Zeolite Cages Research Articles

Confinement in a Zeolite and Zeolite Catalysis.

ConspectusZeolites, accompanied by their initial discovery as natural mines and the subsequent large-scale commercial production, have played indispensable roles in various fields such as petroleum refining and the chemical industry. Understanding the characteristics of zeolites, in contrast to their counterparts with similar chemical compositions and the origin thereof, is always a hot and challenging topic. Zeolites are known as intrinsic confined systems with ordered channels on the molecular scale, and structural confinement has been proposed to explain the unique chemical behaviors of zeolites. Generally, the channels of zeolites can regulate the diffusion of molecules, leading to a visible difference in molecular transportation and the ultimate shape-selective catalysis. On the other hand, the local electric field within the zeolite channels or cages can act on the guest molecules and change their energy levels. Confinement can be simply interpreted from both spatial and electronic issues; however, the nature of zeolite confinement is ambiguous and needs to be clarified.In this Account, we make a concise summary and analysis of the topics of confinement in a zeolite and zeolite catalysis from two specific views of spatial constraint and a local electric field to answer two basic questions of why zeolites and what else can we do with zeolites. First, it is shown how to construct functional sites including Brønsted acid sites, Lewis acid sites, extraframework cation sites, and entrapped metal or oxide aggregates in zeolites via confinement and how to understand the specific role of confinement in their reactivity. Second, the multiple impacts of confinement in zeolite-catalyzed reactions are discussed, which rationally lead to several unique processes, namely, Brønsted acid catalysis confined in zeolites, Lewis acid catalysis confined in zeolites, catalysis by zeolite-confined coordinatively unsaturated cation sites, and a cascade reaction within the confined space of zeolites. Overall, confinement effects do exist in zeolite systems and have already played extremely important roles in adsorption and catalysis. Although confinement might exist in many systems, the confinement by zeolites is more straightforward thanks to their well-ordered and rigid structure, deriving unique chemical behaviors within the confined space of zeolites. A zeolite is a fantastic scaffold for constructing isolated sites spatially and electrostatically confined in its matrix. Furthermore, zeolites containing well-defined transition-metal sites can be treated as inorganometallic complexes (i.e., a zeolite framework as the ligand of transition-metal ions) and can catalyze reactions resembling organometallic complexes or even metalloenzymes. The local electric field within the confined space of zeolites is strong enough to induce or assist the activation of small molecules, following the working fashion of frustrated Lewis pairs. The tactful utilization of structural confinement, both spatially and electronically, becomes the key to robust zeolites for adsorption and catalysis.

Impact of the Zeolite Cage Structure on Product Selectivity in CO-assisted Direct Partial Oxidation of Methane over Rh Supported AEI-, CHA-, and AFX-type Zeolites

In this manuscript, we have demonstrated CO-assisted methane conversion into small oxygenates using a Rh catalyst supported on zeolites with AEI-, CHA-, and AFX-type structures (specifically, SSZ-39, SSZ-13, and SSZ-16 zeolites, respectively). Methanol, formic acid, and acetic acid were obtained as the oxygenate products and their selectivities were unique to each of the zeolite framework structures. Smaller cage structures were preferable to produce smaller oxygenates and vice versa. Among them, the AEI-type structure was highly selective (>80%) in the formation of methanol.

Atomistic simulation study of the adsorptive separation of hydrogen sulphide/alkane mixtures on all-silica zeolites

ABSTRACT The selective separation of the aggressive hydrogen sulphide gas from industrial streams is highly important from environmental and economic aspects. Capture of this substance from industrial gases of light hydrocarbons by all-silica zeolites can be an eco-friendly alternative to the other common absorption/adsorption procedures. The adsorption from binary mixtures of hydrogen sulphide and light alkanes (H2S/CH4, H2S/C2H6, and H2S/C3H8) on preselected all-silica zeolites was studied by atomistic simulations, using a recently developed force field for hydrogen sulphide. In addition to four experimental all-silica zeolite frameworks (DDR, CHA, ACO, CAS), three of their hypothetical relatives were also drawn into the investigations. The smaller pore size zeolites (ACO, CAS, and particularly one of the hypothetical zeolites) showed remarkable separation performances under real ambient conditions. Among the examined structural details of the studied frameworks, the calculated realistic pore size distributions proved the most appropriate in attempts to unravel the connection between adsorption selectivities and framework structural properties. The investigations were completed by a necessary demonstration of the translational accessibility of the inner cages of the smaller pore size zeolites.

