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Hydrofluorocarbons are a class of fluorinated molecules used extensively in residential and industrial refrigeration systems. This study examines the potential of using adsorption processes with the silicalite-1 zeolite to separate a mixture of difluoromethane (CH2F2, HFC-32) and pentafluoroethane (CF3CF2H, HFC-125) at various concentrations. Pure adsorption data were measured using a XEMIS gravimetric microbalance, whereas binary data were determined using the Integral Mass Balance method. Grand canonical Monte Carlo molecular simulations were performed with the Cassandra package. We found that the results from molecular simulations are in satisfactory agreement with experimental loading measurements. Moreover, we show that ideal adsorbed solution theory could not quantitatively match the experimental or computational measurements of binary adsorption or selectivity. Molecular simulations show that refrigerant molecules do not have a uniform distribution in the zeolite framework. [ABSTRACT FROM AUTHOR]

In the liquid phase of heterogeneous catalysis, solvent plays an important role and governs the kinetics and thermodynamics of a reaction. Although it is often difficult to quantify the role of the solvent, it becomes particularly challenging when a zeolite is used as the catalyst. This difficulty arises from the complex nature of the liquid/zeolite interface and the different solvation environments around catalytically active sites. Here, we use ab initio molecular dynamics simulations to probe the local solvation structure and dynamics of methanol and water over MWW zeolite nanosheets with varying Brønsted acidity. We find that the zeolite framework and the number and location of the acid sites in the zeolite influence the structure and dynamics of the solvent. In particular, methanol is more likely to be in the vicinity of the aluminum (Al3+) at the T4 site than at T1 due to easy accessibility. The methanol oxygen binds strongly to the Al at the T4 site, weakening the Al–O for the bridging acid site, which results in the formation of the silanol group, significantly reducing the acidity of the site. The behavior of methanol is in direct contrast to that of water, where protons can easily propagate from the zeolite to the solvent molecules regardless of the acid site location. Our work provides molecular-level insights into how solvent interacts with zeolite surfaces, leading to an improved understanding of the catalytic site in the MWW zeolite nanosheet. [ABSTRACT FROM AUTHOR]

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]

Zeolites are microporous crystalline materials that find a very wide range of applications, which, however, are limited by the size and dimensionality of their pores. Stable silica zeolites with a three‐dimensional (3D) system of extra‐large pores (ELP, i.e. pores with minimum windows along the diffusion path consisting of more than 12 SiO4/2 tetrahedra, 12R) are in demand for processing larger molecules than zeolites can currently handle. However, they have challenged worldwide synthetic capabilities for more than eight decades. In this review we first present a brief history of the discovery of ELP zeolites. Next, we show that earlier successes of zeolites with 3D ELP were not actually zeolites, but rather interrupted structures with, in addition, a composition that severely detracted from their stability. Finally, we present three new fully connected stable silica‐based 3D ELP zeolites ZEO‐1, ZEO‐3 and ZEO‐5, discuss their preparation methods and stability as well as the clear advantage of their increased porosity in catalysis and adsorption processes involving large molecules. We will discuss peculiar characteristics of their preparation and present two new reaction types giving rise to zeolites (1D‐to‐3D topotactic condensation and interchain expansion), highlighting how new synthesis methods can provide materials that would otherwise be unfeasible. [ABSTRACT FROM AUTHOR]

The CH4 oxidation performance of Cu‐chabazite zeolites characterized by distinct Si/Al ratios and Cu loadings has been studied and the observed variations in reactivity have been correlated to the differences in the nature of the formed active centers. Plug flow reactor tests, in situ Fourier‐transform infrared, and X‐ray absorption spectroscopy demonstrate that a decrease in Cu loading shifts the reactivity/redox profile to higher temperatures and increases the CH3OH selectivity and Cu‐efficiency. In situ electron paramagnetic resonance, Raman, ultraviolet‐visible, Fourier‐transform infrared, and photoluminescence spectroscopies reveal that this behavior is associated with the presence of monomeric Cu active sites, including bare Cu2+ and [CuOH]+ present at low Si/Al ratio and Cu loading. Formation of two distinct [Cu2(μ‐O)]2+ moieties at higher Si/Al ratio or Cu loading forces these trends into the opposite direction. Operando electron paramagnetic resonance and ultraviolet‐visible spectroscopy show that the apparent activation energy of monomeric Cu active species decreases with increasing Si/Al ratio, whereas the one of dimeric centers is unaffected. [ABSTRACT FROM AUTHOR]

The legal obligation to swiftly adopt renewable energies has been increased because of the continuous usage of fossil fuels. In this perspective, biomass serves as a pillar to improve the current conditions over different heterogeneous catalysts due to their known advantages. This work is focused on the synthesis of a novel catalyst comprising mono lacunary phosphotungstate and zeolite HY. The catalyst was characterized by number of physicochemical techniques and evaluation of the activity of catalyst for the esterification of most promising bio platforms, levulinic acid and succinic acid to produce fuel additives. After a detailed optimization of both reactions, remarkable conversions of levulinic acid (77%) and succinic acid (96%) with turnover numbers of 2749 and 3427 respectively, were obtained. The order of the reaction and activation energy for the said reactions were calculated in the kinetic study. The sustainable nature of the catalyst was confirmed via regeneration and viability towards other bio-based molecules which enhances its industrial importance. [ABSTRACT FROM AUTHOR]

In this research, a series of consolidated drained compression triaxial tests were carried out to investigate the mechanical performance of Babolsar sand. Next, the parameters such as cement zeolite substitution percentage, cement content, and curing time were determined. The results revealed significant mechanical strength of specimens by replacing zeolite up to 35% compared with cemented sand mixtures for all ranges of cement percentages. Also, the samples showed more ductile behaviour due to increasing strains at failure. Increasing the zeolite substitution by up to 35% generated shearing band failure. However, exceeding the 35% substitution, the barrelling shear mode was predominant. All samples were compressed initially until reaching a point of instant zero dilation and then dilated until the end of the tests. The dilation tendency was higher in zeolite percentages up to 35%. Moreover, increasing the cement content enhanced the dilation of specimens due to hardening and interlocking cement and sand with zeolite. Finally, microstructure analysis results showed the Si/Ca ratio as a key index to approximate triaxial shear strength development. [ABSTRACT FROM AUTHOR]

