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Nanosized faujasite (FAU) crystals have great potential as catalysts or adsorbents to more efficiently process present and forthcoming synthetic and renewable feedstocks in oil refining, petrochemistry and fine chemistry. Here, we report the rational design of template-free nanosized FAU zeolites with exceptional properties, including extremely small crystallites (10-15 nm) with a narrow particle size distribution, high crystalline yields (above 80%), micropore volumes (0.30 cm3 g−1) comparable to their conventional counterparts (micrometre-sized crystals), Si/Al ratios adjustable between 1.1 and 2.1 (zeolites X or Y) and excellent thermal stability leading to superior catalytic performance in the dealkylation of a bulky molecule, 1,3,5-triisopropylbenzene, probing sites mostly located on the external surface of the nanosized crystals. Another important feature is their excellent colloidal stability, which facilitates a uniform dispersion on supports for applications in catalysis, sorption and thin-to-thick coatings. [ABSTRACT FROM AUTHOR]

Abstract: New techniques and methodologies in the spectroscopic characterization of zeolites provide new insights on the complexity of zeolitic materials. In particular, emerging IR and NMR techniques shed new lights on old problems such as acidity. New, rich and quantitative information can be gathered. In particular, the ability to work under the so-called operando conditions yields much valuable data to rationally design better catalysts or zeolite based materials. The work and inspiration of Eric Derouane are often at the core of this new knowledge. [Copyright &y& Elsevier]

Chemical interactions occurring between zeolites and alumina binders during the critical steps of catalyst forming are the focus of this study. Three widely used and commercially significant variants of FAU zeolite, covering a wide range of Si/Al ratios, micro- and meso-porosity and acidic properties (Y [LZY-64, Si/Al = 2.3] and USY [CBV 720 and CBV 760 with Si/Al = 16 and Si/Al = 28, respectively]) were shaped by extrusion with pseudoboehmite to produce bound extrudates. These extrudates were characterized by conventional techniques (XRD, 27Al NMR and IR spectroscopy, N 2 physisorption ...) and compared to their parent powders activated under the same conditions. The catalytic performances of the zeolite powders, their derived alumina extrudates and physical zeolite/γ-Al 2 O 3 mixtures were also evaluated employing two different reactions: i) n-octane hydroisomerization, to probe all catalytic sites and ii) 1,3,5 tri-isopropyl benzene dealkylation to probe only the external/mesoporous surfaces. The bound zeolites systematically displayed catalytic performance superior to their parent powders or physical mixtures, especially in the dealkylation of 1,3,5 tri-isopropyl benzene. Infrared spectroscopy measurements of the number, nature and strength of the acid sites were consistent with these catalytic results demonstrating that new catalytic sites are created and located on the external or mesoporous surface of the zeolites, i.e. at the zeolite-binder interface. The work reported here clearly illustrates that binding and subsequent thermal treatment of zeolite powders to produce commercially representative forms can significantly alter the quality and quantity of active sites creating active centers not usually present in pure powders which are typically studied and reported in much of the open literature. Such a study is also a blueprint for other catalytic phases, other forming processes (spray-drying, oil-dropping, pelletizing ...) and could also be applied to the shaping of adsorbents. Image 1 • Zeolite Y were shaped by extrusion using pseudoboehmite as binder. • Acidic properties of zeolite extrudates were probed using basic probe molecule and monitored by infrared. • Zeolite shaping alter qualitatively and quantitatively the acidic properties of the final compounds. • Zeolite Y extrudates systematically displayed catalytic performance superior to their parent powders or physical mixtures, especially in the dealkylation of 1,3,5 tri-isopropyl benzene. • New acid sites are formed during shaping, reminiscent of amorphous silica-alumina. [ABSTRACT FROM AUTHOR]

Zeolite Y and its ultra‐stabilized hierarchical derivative (USY) are the most widely used zeolite‐based heterogeneous catalysts in oil refining, petrochemisty, and other chemicals manufacturing. After almost 60 years of academic and industrial research, their resilience is unique as no other catalyst displaced them from key processes such as FCC and hydrocracking. The present study highlights the key difference leading to the exceptional catalytic performance of USY versus the parent zeolite Y in a multi‐technique study combining advanced spectroscopies (IR and solid‐state NMR) and molecular modeling. The results highlight a hitherto unreported proton transfer involving inaccessible active sites in sodalite cages that contributes to the exceptional catalytic performance of USY. [ABSTRACT FROM AUTHOR]

Zeolite Y and its ultra‐stabilized hierarchical derivative (USY) are the most widely used zeolite‐based heterogeneous catalysts in oil refining, petrochemisty, and other chemicals manufacturing. After almost 60 years of academic and industrial research, their resilience is unique as no other catalyst displaced them from key processes such as FCC and hydrocracking. The present study highlights the key difference leading to the exceptional catalytic performance of USY versus the parent zeolite Y in a multi‐technique study combining advanced spectroscopies (IR and solid‐state NMR) and molecular modeling. The results highlight a hitherto unreported proton transfer involving inaccessible active sites in sodalite cages that contributes to the exceptional catalytic performance of USY. [ABSTRACT FROM AUTHOR]

[Display omitted] • On methane dearomatization reaction, two main deactivation modes occurs. • Irreversible damage by zeolite amorphization during the isothermal pre-treatment. • Reversible deactivation by coke deposition ("soft", "hard" and carbide species). • 3 descriptors : coke level, micropore volume loss, monoclinic/orthorhombic change. We report a detailed kinetic study of methane dehydroaromatization on three bifunctional Mo/HZSM-5 catalysts (0.9 wt%, 2.7 wt%, and 17.2 wt% Mo). Two main deactivation modes are present: (i) irreversible damage by zeolite amorphization during the isothermal pre-treatment in an inert atmosphere and (ii) reversible deactivation by coke deposition ("soft", "hard" and carbide species). The former occurs at high Mo loading (>4.0 w%) and provides low activity catalysts. Catalysts with a lower and well-balanced molybdenum loading (<4 w%) suffer mainly from the second deactivation mode. The catalyst decay is modelled by semi-empirical laws including time on stream and coke level. The latter initiates textural and structural catalyst modifications leading to an activity loss. Three deactivation descriptors, 1 : coke level on the spent samples, 2: loss of micropore volume, and 3: monoclinic/orthorhombic phase transition of the zeolite are identified. Further characterization indicates that both molybdenum and carbon species are responsible for the catalytic deactivation of well-balanced catalysts. At least 50% of the initially dispersed molybdenum migrates to the external surface of the zeolite to form large clusters of molybdenum carbide. The coke extracted from the zeolite micropores are confirmed to be mainly unsubstituted polyaromatics. [ABSTRACT FROM AUTHOR]

