Zeolite Composites Research Articles

Synthesis of zeolites using kaolin in concentrated sodium hydroxide-aluminate solutions

The synthesis of zeolites through the hydrothermal treatment of kaolin presents a cost-effective and sustainable method of production, however, the phases which remain stable in concentrated alkali solution with elevated NaAl(OH)4 are unclear. This study evaluated the equilibrium precipitation behaviour of zeolites from kaolin under a range of NaOH and NaAl(OH)4 concentrations at 523 K. The precipitates contained three types of low-silica (1:1 Si:Al) zeolites: zeolite JBW, two polymorphs of cancrinite (hydroxy- and aluminate-), and (hydroxy-)sodalite, as well as a novel sodium aluminate-intercalated nepheline-carnegieite phase at concentrated alkali-aluminate conditions. The construction of a phase diagram revealed distinct regions of stability and transition zones between phases through changing NaOH and NaAl(OH)4 concentration. The kaolin-to-zeolite phase transformation at early reaction time and Bayer pre-desilication conditions supported the phase transformation series: kaolinite → solution silicate species → aluminate-cancrinite → sodalite or cancrinite or a mixture. Substitution of caged aluminate [Al(OH)4−] for hydroxide [(OH)−] within zeolites was modelled, and revealed distinct deviation from ideal zeolite composition when starting molar Al2O3:SiO2 ≫ 1. As direct kaolin-to-zeolite technology emerges as a low-cost and low-energy alternative to conventional zeolite production, there will only be continued interest in its use in the future.

Zeolitized fossil woods from alkaline volcaniclastic rocks: Unravelling an uncommon mineralization process

Mineralization of fossil woods with unusual mineral phases remains an underconstrained process despite its relatively common occurrences. Aside from common mineralization agents such as silica or carbonates, there are also atypical mineralization associations, such as zeolite-group phases, but the zeolitization process has not yet been investigated in detail. We studied zeolitized woods collected from two localities in the Cenozoic alkaline České Středohoří Volcanic Complex (Ohře Rift, Czech Republic), where fossil woods of diverse paleobotanical classification were deposited in volcaniclastic rocks of the same origin (lahar) and stratigraphic formation (Upper Oligocene). The identical geological setting allowed the investigation of potential variables influencing this type of mineralization by combining paleobotanical classification, detailed mineralogy, mineral chemistry, geochemistry, Sr isotope analysis and KAr chronology.The new results demonstrate the significant potential of fossil woods mineralized with zeolite-group minerals to be used to reconstruct the formation and deposition conditions of the lahars in which these woods are contained. The composition of zeolites is strongly dependent on thermal conditions and material exchange between wood and host rocks. Dominant mineral phases are phillipsite and chabazite in variable proportions. The phillipsite/chabazite ratio correlates well with the magnitude of the Eu anomaly, suggesting crystallization of phillipsite at a higher temperature under hot-lahar conditions of deposition. Chabazite lacking an Eu anomaly represents the later, colder mineralization stage. The 87Sr/86Sr ratios ranging 0.7042–0.7047 provide an additional line of evidence of fluid derivation from volcaniclastic deposits of the Upper Oligocene Děčín Fm.

Fluidisation of Thermochemical Energy Storage Materials: Degradation Assessment

ABSTRACT Composite zeolites impregnated with anhydrous salt particles are promising materials for use in domestic thermochemical energy storage (TCES), however they have limited power output. Fluidization has the potential to increase the mass and heat transfer of TCES systems. In this study, a composite TCES material of LiX zeolite impregnated with MgCl2 salt is produced. This material and a LiX zeolite batch are then fluidized at different gas velocities to study whether degradation of these particles occurs when fluidizing. Images of the particles after fluidizing are analyzed using a validated method utilizing microscope images and specialized software used to study whether fragmentation or abrasion have been induced by fluidization. Composite particles were found to have increased average diameter by 7%−8%, which could be due to imperfect dehydration of these particles after the impregnation process, but also due to observed salt conglomerates present on the surface of some particles. Overall, excess degradation was not found due to fluidization at any gas velocity. No mass loss was measured in any sample after fluidization, and no appreciable fragmentation was observed. The LiX zeolite and composite particles measured 0.6192 mm and 0.6799 mm prior to fluidization and measured 0.6405 mm and 0.7088 mm after fluidization. However, this change is not statistically significant, and it is shown that a change in diameter is unlikely. Despite this, some fines have been produced which were found to have an average diameter of 3.60 μm (σ = 1, ±2.34 μm), and as such present a hazard if inhaled.

