Synthesis Of Zeolite Research Articles

Synthesis and catalytic application of ZSM-48 zeolite

ZSM-48 is a kind of high-silica zeolite with one dimensional (1D) 10-member ring (10-MR) channel structure.

Facile synthesis and asymmetric device fabrication of zeolite like Co-MOF as a promising electrode material with improved cyclic stability

Facile synthesis and asymmetric device fabrication of zeolite like Co-MOF as a promising electrode material with improved cyclic stability

Designing zeolites for the removal of aqueous PFAS: a perspective

In this perspective, zeolites and their ability to adsorb per- and polyfluoroalkyl substances are explored. Suggestions of modifications and synthesis of old and new zeolites are proposed to enhance adsorption. (A. Stukowski, Modelling Simul. Mater. Sci. Eng., 2010, 18, 015012).

Synthesis and characteristics of Na-A zeolite from coal fly ash and application for adsorption of cerium(III)

Recycling rare earth elements (REEs) from waste is necessary for an environmentally sustainable reuse and wastewater management approach. Na-A zeolite was synthesized from coal fly ash (CFA) and applied for Ce3+ adsorption. Fourier transform infrared (FTIR) spectra show peaks at 790, 500 and 467 cm−1, which are bond vibrations of Si–O–Si, Si with Al–O and Si–O–. The surface area is 15.88 m2/g, with a pore size of 2.14 nm. SEM images show a cubic shape, which indicates the formation of zeolite. Field emission and energy disperse spectroscopy (EDS) shows the formation of Si, Al, Na, and O. Na-A zeolite was applied for Ce3+ adsorption. The optimum conditions for Ce3+ adsorption are 50 ppm concentration, 360 min, and pH 6. The maximum adsorption capacity is 176.49 mg/g. Based on the results, it is found that the adsorption of Ce3+ by Na-A zeolite is pseudo-second-order. The desorption test using HNO3 is more effective than using HCl and H2SO4. A desorption efficiency of 97.22 % is obtained at 4 cycles. Adsorption test using real sample wastewater demonstrates an adsorption efficiency of 83.35 %.

Synthesis of a hierarchical TS-1 zeolite with tunable macropore size and its performance in the catalytic oxidation reactions

Hierarchical TS-1 zeolites with tunable macropore size were synthesized based on a steam-assisted crystallization strategy, which exhibited excellent activity in the catalytic oxidation reactions.

Fluoride-free synthesis of high-silica RHO zeolite for the highly selective synthesis of methylamine

High-silica RHO zeolites with high MMA plus DMA yield in methylamine synthesis were synthesized via interzeolite conversion of SSZ-13 with less OSDA and fluoride-free conditions. The d8r units of RHO were formed by s8r units of decomposed SSZ-13.

Synthesis of self-pillared pentasil zeolites without organic templates and seeds.

Self-pillared pentasil (SPP) zeolites have received considerable interest due to their distinctive intergrowth structure, while the precise process and mechanism for the formation of SPP zeolites remain obscure. Herein, SPP zeolites (ZSM-5) have been successfully synthesized by pre-aging an Al-rich gel without employing any organic templates or seeds for the first time. The as-synthesized SPP zeolites possess a notably high external surface area while the micropores for Ar adsorption are partially blocked by excess Na+, which can be fully recovered by Mg2+ or H+ exchange. The crystallization process is monitored and the impacts of synthesis parameters are investigated. The results show that self-pillaring originates from the partial lattice distortion at the intersections of nanosheets, offering a new insight into the self-pillaring process. Typically, with decreasing SiO2/Al2O3 ratio, more crossovers could be observed in the crystals, hinting that self-pillaring predominately occurs at the (101) plane of twins in the ZSM-5 precursor due to Al-rich lattice distortion. Finally, in the catalytic cracking of n-heptane, H-SPP zeolites exhibit superior performance to commercial H-ZSM-5 zeolites due to their abundant Brønsted acid sites arising from a low framework SiO2/Al2O3 ratio of ∼21 and the short diffusion path originating from the house-of-cards structure.

Synthesis of hierarchical MFI zeolite by interzeolite conversion of spent FAU zeolite for the methanol-to-olefins reaction

Developing a strategy for the resource utilization of spent zeolite catalysts is essential for addressing the environmental hazards of spent catalysts.

Seed-assisted synthesis of a nanosheet-assembled hierarchical SSZ-13 zeolite by coupling a small amount of TMAdaOH with TPOAC

A nanosheet-assembled SSZ-13-TP0.03 was synthesized with TMAdaOH and TPOAC. Pt/SSZ-13-TP0.03 showed enhanced naphthalene hydrogenation compared to other catalysts.