Emulating Solar Spectral Reflectance of Natural Leaf with Bionic Leaf Prepared from 4A Zeolite-Derived Ultramarine Green Pigment.

The emulation of the reflectance of green leaf in the solar spectral band (300–2500 nm) has garnered increasing attention from researchers. Currently, various materials have been proposed and investigated as potential bionic leaves. However, the problems such as poor weather durability, heavy metal pollution, and complex preparation technology still persist. Herein, a bionic leaf is prepared from an ultramarine green pigment as the functional material, polyvinylidene fluoride (PVDF) as the film-forming material, and LiCl as the humidizer. To prepare the ultramarine green pigment, the sulfur anion is added into the β cage of the 4A zeolite. The mechanisms and properties were discussed based on X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and spectroscopic methods. The results show that the as-fabricated bionic leaf based on the 4A zeolite-derived ultramarine green pigment was able to demonstrate a high spectral similarity coefficient of 0.91 with the green leaf. Furthermore, the spectral similarity coefficient was increased to 0.94 after being subjected to a simulated rainforest environment for 48 h, which indicated its high weather durability.

Hydrodeoxygenation of guiacol over ion-exchanged ruthenium ZSM-5 and BEA zeolites

Ion exchanged Ru/ZSM-5 and Ru/BEA catalysts, prepared by replacing the extra framework NH4+ cations in zeolites with Ru3+ ions, are employed for the hydrodeoxygenation of guaiacol. The performance results indicate ion-exchanged Ru zeolites, with extremely low Ru contents (~0.2 wt%), possess a high intrinsic HDO activity compared to the catalysts prepared by the incipient wetness impregnation method. On the basis of TEM, FTIR, XPS and TPD analysis, the NH4+ ions in zeolite were substituted by Ru species, with metal particles entered the zeolite cages and finely dispersed on the support. These ion-exchanged Ru particles exhibit a strong electronic interaction with oxygen atoms of zeolite framework with a mixed Ru(0)-Ru(III) species observed in the reduced samples. In contrast, only Ru0 was detected in the reduced impregnated Ru/ZSM-5. The partial-reduced Ru species over the ion-exchanged Ru/ZSM-5 catalyst shows a high H2 adsorption activity facilitating the hydrogenation of guaiacol to the saturated products (such as 2-methoxycyclohexanol). In addition, ion-exchanged Ru-ZSM-5 and Ru-BEA catalysts present a similar normalized cyclohexane formation rate (based on the concentration of acid sites), suggesting the acid sites play a pivotal role in the deoxygenation of 2-methoxycyclohexanol to cyclohexane.

Construction of Zeolite-Loaded Fluorescent Supramolecular on-off Probes for Corrosion Detection Based on a Cation Exchange Mechanism.

Metal engineering structures are commonly covered and protected by coatings. However, the early local corrosion under the coatings and at defects is difficult to detect and discover. Visibility to the naked eye means that corrosion has already developed and expanded. Therefore, it is practical significant to detect the early corrosion of coated metal. Based on the formation of iron ions and anodic acidification in the local corrosion process, iron ions and proton responsive fluorescent rhodamine B acylhydrazone on-off probes are prepared by newly improved methods and denoted as RBA. RBA are loaded on the surface and in the lattice cage of zeolite (ZEO) to protect RBA from premature exposure to the corrosive environment and fluorescence quenching. In corrosive environments, the RBA loaded on the surface are released and complex with iron ions in the environment to activate fluorescence characteristics. Simultaneously, due to the cation exchange of ZEO, iron ions enter the lattice cage of ZEO and combine with RBA in the lattice cage to turn on fluorescence. When applied in epoxy coatings, the RBA/ZEO effectively indicate the occurrence of corrosion under the coatings and at defects, and accurately locate the corrosion site. Nano-scale ZEO (or RBA/ZEO) fill the micropores such as pinholes and defects of the coatings, and increase the difficulty of diffusion and penetration of corrosive media into the coatings. The application of RBA/ZEO functional filler not only do not weaken the main anti-corrosion performance of the coatings, but also significantly improve it.