Effect of organic/inorganic composites as soil amendments on the biomass productivity and root architecture of spring wheat and rapeseed

Organic and inorganic soil amendments are used to increase crop yields and fertilizer efficiency, as well as to improve the physical and biological properties of soil, increase carbon sequestration, and restore contaminated and saline soils. The present study aimed to evaluate the effect of various zeolite composites mixed with either lignite or leonardite on the biomass production of spring wheat and rapeseed and their root morphology. A pot experiment involved the application of the following treatments: zeolite-carbon, zeolite-vermiculite composites, both mixed with lignite or leonardite, and a control treatment with no amendments. Inorganic composites were applied in a dose of 3% and 6%. The study also included an analysis of the root morphometric parameters and aboveground biomass of spring wheat and rapeseed. The lowest productivity was observed when both crops were not enriched with fertilizers or other amendments, 24.92 g per pot and 29.83 g per pot for spring wheat and rapeseed, respectively. The application of mineral fertilizers in combination with zeolite-carbon composite gave the highest aboveground biomass of spring wheat, 110.11 g per pot. Both zeolite-carbon and zeolite-vermiculite composites modified the morphological parameters of roots, with the control treatment showing the lowest root length and dry matter. Although mineral fertilization was found to have a positive impact root development in relation to untreated control, the treatment amended with zeolite-carbon composite and leonardite exhibited the highest root length and biomass of spring wheat. No other soil amendments improved the properties of rapeseed roots.

Preparation of Photoactive TiO2/LTA Zeolite Composites by Solution Technology in Hydrothermal Conditions

Preparation of Photoactive TiO2/LTA Zeolite Composites by Solution Technology in Hydrothermal Conditions

Green Zeolite Synthesis Assisted with Plants Extract

The study explores the hydrothermal synthesis of zeolite using kaolin clay from Perak in the presence of two different reduction mediums, namely turmeric extract and ginger extract, and a 2M NaOH solution, measuring their efficiency and potential for green synthesis. Before the zeolite synthesis and transformation, the kaolin clay was heated at a temperature of 650 oC for 4 hours in the furnace to produce the metakaolin phase. The synthesized zeolite involves the reaction of NaOH with potential reduction plant extracts to assist the transformation of zeolite. The characterization of the synthesized particles after being ground into a fine powder and subsequently undergoing testing and characterization via X-ray diffraction (XRD) revealed the existence of zeolite phases in both plants with slightly different zeolite compositions. Synthesis mixtures with turmeric plants show better composition of the zeolite phase as compared to ginger mixtures. Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Analysis (EDX) also revealed that the synthesized product using turmeric plant extract was able to produce zeolite LTA with a good grade. The current experimental work shows the possibility of obtaining a well crystalline zeolite from Malaysian kaolin, assisted with plant extract reduction medium.

