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A healthy breath is mainly composed of water, carbon dioxide, molecular nitrogen, and oxygen and it contains many species, in small quantities, which are related to the ambient atmosphere and the metabolism. The breath of a person affected by lung cancer presents a concentration of 1-propanol higher than usual. In this context, the development of specific sensors to detect 1-propanol from breath is of high interest. The amount of propanol usually detected on the breath is of few ppb; this small quantity is a handicap for a reliable diagnostic. This limitation can be overcome if the sensor is equipped with a pre-concentrator. Our studies aim to provide an efficient material playing this role. This will contribute to the development of reliable and easy to use lung cancer detectors. For this, we investigate the properties of a few hydrophobic porous materials (chabazite, silicalite-1, and dealuminated faujasite). Hydrophobic structures are used to avoid saturation of materials by the water present in the exhaled breath. Our experimental and simulation results suggest that silicalite −1 (MFI) is the most suitable structure to be used as a pre-concentrator. [ABSTRACT FROM AUTHOR]

We carried out a mechanistic investigation of the dehydration of fructose catalyzed by a series of proton‐exchanged faujasite zeolites. Using a combination of analytical tools (HPLC, GC, NMR), we could solve and quantify most of the variety of products formed, including (i) cyclic intermediates (ii) transient species (monomeric and dimeric) (iii) byproducts (oligomeric species and humins). The results prove that the reaction goes through a cyclic mechanism, and we could propose a kinetic model matching most of our experimental results and describing the interplay between the different categories of products. By comparing the performances of different catalysts with varying properties, we surprisingly find that increasing the concentration of Brønsted acid sites induces lower catalytic activity. Contrary to general expectations, the mesoporous volume seems to be the most determining parameter for the activity of the catalysts over the set of catalysts evaluated here, which may be explained by the importance of allowing the reactant a significant accessibility to the active sites. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the applicability of zeolite Y as a catalyst for producing bisphenol F (BPF) from phenol and formaldehyde. Catalyst extrudates were prepared by extrusion after adding pseudoboehmite sol (PS) and Ludox (Lu) as alumina and silica binders, respectively. The compressive strength of the catalyst extrudates increased with the addition of Ludox. However, the formaldehyde conversion decreased as more Ludox was used as a binder, resulting in a decrease in the yield of BPF. This decrease is attributed to the reduction in the total amount of acid sites caused by the addition of Ludox. In this study, the Y_PS5_Lu5 catalyst was selected as the most suitable for BPF synthesis. In the BPF synthesis over the Y_PS5_Lu5 catalyst in a catalyst basket reactor, the optimum reaction temperature was determined to be 110 °C. The effect of stirring speed on the yield of BPF was found to be negligible in the range of 200 rpm to 350 rpm. The spent catalyst was able to recover a specific surface area and reaction activity similar to those of a fresh catalyst through regeneration in an air atmosphere at 500 °C. When the Y_PS5_Lu5 extruded catalyst was used in a continuous reaction in a fixed-bed reactor, there was no noticeable deactivation of the catalyst at low space velocities of the reactants. However, when the space velocity was increased to 18.0 h−1, catalyst deactivation was clearly observed. This suggests that periodic regeneration of the catalyst is inevitable in a continuous reaction using the Y_PS5_Lu5 extruded catalyst. [ABSTRACT FROM AUTHOR]

Adsorption of methylene blue from aqueous effluents is a key technique to treat wastewater discharge from chemical industries. Toward methylene blue adsorption, porous metal–organic frameworks have been promising owing to their high surface areas and tunable porosity. The incorporation of polyoxometalates (POMs) into metal–organic frameworks has been found to facilitate methylene blue adsorption due to electrostatic interactions between the anionic polyoxometalate and the cationic methylene blue. However, it remains unclear how the customizable pore of POM@MOF hybrids affects the capture of methylene blue. In this work, we study the effect of the size and environment of metal–organic frameworks on the property of methylene blue capture for [Zr6O4(OH)4(1,4-benzenedicarboxylate)6] (UiO-66) embedding an α-Keggin-type polyoxometalate [α-SiW12O40]4− (SiW12). Tuning pore size and environment based on ligand engineering of the metal–organic frameworks suggests that (i) lengthening the organic linkers and (ii) functionalization of the linker with −NO2 groups could enhance the methylene blue uptakes. Notably, an increase in the loading amounts of SiW12 on UiO-66 functionalized with −NO2 groups led to outstanding methylene blue capture, comparable to that of representative zeolites such as ZSM-5 and zeolite Y. [ABSTRACT FROM AUTHOR]

Internal combustion engine fueled by carbon-free hydrogen (H2-ICE) offers a promising alternative for sustainable transportation. Herein, we report a facile and universal strategy through the physical mixing of Pt catalyst with zeolites to significantly improve the catalytic performance in the selective catalytic reduction of nitrogen oxides (NOx) with H2 (H2-SCR), a process aiming at NOx removal from H2-ICE. Via the physical mixing of Pt/TiO2 with Y zeolite (Pt/TiO2 + Y), a remarkable enhancement of NOx reduction activity and N2 selectivity was simultaneously achieved. The incorporation of Y zeolite effectively captured the in-situ generated water, fostering a water-rich environment surrounding the Pt active sites. This environment weakened the NO adsorption while concurrently promoting the H2 activation, leading to the strikingly elevated H2-SCR activity and N2 selectivity on Pt/TiO2 + Y catalyst. This study provides a unique, easy and sustainable physical mixing approach to achieve proficient heterogeneous catalysis for environmental applications. The integration of Pt-oxide catalyst systems with zeolites demonstrates considerable promise for reducing nitrogen oxide emissions at low temperatures from fossil-fuel or hydrogen-powered internal combustion engines. [ABSTRACT FROM AUTHOR]

Diffusional limitations associated with zeolite microporous systems can be overcome by developing hierarchical zeolites, i.e., materials with a micro- and mesoporous framework. In this work, Y and ZSM-5 zeolites were modified using a surfactant-mediated hydrothermal alkaline method, with NaOH and cetyltrimethylammonium bromide (CTAB). For Y zeolite, after a mild acidic pretreatment, the effect of the NaOH+CTAB treatment time was investigated. For ZSM-5 zeolite, different concentrations of the base and acid solutions were tested in the two-step pretreatment preceding the hydrothermal treatment. The properties of the materials were studied with different physical–chemical techniques. Hierarchical Y zeolites were characterized by 3.3–5 nm pores formed during the alkaline treatment through the structure reconstruction around the surfactant aggregates. The effectiveness of the NaOH+CTAB treatment was highly dependent on the duration. For intermediate treatment times (6–12 h), both smaller and larger mesopores were also obtained. Hierarchical ZSM-5 zeolites showed a disordered mesoporosity, mainly resulting from the pretreatment rather than from the subsequent hydrothermal treatment. High mesoporosity was obtained when the concentration of the pretreating base solution was sufficiently high and that of the acid one was not excessive. Hierarchical materials can be obtained for both zeolite structures, but the pretreatment and treatment conditions must be tailored to the starting zeolite and the desired type of mesoporosity. [ABSTRACT FROM AUTHOR]

Here in, we reported the utilization of guinea corn husk (an agricultural waste) and aluminium can (a municipal waste) for low-cost and sustainable means of zeolite Y preparation. Sodium silicate and sodium aluminate precursors were prepared from guinea corn husk and aluminium wastes respectively. The obtained solutions of the precursors were directly and hydrothermally converted to zeolite Y at 100 °C crystallization temperature for 24 h. The resulting zeolitic material was characterized by its properties. In comparison with collected standard data and commercially available zeolite Y, zeolite Y was successfully prepared from the waste resources. The result of X-ray Diffraction (XRD) indicated zeolite Y with good crystallinity, especially at the characteristic 2θ of 6.23°, 10.9° and 11.86°. The elemental compositions observed from Energy Dispersive X-ray (EDX) are in appropriate proportion and also confirmed the product. The Fourier Transform Infrared (FTIR) spectra showed the major characteristic absorption bands of zeolite in the mid-infrared region. It can be concluded that re-using agricultural and municipal wastes for the preparation of zeolite Y was achieved. This is a sustainable means of preparation of zeolite Y through a waste management approach for potential applications in adsorption, catalysis and ion exchange.