Metal Complexes of Schiff Bases of 3-Hydroxyquinoxaline-2-carboxaldehyde Encapsulated in Zeolite Y Cages: Potential Catalyst for Removing Phenol from Effluent Media

Transition metal complexes are known to be efficient catalyst for many organic transformations. Encapsulation of metal complexes in zeolite cage brings many significant modifications in the structure of the metal complexes, which are very interesting from the catalytic point of view. This study aims in a comparative evaluation of the influence of structure of neat and encapsulated complexes in their catalytic activity. Phenol is one of the major industrial pollutants. Heterogenizing transition metal Schiff bases by encapsulation inside the zeolite would help to minimize the reuse problem of transition metal complexes. This article deals with the synthesis, characterization and catalytic activity studies of Co(II), Ni(II) and Cu(II) complexes of 3-hydroxyquinoxaline-2-carboxaldehyde with ethylenediamine (L1) and an o-phenylene diamine (L2).

Noble metal encapsulated sulfide catalyst for the production of aviation biofuel from the hydroprocessing of non-edible oils

Encapsulation of noble metals inside the zeolite cage has attracted much attention in the area of catalysis due to unique properties, i.e., shape selectivity, higher activity, and product yield. In the combined work, encapsulated Platinum (Pt) inside the sodalite cage combined with sulfided nickel and molybdenum supported on silica-alumina (NiMo(S)/SiO2-Al2O3) is used to improve the catalyst hydrogenation function by providing spillover hydrogen to the nearby active sulfided NiMo sites. Encapsulation ensures the protection of the noble metal sites from poisoning due to the sulfur-containing compounds. They have a higher hydrodynamic diameter than that of the sodalite window cage. Experimental results showed platinum encapsulated sulfided nickel and molybdenum supported on silica-alumina (Pt@SOD-NiMo(S)-SiO2-Al2O3) had a substantial effect on the product composition, yield, and hydrogen consumption compared with the conventional NiMo(S)/SiO2-Al2O3 catalyst for the hydroconversion reaction of jatropha oil to produce carbon–neutral green fuels. Sustainable aviation fuel with lower aromatics and naphthene content (<1%) was produced over the bi-functional Pt encapsulated Ni-Mo(S)/SiO2-Al2O3 catalysts in the reaction temperature range of 380–420 °C. Aromatics and naphthalene obtained in the aviation range product were as much as 15 times lower than the conventional NiMo(S)/SiO2-Al2O3 catalyst. The Pt@SOD-NiMo(S)-SiO2-Al2O3 catalyst showed stable activity for >600 h of the run, whereas state-of-the-art reported catalyst Pt@SOD-NiMo(S)-ZSM-5 had limitations in terms of catalyst life (stable activity only for 350 h).

Strong and Weakly Acidic OH Groups of HY Zeolite into the Different Routes of Cyclohexene Reaction: An IR Operando Study

IR operando study of cyclohexene reaction on HY zeolite (Si/Al = 15) was performed to determine the role of the OH groups located in the different zeolitic cages and the silanol groups (SiOH). A parallel between the product yield and type and amount of OH groups poisoned by coking and pyridine pulses was established. The role of silanol and zeolitic OH groups during cyclohexene conversion and the coverage rate of surface groups of the dealuminated HY zeolite, were evaluated by FT-IR operando study. At the beginning of the reaction, zeolite exhibited a very intense deactivation due to coke formation. Coke is initially deposited on strong acid sites, inhibiting the H-transfer activity. Further, coke formation decreased. At this stage of the reaction, pyridine addition markedly decreased the isomerization activity. In parallel, it is noted that mainly SiOH, OH groups at hexagonal prisms, and perturbed OH groups in sodalite cages were mainly affected, indicating that these groups are responsible for the isomerization steps. These results showed that even weakly acidic sites are active sites for isomerization reaction. In cyclohexene conversion, hydrogen transfer occurs on supercage OH groups of HY zeolite. In contrast, perturbed sodalite OH and hexagonal prisms OH, as well as SiOH groups, are responsible for isomerization steps, as revealed by pyridine pulse addition during the reaction.

Using Low-Pressure Methane Adsorption Isotherms for Higher-Throughput Screening of Methane Storage Materials.