Zeolite Integrate with Natural Absorbance to Increase Crop Production

Mesoporous structure of Zeolites particles with higher micropores able to provide higher surface area that able to increase the efficiency of diffusion mechnism as well as cation exchange capacity (CEC). Theuniquness and unreactive properties of zeolites enable to integrate this materials with other potential material to increase the zeolite absorption and CEC performance. Thus, the goal of this work is to study the effect of natural absorbents(chitosan and charcoal) when integrate with zeolite that function as a soil enhancer for the plants growth. Several experiments at different composition of soil, fertilizer, zeolite and absorbance compositions towards water spinach growth, pH and soil humidity were measured. The results of the plant growth show that both natural absorbance materials significantly assist the nutrient uptake either from the soil or fertilizer by showing higher plant growth, pH and humidity values as compared to soil mixedwith fertilizeronly. Integration of these absorbance with zeolite futher increase the capability of nutrient uptake by giving the highest value of plant growth, pH and humidity values. Detail observation also showed that water spinach grew faster in the sample that had fertilizer added to the zeolite with charcoal as compared to chitosanKeywords:Zeolites, natural absorbance, charcoal, chitosan, pH, humidity, plant growth

CO2-Induced Gate-Opening Adsorption on a Chabazite/Phillipsite Composite Zeolite Transformed from a Faujasite Zeolite Using Organic Structure-Directing Agent-Free Steam-Assisted Conversion.

Organic structure-directing agent-free steam-assisted conversion and Cs+ ion exchange were used to transform the faujasite (FAU)-type zeolite to the Cs+-type chabazite/phillipsite (CHA/PHI) composite zeolite. Compared with the pure PHI-type zeolite, the Cs+-type CHA/PHI zeolite showed gate-opening CO2 adsorption behavior and good thermal stability. In situ powder X-ray diffraction (PXRD) of the CO2 adsorption was measured to elucidate the mechanism for the gate-opening adsorption on the CHA/PHI zeolite. The Na+-type CHA/PHI zeolite did not show such adsorption behavior, and the PXRD pattern of the Na+-type CHA/PHI zeolite did not change with increasing CO2 partial pressure, which suggests that this unique adsorption behavior was caused by the PHI framework transition or Cs+ ions moving in both the CHA and PHI frameworks. Furthermore, in situ Fourier-transform infrared spectra of CO2 adsorption and CO2 breakthrough measurement on the Cs+-type CHA/PHI zeolite suggest that the CHA and PHI frameworks in the CHA/PHI zeolite shared eight-membered-ring windows and that CO2 molecules could easily diffuse from a CHA cage to a PHI framework. The ideal adsorbed solution theory was used to calculate the CO2/N2 separation selectivity for the Cs+-type CHA/PHI zeolite. At 298 and 318 K, the Cs+-type CHA/PHI composite zeolite showed a high CO2/N2 separation coefficient of >10,000 compared with other zeolites with high CO2 adsorption capacity. Furthermore, the CO2 working capacity was calculated for the Cs+-type CHA/PHI zeolite in both the pressure- and temperature-swing processes, and the results showed that the CHA/PHI composite zeolite could selectively separate CO2 from the CO2/N2 gas mixtures released from power generation plants operating using these processes.

Pengolahan Air Sadah Menggunakan Zeolit Buatan Dari Batu Apung Lampung Dan Daun Kerai Payung

This research was conducted to determine the composition and crystal structure of the artificial zeolite produced, as well as the ability of artificial zeolite to reduce calcium and magnesium content in hard water. The zeolite was prepared using the hydrothermal method by mixing sodium silicate from Lampung pumice silica, sodium aluminate from aluminum can waste and charcoal from sunshade umbrellas. The artificial zeolite products were characterized using XRF, XRD, UV-Vis spectrophotometric and ICP-EOS. The results showed that the composition of the artificial zeolite was aluminum, silica, phosphorus, potassium, calcium, titanium, vanadium, chromium, manganum and ferum. The crystal structure of the optimum sample from the UV-Vis spectrophotometric characterization obtained the crystal structure of a natural zeolite type, namely Chabazite. And the artificial zeolite which was tested for adsorption on hard water could reduce the calcium content by 36.57% but could not reduce the magnesium content.