In this study, the hydrogen storage properties of various synthetic zeolites, including Zeolite Y (FAU), Mordenite (MOR), ZSM-12 (MTW), and MCM-22 (MWW) are determined at 77 K and atmospheric pressure. The structures of the zeolites are characterized by XRD, ICP-OES, FE-SEM, TGA and N 2 adsorption-desorption isotherms. The results show that H-MCM-22 zeolite has the highest hydrogen storage capacity at 1.0 bar with 1.19 wt%, followed by H-MOR zeolite with 1.05 wt%, H–Y zeolite with 0.75 wt% and H-ZSM-12 zeolite with 0.60 wt%. The hydrogen adsorption data on FAU, MOR, MTW, and MWW at 77 K obey the Sips isotherm model. The experimental data show that the ultra-micropore volume of the zeolite is effective in hydrogen adsorption at low-pressure ranges. In addition, increasing the aluminum content of the zeolite increases the hydrogen adsorption capacity of the zeolite at atmospheric pressure. Therefore, zeolites with channel sizes close to the kinetic diameter of a hydrogen molecule, large cage volumes, and high aluminum content are potential candidates for energy storage applications. [Display omitted] • ZSM-12 and MCM-22 were synthesized and characterized. • The H 2 adsorption capacities of four zeolites were determined at 77 K and 1.0 bar. • The experimental data were analyzed using the Langmuir, Freundlich, and Sips isotherms. [ABSTRACT FROM AUTHOR]

A temperature-programmed reduction method was developed to stabilize SAPO-37 and molybdenum-(oxy)-carbide-loaded SAPO-37 (SAP-37MoCR). The inorganic framework (Faujasite type SAPO-37) was retained for the first time even after treatment at 550 °C and was confirmed through powder XRD and SEM analysis. SAP-37MoCR exhibits strong acidic sites and is a promising catalyst for MTBE synthesis. Furthermore, the catalyst is stable and recyclable. [ABSTRACT FROM AUTHOR]

Silica-rich Y (FAU topology) and EMC-2 (EMT topology) zeolites have been obtained in the presence of the tetraethylammonium (TEA+) cation as a structure-directing molecule and the corresponding protonic zeolites as seeds. In the presence of USY seeds, Y zeolites were fully crystallized after a few hours at 130 °C but they were unstable and rapidly converted into chabazite, a zeolite with CHA topology. Their stability could nonetheless be greatly improved by decreasing the temperature to 110 °C without significantly modifying the morphology of the crystals and the composition of the framework. Framework SiO2/Al2O3 ratios up to 13 could be obtained, which is the highest value ever reported for Y zeolites synthesized with TEA+ cations as the sole organic molecule. The use of H-EMC-2 as seeds generally led to FAU–EMT intergrowths in which the relative proportion of EMT depended on the composition of the seeds. However, a pure EMT zeolite could be obtained under specific conditions. With a framework SiO2/Al2O3 ratio of 11.2, it constitutes the first example of Si-rich EMT obtained in the absence of crown ether from conventional silica and alumina sources. [ABSTRACT FROM AUTHOR]

Designing photoluminescence sensing devices for gaseous oxygen that combine ease of acquisition with efficient performance is a critical yet challenging task. Herein, a novel oxygen‐sensing probe based on zeolite Y confined silver clusters prepared via a simple approach, is proposed. The large Ag6 clusters formed after hydrogenation exhibit a bright orange emission. They are characterized by a high photoluminescence quantum yield (≈31%) and a long luminescence decay time (>500 µs). A possible formation mechanism of these clusters, which are for the first time observed in Faujasite zeolites, is proposed. Luminescence switching‐off, triggered by oxygen, can be detected in a dual‐channel combination of linear emission‐quenching and lifetime‐reduction, enabling a visual and ultrasensitive (limit of detection of 58 Pa) quantitative detection of oxygen in a wide pressure range (0–100 kPa) with fast response (<1 s), reversibility and reproducibility. A more detailed analysis shows that this high sensitivity is due to the long decay time of the orange emission and the high affinity of the zeolite for O2 adsorption rather than to a high rate constant for quenching. This work contributes to the development of optical oxygen sensing technology and lays the foundation for the design of silver cluster‐based zeolites for photo‐functional applications. [ABSTRACT FROM AUTHOR]

Syngas conversion serves as a gas‐to‐liquid technology to produce liquid fuels and valuable chemicals from coal, natural gas, or biomass. During syngas conversion, sintering is known to deactivate the catalyst owing to the loss of active surface area. However, the growth of nanoparticles might induce the formation of new active sites such as grain boundaries (GBs) which perform differently from the original nanoparticles. Herein, we reported a unique Cu‐based catalyst, Cu nanoparticles with in situ generated GBs confined in zeolite Y (denoted as activated Cu/Y), which exhibited a high selectivity for C5+ hydrocarbons (65.3 C%) during syngas conversion. Such high selectivity for long‐chain products distinguished activated Cu/Y from typical copper‐based catalysts which mainly catalyze methanol synthesis. This unique performance was attributed to the GBs, while the zeolite assisted the stabilization through spatial confinement. Specifically, the GBs enabled H‐assisted dissociation of CO and subsequent hydrogenation into CHx*. CHx* species not only serve as the initiator but also directly polymerize on Cu GBs, known as the carbide mechanism. Meanwhile, the synergy of GBs and their vicinal low‐index facets led to the CO insertion where non‐dissociative adsorbed CO on low‐index facets migrated to GBs and inserted into the metal‐alkyl bond for the chain growth. [ABSTRACT FROM AUTHOR]

The synthesis of zeolites from local resources has been an attractive route to address the demand for more economical means in the production of zeolites for commercial applications. In particular, Philippine bentonite -- a local clay material --has been used as a raw ingredient to synthesize zeolites, faujasite-type (FAU), and analcime-type (ANA) via hydrothermal synthesis. The silicon-aluminum ratio (SAR) and crystallization temperature were varied to investigate the conditions in the synthesis of pure FAU and ANA-type zeolites. X-ray diffraction allowed the identification of zeolite phases upon comparison to reference patterns from the International Zeolite Association database. The sample with the highest degree of crystallinity of 98% (ANA-type) was prepared at a temperature of 150 °C and an initial SAR of 1.18. This sample also exhibited the largest particle size of 29.1 µm in diameter. Scanning electron micrographs showed octahedral, spherical, and cross morphologies of the products, with average particle size ranging from 1.24 (± 0.13) to 29.1 (± 1.66) µm. The transformation of Philippine bentonite to different types of zeolites demonstrates the viability of local clays as raw resource material for hydrothermal synthesis of a wide range of zeolite frameworks. [ABSTRACT FROM AUTHOR]