The utilization of methane for chemical production, often considered as the future of petrochemistry, historically could not compete economically with conventional processes due to higher investment costs. Achieving sustainability and decarbonization of the downstream industry by integration with a methane-to-chemicals process may provide an opportunity to unlock the future for these technologies. Gas-to-chemicals is an efficient tool to boost the decarbonization potential of renewable energy. While the current implementation of carbon capture utilization and storage (CCUS) technologies is of great importance for industrial decarbonization, a shift to greener CO2-free processes and CO2 utilization from external sources for manufacturing valuable goods is highly preferred. This review outlines potential options for how a methane-to-chemicals process could support decarbonization of the downstream industry. [ABSTRACT FROM AUTHOR]

The utilization of methane for chemical production, often considered as the future of petrochemistry, historically could not compete economically with conventional processes due to higher investment costs. Achieving sustainability and decarbonization of the downstream industry by integration with a methane-to-chemicals process may provide an opportunity to unlock the future for these technologies. Gas-to-chemicals is an efficient tool to boost the decarbonization potential of renewable energy. While the current implementation of carbon capture utilization and storage (CCUS) technologies is of great importance for industrial decarbonization, a shift to greener CO2-free processes and CO2 utilization from external sources for manufacturing valuable goods is highly preferred. This review outlines potential options for how a methane-to-chemicals process could support decarbonization of the downstream industry. [ABSTRACT FROM AUTHOR]

Zeolites are widely used in many commercial processes, mostly as catalysts or adsorbents. Understanding their intimate structure at the nanoscale is the key to control their properties and design the best materials for their ever increasing uses. Herein, we report a new and controllable fluoride treatment for the non-discriminate extraction of zeolite framework cations. This sheds new light on the sub-structure of commercially relevant zeolite crystals: they are segmented along defect zones exposing numerous nanometer-sized crystalline domains, separated by low-angle boundaries, in what were apparent single-crystals. The concentration, morphology, and distribution of such domains analyzed by electron tomography indicate that this is a common phenomenon in zeolites, independent of their structure and chemical composition. This is a milestone to better understand their growth mechanism and rationally design superior catalysts and adsorbents. [ABSTRACT FROM AUTHOR]

Zeolites are widely used in many commercial processes, mostly as catalysts or adsorbents. Understanding their intimate structure at the nanoscale is the key to control their properties and design the best materials for their ever increasing uses. Herein, we report a new and controllable fluoride treatment for the non-discriminate extraction of zeolite framework cations. This sheds new light on the sub-structure of commercially relevant zeolite crystals: they are segmented along defect zones exposing numerous nanometer-sized crystalline domains, separated by low-angle boundaries, in what were apparent single-crystals. The concentration, morphology, and distribution of such domains analyzed by electron tomography indicate that this is a common phenomenon in zeolites, independent of their structure and chemical composition. This is a milestone to better understand their growth mechanism and rationally design superior catalysts and adsorbents. [ABSTRACT FROM AUTHOR]

Embryonic ZSM-5 zeolites are harvested from clear ZSM-5 precursor solutions after freeze-drying and calcination. These materials are microporous with pore sizes close to those of ZSM-5 zeolites. Due to their partially formed structure, embryonic zeolites do not display a long range order and are XRD amorphous. Their micropores are highly accessible, and resistive to high temperature treatments and the strength of their acid sites is comparable to zeolites. These characteristics give them superior catalytic performances in the conversion of a bulky model molecule, 1,3,5-triisopropylbenzene. [ABSTRACT FROM AUTHOR]

The mesopores formation in zeolite crystals has long been considered to occur through the stochastic hydrolysis and removal of framework atoms. Here, we investigate the NH4F etching of representative small, medium, and large pore zeolites and show that the zeolite dissolution behavior, therefore the mesopore formation probability, is dominated by zeolite architecture at both nano‐ and sub‐nano scales. At the nano‐scale, the hidden mosaics of zeolite structure predetermine the spatio‐temporal dissolution of the framework, hence the size, shape, location, and orientation of the mesopores. At the sub‐nano scale, the intrinsic micropore size and connectivity jointly determine the diffusivity of reactant and dissolved products. As a result, the dissolution propensity varies from removing small framework fragments to consuming nanodomains and up to full digestion of the outmost part of zeolite crystals. The new knowledge will lead to new understanding of zeolite dissolution behavior and new adapted strategies for tailoring hierarchical zeolites. [ABSTRACT FROM AUTHOR]

Abstract: The improvement of molecular transport properties of hierarchical H-ZSM-5 obtained by desilication was evidenced by studying the desorption of o-xylene and isooctane by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). This technique enabled monitoring simultaneously bands associated with the molecular probes and the zeolite, using powdered sample masses as low as 1mg. Two H-ZSM-5 samples with markedly different crystal sizes were investigated. The first sample was commercial and consisted of small crystallites (ca. 250nm). The second sample were laboratory-made large crystals with coffin-like shape (ca. 17×4×4μm3). The hierarchical derivatives of the small and large zeolite crystals displayed 250 and 120m2 g−1 of mesopore surface area, respectively, in contrast to the 62 and 5m2 g−1 of the parent counterparts. The data based on o-xylene desorption were partly disguised by site-desorption limitations. Desorption experiments using isooctane evidenced a 4-fold reduction in the characteristic diffusion path length on both mesoporous small and large zeolites with respect to their purely microporous analogues. These results confirm the substantial potential for improvement of commercial nanocrystalline zeolites in diffusion-limited reactions upon the introduction of intra-crystalline mesoporosity by post-synthesis modification. [Copyright &y& Elsevier]

Abstract: The adsorption of phenol on supported sulfide CoMo catalysts and on oxides is investigated using IR spectroscopy. On silica, phenol mainly interacts via hydrogen-bonding, whereas on alumina it dissociates on the acid–base pairs of this oxide leading to the formation of strongly adsorbed phenolates species. On a sulfided CoMo catalyst supported on alumina, phenol dissociates on the support but does not interact strongly with the sulfide phase. The accessibility of the various sites of the catalyst after phenol contact is investigated by CO adsorption monitored by IR spectroscopy. As expected, phenolate formation decreases the accessibility of support sites. In addition, a decrease of the sulfide site accessibility is also observed. This is indicative of an indirect poisoning of the sulfide edge sites by phenolate species anchored on the support and in the vicinity of sulfide slabs. Consequently, decreasing the amount or strength of the acid–base paired sites of the support should be a way to limit deactivation. [Copyright &y& Elsevier]

