Zeolites, traditionally defined as crystalline porous aluminosilicates, are among the most effective catalysts in chemical industry. Although, zeolites are often considered as rigid materials, emerging evidence reveals underexplored features related to the flexibility of zeolite frameworks. This dynamic property, along with structural defects, allows zeolites to process molecules larger than their nominal pore apertures under specific stimuli. This perspective examines two key aspects of zeolite flexibility: (1) inferring framework flexibility based on reactivity trends and (2) utilizing this flexibility to improve catalytic performance. Tailoring zeolite flexibility is increasingly recognized as a critical parameter for optimizing catalytic performance. Several examples highlighting the impact of zeolite flexibility on molecular diffusion, adsorption, and reaction processes are presented here. The discussion underscores the critical role of advanced characterization and molecular simulations in guiding the design and synthesis of flexible zeolite catalysts, paving the way for more efficient and sustainable catalytic processes.

In this work, we investigated the dynamics of water in the pores of ultrathin BPH zeolite (Linde Q) nanosheets at different temperatures using 1H time-domain NMR. Relaxation times and pore size distribution were determined by fitting the curves obtained using (i) Hahn and (ii) Carr-Purcell-Meiboom-Gill (CPMG) echo trains. Two distinct relaxation components and pore sizes were identified and assigned to water molecules in micro- and mesopores, respectively. The relaxation behavior within each individual pore adheres to a fast exchange regime, while an intermediate one governs the exchange between water molecules in different pores. The ratio of longitudinal and transversal relaxation times (T11/T21) of ∼2 reflects a strong surface interaction for water in zeolite pores featuring a surface relaxivity of 0.15 nm/ms. The confinement of water in the pores delays the rates of solid-liquid phase transitions, giving rise to a hysteresis loop reflecting a higher stability for confined liquid water or amorphous ice. These results highlight the possibility of tuning the separation capacities of zeolites in wet environments at different temperatures.

The catalytic activity of silanol groups in zeolites has long been overlooked because of their much lower acidity compared to Brønsted acid sites. Here, we demonstrate their non-negligible catalytic role in methanol conversion using pure silica MFI zeolite (Silicalite-1). Two silicalite-1 samples with different crystal sizes, micron-sized (Sil1_micro) and nano-sized (Sil1_nano), were synthesized and investigated by in situ and operando FTIR spectroscopy using probe molecules (carbon monoxide, pyridine, and methanol). multivariate-curve regression by alternating least squares was applied to elucidate the influence of the silanol hydrogen-bonding network on catalytic reactivity. Distinct acid-base behaviors were identified: isolated and weakly hydrogen-bonded silanols are active at low temperatures, whereas strongly hydrogen-bonded silanols become catalytically relevant at higher temperatures. Methanol adsorption studies reveal a unique bidentate coordination mode in Sil1_nano, associated with weakly hydrogen-bonded geminal silanols, which promotes the formation of reactive intermediates and dual coke species. In contrast, Sil1_micro, characterized by a higher fraction of strongly hydrogen-bonded silanols, exhibits a different methanol reactivity pattern. These results demonstrate that silanol groups are active functional entities rather than passive defects, capable of driving methanol reforming-like transformations and steering coke formation pathways.

The catalytic properties of SAPO-34 molecular sieves synthesized using two different organic structure-directing agents (OSDAs), triethylamine (TEA) and tetraethylammonium (TEA+), were investigated in the methanol-to-olefin (MTO) reaction. Although both OSDAs lead to the same CHA-type structure, the two samples exhibit distinct physicochemical properties inducing different performances in the MTO reaction. The amount of incorporated silicon is higher in the SAPO-34 synthesized with TEA (sample N-C), while a higher concentration of Si(4Al) species is obtained when TEA+ (sample P-C) is used. Additionally, the size of the crystals decreased significantly when using TEA+. The differences observed in activity are mainly due to different textural properties and silicon distribution; TEA+ favours the formation of nanocrystals where the dispersion of Si gives rise to a high concentration of Br & oslash;nsted acidic sites while TEA favours the clustering of Si in 'islands' in micron-sized crystals, influencing the catalytic performance of SAPO-34 in the MTO reaction. The N-C sample exhibits high initial selectivity toward light olefins (C2-C4) and strong hydrogen transfer activity, but undergoes rapid deactivation due to its larger crystal size that promotes coke formation. In contrast, the P-C sample shows slightly lower initial selectivity but superior stability and lifetime, enabled by its nanoscale crystal size, larger external surface area, and higher acid site density, which together enhance diffusion, limit coke deposition, and sustain methanol conversion.