Renewable and sustainable energy production has gained significant attention to meet sustainable development goals (SDGs). Pine needles, an abundant typical forestry residue, can be used as a renewable biomass source for sustainable energy production. Pyrolysis is a well‐established and commercialized technique for the thermochemical valorization of lignocellulosic biomass. The present work focuses on improving the bio‐oil yield by introducing SiO2‐Al2O3‐based catalysts, including different zeolites and SiO2‐Al2O3 materials with varying SiO2‐Al2O3 ratios, during the pyrolysis. Bio‐oil yield increased from 45.2 wt.% to 47.2 wt.% with the introduction of SiO2‐Al2O3 catalysts and increased to 51.2 wt.% and 50.6 wt.% with HZSM‐5 and Y‐zeolite, respectively, and decreased to 40.0 wt.% with β‐zeolite catalyst. The pyrolysis experiments of physically mixed biomass and catalyst were carried out in a fixed‐bed down‐flow reactor. Various process parameters such as temperature, retention time, and catalyst‐to‐biomass ratio were examined to evaluate their effect on product yield. The catalyst's introduction slightly decreased phenolic compound content, enhancing carbonyl and hydrocarbon production. Maximum improvement in bio‐oil yield by 6 wt.% was achieved using an H‐ZSM‐5 catalyst at 450°C temperature and 30 min residence time with a catalyst‐to‐biomass ratio of 1:4. [ABSTRACT FROM AUTHOR]

Framework materials such as zeolites and mesoporous silicas are commonly used for many applications, especially catalysis and separation. Here zeolite-mesoporous silica composite catalysts (employing zeolite Y, ZSM-5, KIT-6, SBA-15 and MCM-41 mesoporous silica) were prepared (with different weight percent of zeolite Y and ZSM-5) and assessed for catalytic cracking (using n-heptane, as the model compound at 550 °C) with the aim to improve the selectivity/yield of light olefins of ethylene and propylene from n-heptane. Physicochemical properties of the parent zeolites and the prepared composites were characterized comprehensively using several techniques including X-ray diffraction, nitrogen physisorption, scanning electron microscopy, fourier transform infrared spectroscopy, pulsed-field gradient nuclear magnetic resonance and thermogravimetric analysis. Catalytic cracking results showed that the ZY/ZSM-5/KIT-6 composite (20:20:60 wt %) achieved a high n-heptane conversion of 85% with approximately 6% selectivity to ethylene/propylene. In contrast, the ZY/ZSM-5/SBA-15 composite achieved a higher conversion of 95% and an ethylene/propylene ratio of 8%, indicating a more efficient process in terms of both conversion and selectivity. Magnetic resonance relaxation analysis of the ZY/ZSM-5/KIT-6 (20:20:60) catalyst confirmed a micro-mesoporous environment that influences n-heptane diffusion and mass transfer. As zeolite Y and ZSM-5 have micropores, n-heptane can move and undergo hydrogen transfer reactions, whereas KIT-6 has mesopores that facilitate n-heptane’s accessibility to the active sites of zeolite Y and ZSM-5. [ABSTRACT FROM AUTHOR]

This perspective discusses three alternative techniques which complement conventional infrared spectroscopy for obtaining vibrational information about zeolite catalysts and adsorbed molecules: inelastic neutron scattering, infrared micro-spectroscopy, and two-dimensional infrared spectroscopy. The techniques are illustrated briefly and future prospects for their use discussed. [ABSTRACT FROM AUTHOR]

Zeolites contain proton active sites in diverse void environments that stabilize the reactive intermediates and transition states formed in converting hydrocarbons and oxygenates to chemicals and energy carriers. The catalytic diversity that exists among active sites in voids of varying sizes and shapes, even within a given zeolite topology, has motivated research efforts to position and quantify active sites within distinct voids (synthesis–structure) and to link active site environment to catalytic behavior (structure–reactivity). This Feature Article describes advances and challenges in controlling the position of framework Al centers and associated protons within distinct voids during zeolite synthesis or post-synthetic modification, in identifying and quantifying distinct active site environments using characterization techniques, and in determining the influence of active site environments on catalysis. During zeolite synthesis, organic structure directing agents (SDAs) influence Al substitution at distinct lattice positions via intermolecular interactions (e.g., electrostatics, hydrogen bonding) that depend on the size, structure, and charge distribution of organic SDAs and their mobility when confined within zeolitic voids. Complementary post-synthetic strategies to alter intrapore active site distributions include the selective removal of protons by differently-sized titrants or unreactive organic residues and the selective exchange of framework heteroatoms of different reactivities, but remain limited to certain zeolite frameworks. The ability to identify and quantify active sites within distinct intrapore environments depends on the resolution with which a given characterization technique can distinguish Al T-site positions or proton environments in a given zeolite framework. For proton sites in external unconfined environments, various (post-)synthetic strategies exist to control their amounts, with quantitative methods to distinguish them from internal sites that largely depend on using stoichiometric or catalytic probes that only interact with external sites. Protons in different environments influence reactivity by preferentially stabilizing larger transition states over smaller precursor states and influence selectivity by preferentially stabilizing or destabilizing competing transition states of varying sizes that share a common precursor state. We highlight opportunities to address challenges encountered in the design of active site environments in zeolites by closely integrating precise (post-)synthetic methods, validated characterization techniques, well-defined kinetic probes, and properly calibrated theoretical models. Further advances in understanding the molecular details that underlie synthesis–structure–reactivity relationships for active site environments in zeolite catalysis can accelerate the predictive design of tailored zeolites for desired catalytic transformations. [ABSTRACT FROM AUTHOR]

Uniform and minuscule Ru particles confined in NaY zeolite (Ru@NaY) are prepared via a simple in situ synthesis technique. Transmission electron microscopy studies indicate that the Ru particles are encapsulated within the micropores of NaY zeolite and form a uniform size of 1.5–3.5 nm. Thanks to the effective confinement of Ru particles within the NaY zeolite, as well as the high concentration of B-5 sites and basic sites, the prepared Ru@NaY catalysts show excellent NH 3 decomposition activity and highly efficient H 2 formation. Notably, the 0.1Ru@NaY catalyst achieves a 92.7% NH 3 conversion and a H 2 formation rate of 690 mmol min−1·g Ru −1 at 500 °C and GHSV = 9000 mLNH 3 ·g cat −1·h−1 and shows outstanding stability throughout a 95-h lifetime test. The encapsulation synthesis of Ru clusters in zeolites endows the catalysts with exceptional catalytic activities and excellent stability, thus providing new prospects for the production of H 2 from NH 3 decomposition. [Display omitted] • Ru particles confined within NaY zeolite were prepared via hydrothermal synthesis. • Ru nanoparticles are uniformly sized, highly distributed, and thermally stable. • Ru@NaY catalysts showed high activity and stability for ammonia decomposition. • High level B-5 sites and basic sites accounts for the superior activity of Ru@NaY. [ABSTRACT FROM AUTHOR]