Zeolites have been game-changing materials in oil refining and petrochemistry over the last 60 years and have the potential to play the same role in the emerging processes of the energy and environmental transition. Although zeolites are crystalline inorganic solids, their structures are not perfect and the presence of defect sites – mainly Brønsted acid sites and silanols – influences their thermal and chemical resistance as well as their performances in key areas such as catalysis, gas and liquid separations and ion-exchange. In this paper, we review the type of defects in zeolites and the characterization techniques used for their identification and quantification with the focus on diffraction, spectroscopic and modeling approaches. More specifically, throughout the review, we will focus on silanol (Si–OH) defects located within the micropore structure and/or on the external surface of zeolites. The main approaches applied to engineer and heal defects and their consequences on the properties and applications of zeolites in catalysis and separation processes are highlighted. Finally, the challenges and opportunities of silanol defect engineering in tuning the properties of zeolites to meet the requirements for specific applications are presented. [ABSTRACT FROM AUTHOR]

Hierarchical zeolites are regarded as promising catalysts due to their well‐developed porosity, increased accessible surface area, and minimal diffusion constraints. Thus far, the focus has been on the creation of mesopores in zeolites, however, little is known about a microporosity upgrading and its effect on the diffusion and catalytic performance. Here the authors show that the "birth" of mesopore formation in faujasite (FAU) type zeolite starts by removing framework T atoms from the sodalite (SOD) cages followed by propagation throughout the crystals. This is evidenced by following the diffusion of xenon (Xe) in the mesoporous FAU zeolite prepared by unbiased leaching with NH4F in comparison to the pristine FAU zeolite. A new diffusion pathway for the Xe in the mesoporous zeolite is proposed. Xenon first penetrates through the opened SOD cages and then diffuses to supercages of the mesoporous zeolite. Density functional theory (DFT) calculations indicate that Xe diffusion between SOD cage and supercage occurs only in hierarchical FAU structure with defect‐contained six‐member‐ring separating these two types of cages. The catalytic performance of the mesoporous FAU zeolite further indicates that the upgraded microporosity facilitates the intracrystalline molecular traffic and increases the catalytic performance. [ABSTRACT FROM AUTHOR]

The current energy transition presents many technological challenges, such as the development of highly stable catalysts. Herein, we report a novel "top‐down" synthesis approach for preparation of a single‐site Mo‐containing nanosized ZSM‐5 zeolite which has atomically dispersed framework‐molybdenum homogenously distributed through the zeolite crystals. The introduction of Mo heals most of the native point defects in the zeolite structure resulting in an extremely stable material. The important features of this single‐site Mo‐containing ZSM‐5 zeolite are provided by an in‐depth spectroscopic and microscopic analysis. The material demonstrates superior thermal (up to 1000 °C), hydrothermal (steaming), and catalytic (converting methane to hydrogen and higher hydrocarbons) stability, maintaining the atomically disperse Mo, structural integrity of the zeolite, and preventing the formation of silanols. [ABSTRACT FROM AUTHOR]

The development of catalysts that can operate under exceptionally harsh and unconventional conditions is of critical importance for the transition of the energy and chemicals industries to low‐emission and renewable chemical feedstocks. In this review we will highlight materials and more specifically metal‐containing zeolite catalysts that have been tested under harsh reaction conditions such as high temperature light alkane conversion and biomass valorization. Particular attention will be given to studies that explore the stability and recyclability of metal‐containing zeolite catalysts operating in continuous modes. Metal‐containing zeolites are considered as an important class of catalysts operating outside the comfort zone of current heterogeneous catalytic reactions in both gas and liquid phase reactions. The relationship between the properties of the metal‐containing zeolite and catalytic performance will be explored. [ABSTRACT FROM AUTHOR]

The current energy transition presents many technological challenges, such as the development of highly stable catalysts. Herein, we report a novel "top‐down" synthesis approach for preparation of a single‐site Mo‐containing nanosized ZSM‐5 zeolite which has atomically dispersed framework‐molybdenum homogenously distributed through the zeolite crystals. The introduction of Mo heals most of the native point defects in the zeolite structure resulting in an extremely stable material. The important features of this single‐site Mo‐containing ZSM‐5 zeolite are provided by an in‐depth spectroscopic and microscopic analysis. The material demonstrates superior thermal (up to 1000 °C), hydrothermal (steaming), and catalytic (converting methane to hydrogen and higher hydrocarbons) stability, maintaining the atomically disperse Mo, structural integrity of the zeolite, and preventing the formation of silanols. [ABSTRACT FROM AUTHOR]

The development of catalysts that can operate under exceptionally harsh and unconventional conditions is of critical importance for the transition of the energy and chemicals industries to low‐emission and renewable chemical feedstocks. In this review we will highlight materials and more specifically metal‐containing zeolite catalysts that have been tested under harsh reaction conditions such as high temperature light alkane conversion and biomass valorization. Particular attention will be given to studies that explore the stability and recyclability of metal‐containing zeolite catalysts operating in continuous modes. Metal‐containing zeolites are considered as an important class of catalysts operating outside the comfort zone of current heterogeneous catalytic reactions in both gas and liquid phase reactions. The relationship between the properties of the metal‐containing zeolite and catalytic performance will be explored. [ABSTRACT FROM AUTHOR]

• Wet ball milling of -COK-14 zeolite in presence of a dissolved Al source. • Particle size reduction and framework aluminum introduction result from milling. • Milled and aluminated COK-14 contains Brønsted acid sites. • Milled and aluminated COK-14 loaded with platina is an ideal bifunctional catalyst. The precursor of all-silica COK-14 zeolite (OKO topology) with interrupted framework was subjected to wet ball milling in the presence of aluminum isopropoxide. Alumination and particle size reduction of the zeolite crystals was combined in this way. Wet ball milling resulted in fragmentation of the platelet-shape COK-14 crystals while preserving crystallinity. 27Al NMR spectroscopy of the fully condensed COK-14 zeolite, obtained by calcination of milled -COK-14 precursor, confirmed the incorporation of tetrahedrally coordinated Al atoms in the framework. The creation of Brønsted acid sites was confirmed by pyridine adsorption. Loaded with platinum, the sample showed ideal bifunctional catalytic behavior in hydroisomerization and hydrocracking of n -decane model alkane compound. Aluminum incorporation by milling is an alternative to the atomic layer deposition (ALD) process using trimethylaluminum and to thermal alumination. Wet ball milling in presence of aluminum isopropoxide shows great potential for making siliceous zeolites catalytically active. [ABSTRACT FROM AUTHOR]