Inorganic Chemistry in Dalian University of Technology: Fundamental Science and Solution for Renewable Energy, Environment, Health, and Materials

Inorganic Chemistry in Dalian University of Technology: Fundamental Science and Solution for Renewable Energy, Environment, Health, and Materials

Surfactant-assisted hydrothermal synthesis of core-shell ZSM-5@SSZ-13 zeolite for methanol to olefins reaction

Core-shell structured ZSM-5@SSZ-13 (Z@S-1) zeolite composites were successfully synthesized via adding SSZ-13 modified with a surfactant into ZSM-5 synthetic gel under hydrothermal conditions. The presence of surfactant improved the problems of chemical compatibility and charge matching between zeolites with different topological structures. The factors that controlled the formation of Z@S-1 had been studied in detail. The crystalline phase, morphology, aperture properties and acidity of the samples were characterized by XRD, SEM, N2 adsorption-desorption and NH3-TPD, respectively. The Z@S-1 catalyst exhibits good catalytic performance in the methanol-to-olefins (MTO) reaction compared to SSZ-13 and ZSM-5, owing to its hierarchical structure, suitable acidity, as well as the synergistic catalytic effect with ZSM-5 and SSZ-13. In this work, a simple and facile approach was proposed to synthesized core-shell zeolite composite, which had better to improve chemical compatibility issues derived from different topologies.

Effect of temperature on N-A-S-(H) and zeolite composition, solubility, and structure

This paper investigates the effect of temperature on the composition, solubility, and structure of sodium aluminosilicate hydrate (N-A-S-(H)) and zeolite synthesized using sodium silicate and sodium aluminate solutions across a range of bulk aqueous Si/Al ratios at different temperatures. It was found that temperature had minimal effect on the composition for both N-A-S-(H) and zeolite species. A decrease in N-A-S-(H) and zeolite solubility with increasing temperature was observed and attributed to the temperature-dependent pH. As expected, the solubility of N-A-S-(H) was higher than that of its crystalline counterpart. Estimation of thermodynamic properties also revealed that for both the N-A-S-(H) and zeolite phases, the Van't Hoff expression yielded similar enthalpy and Gibbs free energy of formation data as a three-parameter Gibbs free energy model that includes a heat capacity term. An additional benefit of the Van't Hoff approach is that it obviates the need for estimating the heat capacity from reference reactions.

Ultrasonic-assisted chemical modification of a natural clinoptilolite zeolite: Enhanced ammonium adsorption rate and resistance to disturbing ions

A natural clinoptilolite zeolite was modified by ultrasonic-assisted chemicals (NaOH, FeCl3 and HCl) to improve their performance in ammonium removal from (waste) water. The obtained modified zeolites were characterized by Field Scanning Electron Microscope (FESEM), Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffraction (XRD) and gas sorption techniques to understand the relation between physiochemical factors of the modified zeolites and ammonium adsorption. The highest elimination efficiency of ammonium by the natural zeolite modified by ultrasonic-assisted HCl treatment, HZU2, was ≥ 99%. However, ammonium removal by the raw natural zeolite was only 51.66%. The efficiencies of ammonium removal in the presence of various disturbing anions and cations by the HZU2 and raw zeolite were in the range of 79–93% and 15–30%, respectively. The HZU2 was reused five times presenting stable adsorption removal of ammonium. The theoretical calculations were performed to identify the key kinetics and thermodynamics parameters controlling the adsorption rate. The maximum adsorption capacity (qmax) of HZU2 obtained by the Langmuir model was about 142.85 (mg-ammonium/g-adsorbent) suggesting that the adsorption capacity of a monolayer and the relative content of alkali metal cations are suitable for the improvement of ammonium ion adsorption. The obtained thermodynamics parameters showed that the ammonium adsorption is a spontaneous and exothermic physisorption process. Consequently, we showed that ultrasonic-assisted chemical modification is a promising approach to control both textural properties and chemical composition of natural zeolites to enhance the ammonium removal from wastewater.