The spatial distribution of aluminum in zeolites plays a crucial role in optimizing their catalytic performance. Existing strategies often rely on combinations of inorganic and organic structure-directing agents to guide crystal growth and aluminum incorporation. However, these methods typically result in zeolite crystals with an aluminum-rich surface, providing limited control over the spatial placement of aluminum within the crystal structure. In this study, we explore an alternative "weaving" strategy aimed at synthesizing zeolites with alternating Al-rich and Si-rich nanodomains within single crystals. This approach involves the physical blending of two separately aged, amorphous sols with contrasting Si/Al ratios, followed by freeze-drying and steam-assisted crystallization of the resulting solid in vapor. Unlike conventional hydrothermal synthesis, which produces zeolites with Al-enriched crystal surfaces, this modularized assembly enables systematic modulation of aluminum distribution, resulting in zeolite crystals with comparable bulk and surface Si/Al ratios, an uncommon feature for high-silica zeolites. The resulting interwoven zeolites, with closely matched bulk and surface Si/Al ratios, exhibit nearly a twofold increase in catalytic lifetime in the methanol-to-hydrocarbons reaction compared to a reference zeolite with a similar bulk composition but significant surface aluminum enrichment, underscoring the significant impact of aluminum spatial distribution on catalytic stability.

ZMQ-1 is a recently discovered aluminosilicate zeolite featuring atomically ordered mesopores (28 × 10-membered rings), providing a unique, intrinsically bimodal micro/mesoporous framework. This study systematically investigates how residual inorganic phosphate species, derived from the biphosphonium organic structure-directing agent, influence the textural and acidic properties of the material. Using argon physisorption, solid-state NMR, in situ FTIR, and DFT calculations, we demonstrate that vacuum calcination or targeted postsynthetic washing (NH4Cl, CsNO3) removes ∼90% of residual phosphorus species, which otherwise severely diminishes Brønsted acid sites density and accessibility. Crucially, the determination of accurate molar extinction coefficients for pyridine and 2,6-di-tert-butylpyridine revealed that residual phosphorus markedly hinders probe molecule accessibility and diminishes acid strength. DFT modeling identifies preferred Al substitution sites that orient Brønsted protons toward the 28-MR mesoporous channels. The catalytic potential of this architecture was interrogated via the sterically demanding alkylation of 2,4-di-tert-butylphenol with tert-butyl alcohol. Phosphorus-free ZMQ-1 achieves a 15.5% yield of the bulky target, 2,4,6-tri-tert-butylphenol─a 31-fold increase over hierarchical USY (0.5%) and vastly outperforming amorphous-walled Al-MCM-41. These findings establish ZMQ-1 as a landmark catalyst bridging the gap between zeolitic acidity and mesoporous accessibility and further push the catalytic operating boundaries of nanoporous solid acid catalysts.

Germanium-containing zeolites (Ge-MFI) offer significant potential for catalytic applications, owing to their unique structural properties such as extra-large porosity, facilitated by a broader range of Ge-O-Si angles and Ge-O bonds compared to the Al-O-Si, Al-O, and Si-O found in conventional aluminosilicate zeolites. This study highlights the catalytic performance of the Ge-MFI catalyst in the ring-opening reaction of propylene oxide, an essential step in synthesizing value-added chemicals. Employing in situ and operando FTIR spectroscopy, we investigated the reaction mechanism and product distribution, uncovering how propylene oxide interacts with Ge-based Lewis acid sites and induces group migration that facilitates molecular reorganization. This work demonstrates that incorporating germanium into the MFI framework produces a highly stable and selective catalyst with discrete Lewis acid sites, activated at 450 degrees C. The catalyst achieved a conversion of 37% at 400 degrees C, markedly outperforming its siliceous counterpart (Si-MFI catalyst), which reached only 16%. Furthermore, the Ge-MFI catalyst exhibited superior selectivity toward propionaldehyde, attaining 85% at 350 degrees C compared to 35% for Si-MFI under identical conditions.

This study investigates the impact of selenium in different oxidation states, specifically Se 6+ and Se 4+ , on the structural features of MFI-type zeolites.