A useful correlation between the low-pressure (up to 1.2 bar), low-temperature (195 K) and high-pressure (up to 65 bar), room temperature (298 K) methane storage properties of a range of porous materials is reported. Methane isotherms under these two sets of conditions show a remarkable agreement in both equilibrium adsorption and deliverable capacities for materials with pore volumes that are less than approximately 0.80 cm3/g. This trend holds well for the suite of metal-organic frameworks and porous coordination cages we studied, in addition to a zeolite and porous organic cage. Although it is well known that gravimetric gas storage capacity trends with gravimetric surface area, the 1.2 bar, 195 K excess adsorption capacity of a given framework is a better indicator of its room temperature, 65 bar capacity. Given the significantly smaller sample quantities needed for low-pressure measurements, greater accessibility to researchers around the world, accuracy of the measurement, and higher throughput, we envision this method as a rapid screening tool for the identification of methane storage materials. As excess/total adsorption and gravimetric/volumetric adsorption can be interconverted by simple utilization of the scalar quantities of pore volume or density, respectively, this method can be easily adapted to obtain both gravimetric and volumetric total adsorption capacities for a given adsorbent. In terms of volumetric methane adsorption, we further investigate the relationship between crystallographic and bulk density for the adsorbents studied here. With this analysis, it becomes apparent that in the absence of novel synthetic approaches, reported volumetric storage capacities should be viewed as an optimistic upper limit for a given material and not necessarily a true reflection of its actual adsorption properties as most MOFs have bulk densities that are less than half of their crystallographic values.

Using Molecular Simulations for Elucidation of Thermodynamic Nonidealities in Adsorption of CO2-Containing Mixtures in NaX Zeolite.

Cation-exchanged zeolites are of potential use in pressure swing adsorption (PSA) technologies for CO2 capture applications. Published experimental data for CO2/CH4, CO2/N2, and CO2/C3H8 mixture adsorption in NaX zeolite, also commonly referred to by its trade name 13X, have demonstrated that the ideal adsorbed solution theory (IAST) fails to provide adequately accurate estimates of mixture adsorption equilibrium. In particular, the IAST estimates of CO2/CH4 and CO2/N2 selectivities are significantly higher than those realized in experiments. For CO2/C3H8 mixtures, the IAST fails to anticipate the selectivity reversal phenomena observed in experiments. In this article, configurational-bias Monte Carlo (CBMC) simulations are employed to provide confirmation of the observed thermodynamic nonidealities in adsorption of CO2/CH4, CO2/N2, and CO2/C3H8 mixtures in NaX zeolite. The CBMC simulations provide valuable insights into the root cause of the failure of the IAST, whose applicability mandates a homogeneous distribution of adsorbates within the pore landscape. By sampling 105 equilibrated spatial locations of individual guest molecules within the cages of NaX zeolite, the radial distribution functions (RDFs) of each of the pairs of guest molecules are determined. Examination of the RDFs clearly reveals congregation effects, wherein the CO2 guests occupy positions in close proximity to the Na+ cations. The positioning of the partner molecules (CH4, N2, or C3H8) is further removed from the CO2 guest molecules; consequently, the competition in mixture adsorption faced by the partner molecules is less severe than that anticipated by the IAST. The important message to emerge from this article is the need for quantification of thermodynamic nonideality effects in mixture adsorption.

Selective Adsorption of C6, C8, and C10 Linear α-Olefins from Binary Liquid-Phase Olefin/Paraffin Mixtures Using Zeolite Adsorbents: Experiment and Simulations

The adsorption separation of gaseous olefin/paraffin using porous materials has been extensively studied from both experimental and molecular simulation perspectives, while the adsorption separation of liquid-phase olefin/paraffin has been much less studied. One of the most important reasons for this is that it is difficult to measure the actual adsorption capacity of liquid-phase adsorption separation directly through experiments, and the simulation results of most studies are compared to gas-phase measurements. In this paper, the selective adsorption of linear α-olefins from three binary liquid-phase olefin/paraffin mixtures, 1-hexene/n-hexane (C6), 1-octene/n-octane (C8), and 1-decene/n-decane (C10), by zeolite adsorbents was systematically investigated using batch adsorption experiments and configurational-bias grand canonical Monte Carlo (CB-GCMC) simulations. In the batch experiments, based on the liquid-phase measurement method of the actual adsorption capacity that we developed, a modified commercial 5A zeolite with a relatively large pore volume and surface area was used for adsorption. The results showed that the modified 5A zeolite had larger actual adsorption capacities for C6 and C8 linear α-olefins, which increased by 51% and 56%, respectively, than the standard 5A zeolite that was used in our previous work. The adsorption isotherms of C6, C8, and C10 in the 5A and 13X zeolites were calculated by CB-GCMC simulations. The visualized results of density profiles showed that the olefin molecules were densely distributed at the edge of the zeolite cages and that there were cases where a single molecule was adsorbed over two adjacent cages. The good agreement between the experimental and simulated data proves the completeness of the liquid-phase measurement method that we developed and the reliability of the simulation prediction.

