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Abstract Titanium silicalite-1 (TS-1) nanosheets can be synthesized from the precursor gels containing a diquaternary ammonium template in hydroxide form. The TS-1 nanosheets tend to form unilamellae interconnected in disordered aggregates. Pillaring of TS-1 nanosheets preserves the mesoporosity, but lacks long-range order of nanosheet layers. Here, we report synthesis of multilamellar TS-1 (M-TS-1) with long-range order of nanosheet layers from the precursor gels containing hexanediamine (C 6 DN) and diquaternary ammonium template in bromide form (C 22-6-6 Br 2). Pillaring of M-TS-1 produced pillared TS-1 (P-TS-1) with well-preserved mesoporosity and long-range order of layers. The influences of concentrations of C 22-6-6 Br 2 , C 6 DN, and Ti precursor as well as crystallization time, on the resultant M-TS-1 were investigated. The physicochemical properties of the M-TS-1 and P-TS-1 were studied and compared to the conventional TS-1 zeolite. The presence of mesopores in P-TS-1 enhanced the catalytic performance in reactions involving bulky molecules. Graphical abstract Image 1 Highlights • Multilamellar TS-1 with long-range ordering structure was synthesized from hexanediamine and Gemini-type bromide templates. • Pillared TS-1 with long-range order of zeolite nanosheet layers was achieved. • Influences of concentrations of templates and Ti precursor, crystallization time on the multilamellar TS-1 were investigated. • Mesopores in pillared TS-1 enhanced the Lewis acid sites accessibility and catalytic performance involving bulky molecules. [ABSTRACT FROM AUTHOR]

Abstract Hierarchical lamellar zeolites, comprised of both micro- and mesoporosity, afford high active site accessibility and mass transport in processing of bulky molecules. Here, we report the synthesis of hierarchical lamellar MFI zeolites with sequential intergrowth that is induced by composition variation in the standard recipe of 100SiO 2 /0.5Al 2 O 3 /3C 22-6-6 /18.5Na 2 O/4000H 2 O, where C 22-6-6 stands for the diquaternary ammonium surfactant ([C 22 H 45 N+(CH 3) 2 C 6 H 12 N+(CH 3) 2 C 6 H 13 ]Br− 2) template. The influences of C 22-6-6 concentration, alkalinity, and aluminum amount on the intergrowth of hierarchical lamellar MFI zeolites were investigated. The consequences of intergrowth on mesoporosity were analyzed. In all studied synthesis conditions except for very low alkalinity, hierarchical lamellar MFI zeolites were successfully crystallized. The increasing template concentration in the synthesis gel resulted in an increase in intergrowth and thus mesoporsotiy in the hierarchical MFI products. The increasing alkalinity led to an increase and then a decrease in mesoporosity in the hierarchical MFI products, which reflects the same trend in intergrowth in the hydrothermal synthesis process. The aluminum concentration, however, did not significantly affect the intergrowth and mesoporosity of the resultant hierarchical MFI zeolites. The sequential intergrowth achieved by simple variation in the synthesis composition for lamellar MFI zeolites resulted in higher structure hierarchy, mesoporosity, and acid site accessibility in one-step. Graphical abstract Image 1 Highlights • Hierarchical lamellar MFI zeolites were synthesized in one-step. • Intergrowth enhanced mesoporosity in hierarchical lamellar MFI zeolites. • Intergrowth increased with increasing surfactant template content in synthetic gel. • Intergrowth increased and then decreased with alkalinity in synthetic gel. • Aluminum content in synthetic gel did not influence intergrowth noticeably. [ABSTRACT FROM AUTHOR]

Abstract Volume swelling is a typical mode of battery failures, which happens not only in the operation but also during the storage of rechargeable batteries as a result of electrolyte degradation, particularly the chemical oxidation of electrolyte solvents by the active oxygen released in phase transition of the layered cathode materials. Aiming to remove the active oxygen, we herein propose Pyrite FeS 2 powder as an in-situ oxygen remover based on the fact that FeS 2 can be ultimately oxidized to Fe 2 O 3 and Li 2 SO 4 by the active oxygen, and the redox reaction depletes considerable amount of oxygen. By mixing FeS 2 powder into a conventional LiNi 0.80 Mn 0.10 Co 0.10 O 2 (NMC811) cathode, it is found that under normal cycling conditions of the Li/NMC811 cells, FeS 2 is electrochemically stable while being capable of reacting with active oxygen and hence stabilizing the cell's capacity retention. The concept proposed in this work provides a practically viable and cost-effective approach for preventing volume swelling of the rechargeable batteries based on the layered cathode materials. Graphical abstract Image 1 Highlights • Phase transition and oxygen release is an intrinsic nature of layered cathode materials. • Pyrite FeS 2 is proposed as an in-situ oxygen remover for rechargeable batteries. • In battery FeS 2 is electrochemically stable and capable of removing active oxygen. • FeS 2 suppresses impedance growth and the 2nd structure crack of layered cathode materials. [ABSTRACT FROM AUTHOR]