Zeolite Y is the active phase of the modern fluid catalytic cracking (FCC) catalyst. However, a functional and active FCC catalyst comprises, in addition to zeolite Y, matrices and a binder that introduce some levels of synergistic interaction between the catalyst components, impacting its activity. This study investigates the interactive properties of a zeolite-matrix-binder composite on a typical FCC catalyst using various characterization techniques. Characterization of synthesized FCC catalyst samples reveals changes in the structural composition of zeolite Y dependent upon the type and ratio of binder materials. The binder is important in the crystallization of the final composite. Acidic binder induces dealumination of zeolite, leading to amorphization, loss of Brønsted acid sites, framework structure impairment, and the formation of defective sites. TEM indicates the formation of zeolite-matrix interfaces upon binding of zeolite by the matrix. Depending on the extent and severity of thermal processing, the clay–alumina–silica binder undergoes dehydroxylation to varying degrees by cross-linking of terminal hydroxyl groups between neighboring binder particles, which contributes to the increased thermal and mechanical stability of the bound catalysts. [ABSTRACT FROM AUTHOR]

In this work, we developed cetrimonium bromide (CTAB)‐grafted faujasite nanoparticles (C‐g‐F) as wax inhibitors for the deposits that were formed from a model oil system consisting of 5 wt.% paraffin wax in toluene. Our developed nanomaterials were fully characterized, hydrophobically modified, and their deposition inhibition performance compared with virgin CTAB was investigated in a model waxy oil through cold finger setup (CF), differential scanning calorimetry (DSC), cold flow yield strength, and cross‐polarized microscopy (CPM). Applying our nano‐inhibitors at a concentration of 100 ppm led to more than 50 wt.% inhibition and a 30% reduction of deposit cold yield strength. Interestingly, the presence of FAU nanoparticles in the core structure of C‐g‐F contributed to better dispersibility, enhancing surface wettability (reducing interfacial tension with wax crystals), facilitating inhibitions, and preventing co‐crystallization greater than the surfactant alone. The morphological analysis results showed that C‐g‐F, due to their novel surface features, could suppress the unordered wax crystals from networking, resulting in uniform spherical‐like wax aggregates. Hence, the application of tiny concentrations of C‐g‐F (10 to 300 ppm) outperformed stand‐alone surfactants in nucleating the wax crystals. [ABSTRACT FROM AUTHOR]

In this study, Tunisian raw clay (RC) was utilized as a cheap source of silicium and aluminum for the preparation of faujasite zeolite (FAUsyn) using the alkaline fusion technique. The zeolite's structural analysis was carried out using the XRD, nitrogen adsorption–desorption, and SEM–EDX techniques. The data collected demonstrate that the produced zeolite only included one homogeneous faujasite phase. Textural analysis shows that the FAUsyn prepared from RC has a hierarchical porosity (micro-, meso-, and macropores). The total porosity was found to be 0.33 cm3/g as well as the BET area was equal to 360 m2/g. Adsorption experiments for propene capture were performed using the FAUsyn as adsorbent material. The performance of the column was examined in relation to various parameter impacts, including flow rate (50, 100, and 150 mL/min), input concentration (4, 8, and 12 mg/L), and bed depth (10, 14, and 18 cm). Finally, experimental and theoretical studies were investigated to predict adsorption capacities and kinetics parameters. To clarify and estimate column inputs, a model that incorporates axial dispersion, Langmuir equation, and migration within the adsorbent's pore was improved. COMSOL Multiphysics software was used to execute the model and resolve it computationally. The results of the experiments and the expected breakthrough curves were very well agreed. Modeling obtained results can be extrapolated to industrial level. [ABSTRACT FROM AUTHOR]

A series of nickel (Ni) catalysts were prepared using zeolites Y with different cation types (Na, Mg, Ca, Sr, Ba, Ce, and La) as supports and characterized by using XRD, BET, ICP-OES, XPS, and TEM , as well as NH 3 -TPD, CO 2 -TPD, and H 2 -TPR techniques. Their catalytic performances in decomposition of ammonia (NH 3) to hydrogen (H 2) were evaluated with a fixed-bed flow reactor system. The catalytic activities of the prepared catalysts for NH 3 decomposition decreased in the order of Ni/SrY > Ni/BaY > Ni/LaY > Ni/CaY > Ni/NaY > Ni/MgY > Ni/CeY. The high activity of Ni/SrY catalyst may be attributed to its small Ni nanoparticle size, high basicity and strong interaction between highly dispersed Ni nanoparticles and SrY support. At 600 °C and GHSV of 9000 mLNH 3 ·g cat −1·h−1, 98.0 % NH 3 conversion with about 105.2 mmol min−1·g Ni −1 H 2 formation rate can be accomplished over Ni/SrY catalyst. [Display omitted] • High-activity Ni/Y catalysts were prepared on various cation-exchanged zeolite Y. • Ni/SrY catalyst showed high activity and stability for ammonia decomposition. • Ni/SrY shows superior activity due to its small Ni particle size, high basicity, and strong metal-support interaction. [ABSTRACT FROM AUTHOR]

Erionite (ERI) zeolite has recently attracted considerable attention for its application prospect in the selective catalytic reduction of NOx with NH3 (NH3‐SCR), provided that the high‐silica (Si/Al > 5.5) analog with improved hydrothermal stability can be facilely synthesized. In this work, ERI zeolites with different Si/Al ratios (4.6, 6.4, and 9.1) are synthesized through an ultrafast route, and in particular, a high‐silica ERI zeolite with a Si/Al ratio of 9.1 is obtained by using faujasite (FAU) as a starting material. The solid‐state 29Si MAS NMR spectroscopic study in combination with a computational simulation allows for figuring out the atomic configurations of the Al species in the three ERI zeolites. It is revealed that the ERI zeolite with the highest Si/Al ratio (ERI‐9.1, where the number indicates the Si/Al ratio) exhibits a biased Al occupancy at T1 site, which is possibly due to the presence of a higher fraction of the residual potassium cations in the can cages. In contrast, the Al siting in ERI‐4.6 and ERI‐6.4 proves to be relatively random. [ABSTRACT FROM AUTHOR]

In this research work, we were able to composite Faujasite type zeolite and ZIF-8 metal–organic framework using two different ways to improve the chemical stability of ZIF-8. In these methods, the arrangement of introducing Zn and 2-Methylimidazole as parent material to synthesis of ZIF-8 to zeolite were changed. In addition, the composites were prepared at room temperature under green chemistry conditions. The structure of Fauj/ZIF-8 nanocomposites were confirmed by FT-IR, XRD, SEM, BET, MAP, TGA, NH3-TPD and ICP analysis after synthesis. The Fauj/ZIF-8 nanocomposites with high acidity and micro-meso structure showed good stability. Two prepared composites were used as catalysts in organic reactions including esterification of acetic acid by four different alcohols and aldol condensation of benzaldehyde derivatives 2-X and 4-X. The results of these catalytic applications show that the use of nanocomposites yields is above 90% with good reusability under solvent free condition for esterification and aldol condensation reactions. [ABSTRACT FROM AUTHOR]