As a fundamental industrial catalytic process, the semihydrogenation of alkynes presents a challenge in striking a balance between activity and selectivity due to the issue of over‐hydrogenation. Herein, we develop an efficient catalytic system based on single‐atom Pd catalysts supported on boron‐containing amorphous zeolites (Pd/AZ−B), achieving the tradeoff breaking between the activity and selectivity for the selective hydrogenation of alkynes. Advanced characterizations and theoretical density functional theory calculations confirm that the incorporated B atoms in the Pd/AZ−B can not only alter the geometric and electronic properties of Pd atoms by controlling the electron migration from Pd but also mitigate the interaction between alkene and the catalyst supports. This boosts the exceptional catalytic efficacy in the semihydrogenation of phenylacetylene to styrene under mild conditions (298 K, 2 bar H2), achieving a recorded turnover frequency (TOF) value of 24198 h−1 and demonstrating 95 % selectivity to styrene at full conversion of phenylacetylene. By comparison, the heteroatom‐free amorphous zeolite‐anchored Pd nanoparticles and the commercial Lindlar catalyst have styrene selectivities of 73 % and 15 %, respectively, under identical reaction conditions. This work establishes a solid foundation for developing highly active and selective hydrogenation catalysts by controllably optimizing their electronic and steric properties. [ABSTRACT FROM AUTHOR]

Methanol to aromatic reaction is an alternative pathway to produce aromatics from non‐petroleum resources. Zn‐modified ZSM‐5 zeolite is the widespread catalyst for MTA due to its high activity and selectivity to aromatics. However, a desired high yield of aromatics is usually accompanied with undesired coke formation and fast deactivation of catalyst, because aromatic molecules also serve as the precursor for coke formation. To decouple the aromatic yield and coke formation rate, in this work we use Zn‐ZSM‐5 to investigate coke formation and catalyst deactivation. The coke distribution along the catalyst bed was analyzed and its correlation with the concentration gradient of methanol, olefins and aromatics along the bed was deciphered. Coke was found to form very fast at catalyst bed in the copresence of methanol and aromatics. On the contrary, much less coke was observed at the later layers of the catalyst bed where methanol had been fully converted and aromatics were present in the highest concentration. Based on this finding, we adjusted the reaction conditions to successfully improve the yield of aromatics without reducing catalyst lifetime in compromise, by applying a higher methanol partial pressure that enables a faster consumption of methanol and reduces the period of copresence of methanol and aromatics. [ABSTRACT FROM AUTHOR]

The direct liquid‐phase oxidative carbonylation of methane, utilizing abundant natural gas, offers a mild and straightforward alternative. However, most catalysts proposed for this process suffer from low acetic acid yields due to few active sites and rapid C1 oxygenate generation, impeding their industrial feasibility. Herein, we report a highly efficient 0.1Cu/Fe‐HZSM‐5‐TF (TF denotes template‐free synthesis) catalyst featuring exclusively mononuclear Fe and Cu anchored in the ZSM‐5 channels. Under optimized conditions, the catalyst achieved an unprecedented acetic acid yield of 40.5 mmol gcat−1 h−1 at 50 °C, tripling the previous records of 12.0 mmol gcat−1 h−1. Comprehensive characterization, isotope‐labeled experiments and density functional theory (DFT) calculations reveal that the homogeneous mononuclear Fe sites are responsible for the activation and oxidation of methane, while the neighboring Cu sites play a key role in retarding the oxidation process, promoting C−C coupling for effective acetic acid synthesis. Furthermore, the methyl‐group carbon in acetic acid originates solely from methane, while its carbonyl‐group carbon is derived exclusively from CO, rather than the conversion of other C1 oxygenates. The proposed bimetallic catalyst design not only overcomes the limitations of current catalysts but also generalizes the oxidative carbonylation of other alkanes, demonstrating promising advancements in sustainable chemical synthesis. [ABSTRACT FROM AUTHOR]

The sonohydrothermal (SHT) treatment is an innovative technique allowing the simultaneous coupling of low frequency ultrasound and hydrothermal conditions for the synthesis of materials. The aim of the present work was to investigate, for the first time, the synthesis of zeolite A and its formation mechanism under SHT conditions. The zeolite synthesis was carried out under sonohydrothermal conditions using a specially designed reactor that allows the application of ultrasonic irradiation at 20 kHz in an autoclave-type reactor heated up to 200 °C under autogenous pressure. The conversion kinetics of the amorphous hydrogel to zeolite A and its further conversion to sodalite were studied. Syntheses were performed in the SHT reactor at 80 and 100 °C, varying the synthesis time from 15 minutes to several hours. The required time to obtain fully crystalline zeolite A under sonohydrothermal conditions was only 25 minutes, highlighting a significantly improved crystallization rate compared to silent conditions (a 9.6-fold kinetic gain). In addition, the resulting zeolite A has smaller particles and a more homogeneous particle size distribution than the zeolite synthesized by hydrothermal treatment. These results can be explained by the sonofragmentation of the amorphous gel and the concomitant enhanced mass transfer of the building units at the interface between the crystallite surface and the solution resulting from the acoustic cavitation activity under SHT conditions. Compared to classical hydrothermal heating, a drastic kinetic increase of the transformation of zeolite A into the more stable sodalite phase was also observed under sonohydrothermal conditions. [ABSTRACT FROM AUTHOR]

We herein report that a nanosized beta zeolite can achieve the upcycling of waste polyethylene into gasoline-range fuels under mild conditions. High accessibility to rich acidic sites intrinsic to the nanosized beta zeolite is crucial to the cracking of polyethylene, leading to a high fuel yield of over 90% at 250 °C for 3 h. [ABSTRACT FROM AUTHOR]