In this work, AlPO4-5 4-5 (AFI) zeotype materials were synthesized using the microwave approach in the presence of two organic templates i.e. tripropylamine (R) and tetrapropylammonium (R+). + ). The long- and short-range crystalline order of the samples were investigated by considering the effect of the template's charge on the atomic- level ordering of the AFI framework. Using advanced NMR spectroscopy, we shed the light on the importance of templates' role on the organization of the inorganic framework of aluminophosphates. The spectroscopic data clearly show a wider distribution of Al and P environments in the materials synthesized with the charged template (R+) + ) due to the need of hydroxyl groups charge compensators that induce some bridges distortions. When a charged molecule (R+) + ) was used, aluminum appears to be responsible for the charge compensation mechanism via the association of OH groups, impacting the environment of phosphorus as well. The hydroxyl groups needed for charge compensation in samples synthesized with R+ + persist after calcination. Consequently, the hydrophilicity of the sample synthesized with R+ + features approximatively two times higher values compared to the one synthesized with R.

All-silica, boron and boron-aluminium substituted MFI-type zeolites were prepared. Different amounts of boron were added to the starting reaction mixtures to investigate their influence on the properties of the obtained zeolites. A comprehensive characterization of the materials was conducted using various techniques: X-ray Diffraction (XRD), nitrogen physisorption, Scanning Electron Microscopy (SEM), infrared (IR), Nuclear Magnetic Resonance (NMR) spectroscopy, thermogravimetric analysis (TGA) as well as microcalorimetry. The MFI topology and crystallinity is preserved regardless the amount of heteroatoms that occupied different local environments, while the morphology of the crystals, their thermal stability, and their acidity differ considerably. For instance, boron assuming both tetrahedral and trigonal coordination, affect the interactions of the framework with both the organic structure directing agents (OSDA) and ammonia species giving rise to detectable differences in acidity.

The incorporation of heteroatoms (X) into the zeolite-templated carbon (ZTC) structure is a widely used technique to tailor its properties for specific applications such as gas adsorption, methane and hydrogen storage, and catalysis. However, the literature lacks sufficient data on Fourier-transform infrared spectroscopy (FTIR) analysis of ZTCs due to the challenge in obtaining high-quality FTIR spectra required for accurate assignment of the C-X bands, primarily caused by the black mass effect. In this work we prepared nitrogen (N) and phosphorus (P) doped ZTC samples using FAU type zeolite as a template and furfuryl alcohol as a carbon precursor. The Raman results confirmed the presence of medium-sized aromatic structures and also showed that doping these structures with N and P leads to some defects, although the overall conformation remains structurally intact. The FTIR spectra of the ZTC materials were obtained by controlling the preparation procedure and humidity, enabling clear analysis of the black samples. A Density Functional Theory (DFT) model based on the dimeric buckybowl structure was developed and complemented by experimental results obtained from X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR), and FTIR. The proposed DFT model was then used for deconvolution and precise band assignment of the experimental FTIR spectra. The FTIR deconvolution study also supported the incorporation of N and P into the ZTC as well as the presence of primarily two types of nitrogen species, amide (primary and secondary) and pyridine-like, while P was mainly incorporated as triphenylphosphine oxide and phosphonic acid.

Porosity and Al siting are key levers for optimizing zeolite catalysts, yet they are often addressed independently due to the lack of effective integrated tuning strategies. Herein, we report an integrative methodology for preparing hierarchical zeolite (Z F ) with interconnected mesostructures and tunable Al siting, achieved via regioselective dissolution of Al‐rich domains by presetting accessible and inaccessible zones within parent zeolite (Z P ). Remarkably, ∼60% of the framework channels’ Al atoms were selectively removed without impairing the channel intersections’ Al atoms. Despite a 39% reduction in Brønsted acid sites (BAS), Z F exhibits a 1.8‐fold higher turnover frequency (TOF) than Z P during ethylene transformation at 973K, attributable to the introduction of mesoporosity. Notably, site‐specific 31 P NMR analysis reveals that BAS located at channel intersections exhibits a TOF of 516 h −1 , which is 13 times higher than that of sites within the channels (40 h −1 ). The hierarchical zeolite also demonstrates superior durability and enhanced aromatic selectivity compared to Z P . These results highlight the synergistic benefits of simultaneously tuning porosity and Al siting, offering a new paradigm for the rational design of high‐performance zeolite catalysts and providing deeper insights into the interplay between structure and function in zeolite‐based catalysis.

