient design of zeolites.

Hydrothermal tuning of the morphology and crystallite size of zeolite nanostructures for simultaneous adsorption and photocatalytic degradation of methylene blue dye

We herein have reported on tuning of the morphology and crystallite size of the hydrothermally prepared zeolite nanostructures by using different aluminum sources. The investigation revealed that aluminum sulfate and aluminum chloride precursors produced non-crystalline forms, while aluminum isopropoxide, alumina, and aluminum metal precursors generated analcime nanoparticles with crystallite size of ca. 94.79, 112.57, and 105.87nm, respectively. However, sodium aluminate precursor gave a mixture of analcime and nacrite phases with a crystallite size of ca. 77.95nm. The as-prepared nanostructures were identified using XRD, FT-IR, FE-SEM, EDS, UV–Vis spectroscopy and BET surface area. The results exhibited that the direct optical energy gaps (Eg) and BET surface area were found to be (3.29eV and 20.18m2/g), (3.15eV and 16.28m2/g), (3.21eV and 18.67m2/g), and (2.69eV and 17.82m2/g) for the zeolite products prepared using aluminum isopropoxide, sodium aluminate, alumina, and aluminum metal precursors, respectively. The results also showed that the as-prepared zeolite nanostructures could be simultaneously used as adsorbents and photocatalysts for the removal of methylene blue (MB) dye from aqueous solutions. The adsorption of methylene blue dye over the zeolite adsorbents obeys pseudo-second-order model and intra-particle diffusion model. Interestingly, zeolite photocatalyst prepared using aluminum isopropoxide degraded the MB dye with percentage of 85% and 100% within 180 and 110min in the presence of UV and (UV+H2O2), respectively. The degradation processes followed the pseudo-first-order model. The prepared zeolites are proposed as promising candidates for the removal of MB from aqueous media.

Direct Synthesis of Zeolites from a Natural Clay, Attapulgite

Presently, chemical Si/Al sources are predominantly used as raw materials for the synthesis of zeolites in spite of their high cost. Here, we report for the first time the direct synthesis of a ZSM-5 zeolite by using a natural clay, attapulgite (ATP), as the low-cost and environmentally benign Si/Al source through a vapor-induced transformation (VIT) method, in which the vapor diffuses into ATP and interacts with the framework. In a crystallization recipe, ATP is well present with a pristine crystal structure, and the yield of zeolite reaches 96%. The resultant zeolite exhibits well-defined crystallinity and porosity, which are comparable to the counterpart synthesized from traditional chemical Si/Al sources. In the synthetic process, the formation of Si–F species plays an important role, which promotes the transformation of an ATP crystal to a zeolite crystal. Meanwhile, the metal elements (e.g., Al, Fe, and Mg) of ATP exist in the zeolite products, and at least part of them are located in the zeolite fr...

Control of Natural Zeolite Properties by Mechanical Activation in Stirred Media Mill

AbstractDue to the special characteristics of zeolites, they can be applied in a very wide range of industries, i.e. agricultural, environmental or water treatment purposes. Generally, high added value zeolite products are manufactured by micro- or nanogrinding. However, these processes require high energy input and cause significant wearing of the mill parts. Therefore, the optimization of zeolite grinding, as well as the control of its properties are of a great importance. In the present paper a Hungarian natural zeolite was mechanically activated in stirred media mill for various residence times in distilled water, meanwhile the particle size distribution and the grinding energy were measured. Additionally, on-line tube rheometer was used to study the rheology of the suspension during the grinding process. The particle interaction and the suspension aggregation stability were detected by zeta-potential measurements. Structural changes due to the mechanical activation process were monitored by FTIR. It was found that the material structure of the zeolite, as well as the rheological behaviour of the zeolite suspension and its aggregation stability had been altered due to the mechanical activation in the stirred media mill. It can be concluded that the zeolite product properties can be modified by mechanical activation in order to produce a high added value tailored material.

One-pot synthesis of Ni-SSZ-13 zeolite using a nickel-amine complex as an efficient organic template

We show that a nickel-amine complex (nickel-diethylenetriamine, Ni-DETA) is an efficient organic template for the one-pot synthesis of Ni-SSZ-13 zeolite. The effects of the reaction compositions, including the molar ratios of SiO2/Al2O3, H2O/Al2O3, Ni-DETA/Al2O3, and Na2O/Al2O3, on the synthesis of the pure product were investigated using different temperatures and synthesis times. Physicochemical characterizations, including XRD, SEM, and 27Al NMR, show that the zeolitic product has good crystallinity, uniform crystals, and contains a tetrahedral Al3+ species. The N2 sorption isotherms, TG–DTA curves, IR spectra, and UV–Vis spectra show that Ni-DETA acts as a template in the product obtained. Interestingly, Ni-SSZ-13 zeolite is obtained by the conversion of Ni-Y zeolite produced in the crystallization process.