The synthesis of hierarchical meso-/microporous zeolite materials with spatially controlled morphology, meso-/microporosity, and acidity is an expanding area of research interest for a wide range of applications. Here, we report a one-step dual template synthesis method for integration of 3-dimensional (3D) BEA nanosponge and ultra-thin 2D lamellar MFI into a new type of hierarchical meso-/microporous zeolite composite structures. Specifically, the 2D layered MFI nanosheets were laid over the surface of or interdigitated into the 3D BEA particles in the bulk BEA nanosponge-lamellar MFI (BBLM) zeolite structure, which generated a unique morphology of interconnected micropores and mesopores underneath the ‘skinning’ shell (∼3–10 nm) of MFI nanosheets. The BBLM zeolites have higher mesoporosity than either bare BEA or lamellar MFI zeolites. The micropore size decreases with increasing lamellar MFI component in the composite. The fraction of external acid sites of BBLM zeolite composite, represented by the percentage of active sites accessible to bulky organic base molecules, decreases with increasing MFI component. Additionally, the types of acid sites are diversified in the BBLM composites compared to either bare BEA or lamellar MFI zeolites. The catalysis tests using conversion of benzyl alcohol in mesitylene showed that BBLM zeolites had significant higher activity and durability than single zeolites or their physical mixture. The BBLM zeolite composite provides a good model catalyst with integrated 2D-3D structures and meso-/microporosity for studying a series of important catalytic reactions in hierarchical zeolites. The one-step dual template synthesis method described herein is versatile and facile, which may prove to be a general platform for hierarchical zeolite composite design at the unit-cell scales of zeolites and with potentially broader applicability to other porous materials. [ABSTRACT FROM AUTHOR]

• Pt/TiO 2 catalysts with different Pt aggregation sizes were prepared. • Hydrogenation activity of Pt/TiO 2 showed a volcano-shaped trend with Pt sizes. • Pt activity ranks in the order of nanometer cluster > nanoparticle > single atom. • Relationships between Pt activity and structural/electronic property were discussed. Supported metal catalysts often consist of metal sites ranging from nanoparticles to subnanometer clusters and single atoms. It remains a necessity to differentiate these sites to guide design of optimal catalysts. Here we report a simple method to assess the distribution of metal active sites in catalyst samples. The method takes the advantage of the structure sensitivity of styrene hydrogenation over titania supported platinum (Pt) catalysts with Pt aggregates varied from single atom to ∼1.40 nm nanoparticles. The physicochemical properties were characterized by STEM, XPS, XANES, H 2 -TPR and CO-chemisorption measurements. The reactivity of Pt sites was quantified by styrene hydrogenation at ambient conditions. The nanometer-sized Pt clusters have significantly higher activity than Pt nanoparticles, sub-nanometer clusters or isolated single atoms. The relationship between activity and structural/electronic properties of Pt sites influenced by particle sizes was discussed. Similar relationship was found in the carbon supported Pt catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

The redox mechanism of micro-sized FeS 2 particles in a rechargeable lithium battery is studied by galvanostatic cycling and ac-impedance analysis. It is shown that FeS 2 is irreversibly reduced on the first discharge, turning Li/FeS 2 cell into a combination of Li/FeS and Li/S chemistries, as suggested by two distinct discharge plateaus at ∼1.5 and 2.0 V, respectively. The first discharge consists of an irreversible conversion of FeS 2 to Li 2 FeS 2 intermediate and its subsequent reduction to metallic Fe and Li 2 S. The first discharge suffers an initial voltage delay, suggesting that the discharge progresses in a thermodynamic non-equilibrium condition. The initial voltage delay can be attributed to the large grain boundary resistance (GBR) of pristine FeS 2 particles, which impedes the nucleation of a new solid Li 2 FeS 2 phase causing high polarization. Ac-impedance spectra of the FeS 2 cathode are composed of a semicircle and a straight sloping line, representative of an electrode reaction resistance (R er ) and a Li + adsorption impedance, respectively. The R er is found to decrease progressively during the first discharge and reaches a plateau when the cell is charged above 2.5 V vs. Li/Li + , being consistent with the model that FeS 2 is irreversibly reduced during the first discharge and that the Li 2 S/Li 2 S n redox couple is formed in recharge. It is indicated that Li/FeS 2 batteries face the same problems as Li/S batteries, such as the dissolution of lithium polysulfide, the formation of a redox shuttle, and the loss of sulfur active material. [ABSTRACT FROM AUTHOR]