Inorganic zeolites, or microporous crystalline aluminosilicates, possess high porosity, well-developed specific surface area, uniform pores, and ion-exchange properties, which determine their molecular sieve and adsorption properties. The use of zeolites as catalysts, desiccants for solvents and gases, and selective adsorbents for the separation of low-molecular-weight compounds is widely known. Zeolites also serve extensively as packing materials for chromatographic columns in gas-adsorption chromatography. However, their application to high-performance liquid chromatography (HPLC) is less recognized. In HPLC, the retention of adsorbates depends not only on adsorption interactions but also on the molecular sieve effect in the micropores and kinetically selective effects. Additional interactions with the mobile phase components alter the thermodynamic parameters of the adsorbates interaction with the zeolite, decrease effective pore size, and hinder the diffusion of the separated compounds into the adsorbent's pores. Despite these challenges, zeolites remain promising adsorbents due to their strictly determined pore size (dpore) and geometry, as well as their customizable polarities, which ensure high selectivity for the separation of low-molecular-weight compounds. The most promising zeolites for HPLC are wide-pore zeolites (dpore 0.6–0.8 nm) with 8, 10, 12, and 14-member ring channels. This review offers a concise overview of the classification, composition, and structure of zeolites and their impact on the adsorption properties of these adsorbents. Data on the use of zeolites in HPLC are also systematized. [ABSTRACT FROM AUTHOR]

The rational design of isolated metals containing zeolites is crucial for the catalytic conversion of biomass‐derived compounds. Herein, we explored the insertion behavior of the isomorphic substitution of Ti(IV) in different zeolite frameworks, including ZSM‐35 (FER), ZSM‐5, and BEA. The different aluminium topological densities of each zeolite framework lead to the creation of different degrees of vacant sites for hosting the tetrahedrally coordinated Ti(IV) active sites. These observations show the precise control of the degree of four‐coordinated Ti(IV) sites in a zeolite framework, especially in BEA topology, by tuning the degree of unoccupied sites in the host zeolite structure via dealumination. Interestingly, the more vacancies in the host zeolite structure, the more isolated tetrahedrally coordinated Ti(IV) can be increased, eventually enhancing the catalytic performance in methyl oleate (MO) epoxidation for producing methyl‐9,10‐epoxystearate (EP). The engineered Ti‐β exhibits outstanding performances in bulky MO epoxidation with the amount of produced EP per number of Ti sites up to 17.1±1.8 mol mol−1. This observation discloses an alternative strategy for optimizing catalyst efficiency in the rational design of the Ti‐embedding zeolite catalyst, endeavoring to reach highly efficient catalytic performance. [ABSTRACT FROM AUTHOR]

In the case of CO2 thermal‐catalytic hydrogenation, highly selective olefin generation and subsequent olefin secondary reactions to fuel hydrocarbons in an ultra‐short residence time is a huge challenge, especially under industrially feasible conditions. Here, we report a pioneering synthetic process that achieves selective production of high‐volume commercial gasoline with the assistance of fast response mechanism. In situ experiments and DFT calculations demonstrate that the designed NaFeGaZr presents exceptional carbiding prowess, and swiftly forms carbides even at extremely brief gas residence times, facilitating olefin production. The created successive hollow zeolite HZSM‐5 further reinforces aromatization of olefin diffused from NaFeGaZr via optimized mass transfer in the hollow channel of zeolite. Benefiting from its rapid response mechanism within the multifunctional catalytic system, this catalyst effectively prevents the excessive hydrogenation of intermediates and controls the swift conversion of intermediates into aromatics, even in high‐throughput settings. This enables a rapid one‐step synthesis of high‐quality gasoline‐range hydrocarbons without any post‐treatment, with high commercial product compatibility and space‐time yield up to 0.9 kggasoline ⋅ kgcat−1 ⋅ h−1. These findings from the current work can provide a shed for the preparation of efficient catalysts and in‐depth understanding of C1 catalysis in industrial level. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal CrystEngComm, which focuses on the design and understanding of solid-state and crystalline materials. The contents list includes various articles on topics such as halogen bonding in crown ether chemistry, metal-organic framework-derived materials for enhanced performance of aqueous zinc ion batteries, and the effect of grain boundary doping on the mechanical behavior of Ta bicrystal. The journal is published by The Royal Society of Chemistry, a leading chemistry community. [Extracted from the article]

Hierarchically structured materials are considered to be one of the important options to enhance the mass transportation efficiency in microporous zeolites. Herein, we reported a highly efficient steam-assisted crystallization strategy for the synthesis of a hierarchical TS-1 zeolite with a tunable macropore size. The amorphous SiO2–TiO2 precursor dissolved gradually and acted as both a nutrient supplier and macropore template in situ. The framework Ti content of the synthesized TS-1 zeolites could be tuned over a wide range (Ti wt% = 0.70–1.39) by varying the Ti content of the SiO2–TiO2 precursor. Moreover, the pore size of the macropores could be modulated according to the particle size of the precursor based on the investigation of the formation mechanism of the macropores in the hierarchical TS-1 zeolite. The hierarchical TS-1 zeolite exhibited better catalytic activity in the epoxidation reaction of 1-hexene and hydroxylation of phenol compared to the typical microporous zeolites. The improved performance of the hierarchical TS-1 zeolite was probably caused by the improved diffusion performance of the hierarchical structure. [ABSTRACT FROM AUTHOR]

A series of new composites have been synthesized—TiO2 nanoparticles introduced in the interlayer space of layered mordenite. The effect of the hydrolysis medium of titanium tetraethoxide (water or a mixture of water with ethanol) and hydrolysis time (from 6 to 24 h) on the properties and texture of the composite was studied. Treatment in ethanol leads to partially preserved ordered layered structure of 2D mordenite, presumably due to the slowdown of the hydrolysis of titanium tetraethoxide; this, in turn, provides higher mesoporosity after calcination, created by anatase nanoparticles of ~4 nm in the interlayer space. Immobilization of TiO2 on the zeolite surface is indicated by the formation of Si–O–Ti bonds. [ABSTRACT FROM AUTHOR]

The conversion of methanol over zeolites offers a sustainable alternative for fuels and chemicals production. However, a complete understanding of the competing reaction pathways, particularly those leading to C-C bond formation, remains elusive. This work presents a novel mechanism for selective methanol conversion in ZSM-5 zeolites, involving a Brønsted acid site (BAS)-mediated Meerwein–Ponndorf–Verley (MPV) reduction pathway. Employing a multidimensional solid-state NMR spectroscopy combined with isotopic labeling and theoretical calculations, we identify this pathway for acetaldehyde reduction with methanol, directly contributing to ethene formation. This mechanism, involving carbenium ion intermediates like 1-hydroxyethane or 1-methoxyethane ions, contrasts with the well-established Lewis acid-catalyzed MPV process. Based on reactant adsorption modes, we propose two distinct reaction routes for BAS-MPV reduction, bridging the gap between direct and hydrocarbon pool mechanisms in methanol conversion. We further demonstrate the applicability of this pathway to acetone, highlighting its broader role in the early stages of the reaction. A complete understanding of the competing reaction pathways in methanol conversion over zeolites remains elusive. Here the authors explore a Brønsted acid site (BAS)-mediated Meerwein–Ponndorf–Verley (MPV) reduction pathway within ZSM-5 zeolites, facilitating the conversion of acetaldehyde to ethene. [ABSTRACT FROM AUTHOR]