Comparative environmental assessment of zeolites synthesized from chemicals and natural minerals

Life cycle assessment and green metrics were used to comparatively assess the synthesis of zeolites from natural minerals and chemicals in which the former exhibits a better balance between efficiency and environmental impacts than the latter.

Biopolymer-based fly ash-activated zeolite for the removal of chromium from acid mine drainage

Acid mine drainage (AMD), acid rock drainage, and fly ash from coal burning in power plants both posses widespread environmental and economic problems for many countries. Various biopolymers like chitosan have been used as a low-cost adsorbent for removal of toxic metals from AMD. The present investigation involves the microwave synthesis of low-cost chitosan biopolymer-based fly ash zeolite (CS@FAZ) adsorbent for the removal of chromium (Cr) from the acidic environment. The compositional and surface morphological characterization were conducted using FTIR, XRD, and SEM-EDS analysis. The Synthesized adsorbents were used for the removal of Cr (VI) ion under different experimental conditions, including initial concentration (15 to 60 mg L-1), contact time (0 to 180 minutes), dose (0.25 to 4 g L-1), solution pH (2 to 6). The optimum removal was 67.48% at room temperature 27℃, pH 3, concentration 45 mg L-1 and 0.1 g L-1 dose of CS@FZ adsorbent. The field evaluation parameters such as ionic strength and regeneration capacity show the adsorbent’s potential applicability in the remediation of AMD. The kinetics models and adsorption isotherm were determined to be pseudo-second order (R2 > 0.8952) validated with 27.78 mg g-1maximum adsorption capacity and fitted by Freundlichisotherm (R2 > 0.9264). The present low-cost adsorbent can be used for large scale to eliminate the Cr (VI) from the acid mine drainage.

Synthesis of zeolites from volcanic ash (Tajogaite, Spain) for the remediation of waters contaminated by fluoride.

In the eruptive event of Tajogaite (2021) in La Palma, Canary Islands, large quantities of volcanic ash were accumulated, affecting the local environment and urban areas. In this study, volcanic ash sampled from urban areas (catalogued as municipal waste (20 03 03) by the European Wastes Catalogue) were converted into zeolites by hydrothermal synthesis at 100°C with previous alkaline fusion at 550°C with distilled water. During this process, new phases of zeolite principally type X and sodalite have been identified by XRD at 2h of incubation. These zeolites, with the course of incubation time, present competitive processes where the transformation into sodalite develops after 24h as the predominant phase. The synthesized zeolitic material presents a high concentration as impurities in Fe2O3 (13.70 wt%), Na2O (12.70 wt%), CaO (11.65 wt%), and TiO2 (3.89 wt%) coming from the volcanic ash and NaOH introduced in the synthesis methodology. These impurities impart different physicochemical capabilities to the zeolitic material. The application of zeolites obtained in a preliminary fluoride adsorption experiment with volcanic leachate water rich in fluoride has been tested in a novel way. Removal efficiencies of 41.4% at acidic pH (5.77) have been obtained with 2g L-1 adsorbent zeolitic material doses. A value-added material is obtained and applied in a preliminary way to solve a problem generated by the volcanic ash itself, allowing the End of Waste status and meeting different objectives of the sustainable development goals of the UN Agenda 2030.

Cu-ZSM-5 catalyst synthesis via ion-exchange with ammonia solution of copper hydroxysalts

The properties of dihydroxycarbonate (malachite) and trihydroxynitrate of copper were studied in order to apply their ammonia solutions for the synthesis of copper-substituted ZSM-5 zeolites. Copper concentration and NH4OH/Cu2+ ratio in the solutions varied 1–12 g/l and 6–30, respectively. The parameters of Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherms revealed the favorability of the chosen conditions and the chemical nature of [Cu(NH3)n]2+ ions sorption by zeolite. For both copper salts, the sorption capacity of H-ZSM-5 for Cu2+ ions was higher in the solutions having NH4OH/Cu2+ = 6–10 compared to 30. To identify the synthesis and structure – activity relationship correlations, the ammonia solution and Cu-ZSM-5 samples were characterized by EPR, UV–visible spectroscopy, temperature-programmed reduction by hydrogen (H2-TPR). The calcined Cu-ZSM-5 samples produced at NH4OH/Cu2+ = 6–30 contained two types of the isolated Cu2+ ions (bare Cu2+ and [Cu(OH)]+), differing in their Redox properties. Their reducibility improved with an increase in the copper loading and with a decrease in NH4OH/Cu2+. At NH4OH/Cu2+ = 6–10, the samples additionally comprised the structures of Cu2+ ions with extra-lattice oxygen (ELO), which were formed due to hydrolysis of [Cu(NH3)n(H2O)]2+ to [Cu(NH3)n(OH)]+ and then to [Cu(OH)2Cu]2+. Cu2+–ELO structures possessed a greater ability to complete reduction than both types of isolated Cu2+ ions. Correlations with DeNOx properties in selective catalytic reduction (SCR) of NO by propane and ammonia are discussed.