A series of ZSM-5 zeolites (embryonic, microporous, hierarchical) is studied in the catalytic cracking of polypropylene in the framework of its chemical recycling. Two important zeolite features impact their catalytic performances and allow their design as efficient catalysts: porosity and acidity. They also play a key role in catalyst deactivation and regeneration. A detailed thermogravimetric and spectroscopic (operando FT-IR) analysis of the reaction, including catalyst coking and regeneration, shows the emergence of rules to design fit-for-purpose catalysts to be used in existing or grass-roots FCC units. [Display omitted] • Operando FT-IR-GC-MS study highlights the relative role of the micro- & mesoporous surfaces. • Complementary roles in PP cracking: porosity and acid site strength related to confinement. • Reversible embryonic zeolites deactivation makes PP recycling to fuel or petrochemicals. • The rules to design fit-for-purpose catalysts to be used in existing or grass-roots FCC units. [ABSTRACT FROM AUTHOR]

[Display omitted] • Smaller discrete crystallites of meshed K-CHA improves dynamic adsorption performance. • Nano-sized K-CHA has sharper CO 2 breakthrough, reaches equilibrium more rapidly. • Improved utilisation of fixed-bed for CO 2 separation using nano-sized K-CHA. • Reduced discrete crystallite size increases the mesoporosity of the adsorbent particle. • Nano-sized K-CHA exhibits fewer CO 2 chemisorbed species than micron-sized K-CHA. The performance of K-CHA nanozeolite composed of discrete nanoparticles prepared by an organic template-free direct synthesis is compared to that of conventional micron-sized K-CHA with an order of magnitude difference in particle size and identical chemical composition (Si/Al ratio and cations) for the separation of dilute CO 2 from N 2. Breakthrough curve analysis of the zeolites meshed to identical sizes demonstrates the superior performance of nanozeolites for gas separation due to the significantly faster diffusion of CO 2 molecules through the bed composed of meshed nanozeolite particles evidenced by the enhanced mass transfer, more rapid establishment of equilibrium, and faster desorption of CO 2. Modelling of the CO 2 breakthrough curves indicates enhanced mass transfer properties of the CHA nanozeolite due to the higher linear driving force parameter values. Variation of the modelling parameters and back-calculation of the diffusion coefficients indicates that axial diffusion contributes significantly to the mass transfer behaviour, yet also reveals significantly lower micropore diffusion resistance for the nano-sized K-CHA. These results demonstrate for rapid kinetically controlled sorption-based separations, that by reducing the size of the discrete crystallites of the meshed adsorbent particle by an order of magnitude, significant improvements in the utilization of the bed can be achieved due to the shortening of the mass-transfer zone, improving the separation performance. [ABSTRACT FROM AUTHOR]

There is an increasing demand for porous materials able to separate the components of natural gas, mainly CH 4 and CO 2. Flexible small pore zeolites are interesting candidates due to their high sorption capacity and ability to selectively separate molecules of similar sizes. This selectivity comes from their small pores, large cavities, and pore shapes which can be controlled by the introduction of different extra-framework cations such as Na+, K+, Cs+. Furthermore, the extra-framework cations selectively provide access to the pores and cages of the zeolite depending on the nature of the molecules present. The strategy to prepare CHA-type zeolites across a range of particle sizes, from micron-sized dimensions to nanocrystals with a size of 50 nm, was investigated. The quantities of extra-framework cations and the hydrothermal conditions were optimised in order to avoid the formation of secondary structural phases and selectively target the CHA phase. The CHA-type zeolites were characterised by electron microscopy, elemental analysis, MAS NMR and FTIR spectroscopy, and PXRD. The Si/Al ratio of the obtained CHA zeolite was between 1.7 and 2.6 which is ideal for gas separation applications. The nanosized as-synthesised CHA zeolite (Si/Al = 2.4) demonstrates a high CO 2 storage capacity (4.6 mmol/g) making it an ideal candidate for gas separation applications. [Display omitted] • Strategy to prepare CHA type zeolites across a range of particle sizes. • Phase transition in template free precursors. • Monodispersed nanosized CHA zeolite samples with a Si/Al ratio of 2.4. • CO 2 storage capacity of CHA zeolite. [ABSTRACT FROM AUTHOR]

Still, the challenging questions are how to control hydroxyls in zeolites using different synthesis methodologies and how to identify them and relate them to the reactivity of zeolites. Optimizing the combination of alkali metal cations and organic cationic SDAs for obtaining new zeolites will be crucial for controlling the Al site distribution and performance of new zeolite catalysts by controlling the bridged hydroxyls. The ideal crystalline framework of zeolites is perturbed by hydroxyl groups. [Extracted from the article]

Zeolites are widely used in industrial processes, mostly as catalysts or adsorbents. Increasing their micropore volume could further improve their already exceptional catalytic and separation performances. We report a tunable extraction of zeolite framework cations (Si, Al) on a faujasite-type zeolite, the archetype of molecular sieves with cages and the most widely used as a catalyst and sorbent; this results in ca. 10% higher micropore volume with limited impact on its thermal stability. This increased micropore volume results from the opening of some of the small (sodalite) cages, otherwise inaccessible to most molecules. As more active sites become accessible, the catalytic performances for these modified zeolites are substantially improved. The method, based on etching with NH4F, is also applicable to other cage-containing microporous molecular sieves, where some of the most industrially relevant zeolites are found. [ABSTRACT FROM AUTHOR]