Low‐T CO Oxidation over Cu−CHA Catalysts in Presence of NH3: Probing the Mobility of CuII Ions and the Role of Multinuclear CuII Species

The Cover Feature portrays two CuII ions as trapeze artists swinging inside a CHA zeolite cage until they join hands to form a single complex. In their Communication, reporting CO titration experiments over preoxidized Cu-CHA catalysts, R. Villamaina et al. provide evidence that NH3 ligands, like trapezes, mobilize initially isolated CuII ions to form the dimeric complexes with removable oxygen needed for CO oxidation. This is confirmed by transient kinetic analysis, which shows that the rate of CuII reduction is 2nd order in the ZCuIIOH species. These findings may be relevant for elucidation of the reduction half cycle in the redox mechanism of the Standard NH3-SCR reaction over Cu-CHA systems. More information can be found in the Communication by R. Villamaina et al.

Role of metal co‐cations in improving CuY zeolite performance for DMC synthesis: A theoretical study

First principle calculations based on density functional theory are conducted to investigate the influence of metal cations including Mg2+, Ca2+, Sr2+, Ba2+, La (OH)2+ and Ce (OH)2+ in the small cage of zeolite on the electronic environment of adjacent active center, Cu+ in CuY zeolite as well as the process of CO insertion into CH3O to form CH3OCO for oxidative carbonylation of methanol. The study explains the theoretical reasons for the effects of metal cations on the catalytic activity of zeolites. It was found that, the presence of co‐cations in the small cage can affect the electronic properties and also the catalytic activity in two ways. Firstly, the presence of co‐cations, viz., Ca2+, Sr2+, Mg2+, Ba2+ and La species in small cage hinders the migration of active Cu+ cations from the super cage to small cage. Secondly, the co‐cations greatly affect the charge transfer from zeolite framework to Cu+ present in the adjacent super cage, leading to the increase of the net charge and binding energy of Cu+. The findings can improve the CO adsorption and insertion efficiencies, and the stability of transition states, which results in the enhanced catalytic activity of corresponding zeolites.

π‐Interactions between Cyclic Carbocations and Aromatics Cause Zeolite Deactivation in Methanol‐to‐Hydrocarbon Conversion

AbstractThe understanding of catalyst deactivation represents one of the major challenges for the methanol‐to‐hydrocarbon (MTH) reaction over acidic zeolites. Here we report the critical role of intermolecular π‐interactions in catalyst deactivation in the MTH reaction on zeolites H‐SSZ‐13 and H‐ZSM‐5. π‐interaction‐induced spatial proximities between cyclopentenyl cations and aromatics in the confined channels and/or cages of zeolites are revealed by two‐dimensional solid‐state NMR spectroscopy. The formation of naphtalene as a precursor to coke species is favored due to the reaction of aromatics with the nearby cyclopentenyl cations and correlates with both acid density and zeolite topology.

π‐Interactions between Cyclic Carbocations and Aromatics Cause Zeolite Deactivation in Methanol‐to‐Hydrocarbon Conversion

The understanding of catalyst deactivation represents one of the major challenges for the methanol-to-hydrocarbon (MTH) reaction over acidic zeolites. Here we report the critical role of intermolecular π-interactions in catalyst deactivation in the MTH reaction on zeolites H-SSZ-13 and H-ZSM-5. π-interaction-induced spatial proximities between cyclopentenyl cations and aromatics in the confined channels and/or cages of zeolites are revealed by two-dimensional solid-state NMR spectroscopy. The formation of naphtalene as a precursor to coke species is favored due to the reaction of aromatics with the nearby cyclopentenyl cations and correlates with both acid density and zeolite topology.