Displacement of enzyme mimic nanomaterials has been developed due to disadvantages of natural enzymes. Peroxidase reaction could be used for H2O2 colorimetric evaluation in different media. We aim to develop a new method based on the best catalytic activity of metal Nanozyms. A method for H2O2 detection was carried out by TMB peroxidation of metal nanozymes. In this way peroxidase activity of Ag-nano zeolite Y, Cu-nano zeolite Y, Zn-nano zeolite Y and Ag, Cu, Zn-nano zeolite Y was evaluated by Central Composite Design. Total of 28.42% from three metals was exchanged in multi metal nano zeolite Y (mMy) with higher peroxidase- like activity. Nanozyme Km and Vm were evaluated 0.076 and 8.76 × 108, respectively which produced fast and sensitive catalytic reaction. H2O2 method detection carried out by LOD level of 0.12 ppm, and recovery parameters of 99%, in the linear range of 0.5–50 ppm. The mMy nanozyme was validated for H2O2 colorimetric detection. In conclusion an applicable way as a fast, sensitive, accurate and reproducible method has been suggested for occupational exposure monitoring. Performance of validated method is higher than international OSHAVI-6 method. [ABSTRACT FROM AUTHOR]

Indoor air pollution remains a major concern, with formaldehyde (HCHO) a primary contributor due to its long emission period and associated health risks, including skin allergies, coughing, and bronchitis. This study evaluated the adsorption performance and economic efficiency of various adsorbents (biochar, activated carbon, zeolites A, X, and Y) selected for HCHO removal. The impact of thermal treatment on adsorbent regeneration was also assessed. The experimental apparatus featured an adsorption column and HCHO concentration meter with an electrochemical sensor designed for adsorption analysis. Zeolite X exhibited the highest adsorption performance, followed by zeolite A, zeolite Y, activated carbon, and biochar. All adsorbents displayed increased HCHO removal rates with an extended length/diameter (L/D) ratio of the adsorption column. Zeolite A demonstrated the highest economic efficiency, followed by zeolite X, activated carbon, zeolite Y, and biochar. Higher L/D ratios improved economic efficiency and prolonged the replacement cycle (the optimal timing for adsorbent replacement to maintain high adsorption performance). Sensitivity analysis of adsorbent regeneration under varying thermal treatment conditions (150, 120, and 80°C) and durations (60, 45, and 30 min) revealed minimal changes in adsorption efficiency (±3%). The results indicated the potential of adsorbent regeneration under energy-efficient thermal treatment conditions (80°C, 30 min). In conclusion, this study underscores the importance of a comprehensive assessment, considering factors such as adsorption performance, replacement cycle, economic efficiency, and regeneration performance for the selection of optimal adsorbents for HCHO adsorption and removal. Implications: This study underscores the importance of adsorption technology for the removal of formaldehyde and similar volatile organic compounds (VOCs), highlighting the potential of alternative adsorbents, such as environmentally friendly biochar, in addition to traditional strategies, such as activated carbon and zeolites. Our findings demonstrate the feasibility of adsorbent regeneration under energy-efficient thermal treatment conditions. These results hold promise for improving indoor air quality, reducing environmental pollutants, and enhancing responses to air contaminants like fine dust and VOCs. [ABSTRACT FROM AUTHOR]

This document discusses the development and applications of zeolites and zeolite-like materials as catalysts. Zeolites are mineral group of hydrous framework silicates that have been synthesized on a technical scale since the mid-20th century. They are widely used as ion exchangers, adsorbents, and catalysts in various industries. The document presents several studies on the synthesis, characterization, and application of zeolites and zeolite-like materials as catalysts, covering topics such as hydrocracking, catalytic cracking, isomerization, oxidation, and condensation reactions. The studies explore the effects of different catalyst compositions, structures, and reaction conditions on catalytic performance. [Extracted from the article]

Ti-aluminosilicate gels were used as supports for the immobilization of Fe, Co, and Ni oxides (5%) by impregnation and synthesis of efficient photocatalysts for the degradation of β-lactam antibiotics from water. Titanium oxide (1 and 2%) was incorporated into the zeolite network by modifying the gel during the zeolitization process. The formation of the zeolite Y structure and its microporous structure were evidenced by X-ray diffraction and N2 physisorption. The structure, composition, reduction, and optical properties were studied by X-ray diffraction, H2-TPR, XPS, Raman, photoluminescence, and UV–Vis spectroscopy. The obtained results indicated a zeolite Y structure for all photocatalysts with tetracoordinated Ti4+ sites. The second transitional metals supported by the post-synthesis method were obtained in various forms, such as oxides and/or in the metallic state. A red shift of the absorption edge was observed in the UV–Vis spectra of photocatalysts upon the addition of Fe, Co, or Ni species. The photocatalytic performances were evaluated for the degradation of cefuroxime in water under visible light irradiation. The best results were obtained for iron-immobilized photocatalysts. Scavenger experiments explained the photocatalytic results and their mechanisms. A different contribution of the active species to the photocatalytic reactions was evidenced. [ABSTRACT FROM AUTHOR]

Hierarchical ZSM5 and Y zeolites were prepared through a surfactant-mediated strategy with NH4OH changing the duration of the treatment and the amount of CTAB surfactant and taking as reference multiples of the critical micellar concentration (CMC). The materials were characterized using powder X-ray diffraction, N2 adsorption isotherms at −196 °C, and SEM and TEM microscopy. The catalytic performance was evaluated in Friedel–Crafts acylation of furan with acetic anhydride at 80 °C. The alkaline surfactant-mediated treatment had different effects on the two zeolites. For ZSM5, the CTAB molecular aggregates can hardly diffuse inside the medium-size pores, leading mainly to intercrystalline mesoporosity and increased external surface area, with no positive catalytic impact. On the other hand, for large-pore Y zeolite, the CTAB molecular aggregates can easily diffuse and promote the rearrangement of crystal units around micelles, causing the enlargement of the pores, i.e., intracrystalline porosity. The optimized Y-based sample, treated for 12 h with a CTAB amount 32 times the CMC, shows an increase in product yield and rate constant that was not observed when a higher amount of surfactant was added. The reuse of spent catalysts upon thermal treatment at 400 °C shows a regeneration efficiency around 90%, showing good potentialities for the modified catalysts. [ABSTRACT FROM AUTHOR]

The simultaneous capture and detection of biomolecules is crucial for revolutionizing bioanalytical platforms in terms of portability, response time and cost‐efficiency. Herein, we demonstrate how the sensitivity to external stimuli and changes in the local electronic environment of silver clusters lead to an advantageous biosensing platform based on the fluorometric response of bioactive luminescent silver clusters (BioLuSiC) confined in faujasite X zeolites functionalized with antibodies. The photoluminescence response of BioLuSiC was enhanced upon immunocomplex formation, empowering a wash‐free and quick biodetection system offering optimal results from 5 min. Proteins and pathogens (immunoglobulin G and Escherichia coli) were targeted to demonstrate the biosensing performance of BioLuSiC, and a human serum titration assay was also established. BioLuSiC will pave the way for innovative bioanalytical platforms, including real‐time monitoring systems, point‐of‐care devices and bioimaging techniques. [ABSTRACT FROM AUTHOR]