The study reports a novel catalyst based on supported molybdenum-carbide (Mo 2 C) phase for oxidative dehydrogenation of ethane with CO 2 (ODH-CO 2). The optimal result is obtained with MoS 2 -precursor as the intermediate supported on a non-acidic embryonic zeolite, which is transformed in situ to Mo 2 C (Mo 2 C@EZ). The ultimate catalyst and its intermediates are characterized. 66% conversion of ethane, 58% of ethylene yield, and 56% conversion of CO 2 to CO with the in situ co-produced hydrogen obtained from ethane to ethylene transformation are the achievements of utilizing Mo 2 C@EZ. The performed techno-economic study on Mo 2 C@EZ results in a potentially CO 2 negative route for ethylene production with 109% of CO 2 reduction per ton of produced ethylene in comparison with a conventional ethane cracker. The process is expected to be cheaper in capital expenditure (CAPEX) and operating expenses (OPEX) thanks to a simpler product slate, lower energy demand, and no requirement for steam dilution. [Display omitted] • Embryonic zeolite supported Mo 2 C catalyst is prepared and comprehensively characterized. • The catalyst is employed for oxidative dehydrogenation of ethane with CO 2 (ODH-CO 2). • The proposed catalyst allows designing a potentially CO 2 negative technology. • 109% of CO 2 reduction in comparison to state-of-the-art ethane cracker is achieved. • A technico-economical analysis of the proposed ODH-CO 2 process is performed. [ABSTRACT FROM AUTHOR]

Natural gas will play a significant role in the transition from fossil to green(er) energy production. Its major component, methane (CH 4) is an attractive resource to co-generate hydrogen (H 2) and added value chemicals (important building blocks such as olefins and aromatics) for petrochemistry. We highlight the advantage of using a novel dual catalyst system containing a monofunctional Al-free metallic single site catalyst referred as S-Mo (Si/Al ∼ ∝) where Mo is atomically dispersed in the zeolitic framework and a monofunctional acidic H-ZSM-5 catalyst referred as S-Al (SiAl = 128) to achieve superior yields of high value products. Under severe reaction (850 ºC) and regeneration (700 ºC) conditions, the Mo-S catalyst is stable and does not suffer from irreversible structural damage by losing its Mo atomic dispersion, and deactivation by coke deposition, thus ensuring steady catalytic performances in multi-cycle catalytic tests. Conversely, the current bifunctional catalysts prepared by Mo impregnation on an acidic catalyst suffer from irreversible damage during coke combustion due to the formation of Al₂(MoO₄)₃ or AlMoO 6 Anderson entities. This new approach opens novel and promising pathways to develop methane upgrading processes based on the physical separation and operation of a non-deactivating metallic catalyst and a regenerable acidic catalyst. [Display omitted] • Catalytic systems involving single site Mo-MFI lead to a stable methane conversion and hydrocarbons production. • Best MDA performances are obtained with a dual bed configuration of two monofunctional single sites Mo-MFI and HZSM-5 catalysts. • The single site Mo-MFI in dual bed configuration displays no coke formation and a high thermal and hydrothermal stability. • Dual bed configuration allows managing separately the reactional temperature of both layers to find the best balance between activity and coke formation. [ABSTRACT FROM AUTHOR]

SAPO-34 crystals are etched in fluoride medium. The interface between crystalline domains is dissolved and yields a hierarchical material with a system of straight intersecting mesopores that improve the access to micropore space. [ABSTRACT FROM AUTHOR]

The impact of the textural properties of H-ZSM-5 zeolites in the conversion of ethanol to hydrocarbons at 623 K and under 3.0 MPa pressure is investigated. We highlight that the lifetime of the catalysts is not correlated to the coking rate but to the number of pore mouths. The addition of macropores (fluoride leaching) or mesopores (alkaline leaching) to micron-sized zeolites is a simple approach to increase the number of pore mouths and reduce the diffusion path length of molecules in the micropores. However, the most efficient way is to reduce the zeolite crystal size to nanometers. The longest catalyst lifetime ( > 100 h) is obtained with a hierarchical nanometer-sized zeolite even though most of its acid sites are poisoned. The important impact of the nature of coke on the catalysts regeneration is also highlighted. [ABSTRACT FROM AUTHOR]

The accessibility to sodalite (SOD) cages in nanosized zeolite X (FAU-type framework) is tuned by varying the nature and location of extra-framework exchangeable cations (Na+, Li+, Cs+, K+ and Rb+). Hyperpolarized (HP) and EXchange SpectroscopY (EXSY) 129Xe NMR experiments highlight the connectivity between SOD- and super (SUP)-cages, in particular that its diffusion pathway from sodalites to supercages depends mainly on the size and location of extra-framework cations present in the zeolite. These 129Xe NMR results are supported by DFT simulations. Based on the computed adsorption energies of Xe in both SOD and SUP cages of zeolite X with different cationic compositions, it is concluded that xenon penetration in SUP cages is always favorable while the adsorption in the SOD cages is possible only if small cations (Na+, Li+, K+) are present. [Display omitted] • The accessibility to sodalite cages in nanosized zeolite X is tuned by varying the nature and location of extra-framework cations. • Hyperpolarized 129Xe NMR experiments highlight the connectivity between sodalite and supercages. • Accommodation of Xe in supercages is always favorable while sodalite cages are only accessible when small cations are present. [ABSTRACT FROM AUTHOR]

FER-type zeolites were synthesized in the presence of Na-Ethylendiamine (Na–En), Na–Pyrrolidine (Na–Py) and Na–K. The crystallization times varied between 96 and 240 h. Ferrierite harvested from the Na–En synthesis was also used as seeds and reduced crystallization time from 240 to 30 h. The product of seeded synthesis was not uniform: nanosized with micronsized crystals as well as complex aggregates of different sizes were obtained. Hierarchical FER-type zeolites were prepared using seeded Na–En synthesized FER as a parent. Secondary pores in zeolite crystals were formed by etching at room temperature with HF-NH 4 F containing solutions, using the HF concentration and treatment time as variables. Crystal morphology and physicochemical characteristics of micron-, nano-sized and hierarchical FER-type crystals were studied by complementary methods including: X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry (TG/dTG), 27 Al and 29 Si MAS NMR, IR spectroscopy of adsorbed probe molecules (Pyridine, Acetonitrile and Lutidine), nitrogen adsorption and chemical analysis. We demonstrate that FER-type zeolites with pre-determined properties can be easily prepared. [ABSTRACT FROM AUTHOR]

A facile and rapid photochemicalmethod for preparing supportedsilver nanoparticles (Ag-NPs) in a suspension of faujasite type (FAU)zeolite nanocrystals is described. Silver cations are introduced byion exchange into the zeolite and subsequently irradiated with a Xe–Hglamp (200 W) in the presence of a photoactive reducing agent (2-hydroxy-2-methylpropiophenone).UV–vis characterization indicates that irradiation time andintensity (I0) influence significantlythe amount of silver cations reduced. The full reduction of silvercations takes place after 60 s of a polychromatic irradiation, anda plasmon band of Ag-NPs appears at 380 nm. Transmission electronmicroscopy combined with theoretical calculation of the plasmon absorbanceband using Mie theory shows that the Ag-NPs, stabilized in the microporesand on the external surface of the FAU zeolite nanocrystals, havean almost spheroidal shape with diameters of 0.75 and 1.12 nm, respectively.Ag-NPs, with a homogeneous distribution of size and morphology, embeddedin a suspension of FAU zeolites are very stable (∼8 months),even without stabilizers or capping agents. [ABSTRACT FROM AUTHOR]