NaY Zeolite Synthesis from Vermiculite and Modification with Surfactant

This work focuses on preparing NaY zeolite using alternative sources of silica and modifying the zeolite with the surfactant cetyltrimethylammonium bromide. Two different hydrothermal synthesis routes were employed: the conventional method using sodium silicate as the silica source, and the other is a sustainable approach using vermiculite clay as the silica source. In traditional zeolite synthesis, sodium silicate is often used as the source of silica. However, . The vermiculite was subjected to an acid treatment, followed by a primary treatment to obtain silica. Using the ion exchange method, the NaY zeolite was modified by an organic surfactant CTABr. Based on the various characterization techniques, it was possible to verify the obtaining of NaY zeolite through the conventional and sustainable routes, in which the structural properties were maintained. They used the sustainable path to synthesize NaY zeolite, which allowed for obtaining a material with low synthesis cost and properties similar to those synthesized conventionally. The structures of the NaY zeolites were maintained after the modification process with the surfactant Cetyltrimethylammonium Bromide (CTABr), demonstrating the structural stability of the zeolites and the efficiency of the modification process.

One-pot template-free synthesis of metal-doped ETS-10 zeolites for Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate

Three types of metal-doped ETS-10 zeolites including Ni-ETS-10, Al-ETS-10, and Ga-ETS-10 were successfully synthesized by one-pot template-free hydrothermal treatments. The effect of doping metals on the crystallinity, morphology, textural property, and basicity of the produced zeolites was systematically studied. It was found that doping with an appropriate amount of Ni could enhance the crystallinity and basicity of ETS-10 zeolites in comparison with Al and Ga, and the Ni species mainly existed in two forms of framework coordination and exchange site connection within Ni-ETS-10. The catalytic evaluation by the liquid Knoevenagel condensation reaction of benzaldehyde with ethyl cyanoacetate confirmed the superiority of ETS-10 and metal-doped ETS-10 in comparison with the contrast base zeolites of NaY and KY. And the 0.4Ni-ETS-10 catalyst exihibted the best performance with 75.6 % yield of ethyl ɑ-cyanocinnamate (ECC) among all the synthesized (metal-doped) ETS-10 zeolites. It is reasonable to expect that the demonstrated work has important implications for the design and facile synthesis of new-type high-performance base zeolite catalysts.

Crystal growth regulation of Cu-SSZ-13 zeolites for effective catalytic reduction of NOx from automotive exhausts

In this study, glucose was used in the synthesis of SSZ-13 zeolites; it acted as a zeolite growth regulator to successfully change the morphology of SSZ-13 zeolites. The particle size of the SSZ-13 zeolites reduced from 10 to 3 μm, and the morphology of the zeolite surface changed from rough and irregular spherical to smooth and uniform cubic. The glucose-modified SSZ-13 zeolites were ion-exchanged with Cu2+ ions (named as Cu-SSZ-13-Glu) and tested for the catalytic reduction of NOx with NH3 (NH3–SCR). The results demonstrated that the catalyst Cu-SSZ-13-Glu exhibited better NH3–SCR catalytic performance than that of conventional Cu-SSZ-13, with a wider effective reaction window, superior low-temperature SCR performance, favorable anti-SO2 poisoning ability, and excellent hydrothermal stability. The characterization results of the Cu-SSZ-13-Glu sample revealed an increase in crystallinity as well as acidic sites, and an improvement in the redox properties. After hydrothermal aging, compared with traditional Cu-SSZ-13, the Cu-SSZ-13-Glu zeolites exhibited a more stable structure and maintained higher crystallinity, larger specific surface area, and microporous volume. Moreover, the Cu2+ ions in the Cu-SSZ-13-Glu zeolites were more stable, and fewer CuOx species were generated after hydrothermal aging, retaining more Cu2+ ions species and acidic sites. To summarize, the simply prepared Cu-SSZ-13-Glu zeolites exhibited excellent catalytic activity and hydrothermal stability, showing broad application prospects in the field of nitrogen oxide removal from automotive exhausts.