Synthesis of hybrid materials by immobilizing para-aminobenzoic acid complexes of Eu3+ and Tb3+ in zeolite Y and their luminescent properties

Two new lanthanide containing zeolite Y based luminescent hybrid materials were synthesized and characterized. Exchange of Na+ from zeolite Y with lanthanide ions (Eu3+ or Tb3+) was carried out by ultrasonication and annealing. Para-amino benzoic acid was introduced to the ion exchanged zeolite Y to form complex with the lanthanide ion. Characterizations of the materials were carried out using IR spectroscopy, PXRD, SEM, UV–Vis absorption spectroscopy, TG–DTA and DSC analysis. Luminescence properties of these materials were studied using photoluminescence spectroscopy. Complex formation inside the zeolite cage increased the luminescence efficiency of the lanthanide ions through antenna effect. Tb3+ containing hybrid material showed efficient energy transfer due to the optimal energy level matching of the triplet level of ligand and the emissive level of Tb3+. Zeolite Y structure acts as a protective barrier against the degradation of organic part as is evident from the high thermal stability of the materials.

Nanozeolite ZSM-5 electrolyte additive for long life sodium-ion batteries.

A novel low cost sodium-ion battery electrolyte additive ZSM-5 nanozeolite, which improves cycle life, is demonstrated in a Na-ion cell. The addition of this zeolitic small molecule scavenger removes electrolyte decomposition products, and has beneficial properties compared to traditional organic additives such as fluoroethylene carbonate (FEC). Capacity retention after 480 cycles improves from 40% (none) compared to 62% (ZSM-5). This is due to the enhanced interface stability over the cell life-time, as shown by XPS.

Synthesis and characterization of zeolite encapsulated ruthenium complexes of anthranilic acid and 4-aminobenzoic acid

Encapsulated metal complexes using anthranilic acid and 4-aminobenzoic acid as ligands are found to have an immense variety of applications, as they possess great catalytic and bio-mimetic properties. The present work comprises the synthesis and characterization of zeolite encapsulated ruthenium complexes. The flexible ligand method employed involves the reaction of the ligand with the metal already introduced within the supercages of the zeolite.Chemical analysis suggested that the Si/Al ratio is retained as 2.6 even after complex formation indicating the absence of any dealumination. The data obtained by the BET method shows significant reduction in surface area and pore volume as a result of the encapsulation of complexes. The X-ray diffraction patterns reveal the retention of zeolite framework even after encapsulation. Scanning electron micrographs of the complexes before and after soxhlet extraction indicate the absence of surface adsorbed complexes. TG analysis shows that the decomposition of the complex and partial decomposition of the zeolite cage occurs in the range 25–300 °C. The small mass loss in different stages of decomposition is an indication of the high thermal stability of the zeolite framework. The IR spectral data show the coordination of nitrogen atoms of the ligands to the metal. The electronic spectra of the zeolite encapsulated complexes RuYAA and RuYABA indicate an octahedral geometry. The complex is assigned a six coordinate structure on the basis of the observations made from EPR spectra. The axial symmetry of the encapsulated complexes is consistent with the presence of a paramagnetically active Ru(III) ion.

The adsorption mechanisms of organic micropollutants on high-silica zeolites causing S-shaped adsorption isotherms: An experimental and Monte Carlo simulation study

The adsorption of organic micropollutants (OMPs) on high-silica zeolites is characterized by adsorption isotherms with various shapes. The occurrence of an S-shaped adsorption isotherm indicates the lack of adsorption affinity for OMPs at low, environmentally relevant equilibrium concentrations. In this study, S-shaped isotherms were observed during batch experiments with 2,4,6-trichlorophenol (TCP) and FAU zeolites. This is the first time that an S-shaped isotherm is reported for the adsorption of OMPs on high-silica zeolites. Monte Carlo (MC) simulations in the grand-canonical ensemble were used to obtain a better understanding of the mechanism of the S-shaped adsorption isotherms. From the MC simulation results, it was observed that multiple TCP molecules were adsorbed in the supercages of the FAU zeolites. It was found that the π-π interactions between TCP molecules give rise to the adsorption of multiple TCP molecules per supercage, and thus causing an S-shaped adsorption isotherm. Simulations also revealed that water molecules were preferentially adsorbed in the supercages and sodalite cages of the FAU zeolites. FAU zeolites with a higher Al content adsorbed a higher amount of water molecules and a lower amount of TCP, and showed less pronounced S-shaped isotherms.