Mild Dealumination of H-ZSM-5 Zeolite for Enhanced Conversion of Glucose into 5-Hydroxymethylfurfural in a Biphasic Solvent System

Transformation of lignocellulosic biomass into high-value chemicals is a viable strategy for sustainable development of a bio-based economy. 5-Hydroxymethylfurfural (HMF) is one of potential platform bio-chemicals for the manufacture of various renewable products. In this work, a commercial H-ZSM-5 zeolite was used as a starting material for preparing a series of acid catalysts with bifunctionality for direct dehydration of glucose to HMF in a biphasic water/tetrahydrofuran system. The pristine H-ZSM-5 was mildly dealuminated by refluxing with dilute nitric acid solutions to adjust its acid properties. Although the acid treatment slightly altered the elemental composition, textural properties, and morphology of zeolite, the total acidity and distribution of acid sites were significantly modified. Some non-framework aluminum (Al) oxide clusters were removed from the parent H-ZSM-5 simultaneously with a partial hydrolysis of zeolitic framework. An increased fraction of coordinatively unsaturated framework Al species enhanced the number of Lewis acid sites. Using 0.1 M solution in the treatment provided the suitable catalyst (0.1DeAl.H-ZSM-5), giving a glucose conversion and HMF yield of >99% and 64.7%, respectively, and a good reusability under the optimized reaction conditions. These results show the industrial potential of the proposed method for simple but efficient preparation of H-ZSM-5 catalysts for producing HMF via the catalytic dehydration of glucose.

Water filter application with zeolit composite material in laying hens farm towards the egg quality

This study aimed to analyze the physical, chemical, and microbiological properties of applying an antibacterial water filter made from zeolite composites in laying hens. This study used a completely randomized design with a factorial pattern with 2 factors and 3 replications for egg quality. Factor A is the zeolite treatment, and factor B is the day of egg collection after being filtered. If the measures show a significant difference, it is continued with the least significant difference test, and the chemical quali-ty of the eggs and the microbiology of the eggs are tested using the t-test analysis (paired samples). The results showed that there was a significant interaction between the zeolite treatment and the day after the filter was installed after the eggs were collected. This increases the value of egg length, egg width, shell weight, shell thickness, and haugh units. Furthermore, the chemical quality of eggs treated with zeolite alone on day 3 had a significant effect (P<0.05) on the dry matter and egg fat content . The microbiological quality of the eggs also showed that the zeolite treatment reduced the TPC value and effectively killed Escherichia coli and Salmonella sp. It was concluded that the application of zeolite filters to the drinking water of laying hens could improve physical quality, maintain chemical quality, and is effective as an antibacterial against bacterial populations, Escherichia coli and Salmonella sp bacteria in eggs.

Lignocellulose nanofibrils/guar gum-based ethylene scavenging composite film integrated with zeolitic imidazolate framework-8 for food packaging

Ethylene, a ripening hormone, is critical in limiting the shelf life of fresh produce, specifically climacteric fruits and vegetables. A simple and benign fabrication approach is used to transform sugarcane bagasse, an agro-industrial waste into lignocellulosic nanofibrils (LCNF). In this investigation, biodegradable film was fabricated using LCNF (extracted from sugarcane bagasse) and guar gum (GG) which was reinforced with zeolitic imidazolate framework (ZIF)-8/zeolite. The LCNF/GG film not only acts as a biodegradable matrix to hold the ZIF-8/zeolite composite, but also possesses ethylene scavenging, antioxidant, and UV-blocking properties. The characterization results suggested that pure LCNF showed antioxidant activity of around 69.55 %. The LCNF/GG/MOF-4 film has shown lowest UV-transmittance (5.06 %) and highest ethylene scavenging capacity (40.2 %) among all the samples. After 6 days of storage at 25 ± 2 °C, packaged control bananas samples underwent significant degradation. In contrast, a banana package consisting of LCNF/GG/MOF-4 film maintained their high quality in terms of colour. Fabricated novel biodegradable film has potential application prospects for being used in prolonging the shelf life of fresh produce.

Three-dimensional inhomogeneity of zeolite structure and composition revealed by electron ptychography.