Facile synthesis of hierarchical SAPO-56 zeolite as a highly efficient catalyst for CO2 hydrogenation to methanol

Catalytic conversion of CO2 over zeolite-based catalysts has been deemed as a promising route and extensively investigated, while many issues remain intractable. Herein, for the first time, the novel AFX-type zeolite SAPO-56 was developed and impregnated with Cu nanoparticles to construct the bifunctional catalyst for further promoting CO2 transformation. By a systematically comparative analysis on the physicochemical properties and catalytic performance of different catalysts, the corresponding catalytic mechanism for a highly efficient methanol synthesis process from CO2 was comprehensively understood. The results showed that up to 16.4 % of CO2 can be converted into methanol with a relatively high selectivity of 80.9 % via 5% Cu/SAPO-56 catalysts at 280 °C though the formate activation pathway. This may be directly related to the specific Lewis acid sites (LAS) derived from the EFAl (extra framework aluminum) species located in the six-membered rings of SAPO-56 that endows it with distinguished adsorption capability of CO2. Furthermore, the copper nanoparticles that are highly dispersed on the surface or in the porous channel of SAPO-56 zeolite facilitate the ease of CO2 activation. Besides, the introduced hierarchical structure was considered to have played an indispensable role in improving methanol productivity. Meanwhile, all its own multiple superiorities also ensure Cu/SAPO-56 a remarkable stability, indicating the great potential for practical and industrial application.

(Invited) Computational Predictions of Site-Dependent Reactivities for Complex Reactions in Confinement

It is well known that the relatively high overpotentials for oxygen evolution reactions arise from similar binding energies for HO* and HOO* intermediates that tend to move in lockstep on different catalysts. A strategy to break this scaling limitation is through differential stabilization of the two intermediates by engineering the reaction environment. Nanoporous materials such as zeolites and metal-organic frameworks provide such a possibility through their well-defined pore space that presents microscopically tunable reaction environments. Yet the predictive understanding of catalytic actions in these heterogeneous catalysts requires the ability to describe not only the electronic structure at the active site, but also how the extended environment interacts with the reacting species through individually weak yet collectively significant non-covalent interactions. In this talk, we present a new computational procedure that couples quantum-chemical methods and forcefield-based sampling to enable a consistent calculation of local activation energies for articulated reactants. As a first application, we studied hydrocarbon reactions in four different zeolites and showed how the method allows for the estimation of transition-state entropy and for the systematic calculation of site-dependent activation energies. The latter can be used to derive rigorous ensemble-averaged barriers for comparison with experiments, as well as guiding future strategies for controlling Al distributions during zeolite synthesis.

Synthesis and kinetic analysis of zeolites based on fly ash

ABSTRACT Rational utilization of fly ash, a widely emitted solid waste, was explored by investigating the effects of various factors on the types and properties of zeolites prepared from fly ash. Additionally, the mechanism for adsorption of ammonium nitrogen onto NaP zeolite synthesized via a one-step hydrothermal method was explored. The characterization studies included scanning electron microscopy (SEM), X-ray diffraction (XRD), and adsorption of ammonium nitrogen from wastewater. The effects of the crystallization time, solid‒liquid ratio, alkali concentration, and crystallization temperature on the performance of the fly ash-derived zeolites were systematically investigated. Adsorption isotherms and kinetic models were employed to analyze the adsorption behavior and mechanisms. The results indicated that the optimal conditions for the zeolite synthesis included a 24-hour crystallization time, a solid‒liquid ratio of 1:10, an alkali concentration of 3 mol/L, and a crystallization temperature of 150°C. Under these conditions, the zeolite exhibited intense diffraction peaks, a large surface area, a regular morphology, and an ammonia-nitrogen adsorption rate of 73.01%. An orthogonal test revealed that the alkali concentration had the most significant impact on the zeolite synthesis, with a range value of 14.28. The isothermal adsorption data for ammonia-nitrogen were consistent with the Freundlich model, while the kinetic studies showed that pseudosecond-order kinetics governed the process.

Characterization and application of lamellar zeolite‐X prepared from kaolin

AbstractA simple and effective method was reported for the rapid synthesis of zeolite X from kaolin by adding a template agent. The results of X‐ray diffraction confirm the good crystallinity of the synthesized X‐zeolite with lamellar structure. Transmission electron microscopy images clearly demonstrate the lamellar structure of the synthesized X‐zeolite. The corresponding selective electron diffraction pattern suggests that the crystal structure of X‐type zeolite is octahedral. The co‐existence and uniform distribution of Si, Al, O, and Na in the layered structure of the synthesized X‐type zeolite are detected by element mapping. In addition, N2 adsorption–desorption measurement indicates that the specific surface area of the lamellar zeolite X is 153.4625 m2 g−1. The micropore surface area is 148.8374 m2 g−1, and the micropore volume is 0.073377 m2 g−1. After exploring the influence of different temperatures on the adsorption of carbon dioxide, the research shows that two‐dimensional zeolite X has the best adsorption capacity for carbon dioxide. The adsorption and separation performance of CO2/CH4 was investigated. The study showed that the adsorption and separation coefficient of two‐dimensional zeolite X was the highest.