This study reports the seeded synthesis of MFI‐type (ZSM‐5) zeolite in fluoride medium at pH = 8.5. Crystal growth kinetics of the resulting zeolite (ZSM‐5‐F) as a function of seed content and crystallization temperature is studied. The crystallization time is reduced to 1.5 h and crystals with sizes below 200 nm and a Si/Al ratio of 23.6 are obtained. A zeolite with similar characteristics but synthesized in a hydroxyl medium (ZSM‐5‐OH) is used to evaluate ZSM‐5s synthesized in different crystallization media. Their physicochemical properties are compared and particular attention is paid to the nature, number, and distribution of silanol sites. The two zeolites exhibit similar number of Brφnsted acid sites; however the material synthesized in a hydroxyl medium contains a substantially larger number of surface and internal silanols that impact significantly its catalytic performance in methanol to hydrocarbon transformation. While the two materials exhibit similar selectivity in methanol transformations, the catalyst synthesized in fluoride medium shows superior activity and resistance to deactivation. The results suggest that seeded synthesis in a fluoride medium can be used for the preparation of superior zeolite catalysts. [ABSTRACT FROM AUTHOR]

Highlights: [•] Hierarchization of ZSM-22 favors hydroisomerization and limits hydrocracking [•] Hierarchical ZSM-22 has lower acidity in micropores and higher acidity in pore mouths [•] Branching occurs in pore mouths; hydrocracking in pore mouths and micropores [•] Hierarchization is a unique tool to design superior hydroisomerization catalysts [•] Pristane is a convenient model molecule for probing pore mouth catalysis [Copyright &y& Elsevier]

Commercial zeolites with CHA, MFI, and LTL framework topology are subjected to acid treatment with chromic acid (H 2 CrO 4) solutions with concentrations ranging between 0.1 and 10 w /%. As chromic acid forms polymeric species as a function of concentration, specific effects are obtained with these three zeolites, differing by their framework topology, pore size, Si/Al ratios and crystal size. The etched zeolites are characterized by X-ray diffraction, SEM, TEM, N 2 physisorption, ICP-AES, 27Al and 29Si MAS NMR, 29Si{1H} cross-polarization spectra, EDX. Their acidic properties are probed with pyridine and d 3 -acetonitrile by in situ FTIR. Results indicate that the 8 MR (CHA) and 10 MR (MFI) zeolites are more resistant to acid treatment with chromic acid than the 12 MR (LTL) zeolite. This paves the way for rational control of zeolite dealumination since adjusting chromic acid concentration will generate anions appropriate for treating a particular zeolite. [Display omitted] • CHA, MFI, and LTL zeolites are subjected to treatment with chromic acid (H 2 CrO 4). • Chromic acid forms polymeric species as a function of concentration. • CHA and MFI zeolites resist more to the chromic acid treatment than the LTL zeolite. • Tuning the acid concentration yields anions apt for treating a particular zeolite. [ABSTRACT FROM AUTHOR]

Abstract: Ring-opening reactions of decalin and methylcyclohexane (MCH) over bifunctional catalysts (1.2Ir/WO3/Al2O3) were investigated. A series of catalysts containing up to 5.3at. W/nm2 and 1.2wt.% Ir was prepared. The acidity of the solids was monitored by low-temperature CO adsorption followed by infrared spectroscopy. Characterization of the Ir metal phase was performed by H2 chemisorption and X-ray diffraction. The activity and product selectivity patterns obtained for the decalin ring-opening reaction were compared with those observed for MCH. For both naphthenes, ring contraction precedes ring opening, suggesting a similar ring-opening mechanism. Kinetic modeling based on the proposed reaction network allowed the determination of the activation energies and initial rates. Based on the yields and products distribution obtained for the decalin reaction, the potential for improvement of the cetane number is discussed. [Copyright &y& Elsevier]

Abstract: This paper reports the interaction of aromatic compounds (as phenol, ethylphenols, and guaiacol) representative of oxygenated functions of pyrolysis bio-oils, with sulfided (Co)Mo/Al2O3 catalyst in order to determine the origin of catalyst deactivation in hydrodeoxygenation (HDO) reaction. Infrared spectroscopy shows that all the studied phenolic compounds anchor on the alumina support as phenate-type species, whereas only the most basic ones (2(4)-ethylphenol and guaiacol) interact also with the sulfide phase. At 623K (typical temperature of the HDO reactions), only phenate species on the support are formed that is confirmed by study of the catalyst tested in HDO reaction. Phenate-type species anchored on alumina hinder the accessibility of the sulfide edge sites. This shows that the nature of the oxygenated compound (basicity and nature of the substituent) as well as the surface properties of the catalyst support are crucial in the mode and extent of HDO active sites poisoning. [Copyright &y& Elsevier]

Abstract: Ring-opening reactions of decalin and MCH were studied over monofunctional acid (WO3/Al2O3) and metal (Ir/Al2O3) catalysts containing, respectively, up to 5.3 at. W/nm2 and 1.8wt% Ir. The catalysts were characterized by X-ray diffraction, Raman spectroscopy, low-temperature CO adsorption followed by infrared spectroscopy, and H2 chemisorption. A reaction network was proposed for both molecules and used to determine the kinetic parameters. Kinetic modeling allowed relating characterization results and catalytic performance. For WO3/Al2O3 catalysts, ring contraction precedes ring opening of both molecules. The evolution of ring contraction activity was consistent with the development of relatively strong Brønsted acid sites. Ring opening occurs according to a classic acid mechanism. For Ir/Al2O3 catalysts, only direct ring opening was observed. Ring opening proceeds mostly via dicarbene mechanism. Analysis of products indicated that monofunctional metal catalysts are better suited than acid solids for upgrading LCO. [Copyright &y& Elsevier]