Germanium is known to occupy tetrahedral sites by substituting silicon in germanosilicate zeolites. In this study, we present pioneering findings regarding the synthesis of zeolites with an MFI structure (GeMFI) incorporating a high germanium amount (16% Ge). Remarkably, the germanium atoms feature a slight electron deficiency with respect to GeO2, and the typical coordination number of 4, as usually reported for the germanosilicate zeolites, is exceeded, giving rise to Ge dimers in a double-bridge configuration. Notably, the compensation of the ammonium template is achieved not through fluorine ions in the [415262] cages of the framework, as conventionally considered, but rather through oxygen. The GeMFI zeolite with the high Ge content reported in this work demonstrated exceptional thermal and hydrothermal stability, surpassing up to 1050 °C, thanks to both the double-bridge configuration and the defect-free structure. The unexpected role of germanium in MFI zeolite challenges previous assumptions, representing a paradigm shift in the understanding of porous germanosilicate structures, paving the way for a reevaluation of their synthesis, hydrolysis, and potential applications.

Zeolites are critical materials in industrial catalysis, where optimizing both active site distribution and mass transport properties is essential for achieving high activity, selectivity, and stability. However, simultaneously controlling the aluminum site placement and porosity during zeolite synthesis remains a fundamental challenge, limiting the rational design of next-generation catalysts. In this work, we present an intentionally moderated synthesis strategy that enables concurrent tuning of aluminum distribution and hierarchical structuring in nanosized Beta (BEA) zeolite, by employing an asymmetrical organic structure-directing agent (methyltriethylammonium, MTEA+). Partial substitution of conventional TEA+ with MTEA+ leads to stronger electrostatic interactions with aluminosilicates, which decelerate nucleation, modulate Al spatial distribution, and prevent dense nanoparticle aggregation during crystallization. The resulting BEA zeolite features a loosely assembled mesoporous architecture with framework Al atoms preferentially located near the external surface and occupying T7, T1, and T2 tetrahedral sites. This dual-level control over porosity and aluminum siting enhances the catalyst performance in the methanol-to-gasoline reaction, offering an improved lifetime and hydrocarbon selectivity. Overall, our findings provide a generalizable approach to tailoring both framework architecture and active site positioning of zeolite catalysts, opening alternative pathways for the design of advanced porous materials in hydrocarbon conversion and beyond.

The synthesis of ultrathin BPH zeolite nanosheets from an aluminosilicate colloidal suspension using exclusively inorganic structure directing agents under mild conditions is reported. The improved synthesis yields nanosheets of 4-7 nm and a Si/Al ratio of 1.5; combined 3D electron diffraction and DFT calculations reveal the spatial distribution of extra-framework cations throughout the microporous structure. The ultrathin BPH nanosheets exhibit high and regular intersheet mesoporosity, and substantially improved thermal stability. The notable mesoporosity bestows exceptional water adsorption behavior typically unseen for zeolites; the as-prepared material consists of up to 49% adsorbed H2O by weight and adsorbs up to 32 wt % H2O at 90% relative humidity. H-2 MAS NMR spectroscopy identifies different types of (OH)-H-2 environments ascribed to silanol species exhibiting two motion behaviors. H2O sorption analysis demonstrates reproducible behavior over multiple cycles and low temperature regeneration, making the ultrathin BPH nanosheets attractive candidates for gas drying and membrane applications.

ITQ-1 layered zeolites, with MWW framework, were prepared using different synthesis and calcination procedures and fully characterized by means of X-ray diffraction, scanning electron microscopy, N2 sorption and vibrational and nuclear magnetic resonance spectroscopies. Exploring different compositions of the precursor gel, the role of the Organic Structure Directing Agent (OSDA) was definitely disclosed. We proved that the concentration of OSDA in the synthesis gel affects the short-range crystalline order of zeolite crystals. In particular, diluted precursor gels led to the formation of low-density materials in the form of hollow spheres, with partially disordered layers, thinner crystals and high defectivity. In general, all ITQ-1 samples had the same crystalline structure but different morphology, either rose-like or hollow spheres. Moreover, the calcination procedure had an impact on the structural defects of the ITQ-1 zeolite: the higher the removal rate of the OSDA, the higher the defectivity degree of the zeolite.