We report a series of mesoporous silicate sorbent materials templated by long-chain primary alkylamines that display record level of desulfurization of the jet fuel JP-8. Pure silica frameworks and those with a Si:Zr synthesis molar ratio ranging from 44:1 to 11:1 were investigated. The optimum sorbent was identified as dodecylamine-templated silica-zirconia synthesized from a gel with Si:Zr molar ratio of 15:1. With an optimized silver loading of 11 wt.%, a saturation adsorption capacity of 39.4 mgS g −1 and a silver efficiency of 1.21 molS mol Ag −1 were observed for JP-8. This sorbent displayed exceptional regenerability, maintaining 86% of its initial capacity in model fuel after solvent regeneration with diethyl ether. Low-cost, portable and reusable sorbents for the desulfurization of JP-8 jet fuel are needed to make solid oxide fuel cells (SOFCs) a reality for military power needs. SOFCs require ultra-low sulfur content fuel, which traditional desulfurization methods cannot achieve. [ABSTRACT FROM AUTHOR]

Highlights: [•] Conventional separator is coated with a 50PEO-50SiO2 (wt.%) composite layer. [•] Composite coating increases tensile strength and electrolyte wettability. [•] Coated separator offers an alternative approach for making gel polymer Li/S battery. [•] Li/S battery takes benefits of gel polymer electrolyte at the expense of capacity. [Copyright &y& Elsevier]

Abstract: In this communication, we disclose a proof-of-concept lithium/sulfur liquid battery that has exceptionally high capacity density. In such a battery, the cathode consists of a highly porous carbon cloth (CC) as the cathode current collector and a porous sulfur paper as the source of active material. In the first discharge, sulfur is reduced on the CC surface into high order lithium polysulfide (PS), which dissolves into liquid electrolyte and serves as the catholyte of the so-called “Li/S liquid battery”. By adopting a LiNO3-contained electrolyte to protect Li anode, the Li/S liquid cell is shown to cycle reversibly between 1.7 V and 2.8 V with an initial capacity of 778 mAh g−1 S, corresponding to a capacity density of 10.1 mAh cm−2 CC, which could be the highest capacity density among the rechargeable Li/S batteries reported ever. This work reveals that the high capacity density Li/S batteries can be made through a “Li/S liquid cell” by employing a highly porous carbon electrode to accommodate the insoluble sulfur reduction products (Li2S2/Li2S) with appropriate protection of the Li anode. [Copyright &y& Elsevier]

Abstract: A nano-sized non-noble metal catalyst containing hemin supported on carbon black was synthesized for the oxygen reduction reaction (ORR). The hemin supported on carbon black was heat-treated (HT), and subjected to additional ultrasound treatments to increase the BET surface area and available active sites for the ORR. The HT hemin supported on carbon black was characterized with thermogravimetric analysis (TGA), elemental analysis, transmission electron microscopy (TEM), and BET surface area analysis. The catalytic activity of the synthesized electrocatalysts was analyzed with cyclic voltammetry (CV), rotating disk electrode (RDE), and rotating ring disk electrode (RRDE). The effect of BET surface area on formal potential, anodic and cathodic peak currents, limiting currents, half wave potentials, and kinetic rate constant for ORR were studied. We found an apparent correlation between catalytic activity and BET surface area for this particular catalyst. Increasing BET surface area, the ORR catalytic activity increases significantly. Our research on HT hemin indicates that the catalytic activity for ORR significantly improves by reducing the particle size and increasing the surface area. [Copyright &y& Elsevier]