Abstract: The present paper investigates the development of Ir-based catalysts supported on tungstated aluminas for the ring opening reaction of naphthenic molecules using methylcyclohexane (MCH) as a model compound. A series of tungstated aluminas WO x /Al2O3 containing up to 6.0at.W/nm2 was prepared. Ir-based catalysts containing 1.2wt% were obtained by impregnation of these solids. The performance of Ir/WO3/Al2O3 catalysts for methyl cyclohexane ring opening was found to be similar to that observed over the corresponding zirconia-based system indicating that the metal–acid balance (and not the nature of the support) is the key parameter for optimum performance. [ABSTRACT FROM AUTHOR]

Abstract: Tungstated zirconias consist typically of WO x species deposited on zirconia support. Additives like Si can be added to stabilize the catalyst surface area. The aim of this work is to identify the location of the Si (surface or bulk) as a function of W addition. Zirconia doped with 1.2wt% Si remained purely tetragonal and exhibited a high specific surface area (150m2/g) following calcination at 1023K. Infrared quantification of the silanol band at 3745cm−1 indicated that Si is essentially present at the surface. The 29Si NMR chemical shift of the zirconia is characteristic of isolated silicium. This result is corroborated with infrared by the absence of the structural band ascribed to Si–O–Si vibrations. NMR and infrared results indicated that W addition brings about a progressive evolution of the Si environment towards that of silica-like species. These results can be tentatively explained by a ligand enhanced dissolution of the support on W deposition. Si leached from the surface will then aggregate, forming small SiO2-like domains on the zirconia. [Copyright &y& Elsevier]

Five silica samples (four precipitated silicas provided by commercial suppliers and one with the MCM-41 structure) have been studied by infrared spectroscopy and by a homemade thermogravimetry−infrared spectrum (TG-IR) setup. The silanol amount, accessibility to water, and different alcohols, and the affinity to water of these various silicas were compared and quantified. TG-IR measurements allowed the precise determination of the integrated molar absorption coefficient of the (ν+δ)OH band, ε(ν+δ)OH= (0.16 ± 0.01) cm μmol−1. It is independent of the sample origin and the concentration of silanol groups on silicas. For the precipitated dried samples evacuated at room temperature, the silanol concentration COHvaries between 3.6 and 7.0 mmol g−1. It is 5.3 mmol g−1in the case of the MCM-41 sample. Exchange experiments with D2O, followed by back-exchanges with different alcohols (methanol, propan-2-ol, 2-methyl-propan-2-ol, and 3-ethyl-pentan-3-ol) have been followed by infrared spectroscopy. All of the silanols of the MCM-41 sample are accessible to water and alcohol molecules. By contrast, about 20% of the silanols in precipitated samples are not exchanged by D2O (internal silanols). Accessibility decreases with alcohol size; the main effect is relative to methanol. Taking into account the sample specific surface areas and the silanol accessibility to D2O, the surface silanol density of precipitated silicas is close to 8 OH per nm2, at maximum coverage. At variance, the silanol surface density of the MCM silica is much lower, 4 OH per nm2. The TG-IR setup has also been used to determine the amount of water adsorbed on silicas through the intensity of the δH2O band. It varies linearly with the concentration of adsorbed water, whatever the silica sample. The integrated molar absorption coefficient of two bands, εδH2O= (1.53 ± 0.03) cm μmol−1and ε(ν+δ)H2O= (0.22 ± 0.01) cm μmol−1, have been determined. The number of H2O molecules adsorbed per nm2has been compared on the five samples under an equilibrium pressure of 13 hPa at room temperature. Taking into account the number of silanols accessible to D2O for each sample, the silica−water affinity has been defined by the H2O/(SiOHsurf) ratio. It is close to 0.8−0.9 for the precipitated samples but lower (0.7) in the case of the MCM one. This result is explained by the more important amount of isolated silanol groups presented by this sample. [ABSTRACT FROM AUTHOR]

An accessibility index (ACI) was derived from infrared spectroscopy of substituted alkylpyridines with different size (pyridine: 0.57nm, 2,6-lutidine: 0.67nm, and 2,4,6-collidine: 0.74nm) over hierarchical porous ZSM-5 crystals. The samples were prepared by selective silicon extraction of a commercial sample in NaOH (desilication), and they contained different degrees of intracrystalline mesoporosity. Our results demonstrate the enhanced accessibility of Brønsted acid sites in the hierarchical zeolites. For example, a relatively bulky molecule such as collidine, which probes practically no acid site of the parent medium-pore MFI structure, can access up to 40% of the acid sites in the mesoporous sample. The ACI is a powerful tool to standardize acid site accessibility in zeolites, and can be used to rank the effectiveness of synthetic strategies to prepare hierarchical zeolites. [Copyright &y& Elsevier]

Abstract: The present paper is the second part of a systematic study of the influence of W and Ir loading on the activity of Ir/WO3/ZrO2–SiO2 catalysts for the ring-opening reaction of naphthenic molecules using methylcyclohexane (MCH) as a model compound. A series of Si-stabilized tungstated zirconias, WO x /ZrO2–SiO2, containing up to 3.5 atom W/nm2, was prepared. Ir-based catalysts containing up to 1.2 wt% were obtained by impregnation of these solids. Characterization of the metal dispersion and catalyst acidity was described in a previous article. The objective of the present study was to determine the best metal/acid balance for optimal performance of Ir/WO x /ZrO2–SiO2 catalysts in the ring-opening reaction of MCH. Monofunctional (acid WO x /ZrO2–SiO2 or metal Ir/ZrO2–SiO2) and bifunctional (Ir/WO3/ZrO2–SiO2) catalysts were examined. Based on the analysis of the yields and products distributions, a reaction network was proposed, and kinetic data (e.g., activation energies, initial rates) were calculated. Correlations between characterization results obtained earlier (e.g., acidity, dispersion) and catalytic performance are also reported. The monofunctional acid catalysts WO x /ZrO2–SiO2 showed a low selectivity for ring opening. The ring-contraction activity developed for W surface density above a threshold value of 1 atom W/nm2. This was attributed to the appearance and the development of a relatively strong Brönsted acidity monitored by infrared measurements. MCH ring contraction and C5 naphthene ring opening occur according to a classic acid mechanism. For low conversions, the monofunctional metal catalysts Ir/ZrO2–SiO2 exhibited significant selectivity for ring opening that decreased with increasing conversion. Because of the lack of ring-contraction products, the observed activity was attributed to the direct ring opening of the MCH. Ring opening and cracking occur according to a dicarbene mechanism. The study of MCH conversion on Ir/WO x /ZrO2–SiO2 catalysts indicated that MCH ring contraction to alkylcyclopentanes occurs before ring opening. The best yields for ring opening were obtained with the 1.2% Ir/WO x /ZrO2 (1.5 atom of W/nm2). Further increases in W surface density led to a decrease in the indirect ring-opening yield, attributed to a decrease in Ir dispersion. For bifunctional metal/acid catalysts, analysis of the mechanism is less straightforward. The activation energy for C6 ring contraction and indirect C6 ring opening is a function of the metal/acid ratio. For high ratios, indirect ring opening occurs essentially over metallic sites. A decrease in the metal/acid ratio enhances the contribution of acid mechanism. [Copyright &y& Elsevier]