The sorption properties of zeolites are controlled by several factors, i.e. Si/Al ratio of the aluminosilicate framework [AlSiO4]-, the type and position of the extraframework (EF) cations, and the applied temperature. Here we investigate the flexibility of CHA framework as a function of EF cation-content and temperature (20–350 °C). Two CHA forms (Na- and Cu-CHA) with Si/Al = 2 were analysed. The main objectives were: (i) to shed light on the HT behaviour of Na-CHA, for which contrasting results exist in literature; (ii) define the role of temperature and EF cation-type in the response to the heating stimuli. We show that at 75 °C, Na-CHA undergoes a severe contraction of the unit-cell volume (-12%) accompanied by a symmetry lowering (R-3m to I2/m). The transformation is reversible, if the dehydrated Na-CHA is exposed to ambient conditions. In contrast, Cu-CHA experiences a significant different dehydration path, which involves minor changes of the CHA framework, and a net positive thermal-expansion after dehydration. The implications of the observed transformations for gas separation processes are finally discussed. [ABSTRACT FROM AUTHOR]

The thermal stability of zeolites underlies their many applications. Structural collapse usually occurs through a series of reactions, involving an initial low‐density amorphous state (LDA), a high‐density melt (HDA), and, eventually, a dense recrystallization product. The LDA–HDA transition resembles a glass melting process; the HDA phase can sometimes be quenched into a glass. Using isothermal as well as nonisothermal in situ observation methodology on the faujasitic zeolite X and its potassium‐for‐sodium ion‐exchanged derivatives, we find a pronounced mixed‐alkali effect in the characteristic nonisothermal transition temperatures as well as in the isothermal reaction timescale of the LDA–HDA transition. The latter is taken as being directly related to the viscosity of the liquid into which the zeolite framework is melting; the apparent viscosity associated with this melting process was found to reach as high as 1015 Pa.s at 740°C. The observed mixed‐alkali effect is similar to the one observed in the dynamics of common oxide glasses and their corresponding melts. [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 synthesis of carbon–heteroatom bonds, a crucial element in organic chemistry, often requires obstacles in direct amine integration with olefins. This study introduces a sustainable approach for producing nitrogen-bearing molecules through the Markovnikov hydroamination of vinylarenes with carboxamides, employing Hβ zeolite as an effective heterogeneous catalyst in a solvent-free environment. We explored the method's adaptability over various substrates, achieving consistently high yields and regioselectivity in the resultant products. The procedure's scalability to gram-level production and the catalyst's sustainable reuse for multiple cycles (up to five) underscores its viability for industrial application, indicating a significant increase in organic synthesis activity. [ABSTRACT FROM AUTHOR]

Achieving compatibility of composite solid electrolytes among materials for fabricating lithium‐ion batteries presents a significant challenge. This work aimed to study the role of the ZSM‐5 zeolite paracrystalline on the compatibility of CMCh‐based CSE. The ZSM‐5 zeolite intermediates and products were synthesized using the free organic template method, while the CSE membranes were fabricated by combining CMCh, ZSM‐5, and lithium perchlorate (LiClO4) using the solution‐casting method. The result showed that the synthesis of ZSM‐5 zeolite has been successfully performed. FTIR spectrum at wavenumber ~950 cm−1 of ZSM‐5 zeolite indicates that secondary building unit (SBU) structures exist. The SBU structure of ZSM‐5 zeolite indicates the paracrystalline structure of ZSM‐5 zeolite, which is compatible with the CMCh structure. The characterizations in this work were conducted to study the interaction, morphology, crystallinity index, thermal stability, mechanical strength, and ionic conductivity through FTIR, SEM, XRD, TGA, tensile tester, and EIS, respectively. The CSE of CMCh/Z5AH‐LiClO4 was the optimum condition exhibiting ionic conductivity as high as 4.35 x 10−6 S cm−1 with a crystallinity index of 34.25 %, a tensile strength of 46.67 MPa and onset thermal degradation of 262.61 °C. These results suggest that CMCh/Z5AH‐LiClO4 holds promise as a solid electrolyte material for lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

It has been known that plastics with undegradability and long half‐times have caused serious environmental and ecological issues. Considering the devastating effects, the development of efficient plastic upcycling technologies with low energy consumption is absolutely imperative. Catalytic hydrogenolysis of single‐use polyethylene over Ru‐based catalysts to produce high‐quality liquid fuel has been one of the current top priority strategies, but it is restricted by some tough challenges, such as the tendency towards methanation resulting from terminal C−C cleavage. Herein, we introduced Ru nanoparticles supported on hollow ZSM‐5 zeolite (Ru/H‐ZSM‐5) for hydrocracking of high‐density polyethylene (HDPE) under mild reaction conditions. The implication of experimental results is that the 1Ru/H‐ZSM‐5 (~1 wt % Ru) acted as an effective and reusable bifunctional catalyst providing higher conversion rate (82.53 %) and liquid fuel (C5−C21) yield (62.87 %). Detailed characterization demonstrated that the optimal performance in hydrocracking of PE could be attributed to the moderate acidity and appropriate positively charged Ru species resulting from the metal‐zeolite interaction. This work proposes a promising catalyst for plastic upcycling and reveals its structure‐performance relationship, which has guiding significance for catalyst design to improve the yield of high‐value liquid fuels. [ABSTRACT FROM AUTHOR]

Herein, we report a highly selective production route for butadiene from γ‐valerolactone over zeolite catalysts. The catalytic performance of eight zeolites with different framework topologies were compared, revealing that zeolites with narrower 10‐membered ring channels exhibit enhanced selectivity of butadiene. Specifically, ZSM‐35 and ZSM‐22, featuring the narrowest 10‐membered ring channels, demonstrate the highest butadiene selectivity to 61 % and 59 %, respectively. Notably, surface passivation of ZSM‐35 leads to a remarkable increase in butadiene selectivity to 82 %, maintaining a 99 % conversion. Additionally, we propose a reaction network and identify cyclopentenone as a key intermediate in the transformation of γ‐valerolactone to butadiene. Both experimental and theoretical results conclude that confinement effect of 10‐membered ring channels improves the selectivity of butadiene. [ABSTRACT FROM AUTHOR]