In this study, zeolite Y was synthesised using a novel method. The heat generated from the reaction of H2SO4 with metakaolin was used as a heat source instead of applying external heat for the dealuminated process. The synthesised zeolite Y produced was analysed by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier-infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS) and Brunauer–Emmett–Teller (BET). Zeolite Y synthesis was mesoporous because of its pore diameter (30.53 nm), as shown in the BET results. Surface area and pore size decrease after adsorption due to dye deposition on the adsorbent's surface. FTIR has bonds like O–H, C–H, –CH3, and –COOH responsible for adsorption. The maximum adsorption capacity of eosin yellow (EY) and methyl orange (MO) on to zeolite Y by the Langmuir isotherm was 52.91 mg/g and 20.62 mg/g respectively, at pH 2.5 and 8 for EY and MO dye. The batch adsorption studies were conducted, and the influence of different parameters (i.e., adsorbent dose, adsorption time, initial dye concentration, pH and temperature) was investigated. Experimental data were analysed by two linear model equations (Langmuir and Freundlich isotherms), and it was found that the Langmuir isotherm model best describes the adsorption data for methyl orange and Freundlich isotherm for eosin yellow, respectively. Adsorption rate constants were determined using linear pseudo-first-order and pseudo-second-order. The results showed that MO and EY dye adsorption onto zeolite Y followed a pseudo-second-order kinetic model. Thermodynamic studies show that adsorption was an exothermic reaction (enthalpy < 0) and feasible ( (G i b b s f r e e e n e r g y) < 0 ) at various temperatures under investigation. [ABSTRACT FROM AUTHOR]

Nanofibers have attracted a lot of interest in the biomedical field. Researchers in biomedical field are highly interested in polyethersulfone/polyvinylpyrrolidone (PES/PVP)-zeolite hybrid composite nanofiber. This research study on the development of biocompatible hybrid nanofiber containing zeolite, nanofiber membranes based on polyestersulfone as the first component and polyvinylpyrrolidone loaded with zeolite as the second component were prepared using the double axials electrospinning method. 3-(4,5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide results and cell culture also showed that the PES/PVP-zeolite hybrid nanofiber scaffolds made in this study have excellent compatibility for the growth of L929 fibroblasts. Therefore, PES/PVP-zeolite hybrid nanofiber can provide biomedical applications. [ABSTRACT FROM AUTHOR]

The need for prehospital hemostatic dressings that exert an antibacterial effect is of interest for prolonged field care. Here, we consider a series of antibacterial and zeolite formulary treatment approaches applied to a cotton-based dressing. The design of the fabric formulations was based on the hemostatic dressing TACGauze with zeolite Y incorporated as a procoagulant with calcium and pectin to facilitate fiber adherence utilizing silver nanoparticles, and cellulose-crosslinked ascorbic acid to confer antibacterial activity. Infra-red spectra were employed to characterize the chemical modifications on the dressings. Contact angle measurements were employed to document the surface hydrophobicity of the cotton fabric which plays a role in the contact activation of the coagulation cascade. Ammonium Y zeolite-treated dressings initiated fibrin equal to the accepted standard hemorrhage control dressing and showed similar improvement with antibacterial finishes. The antibacterial activity of cotton-based technology utilizing both citrate-linked ascorbate-cellulose conjugate analogs and silver nanoparticle-embedded cotton fibers was observed against Staphylococcus aureus and Klebsiella pneumoniae at a level of 99.99 percent in the AATCC 100 assay. The hydrogen peroxide levels of the ascorbic acid-based fabrics, measured over a time period from zero up to forty-eight hours, were in line with the antibacterial activities. [ABSTRACT FROM AUTHOR]

The ZnO/Zeolite composite was obtained by the method of deposition of zinc oxide on the surface of hydrogen form of the faujasite-type Zeolite Y that was impregnated with a hydrolysis product of zinc acetate precursor and calcinated at 300 °C for this. The deposition of zinc oxide covering the nanoparticles of the initial Zeolite was confirmed by SEM. The zinc oxide phase of the hexagonal syngony of the wurtzite type with a content of 20 wt. % in the synthesized ZnO/Zeolite composite was proved by XRD and XRF. The BET surface, the total, and the micropore volume of the initial Zeolite decreased, and the average pore size rose as a result of ZnO deposition. The centers with pKa = 9.45 which were OH− groups attached to the edge regions of the surface doubled after zinc oxide deposition on the Zeolite since ZnO nanoparticles tended to interact with the water molecule. That was the very reason for the advanced photocatalytic activity of ZnO/Zeolite composite toward the anionic dye. Congo red dye (8.0, 25.0, and 50.0 mg/L) was decolorized completely for only 1 min, but methylene blue dye (8.0 mg/L) decomposed incompletely even after 1 h of UV irradiation. [ABSTRACT FROM AUTHOR]

A method for the separation of a mixture of n-pentane and neopentane using a nano-crystallite of zeolite Y is reported. This method judiciously combines two well-known, counter-intuitive phenomena, the levitation and the blowtorch effects. The result is that the two components are separated by being driven to the opposite ends of the zeolite column. The calculations are based on the non-equilibrium Monte Carlo method with moves from a region at one temperature to a region at another temperature. The necessary acceptance probability for such moves has been derived here on the basis of stationary solution of an inhomogeneous Fokker–Planck equation. Simulations have been carried out with a realistic and experimentally relevant Gaussian hot zone and also a square hot zone, both of which lead to very good separation. Simulations without the hot zones do not show any separation. The results are reported at a loading of 1 molecule per cage. The temperature of the hot zone is just ∼30 K higher than the ambient temperature. The separation factors of the order of 1017 are achieved using single crystals of zeolite, which are less than 1 μm long. The conditions for including the hot zone may be experimentally realizable in the future considering the rapid advances in nanoscale thermometry. The separation process is likely to be energetically more efficient by several orders of magnitude as compared to the existing methods of separation, making the method very green. [ABSTRACT FROM AUTHOR]

To handle huge amount of glycerol produced in biodiesel industry, glycerol is transformed to value-added products. In this regard, glycerol acetalization to solketal is industrially attractive. As in this process various by-products can be formed, designing highly selective catalysts is of great importance. In this line, we wish to report a novel catalyst that benefits from strong acidity, high specific surface area and thermal stability, which can selectively form solketal in glycerol acetalization. To prepare the catalyst, hierarchical zeolite was prepared via a novel method, in which partially dealuminated NaY was treated with PluronicF-127 and then reacted with NH4NO3 to furnish the H-form zeolite. Hierarchical faujasite was then achieved through calcination and template removal. Subsequently, it was functionalized with ionic liquid and used for the immobilization of heteropolyacid. The results indicated the importance of the mesoprosity of zeolite and the presense of ionic liquid functionality for achiveing high solketal yield. Moreover, among three investigated heteropolyacids, phosphomolybdic acid exhibited the highest catalytic activity. In fact, using 10 wt% catalyst at 55 °C and glycerol to acetone molar ratio of 1:20, solketal with yield of 98% was furnished under solvent-less condition. Besides, the catalyst was recyclable with low leaching of heteropolyacid. [ABSTRACT FROM AUTHOR]