Using in situ 13C MAS NMR, it has been demonstrated that propane is carbonylated with carbon monoxide to produce isobutyraldehyde and isobutyric acid at 100–150 °C on sulfated zirconia. Isobutyraldehyde represents the intermediate reaction product, which is almost completely converted into the acid at 150 °C. The selective formation of isobutyraldehyde at low temperatures on SZ indicates that principally the secondary C&z.sbnd;H bond of propane is activated, rather than its C&z.sbnd;C bond. This pathway of the alkane activation can be realized either on Lewis acid sites of SZ or by direct formylation by the formyl cation formed as equilibrated species from the formate. Infrared spectroscopy provides evidence that the sulfate groups of SZ are responsible for the aldehyde oxidation. The formation of surface dithionate species as a result of sulfur reduction is suggested. These dithionate species are readily reconverted into sulfate groups by an oxidizing treatment in an O2 atmosphere. [Copyright &y& Elsevier]

A technique for the quantitative determination of adsorbed species on zeolites and other solids was designed by coupling infrared spectroscopy and in situ thermogravimetry. The weight of H-Y zeolites in an infrared spectrometer was monitored upon pyridine adsorption by a McBain type microbalance. Improved extinction coefficients for the pyridinium band and for ν(OH) bands were determined on these reference materials. The influence of the temperature used for desorption of physisorbed pyridine was studied. [Copyright &y& Elsevier]

Cumene conversion under an excess of benzene is studied over a series of mordenite (MOR) zeolites (Na-MOR, HNa-MOR, H-MOR and dealuminated H-MOR) by in situ 13C and 1H MAS NMR spectroscopy in the temperature range 298–473 K. By tracing the fate of 13C labeled atoms in the benzene molecule, intermolecular transalkylation, disproportionation and isomerization reactions are highlighted. The reactivity of MOR-based catalysts in these reactions is found to increase in the following order: Na-MOR. Transalkylation and disproportionation require mild conditions (T=298–393 K, weak acidity), while isomerization to n-propylbenzene needs more severe conditions (T>473 K, strong acid sites). The reaction mechanisms are discussed. [Copyright &y& Elsevier]

• The use of FER as catalyst for the dehydration of iso-butanol results in an excellent selectivity for n-butenes. • The external Brønsted acid sites function as isobutanol dehydration active sites. • High external Brønsted acidity improves selectivity to n-butenes. • Use of in-situ and operando characterisation toolboxes allowed identifying the active sites. The conversion of isobutanol to light olefins over zeolites was investigated by IR operando spectroscopy. FER zeolites showed a surprisingly high selectivity for the direct conversion of iso-butanol to linear butenes, hence catalyzing dehydration and skeletal isomerization in one step. As a fundamental understanding of the separate reactions is required to design superior catalysts, an in-situ and operando FT-IR mechanistic study of the reaction was carried out. The spectroscopic data, the derived species participating and their respective role are analyzed using chemometric (PCA and MCR-ALS) tools. We highlighted the role played by the external acid sites and the requirement of a specific distance between these sites to ensure the n-butene selectivity and point that the internal Brønsted acidity has an adverse effect on the catalyst stability. Moreover, there is no correlation between the carbon species formed on the surface and the exceptional selectivity towards n-butenes, allowing to exclude a "carbon pool" mechanism. [ABSTRACT FROM AUTHOR]

NH 4 -SSZ-13 is etched with an aqueous solution of 40 w /% NH 4 F under different time/temperature conditions to obtain hierarchical derivatives. The etched zeolites are characterized by XRD, SEM, N 2 physisorption, 29Si/27Al/19F MAS NMR, ICP-AES, and their acidity monitored by in situ FTIR spectroscopy using acetonitrile as a probe molecule. The results highlight that the zeolite is very sensitive to high temperature and high liquid-solid ratio treatments leading to substantial crystallinity losses. These two parameters need careful tuning to obtain hierarchical derivatives retaining important characteristics as micropore volume and framework Si/Al ratio. The catalytic activity of the modified SSZ-13 is evaluated in the n-propanol conversion. Image 1 • Zeolite SSZ-13 (CHA-type) is subjected to chemical etching in an aqueous NH 4 F solution to introduce mesopores. • The hierarchical zeolite preserved the parent zeolite properties in terms of framework composition and Brønsted acidity. • The obtained SSZ-13 derivatives show higher coke contents but slower deactivation in the dehydration of n-propanol. [ABSTRACT FROM AUTHOR]

The texture and acidity of a parent synthetic erionite zeolite (ERI structure) are modified by a two-step top-down treatment involving acid (HNO 3) and base (NaOH) biased leaching as well as an unbiased HF/NH 4 F leaching. These zeolites are compared to a bottom-up prepared nanosized ERI, UZM-12. The structural (XRD, 29Si MAS NMR), textural (N 2 adsorption-desorption, STEM) and acidic (FT-IR spectroscopy of adsorbed probe molecules) properties of the parent and hierarchical ERI are also carefully monitored. Among all top-down hierarchization strategies applied for 8-ring ERI structure, the sequential leaching in acid (HNO 3) and caustic (NaOH) solutions is the most efficient to add mesoporosity to the native microporosity. The catalytic performances of the hierarchical materials and their parent are assessed in the dealkylation of 1,3,5-triisopropylbenzene (TiPBz); they are in line with the mesoporous external surface area and the external surface acid site density for all samples. The best top-down hierarchical ERI has similar catalytic properties as the nanosized ERI, UZM-12. Image 1 • Synthetic erionite modified by a top-down treatment compared to a bottom-up prepared UZM-12. • Mesoporosity added to the native microporosity by sequential acid/caustic leaching. • Optimized textural and acidic parameters enhances the TiPBz dealkylation. • Best top-down hierarchical ERI has similar catalytic properties as the nanosized UZM-12. [ABSTRACT FROM AUTHOR]