The utilization of the water–zeolite pair as an adsorbate–adsorbent system has garnered significant attention in the realm of thermochemical energy storage, offering great potential for various applications. Despite promising results in laboratory settings, widespread implementation of this technology has yet to be realized. Recent advancements in mobile thermal energy storage (m‐TES) employing thermochemical materials have opened new avenues for enhancing the practicality and cost‐effectiveness of solar thermal energy harnessing and waste heat recovery. This experimental study investigates the feasibility of storing thermal energy in zeolites, charged externally to the heat recovery reactor, and discusses the potential applications of externally charged zeolites for m‐TES over short distances, shedding light on their practicality and significance in advancing the field of mobile thermal energy storage. Our findings reveal that zeolites charged at 200°C and subsequently stored outside the discharging unit exhibit an impressive energy storage density (ESD) exceeding 110 kWhth/m3 under conditions of 0.45 m/s air velocity and 60% relative humidity during zeolite discharging. These ESD values are comparable to previously reported figures in the literature. Moreover, ESD values of 30.6 kWhth/m3 were achieved by charging zeolite beads contained within packed transportable tubes constructed from stainless‐steel mesh. [ABSTRACT FROM AUTHOR]

In this study, mesoporous FAU zeolites with pores in the range of 3–4 nm were successfully synthesized by acid leaching method using several organic acids. Zeolite samples were treated with six organic acids (acetic, oxalic, succinic, adipic, malic, and D-tartaric acid) in microwave-assisted acid leaching to investigate the influence of specific acids on formation of mesostructured zeolite ability to evaluate their influence on mesostructure formation and potential applications. X-ray diffraction (XRD) demonstrated that all synthesized samples retained the initial crystalline structure. The nitrogen physisorption curves indicated that all samples possess mesoporous structures. According to TEM results, the proposed mechanism of the method was due to acid diffusion and corrosion from the external to internal structure leading to the formation of the mesoscale pores. The adsorption capacity was investigated with methylene blue (MB), and the results varied according to the acid used but were generally much higher than untreated zeolite X. These findings suggest that the one-step microwave-assisted acid leaching method holds significant potential for practical applications due to its efficiency and simplicity. [ABSTRACT FROM AUTHOR]

Membrane osmotic distillation (OD) is applied in this work for the partial dealcoholization of beer (5.2 v/v% alcohol content) to diminish its ethanol content by around 50% giving rise to a low alcohol beer. A compromise is sought between the low alcoholic degree achieved and beer sensory properties. Moreover, the feasibility of the membrane OD process intensification is studied thanks to its combination with membrane pervaporation (PV). Two successive PV stages, one hydrophobic and the other hydrophilic, allow the production of recycled water (with less than 0.5 wt% ethanol) for the membrane OD operation and bioethanol (99% ethanol) as valuable byproduct. [ABSTRACT FROM AUTHOR]

This document provides a summary of a collection of articles on porous nanomaterials. It discusses the importance and applications of these materials, such as catalysis, drug delivery, and energy storage. The document highlights recent advancements in the synthesis and characterization of porous nanomaterials, focusing on silica, carbon-based materials, metal-organic frameworks (MOFs), and zeolites. It also presents specific studies on the synthesis and application of these materials, as well as their potential in various industries. The summary acknowledges the contributions of the authors to the Special Issue and emphasizes the need for continued research in this field. [Extracted from the article]

In this work, a meso-macroporous analcime/sodalite zeolite composite was produced by a hybrid synthesis process between a complex template method and hydrothermal treatment at 220 °C of naturally abundant kaolinitic-rich clay, using dodecyltrimethylammonium bromide as an organic soft template to enhance the mesoporous structure. The chemical and morphological properties of the developed zeolites composite were characterized using powder X-ray diffraction (PXRD), attenuated total Reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), N2 adsorption/desorption; and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) methods were used to study the morphology, chemical composition and structure of the product. Two types of zeolite particles were obtained:(1) hollow microsphere with an attached analcime icositetrahedron of 30–40 µm in size and (2) sodalite microsphere with a ball-like morphology of 3–4 µm in size. Both N2 adsorption/desorption and surface area data confirmed the high potentiality of the produced zeolite composite to act as an excellent adsorbent to remove inorganic pollutants such as Cu, Cd, Cr, Ni, Zn, and Pb ions, organic pollutants such as dyes, phenolic compounds, and surfactants from water; and their high catalytic activity, especially in the oxidation reaction of volatile organic compounds. The catalytic activity and adsorption ability of the produced analcime/sodalite composite will be tested experimentally in future work. [ABSTRACT FROM AUTHOR]

The present study aims to investigate how the use of high‐range water reducer (HRWR) and variations in water/cement (W/C) ratio affect the properties of self‐consolidating concrete (SCC) while taking into account different proportions of polypropylene fibers (PF) and natural zeolite (NZ). A total of 28 samples were cast and analyzed. PF fractions ranging from 0% to 1.5% by weight were added, along with a substitution of 10% NZ for cement (50 kg/m3). Four W/C ratios (0.30, 0.35, 0.40, and 0.45) were tested, in addition to seven HRWR contents ranging from 5 to 6.5 kg/m3. Various tests were conducted to assess slump, T500, V‐funnel, L‐box, modulus of elasticity, and compressive, tensile, and flexural strengths. Novel models were developed to predict the properties of hardened concrete based on W/C, HRWR, PF, and NZ content. Findings indicated that optimal performance of PF‐reinforced SCC with NZ was achieved when up to 0.75% PF was combined with an HRWR content equivalent to 1.25% of the cement fraction and NZ ratio. Furthermore, the proposed models offer accurate predictions of both fresh and hardened‐state properties of PF‐reinforced SCC with NZ based on W/C and HRWR ratios. [ABSTRACT FROM AUTHOR]