Micro-mesoporous zeolite shows great potential in the field of fuel denitrogenation. However, the current preparation method of zeolite with composite pores still has the problems of high cost and low denitrification rate. Herein, we prepared a low-cost phosphorus doped zeolite by directly impregnated Y zeolite in phosphoric acid and calcinated at 400 °C firstly. Experimental results showed that phosphorus doped 10 wt.% PA/MY provided optimum denitrogenation performance with denitrogenation rate as high as 97% compared to unmodified MY zeolite (21.11%) and ion exchanged 1.0 MHY zeolite (91.38%). What's more, it was found that the introduction of phosphorus led to the formation of P–O tetrahedra and Al–O–P bonds in zeolite, which increased the amount of mesopore and the Lewis acid in zeolite. Meanwhile, the comparative study found that ion exchanged MHY zeolite depended on the limited pore matching effect of micropores and nitrogen-containing molecules and the chemisorption reaction of non-regenerable Brøsted acid to achieve denitrogenation performance. However, phosphorus doped zeolite PA/MY not only had a better size matching effect between the mesopore and the size of nitrogen-containing molecules, but also had more Lewis acid to play a major role in denitrogenation. The Lewis acid on PA/MY zeolite also had the advantage of being easy to regenerate by desorption of the nitrogen-containing molecules absorbed. This study showed good prospects for the industrial application of the doped zeolite. [ABSTRACT FROM AUTHOR]

Isomorphous substitution of Zn-Y zeolite (Zn-DYZ) was successfully conducted with different Zn/Al ratios of 0.5:9.5, 1:9, 1.5:8.5, and 2:8 mol ratios (hereafter designed as Zn-DZY-1, Zn-DZY-2, Zn-DZY-3, and Zn-DZY-4, respectively) by the hydrothermal synthesis method. Spectroscopic studies indicate that Zn is decorated into the zeolite framework. The insertion of Zn instead of Al in the zeolite framework in small amounts (0.5:9.5, 1:9 mol ratios of Zn/Al) does not affect the zeolite framework. However, at high Zn loading (mainly Zn-DZY-4, 2:8 mol ratio), the zeolite structure collapse due to the imbalance in electrical charge, as confirmed by XRD analysis. In addition, by increasing the loading of Zn, the deviation of d-spacing and shift in the peak position of the XRD pattern occurs, which is related to the radius of zinc ion compared to aluminum, thus causing the lattice expansion. A significant increase in BET surface area and pore volume was observed in Zn-DZY toward NaY (870 toward 906.5 and 0.37 cm3 g−1 towards 0.392 cm3 g−1, respectively), which may be related to the expansion of the zeolite framework because of the replacement of Zn instead to that of Al. These results confirm by XPS data. The XPS results show two different chemical environments are related to Al-O-Zn and Si–O-Zn with bit shifts. In addition, the peak position is higher than toward ZnO which is a significant reason for the formation of ZnO42− in the zeolite framework. The photocatalytic activity of the related catalysts is investigated in the removal of methyl orange. The effect of several parameters including catalyst loading, pH, dye contamination, and zinc loading was studied in the photodegradation process. The best results were obtained in the presence of 32 ppm methyl orange, 70 mg catalyst, pH = 7, and 1:9 Zn/Al ratio under UV irradiation. It was found that the photodegradation kinetics follows pseudo-first-order kinetics. COD experiment was used to measure the mineralization of methyl orange (69%). In addition, the activation energy Ea = 64,498.18 kJ mol−1 and ln A = 2.8079 kJ mol−1 was achieved based on the Arrhenius equation. Moreover, the antibacterial activity of Zn-DZY-2 is increased toward NaY for both E. coli and S. aureus. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to prepare Polystyrene grafted with Zeolite Y (Zeosty) for Uranyl ion [U(VI)] adsorption from aqueous solution. The adsorption mechanism has been explained by studying kinetic, isothermal and thermodynamic models. Design/methodology/approach: Polystyrene was grafted with Zeosty by a simple hydrothermal technique. Zeosty was characterized by different techniques such as X-ray diffraction, scanning electron microscope, energy dispersive X-ray and Infrared spectroscopy to confirm its structure and its molecular composition. Zeosty was used for U(VI) adsorption from an aqueous solution in a series of batch experiments. The effects of pH, contact time, initial U(VI) concentration and temperature on the adsorption process were investigated. Findings: The results showed that the adsorption of U(VI) on the prepared reached equilibrium at pH 6 with a removal efficiency of 98.9%. Adsorption kinetics and isotherms models are studied on the experimental data to estimate the mechanism of the adsorption reaction was chemisorption and homogenous reaction. The activity of Zeosty increased at high temperatures, resulting in the adsorption capacity increase. Thermodynamic parameters ΔGo, ΔHo and ΔSo indicate that the adsorption processes are spontaneous and endothermic. Zeosty has an effective surface and could be considered a valuable adsorbent for U(VI) removal from aqueous waste. A comparison study proves that the new adsorbent has high effective behavior in the adsorption process, and it is considered a new reliable adsorbent for U(VI) removal from wastewater. Originality/value: This study is complementary to the previous study using the same technique to prove that the effective fine particle adsorbents need solid support to enhance their absorption capacities. [ABSTRACT FROM AUTHOR]

In this paper, the composition and properties of two different activated calcinated clays were investigated under selected curing conditions. The tendency of metabentonite and metakaoline to form geopolymers and zeolites was investigated by FTIR spectroscopy, TGA and DSC techniques, PXRD, HT-PXRD, SEM, and BET-N2 adsorption analyses. The selection of the optimal sample compositions was done on a basis of preliminary results obtained from bentonite and kaolin clays activated at calcination temperatures (700, 750, 800 °C) with a holding time of 3 h in a combination with different NaOH concentrations (5, 10, 20 mass%). In a more detailed examination, the samples calcined at a temperature of 800 °C with different NaOH concentrations were studied. For metakaolin-based samples, dominant geopolymer formation was achieved using 5 mass% NaOH. The zeolite amount increased concomitantly with the concentration of the alkali activator, whereas zeolite A and zeolite P were determined as the predominant phases. For metabentonite-based samples, 10 mass% NaOH concentration was found to be optimal by the means of geopolymer formation. At higher alkaline activator concentrations, the presence of zeolitic phases faujasite and gobbinsite was confirmed. However, the determined degree of crystallinity was significantly lower than in the corresponding activated metakaolin samples. With a gradual increase in NaOH concentration, the specific surface area of the metabentonite-based samples increased reaching a value of 218.95 m2 g−1 promising for adsorption applications. The opposite effect was observed for the metakaolin-based samples, and this result is caused by the increased formation of zeolite phases and corresponding changes in their channel dimensions. [ABSTRACT FROM AUTHOR]

The present study proposed fabricating an industrially feasible zeolite membrane on an indigenously developed inexpensive tubular ceramic substrate. A type of zeolite framework, Faujasite, was deposited on the substrate using source materials, such as alumina and silica, by hydrothermal treatment. The membrane was characterised by XRD, FESEM, zeta potential, and contact angle analyses. Distinguishable physical and structural characteristics of the zeolite membrane from ceramic substrate substantiated a formation of the composite membrane. Further, the potentiality of the membrane was assessed on the removal of hexavalent chromium from synthetic wastewater at various operating parameters in a crossflow system. The prepared membrane offered a maximum chromium removal of 82% with a flux of 5.05 × 10-5 m³m-2s-1 at the operating conditions of 1,000 ppm concentration, 345 kPa pressure, and 1.11 × 10-6 m³s-1 crossflow rate. The membrane revealed its essential employment by providing a higher flux with better rejection than other membranes applied in chromium removal. [ABSTRACT FROM AUTHOR]