Alkaline‐earth metal cations impact the rate of crystallization and the adsorption of N 2 and CO 2 on nanosized chabazite zeolites. In this study, either calcium or barium is added to precursor mixtures containing alkali‐metal cations (Na + , K + , Cs + ) to prepare chabazite (labeled Ca‐CHA and Ba‐CHA), and are compared to a reference sample (Ref‐CHA) synthesized using exclusively Na + , K + , and Cs + . Partial substitution of the Na + and the pore‐blocking Cs + extra‐framework cations is observed for Ca‐CHA depending on the molar ratio of K 2 O used in the synthesis, while a change to the amount of Na + cations only is observed for Ba‐CHA. The type of alkaline‐earth metal cation affects the crystallization rate; slower in the presence of Ca 2+ (10 h to full crystallinity) and similar rates in the presence of Ba 2+ (4 h to full crystallinity); the crystallite size and morphology remained similar. The presence of Ca 2+ or Ba 2+ extra‐framework cations leads to N 2 uptake values of 290 and 169 mmol g −1 (−196 °C, 100 kPa), respectively, while at low CO 2 pressure (<1 kPa, 25 °C), the physisorbed CO 2 capacity for Ref‐CHA, Ca‐CHA, and Ba‐CHA zeolites is 0.63, 0.66, and 0.59 mmol g −1 , respectively. Interestingly, an opposite effect is observed for the amount of chemisorbed CO 2 species.

Organic templates provide structure for the frameworks of porous materials via a panel of weak and strong electrostatic interactions, i.e., van der Waals forces, hydrogen bonds, and Coulomb interactions. The interactions between the inorganic framework and the organic templates are not obvious, especially when there is no geometrical specificity between them. Then, one molecule may lead to different framework topologies, and similarly, a framework topology may be obtained with more than one template. In this work, we used two different templates, i.e., triethylamine (TEA0) and tetraethylammonium (TEA+), to synthesize aluminophosphate-five (AFI) zeotypes (AlPO-5 and SAPO-5) under microwave conditions. The syntheses were carried out using both molecules under identical experimental conditions, i.e., with the same reagents, molar composition, crystallization time, and temperature. The structural and hydrophilic properties of the obtained materials were found to be highly dependent on the template used. A large set of characterization techniques was explored to understand short- and long-range order features. X-ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma mass spectrometry (ICP-MS), energy dispersive X-ray (EDX) microanalysis, thermogravimetric analysis (TGA), nitrogen sorption, Fourier transform infrared (FT-IR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy were used. Through these investigations, we elucidated the impact of templates on the synthesis process and the resulting properties. Our findings reveal that the templates served as space-filling agents, occupying the channels within the framework. Furthermore, the charge of the template exerted a significant influence on various aspects, including morphology, silicon content, and atomic-scale ordering. These modifications contributed to the enhancement of hydrophilicity in the AlPO-5 and SAPO-5 materials. This discovery provides a promising method for tailoring the properties of aluminophosphate-based water adsorbents in a straightforward manner. The atomic-scale ordering induced by templates leads to significant differences in the hydrophilic properties of AFI zeotypes.

ZEO-1 is the first stable extra-large pore zeolite with a substantial amount of aluminum in the framework achieved directly upon synthesis, and here we present a comprehensive analysis of its physicochemical properties. Our findings show that varying the different synthesis parameters of ZEO-1 allows for controlling its crystallization kinetics, crystal size, and morphology. Investigating the acidic properties of ZEO-1 using 27Al and 1H solid-state nuclear magnetic resonance shows that ZEO-1 exhibits potentially three different aluminum populations. The acidic nature of the hydroxyl species within ZEO-1 is studied using pyridine and 2,6-ditert-butylpyridine and carbon monoxide via in situ infrared spectroscopy, where the extinction coefficient for the 1545 cm(-1) pyridinium band is determined. Density functional theory modeling suggests that the active sites within ZEO-1 potentially occupy four different tetrahedral sites, where three of these sites are most likely located within the 12-membered ring channel, while one site is located in the 16-membered ring channel. The catalytic performance comparison of ZEO-1 with zeolites Beta and USY in the alkylation of phenol by tert-butyl alcohol, n-hexane cracking, and anisole dismutation reveals intriguing insights. ZEO-1 exhibits selectivity similar to Beta zeolite, consistent with density functional theory modeling predictions. Despite displaying weaker overall Br & oslash;nsted acid sites compared to Beta, ZEO-1's acidity remains comparable to USY zeolite. Moreover, ZEO-1 demonstrates consistent performance relative to large-pore zeolites with enhanced stability in the anisole dismutation test.