This study evaluated the effectiveness of zeolite, both alone and in combination with mineral fertilizers, in improving the yield and quality of table beets (Beta vulgaris L.) grown in dark chestnut soils of southeast Kazakhstan. The research was conducted at the Kazakh Research Institute of Horticulture during the 2022-2023 growing seasons using a randomized complete block design with six treatments: control (no fertilizers), zeolite 2 t/ha, N45P45K45 (single dose of mineral fertilizers), N90P90K90 (double dose of mineral fertilizers), zeolite 2 t/ha + N45P45K45, and zeolite 2 t/ha + N90P90K90, replicated three times. The application of zeolite significantly improved soil physical properties, such as water permeability and soil density, enhancing root development and water retention. Nutrient availability, particularly nitrate nitrogen and mobile phosphorus, increased significantly in zeolite-treated plots. The combination of zeolite and mineral fertilizers resulted in the highest improvements, with nitrate nitrogen content reaching 40.5 mg/kg and mobile phosphorus 89.2 mg/kg. Moreover, zeolite reduced heavy metal concentrations, particularly cadmium, by 50% compared to the control. Table beet yield significantly increased with zeolite application, with the highest yield of 62.7 t/ha achieved with 2 t/ha zeolite combined with double dose N90P90K90 fertilizers, compared to 42.8 t/ha in the control. Marketable yield also improved, indicating better crop quality. Nutrient composition of the beets improved, with increased dry matter content (21.9%) and reduced nitrate content (240 mg/kg) in zeolite-treated variants. In conclusion, zeolite, especially when combined with mineral fertilizers, effectively enhances soil health, nutrient availability, and table beet yield and quality. [ABSTRACT FROM AUTHOR]

A zeolite pot experiment was conducted at the Agricultural Research Council Infruitec-Nietvoorbij in Stellenbosch, South Africa, under greenhouse conditions. The experiment aimed to investigate the impact of zeolite application on soil enzyme activities in sandy soils cultivated with Swiss chard (Beta vulgaris Var. cicla) and cabbage (Brassica oleracea Var. capitata L.) over two years (2018-2019). Different zeolite-to-soil ratios (0:1, 1:9, 2:8, and 3:7 w/w) were used, with each pot containing 12 kg of soil. The experiment involved 72 pots for each vegetable, arranged in a randomized complete block design (RCBD). Soil enzyme activities, including acid phosphatase, ß-glucosidase, and urease, as well as soil chemical properties (pH, total plant-available nitrogen, organic carbon, and phosphorus), were analyzed. Key findings indicate that the effect of zeolite application on enzyme activities varied between the vegetable species. Zeolite application significantly increased (P<0.05) soil pH across all treatments. However, higher zeolite levels decreased (P<0.05) soil phosphorus availability, likely due to phosphorus adsorption by zeolite. Acid phosphatase activity decreased with rising zeolite levels, possibly due to increased soil pH. Additionally, zeolite application reduced (P<0.05) soil organic carbon, which may explain some of the enzyme activity responses. Alteration Index Three (AI3) scores suggested improved soil biological activity with zeolite application, although responses varied between crops. Cabbage soils showed improvement in all treatments, while Swiss chard soils exhibited mixed responses. In conclusion, while zeolite application can enhance soil pH and nutrient retention, it may also reduce phosphorus availability and organic carbon. The enzyme activity responses observed are complex and crop-specific, highlighting the need for tailored soil management practices. Further research is recommended to explore the long-term impacts and optimal integration of zeolite with organic amendments for sustainable soil fertility management. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Zeolitic carrier materials offer ion release and uptake functionality for a wide range of applications. The release kinetics are controlled by the mobility of the target species within the zeolite framework and at its surface. Here, we achieve control over the release dynamics and the quantity of released Co2+ ions from a faujasitic zeolite through mechanical amorphization of the zeolite framework. We identify a two‐step reaction mechanism in which ion release and reintegration compete on short and intermediate timescales. The competition between these two processes is governed by the degree of amorphization, with a timescale ranging from a few minutes to several days. [ABSTRACT FROM AUTHOR]

The cold sintering process (CSP) was used to produce membranes and improve the densification of a geopolymer-zeolite matrix, fully recycling a waste geopolymer powder. The role of CSP parameters were studied varying temperature (25, 40 and 80°C), applied pressure (56 MPa and 168 MPa) and reactive solution (H 2 O, KOH or NaOH 2, 4, 6, 8 M). CSP applied on the waste geopolymer powder (molar ratio Si/Al = 2.0 and K/Al = 1.0) resulted in relative densities ranging from about 50–77%, while modal pores varied from 0.006 µm to 0.017 µm in the mesopore range. Compressive strength was up to 45 MPa. The addition of 10 wt% of the waste geopolymer powder to a geopolymer- zeolite powder containing 81% of in situ synthetized NaA phase allowed a densification approaching 70% with mechanical strength up to 7.4 MPa. • Membranes were produced by cold sintering process (CSP). • A waste geopolymer powder was recycled to produce membranes. • Relative densities were 50–77% and modal pores 0.006–0.017 µm. • CSP on a geopolymer-NaA zeolite powder allowed a densification approaching 70%. [ABSTRACT FROM AUTHOR]

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Zeolites have been used as a separation membrane material by taking advantages of their unique adsorption properties and molecular sieving properties based on the micropores. Zeolite membranes are widely used in practical applications, mainly for dehydration of organic solvents. Furthermore, the research and development continue toward large-scale implementation in the energy and carbon neutral field. The high heat and chemical resistance of zeolite membranes are also expected to be utilized as membrane reactors. Zeolite membrane and membrane separation will contribute to the fulfillment of a carbon-neutral society through energy saving in separation, reaction, and CO2 recovery. In this review, the basic structure, the synthesis methods and the applications of zeolite membranes are introduced. The recent research trends of zeolite membrane in the research and applications are also explained. [ABSTRACT FROM AUTHOR]

Surface modification of zeolite is known to enhance its adsorption capacity for volatile organic compounds (VOCs). In this study, a hydrophobic adsorbent, NaY@LDHs, with layered double hydroxides (LDHs) as the shell and NaY zeolite as the core, was successfully synthesized. It was found that treating LDHs with ethanol can result in a larger specific surface area and pore volume, enhancing the adsorption performance of toluene under wet conditions. SEM imaging reveals that the LDHs shell grows vertically on the surface of the NaY zeolite. The dynamic adsorption experiment of toluene showed that under humid conditions, NaY@LDHs exhibited a saturated adsorption capacity of 32.42 mg/g, representing a significant 87% increase compared to the parent NaY zeolite. The kinetic results show that the adsorption of toluene on NaY@LDHs is primarily physical adsorption, and other factors influence the adsorption process in addition to intraparticle diffusion. Therefore, the air layer formed by the LDHs shell on the surface of NaY zeolite imparts a hydrophobic effect, making NaY@LDHs a promising material for adsorbing volatile organic compounds in a wet environment. [ABSTRACT FROM AUTHOR]