Hydrothermal liquefaction (HTL) is the direct conversion of wet biomass into bio‐oil at high temperature (200–400°C) and high pressure (10–25 MPa). In this work, we investigated HTL with 4.5 g of Chlorella and 45 ml of water/ethanol (1:1 vol. ratio) in a 100 ml reactor. Bio‐oils produced are characterized via elemental analysis, thermogravimetric analysis, and gas chromatography–mass spectrometry (GC–MS). HTL of Chlorella was investigated at 240 and 250°C for 0 and 15 min under an air or H2 atmosphere and with and without 5% zeolite Y. Temperature increased the bio‐oil yield from 38.75% at 240°C to 43.04% at 250°C for 15 min reaction time. Longer reaction time increased the bio‐oil yield at 250°C from 39.14% for 0 min to 43.04% for 15 min. The H2 atmosphere had a significant effect for HTL at 240°C. Zeolite Y increased the bio‐oil yield significantly from 32.03% to 43.06% at 250°C for 0 min. The carbon content of bio‐oil increased with the temperature while the oxygen content decreased. The boiling point distribution of bio‐oils in the range of 110–300°C varies with temperature, and atmosphere. At 240°C for 15 min, the 110–300°C range increased from 31.19% in air (240‐15‐air) to 39.25% in H2 (240‐15‐H2). The H2 atmosphere increased the content of hydrocarbons, alcohols, and esters from 69.61% in air (240‐0‐air) to 82.83% in H2 (240‐0‐H2). Overall, temperature, reaction time, atmosphere, and catalyst all significantly influenced the yield and/or quality of bio‐oils from HTL of Chlorella. [ABSTRACT FROM AUTHOR]

[Display omitted] • Glucose isomerization is performed in different solvents using metal doped zeolite Y. • Ethanol favours fructose production, methanol favours alkyl fructoside production. • Nature of acid sites differs within the pore and outside of the pore. • NMR relaxation confirms that mechanism is dependent on pore uptake of solvent used. • DRIFTS measurements show that metal doping increase Lewis acidity of zeolite Y. Sn and Ga doped zeolite Y catalysts were tested for the isomerization of glucose to fructose carried out in different solvents (water, methanol and ethanol). Therein, ethanol favoured a Lewis acid site catalyzed pathway that promotes glucose isomerization to fructose, whereas methanol resulted in an equal distribution of products (mannose, fructose and alkyl fructoside). In contrast, the catalysts were totally inactive in water solvent. NMR relaxation measurements, including solvent displacement experiments, suggested that the lack of catalytic activity in water is due to the strong adsorption of this solvent within the zeolite pores blocking reactants from the Lewis acid sites active for the sugar isomerization. In comparison, ethanol adsorbs relatively more strongly than methanol, hence is retained in the pores where solvated fructose is preferentially prevented from the further reaction on Brønsted acid sites situated outside of the pore space. NMR relaxation measurements using pyridine and tetrahydrofuran (THF) and pyridine-DRIFTS measurements suggest metal doping had little effect on the overall relative acid strength of the zeolites but resulted in zeolites with increased Lewis acid strength relative to the non-doped zeolites. The results reported provide direct experimental evidence on the importance of adsorption properties of solvents within zeolites used for glucose to fructose isomerization and may serve as a starting point for a new approach towards designing and optimizing such catalytic systems. [ABSTRACT FROM AUTHOR]

In this study, zeolite Y was synthesized from sodium silicate, aluminum hydroxide, sodium hydroxide and distilled water under hydrothermal method. The Box–Behnken design was used as a response surface method considering seven factors affecting the crystallization of zeolite to determine the number of experiments. The linear, square and interaction effects of the factors were investigated. The factors consist of four factors for the gel composition, including the molar value of Si, Al, Na and H2O and three factors for the synthesis conditions, including aging time, crystallization time and temperature. The XRD patterns of the synthesized samples were compared with the XRD pattern of standard zeolite Y. Among the samples, sample 50 with the highest intensity and maximum total area of 14 peaks, was selected as the reference sample and it was used to determine the relative crystallinity percentage of the remaining samples. Based on the results of the experiments, it was concluded that changes in the gel composition have a more significant effect on the response in comparison with changes in the synthesis conditions. In addition, optimization of the obtained model was carried out and a zeolite with higher relative crystallinity than the standard zeolite Y was synthesized. At the optimal point, zeolite Y was synthesized with a relative crystallinity of 117.5%. The composition of the gel was 0.59 SiO2: 0.0563 Al2O3: 0.4266 Na2O: 12.376 H2O. The total synthesis time was 30 h. [ABSTRACT FROM AUTHOR]

Fluid catalytic cracking (FCC) is one of the most important processes in gasoline/diesel oil production, but the strong endothermic effect accompanied by this reaction often results in the deactivation of the catalyst. In this paper, a novel multifunctional phase change material (PCM)@Catalyst composite was designed and constructed, in which the PCM could be used to store waste heat and regulate the temperature for enhancing the catalytic efficiency of the FCC catalyst. Firstly, a core/shell Al-12wt%Si@Al2O3 was prepared via subsequent vapor treatment and high-temperature calcination of an Al-12wt%Si sphere. The Al species in the Al-12wt%Si served as the source of metal ions and was transformed in situ into a well-defined Al2O3 shell, which greatly improved the thermal stability and prevented the leaking of the Al-12wt% Si core in the high-temperature situation. The PCMs@Catalyst composite was then fabricated by casting the mixed powder of Al-12wt%Si@Al2O3 and Y zeolite into a granulated structure. The FCC results demonstrate that Al-12wt%Si@Al2O3/Y zeolite can optimize product distribution and reduce coke yield. This design concept and synthesis strategy can be extended to the production of a wide variety of hierarchical PCM@Catalyst composites for other reactions. [ABSTRACT FROM AUTHOR]

A sustainable defect‐engineering strategy for the dealumination of Y zeolite is described. This strategy includes the green synthesis of a well‐crystallized Y zeolite with point defects arising from the incorporation of Fe atoms by using Fe‐containing perlite and the subsequent preparation of ultra‐stable Y (USY) zeolite by efficient steaming dealumination. The systematic characterizations verify that Fe atoms originally existing in the perlite are incorporated into the as‐synthesized Y zeolite and function as point defects, leading to the distortion of framework Al. The step‐by‐step investigation of dealumination process shows that vacancies are formed by the extraction of framework Fe in ammonium exchange, and the framework dealumination is promoted under the combined effect of the distorted framework Al and the formed vacancies during steaming treatment. The resulting USY zeolite owns excellent features in (hydro)thermal stability, pore structure and acid property, and exhibits outstanding catalytic performance in the cracking of n‐octane and 1,3,5‐triisopropylbenzene. [ABSTRACT FROM AUTHOR]

A promoted NaY zeolite ion exchanged by Cu, Zn, Co, and Ni characterized by XRD, FESEM, BET surface area, TGA, and XRF techniques, and evaluated in desulfurization of diesel fuels as an adsorbent. Commercial diesel fuel containing 2020 ppm sulfur-containing materials is used as feed, which is reduced to 89, 75, 78, and 75 ppm by Co, Ni, Cu, and Zn ion-exchanged zeolite Y, respectively. Also, the recycle life results exhibited a high thermal and chemical stability of prepared adsorbents at 4500C. It showed that the desulfurization capacity of prepared zeolites is stable after seven cycles of the adsorption process. The optimum calcination temperature showed that the most of adhered organic molecules were eliminated from the adsorbents between 450 and 5000C. The contact time result showed that more than 92% of the desulfurization process has done in the initial 10 min. The diesel efficiency yield results showed that the most of diesel have released after the desulfurization process, and Cu, Co, Zn, and Ni ion-exchanged zeolites passed about 94, 90, 87, and 91% refined diesel after desulfurization, respectively. Therefore, an ion-exchanged zeolite Y has been considered a useful adsorbent for industrial applications. [ABSTRACT FROM AUTHOR]