Structural and compositional inhomogeneity is common in zeolites and considerably affects their properties. Thickness-limited lateral resolution, lack of depth resolution, and electron dose-constrained focusing limit local structural studies of zeolites in conventional transmission electron microscopy (TEM). We demonstrate that a multislice ptychography method based on four-dimensional scanning TEM (4D-STEM) data can overcome these limitations. Images obtained from a ~40-nanometer-thick MFI zeolite exhibited a lateral resolution of ~0.85 angstrom that enabled the identification of individual framework oxygen (O) atoms and the precise determination of the orientations of adsorbed molecules. Furthermore, a depth resolution of ~6.6 nanometers allowed probing of the three-dimensional distribution of O vacancies, as well as the phase boundaries in intergrown MFI and MEL zeolites. The 4D-STEM ptychography can be generally applied to other materials with similar high electron-beam sensitivity.

Precise tuning of the properties of MOR-type zeolite nanoparticles to improve lower olefins selectivity in composite catalysts for CO2 hydrogenation

CO2 utilization is a key technology for carbon neutrality and is in high demand worldwide; however, many challenges need to be overcome. Composite catalysts consisting of zirconia-based catalysts for CO2 hydrogenation and zeolite-based solid acid catalysts for methanol-to-olefins reaction have been realized one-pass synthesis of olefins from CO2. High selectivity for olefins is essential for utilizing this promising process, and in this work, we precisely tuned the properties of MOR-type zeolites using multiple-step post-synthetic treatments. Miniaturization by milling and recrystallization helped realize the optimization of the zeolite composition related to the acid strength as well as enhance gas diffusion. Defect-healing treatment recently developed by us was applied, and the defects generated in the framework during these processes were successfully removed. Finally, the optimized sample showed high catalytic activity in sequential CO2 hydrogenation to hydrocarbons with the olefin selectivity with an improvement in the olefin/paraffin ratio from 0.69 to 1.4.

Silver-Doped Zeolitic Imidazolate Framework (Ag@ZIF-8): An Efficient Electrocatalyst for CO2 Conversion to Syngas

To enable the reuse of carbon dioxide (CO2), electrocatalytic reduction of CO2 (CO2RR) into syngas with a controllable H2/CO ratio is considered a cost-effective and intriguing approach. Here, a number of silver (Ag)-doped, zeolitic imidazole framework composites were prepared by a facile method. The outcomes demonstrate that CO2 electroreduction on Ag-doped ZIF-8 catalysts produces just CO and H2, without having any liquid fuel, resulting in a total faradaic efficiency approaching 100%. The most optimal Ag-Zn-ZIF-8 (10% Ag, 90% Zn) demonstrates good selectivity for syngas (CO and H2) that can be easily adjusted from 3:1 to 1:3 (H2/CO) by changing the applied voltage during the CO2 conversion process.

Unit Cell Volume as a Measure of the Framework Composition of ZSM-5 Type Zeolites

A simple X-ray powder diffraction procedure is proposed to determine the framework composition of ZSM-5 type zeolites. The procedure is based on a linear relation between the unit cell volume and the framework aluminum content found by analyzing two families of ZSM-5 zeolites with different SiO2/Al2O3 ratios. One family consisted of products synthesized in the presence of TPA+ cations while hydrogen forms were included in the second series of samples. Linear relationships between cell constants, cell volume (Vu.c.), and the framework aluminum content (NAl) were established. For the samples synthesized in the presence of an organic template and sodium cations, the relation between NAl and Vu.c. is given by NAl = (Vu.c. – 5332 Å3)/15.13. A similar equation was computed for H-ZSM-5 zeolites: NAl = (Vu.c. – 5330 Å3)/15.40. Equations derived can be used to evaluate the number of framework aluminum in the unit cell. In this way, the ratio of the framework and nonframework aluminum atoms in the samples of ZSM-5 type zeolites subjected to heat treatment can be estimated.