The recycling of polyethylene terephthalate (PET) waste plastics has garnered global attention as an essential area of research to address. Chemical upcycling methods, such as glycolysis, offers a visible solution by directly converting PET wastes into high-valued monomers, enabling their reintegration into the plastic life cycle. However, the recovery of metal salt catalyst and the thermal stability of organic catalyst pose challenges in PET glycolysis. Zeolites with strong Brønsted acid are widely used in the degradation of polyolefins, but in PET glycolysis, they face the problems of acid site mismatch and difficult contact with PET. In this work, nanosized FAU-type zeolite catalysts (100-FAU) were employed to carry out PET glycolysis, which were green synthesized at low temperature without organic template. In comparison to commercial FAU-type catalysts, 100-FAU exhibits enhanced Lewis acidity and basicity along with increased accessibility to active sites. The 100% degradation of PET was achieved within 1 h, resulting in a BHET yield of 64.2%. Prolonging the reaction time to 1.5 h led to an enhanced BHET yield of 72.1%. The quality of the primary product bis(2-hydroxyethyl) terephthalate (BHET) was verified through IR, DSC, and NMR characterizations. Furthermore, as a solid catalyst with high thermal stability, zeolite can be easily recovered via filtration and demonstrated stable performance over at least 5 cycles, and proved effective for glycolysis of commercially waste PET plastics. The acid–base dual-functional catalytic mechanism of Na-form FAU in PET glycolysis was proposed. Under its guidance, the promoting effect of other Na-form nanosized zeolites on PET degradation was verified. [ABSTRACT FROM AUTHOR]

Ni-based catalysts are highly reactive for dry reforming of methane (DRM) but they are prone to rapid deactivation due to sintering and/or coking. In this study, we present a straightforward approach for anchoring dispersed Ni sites with strengthened metal-support interactions, which leads to Ni active sites embedded in dealuminated Beta zeolite with superior stability and rates for DRM. The process involves solid-state grinding of dealuminated Beta zeolites and nickel nitrate, followed by calcination under finely controlled gas flow conditions. By combining in situ X-ray absorption spectroscopy and ab initio simulations, it is elucidated that the efficient removal of byproducts during catalyst synthesis is conducted to strengthen Ni–Si interactions that suppress coking and sintering after 100 h of time-on-stream. Transient isotopic kinetic experiments shed light on the differences in intrinsic turnover frequency of Ni species and explain performance trends. This work constructs a fundamental understanding regarding the implication of facile synthesis protocols on metal-support interaction in zeolite-supported Ni sites, and it lays the needed foundations on how these interactions can be tuned for outstanding DRM performance. Ni-based catalysts are highly reactive for DRM, but they tend to deactivate quickly due to sintering and/or coking. Here a simple method for anchoring dispersed Ni sites in dealuminated Beta zeolite, enhancing metal-support interactions, results in a catalyst with superior stability and performance for DRM. [ABSTRACT FROM AUTHOR]

Bilayer structure with functional overlayer has been commonly adopted to resolve the issue of moisture poisoning in chemiresistors. However, the conventional overlayers always suffer from blocking access of gas molecules to sensing layer due to lacking porosity and deteriorated adsorption capability. Herein, taking advantages of the well-defined porous structure and hydrophobic nature of pure silica zeolite, we assembled an overlayer of Pd-PdO clusters-encapsulated mesoporous silicalite-1 (MFI) zeolite (named M-S-1) on ZnO sensing layer, to prevent moisture poisoning, and enhance gas diffusion and adsorption capabilities. The inherent capability of MFI zeolite to incorporate monodispersed nanometric (ca. 3 nm) Pd-PdO cluster in its void space is of great importance for the NO2 adsorption. The Pd-PdO@M-S-1 overlayer can attain negligible moisture interference to the ZnO layer without significantly altering the gas selectivity and baseline resistance, and enhance gas response. Consequently, the Pd-PdO@M-S-1/ZnO bilayer sensor can ultra-selectively (Snitrogen dioxide/Sinterference gas > 4), and ultra-stably detect trace level of NO2 (9.5 ppb) at low temperature (370 K) under high levels of humidity (90% RH). This work exemplifies a next-generation solution to design bilayer sensors using zeolite overlayer for eliminating the humidity dependence of the gas-sensing properties. [ABSTRACT FROM AUTHOR]

The removal of Sunset Yellow (E110) on natural zeolite and zeolite modified with the cationic surfactant cetyl pyridinium chloride (CPC) was studied using the adsorption method. The structural characteristics of the surfactant-modified zeolite (SMZ-CPC) were investigated using X-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) analysis, and the scanning electron microscopy (SEM) images. The effect of different parameters on the adsorption process, such as equilibration time and amount of adsorbent at 298 K, were determined using UV–Vis spectroscopy. The maximum dye removal percentage on SMZ-CPC was obtained with 0.08 g of adsorbent in 30 min. The results show that the zeolite modified with CPC surfactant (SMZ) has a higher adsorption capacity for Sunset Yellow than the unmodified zeolite (natural form). The experimental adsorption data were nonlinearly analyzed using isotherm equations such as Langmuir, Freundlich, Temkin, Langmuir-Freundlich (or Sips), and Extended Langmuir (EL). The experimental data were better fitted with the Sips isotherm. The adsorption kinetic data were analyzed using eight models in nonlinear forms: the pseudo-first-order (PFO), pseudo-second-order (PSO), integrated kinetic Langmuir (IKL), Elovich, intraparticle diffusion (IPD), mixed order rate equation (MOE), fractal-like pseudo-first-order (FL-PFO) and fractal-like pseudo-second-order (FL-PSO). According to the results of the coefficient of determination (R2), Elovich kinetic model well expressed E110 adsorption onto SMZ-CPC. Most of the dye removal takes place in less than 5 min and the maximum adsorption capacity is 5.06 mg/g. The results of this study show that zeolite modified with cationic surfactant is an effective adsorbent for removal anionic dyes from an aqueous solution. [ABSTRACT FROM AUTHOR]

Owing to the structural stability, modifiable acidity, and abundant pores/channels, zeolite‐based materials can act as catalysts or supports for effective conversion of volatile organic compounds (VOCs). In this review, a series of VOC oxidation processes catalyzed by zeolite‐based materials will be introduced, which include thermal oxidation, photocatalytic degradation, plasma‐driven removal, catalytic ozonation, microwave‐assisted degradation, and hybrid systems, where the specific roles, modification strategies, and structure–performance relationships of zeolites are discussed in depth. The following topics will also be covered, including the catalytic mechanisms of VOC oxidation, types of zeolite‐based materials in VOC catalytic oxidation, operation parameters in the processes, and reactor designs for efficiency optimization and cost control. [ABSTRACT FROM AUTHOR]