Fast synthesis of ZSM-22 zeolite by the seed-assisted method of crystallization with methanol

This is a study of the fast synthesis of ZSM-22 zeolite using crystallization seeds and a cheap source of silica. The effect of crystallization time, addition of methanol as organic solvent, SiO2/Al2O3 ratio (SAR), alkalinity (OH−/SiO2 ratio), addition of potassium cation, and agitation were studied on the properties of the produced zeolite. Syntheses were performed at 170 °C with a fixed seed:SiO2 mass ratio of 10%. The seeds were synthesized by the hydrothermal method at 160 °C in the presence of 1,6-diaminohexane organic template. Products were characterized using X-ray diffraction, thermal analysis, nitrogen adsorption at −196 °C, and scanning electron microscopy. Under static conditions the best result was reached after 6 h of crystallization, obtaining a ZSM-22 with 80% crystallinity, in the presence of methanol, low alkalinity, without addition of K+ and SAR 100. The synthesis of ZSM-22 with SAR 50 using the same method resulted in a slightly lower crystallinity than with SAR 100. The increase in alkalinity or potassium concentration in the synthesis reaction medium decreased the crystallinity of the zeolite. Synthesis with the same composition under agitated condition increased the crystallinity and specific surface area of the zeolite and decreased reaction time from 6 to 4 h. The fastest synthesis was obtained under agitation with low methanol content in the reaction medium, obtaining the ZSM-22 structure after 3 h of reaction with higher crystallinity and surface area. The importance of fast synthesis is to reduce the cost of the zeolite production.

Synthesis of hierarchical ZSM-5 zeolites by solid-state crystallization and their catalytic properties

Hierarchically porous structure is important to promote mass transport and active site utilization of zeolites for many petrochemical reactions involving bulky molecules. Their conventional hydrothermal synthesis with meso-template materials is often complicated and expensive, and produces a large amount of aqueous pollute. We demonstrate here successful synthesis of mesoporous zeolites of MFI structure by solid-state crystallization without meso-template. Aluminosilicate nanogels are produced with only precursors and the dried nanoparticles are then transformed into nanocrystals in solid state using only their intrinsic water storage. After orientating with each other at edges, these nanocrystals join into monolithic zeolites with connecting inter-lattice mesopores. The produced hierarchical ZSM-5 zeolites exhibit superior stability and excellent catalytic performance in reactions such as Friedel-Crafts benzylation, lignin ethanolysis, and naphthalene hydrogenation. Compared with conventional synthesis routes, this new solid crystallization approach simplifies zeolite production, lowers the cost, and avoids toxic liquid waste, which may greatly benefit many energy applications.

7-11.加圧型ニーダーを用いた人工ゼオライト製造パイロットプラントの開発((3)環境対策,Session 7 環境対策・リサイクル)

7-11.加圧型ニーダーを用いた人工ゼオライト製造パイロットプラントの開発((3)環境対策,Session 7 環境対策・リサイクル)

Solvent‐Free Synthesis of ITQ‐12, ITQ‐13, and ITQ‐17 Zeolites

AbstractDevelopment of the sustainable routes for synthesis of ITQ‐family zeolites is very important because of their unique structures and excellent catalytic and adsorptive properties. The burden of costly raw materials and low efficiency of synthesis put a strong challenge for their widespread commercial application. Here, we show an alternative and simple route for synthesis of ITQ‐12, ITQ‐13, and ITQ‐17 zeolites using commercially available organic templates by a facile grinding process of anhydrous starting raw solids, followed by heating at 140—180 °C. Compared with the conventional hydrothermal synthesis, this approach has obvious advantages such as employment of low‐cost organic templates with very high effectiveness, high yield of zeolite products, short crystallization time, and relatively simple procedures. This methodology might open a pathway to synthesize ITQ zeolites with more sustainable manner.

Sustainable utilization of rice husk ash from power plants: A review

To move towards sustainability, finding sustainable ways of using rice husk ash for a large rice producing country like Thailand is essential. This review seeks to find sustainability characteristics of the uses of rice husk ash from power plants. It also reviews how rice husk ash is produced from different power generation technologies. Characteristics of rice husk ash are affected by different factors such as sources, preparation methods and combustion technologies. Different forms of rice husk ash, amorphous and crystalline, suit different applications. Ash from moving grate technology is suggested for use as adsorbent while that from fluidized bed is suggested for use as filler in polymeric composites and in the synthesis of innovative ceramic compounds. The ash from suspension fired technology is suggested for use in the construction industry and zeolite production. In addition to technical viability, using rice husk ash to substitute conventional products helps gain both environmental and economic benefits. Despite claiming sustainable applications of rice husk ash, many research papers report only technical performances of the products. This paper draws out sustainability characteristics of different rice husk ash applications using the “triple bottom line” framework. Potential reduction of greenhouse gas emissions, cost saving and employment generation of rice husk ash use options have been investigated. Results from the review suggest that using the ash to replace charcoal is the most sustainable option when comparing with other alternatives such as Portland cement, commercial silica and lime. This option could help to reduce GHG up to 1005 kg CO2eq/t product, to save cost up to 8000 THB/t product, as well as to help generate employment for about 5 person-years/M THB spent in the sector. However, to make the sustainability assessment more comprehensive, other sustainability indicators such as fossil fuel depletion, human toxicity, ecotoxicity, particulate matter formation, total net profit (TNP), total value added (TVA), and incomes of workers are also needed to be considered in future research.