Zeolite Y samples with microporous and hierarchical structures containing Ti–Ni and Ti–Co oxides were obtained as active photocatalysts. Different Ti amounts (5, 10% TiO2) were supported, followed by the loading of Ni or Co oxides (5%). X-ray diffraction evidenced the presence of TiO2 as an anatase. N2 adsorption–desorption results showed type IV isotherms for hierarchical zeolite Y samples, and a combination of type IV and I isotherms for zeolite Y samples. UV–Vis diffuse reflectance spectra showed a shift in the absorption band to visible with increasing Ti loading and especially after Co and Ni addition. A significant effect of the support was evidenced for Ti and its interaction with Co/Ni species. The zeolite Y support stabilized Ti in the 4+ oxidation state while hierarchical zeolite Y support favored the formation of Ti3+ species, Ni0 and Ni2+ and the oxidation of Co to 3+ oxidation state. Photocatalytic activity, under UV and visible light irradiation, was evaluated by the degradation of amoxicillin, used as a model test. The photocatalytic mechanism was investigated using ethanol, p-benzoquinone and KI as ·OH and ·O2− radicals and hole (h+) scavengers. The best results were obtained for the immobilized Ni-Ti species on the hierarchical zeolite Y support. [ABSTRACT FROM AUTHOR]

Extensive research has been conducted on platinum nanoparticles or clusters supported on zeolite for various catalytic applications, primarily due to the well-defined structure contained within the pore. The preparation and characterization of these particles have been thoroughly examined using advanced techniques such as X-ray absorption fine structures (XAFSs), both in situ and ex situ. In this study, we employed the Wavelet method to analyze the structure of platinum nanoparticles encapsulated within the supercage of a Y zeolite, where XAFS data were collected over a temperature range of 100 K to 423 K, both with and without hydrogen. The adsorption of hydrogen caused a relaxation in the structure of the platinum nanoparticles, thus leading to a decrease in the Pt–Pt distance and resulting in a lower Debye–Waller factor compared to bare nanoparticles. This structural change induced by hydrogen chemisorption aligns with the findings of the density functional theory (DFT) calculations for Pt13 nanoparticles located in the supercage. The relaxation of the structure results in charge redistribution, thereby ultimately generating atomic hydrogen with a partial negative charge, which is crucial for catalytic processes. [ABSTRACT FROM AUTHOR]

Iron inclusion in the composition of the zeolite crystal structure endows it with new and useful properties. However, direct synthesis involving Fe, frequently creates unfavorable conditions that hinder the crystallization process and generate impurity phases. For this reason, novel methods, which include iron within the zeolitic matrix, are being sought out. This article presents a one-pot synthesis of iron-modified zeolite X. The resulting materials were characterized, and their textural, electrical, and magnetic properties were studied. [ABSTRACT FROM AUTHOR]

In this work, two palladium-based catalysts with either ZSM-5 or Zeolite Y as support material are tested for their performance in selective catalytic reduction of NOx with hydrogen (H2-SCR). The ligh-toff measurements in synthetic exhaust gas mixtures typical for hydrogen combustion engines are supplemented by detailed catalyst characterization comprising N2 physisorption, X-ray powder diffraction (XRD), hydrogen temperature programmed reduction (H2-TPR) and ammonia temperature programmed desorption (NH3-TPD). Introducing 10% or 20% TiO2 into the catalyst formulations reduced the surface area and the number of acidic sites for both catalysts, however, more severely for the Zeolite Y-supported catalysts. The higher reducibility of the Pd particles that was uncovered by H2-TPR resulted in an improved catalytic performance during the light-off measurements and substantially boosted NO conversion. Upon exposition to humid exhaust gas, the ZSM-5-supported catalysts showed a significant drop in performance, whereas the Zeolite Y-supported catalyst kept the high levels of conversion while shifting the selectivity from N2O more toward NH3 and N2. The 1%Pd/20%TiO2/HY catalyst subject to this work outperforms one of the most active and selective benchmark catalyst formulations, 1%Pd/5%V2O5/20%TiO2-Al2O3, making Zeolite Y a promising support material for H2-SCR catalyst formulations that allow efficient and selective NOx-removal from exhaust gases originating from hydrogen-fueled engines. [ABSTRACT FROM AUTHOR]

Exhaustion of fossil resources and deterioration of the ecosystems have led to the development of environmentally friendly processes of "green" chemistry and the active use of renewable bioresources such as carbohydrates. 5-Hydroxymethylfurfural (5-HMF) is a promising platform substance which can be used as feedstock for syntheses for new generation of biopolymer materials, fuels, pharmaceuticals, pesticides, food additives and a number of other important chemicals. Polycationic forms of faujasite zeolites are characterized by Brønsted and Lewis acidity. They are known to be effective catalysts for a range of petrochemical reactions. Therefore, the aim of this research was to study the activity of polycationic faujasite zeolite catalysts in glucose conversion into 5-HMF. A number of polycationic samples of similar chemical composition were synthesized under different hydrothermal conditions. The obtained catalysts were characterized by using FTIR spectroscopy, pyridine adsorption, ammonia TPD, low-temperature nitrogen adsorption/desorption, and DTA/TG. Having similar chemical composition, the synthesized samples were characterized by different Brønsted to Lewis acidity ratio, by the additional occurrence of extra-framework alumina at high temperatures. The main product of glucose conversion was 5-HMF. The samples subjected to modification under mild hydrothermal conditions were observed to show the highest acidity and the best catalytic performance in glucose dehydration. The yields of 5-HMF were found to increase with increasing number of medium-strength acid sites in the samples. Glucose dehydration over polycationic faujasite zeolites proceeds with up to 40–50% 5-HMF yields and 50% selectivity. The greater the weight loss of catalysts in DTA/TG investigations, the greater were the yields of 5-HMF in glucose conversion. Weight losses correlate with acidity of the catalysts. Therefore, polycationic faujasite zeolites can be considered as promising catalysts for glucose conversion into 5-HMF, warranting further studies in this direction. [ABSTRACT FROM AUTHOR]

In this paper, the sorption of NH3, H2O, SO2 and CO2 was tested for several selected inorganic materials. The tests were performed on samples belonging to two topologies of materials, faujasite (FAU) and framework-type MFI, the structures of which differ in pore size and connectivity. All sorbates are important in terms of reducing their emissions to the environment. They have different chemical nature: basic, alkaline, and acidic. They are all polar in structure and composition and two of them (ammonia and water vapor) can form hydrogen bonds. These differences result in different interactions with the surface of the adsorbents. This paper presents experimental data and proposes a mathematical description of the sorption process. The best fit of the experimental data was obtained for the Toth and GAB models. The studies showed that among the selected samples, faujasite has the best sorption capacity for ammonia and water vapor, while the best sorbent for sulfur dioxide is the MFI framework type. These materials behave like molecular sieves and can be used for quite selective adsorption of relevant gases. In addition, modification of the faujasite with organic silane resulted in a drastic reduction in the surface area of the sorbent, resulting in significantly lower sorption capacities for gases. [ABSTRACT FROM AUTHOR]