Abstract: Applications requiring hydrogen fuel, including portable, mobile and stationary fuel cells for power generation, are increasing. The conversion of JP-8 to hydrogen offers an energy dense feedstock for hydrogen production through fuel reformation. Unfortunately, organic sulfur compounds in logistical fuels, even at part per million levels, can poison reformer and fuel cell catalysts. In this work, adsorbents based on silica supported gold ions and gold nanoparticles were synthesized and evaluated for the adsorptive desulfurization of JP-8 jet fuel. The adsorbents were evaluated with JP-8 fuel containing 430 ppmw sulfur under ambient conditions. The preparation, as well as the sulfur removal and adsorption characteristics for two adsorbents are described in this work. [Copyright &y& Elsevier]

Abstract: A bio-material, hemin, was heat-treated and used as an oxygen reduction reaction (ORR) electrocatalyst. In addition to heat-treatment, two methods were used to improve the catalysts'' electrochemical activity. First, high surface area graphene nanoplatelets (GNP) were chosen as a catalyst support. Second, ultrasound was used to break the catalyst samples into smaller pieces. Hemin supported on GNP and heat-treated at 600°C showed significantly higher catalytic activity than those without ultrasonic treatment. Furthermore, a single fuel cell fabricated with the synthesized catalyst yielded a power density of 300mWcm−2. [Copyright &y& Elsevier]

Abstract: A three-dimensional La(III) based metal-organic framework, La2[NC5H3(CO2)2]3·3H2O, was assembled using the aromatic linker 3,5-pyridinedicarboxylate. This new compound was synthesized hydrothermally and is an unusual example of a lanthanum containing metal-organic network. The compound contains two distinct La centers, each adopting a nine-coordinate geometry. The structure is built up from zig-zag chains that link via bridging water molecules into a double chain defining edge-sharing six rings. These double chains are arranged into layers and connect through 3,5-pyridinedicarboxylate ligands to give the extended 3-D coordination framework. The material is thermally stable to ca. 360°C and transforms to an unknown compound before finally decomposing to phase-pure La2O3 at 800°C. The synthesis, structure, morphology and properties of the new material are described. [Copyright &y& Elsevier]

Abstract: A three-dimensional Bi(III) based metal–organic framework was synthesized under hydrothermal conditions using the multidentate organic linker 3,5-pyridinedicarboxylate. Bismuth oxide 3,5-pyridinedicarboxylate, Bi2O2[NC5H3(CO2)2], contains embedded 1-D cationic bismuth oxide chains that propagate along the crystallographic c-axis. The oxygens of the Bi2O2 core are three-coordinate and bond strongly to the Bi atoms. Thermogravimetric analysis shows that the material possesses high thermal stability up ca. 400°C before decomposing to phase-pure Bi2O3 at 800°C. The structure, crystallinity, morphology and properties of the material are discussed. [Copyright &y& Elsevier]

Abstract: A three-dimensional strontium-based metal-organic framework was constructed using 1,3,5-benzenetricarboxylic acid, [Sr3((OOC)3C6H3)2(H2O)4]·H2O. This new compound was synthesized hydrothermally and is a rare example of a strontium metal-organic network. The compound network contains three distinct Sr centers, one of which is seven-coordinate and the other two are nine-coordinate geometry. The benzene rings form a herring-bone type of arrangement down the a-axis. The material is thermally stable to ca. 230°C and transforms to an unknown material before finally decomposing to phase-pure SrCO3 at 650°C. The synthesis, structure, morphology and materials properties are discussed. [Copyright &y& Elsevier]

Hierarchical two-dimensional (2D) lamellar zeolites represent a young emerging field and a novel expression of the zeolite frameworks. Accompanied with synthesis and catalytic performance investigation, assessment on the local environment and catalytic behavior of acid sites in 2D zeolites are needed. Here, we described the local environment of Lewis acid sites and evaluated catalytic activities of external acid sites (i.e. sites on external surface and in mesopores) in 2D lamellar titanium silicalite-1 (TS-1) zeolites. For comparison purpose, four TS-1 zeolites, including 3D TS-1, multilamellar 2D TS-1 without pillarization and with pillarization by silica and silica/titania, respectively, were prepared. The local environment of Ti-sites, including coordination status of Ti-atom, speciation of hydroxyl (-OH) group that hints degree of confinement, acid site strength and accessibility, was collectively assessed by spectroscopic and organic base titration measurements. Kinetic studies of cyclooctene (C 8 H 14) epoxidation with hydrogen peroxide (H 2 O 2) discerned catalytic activity of external Ti-sites that decreased with increasing mesoporosity due to decrease in site confinement. Image 1 • External Lewis acid sites in 2D TS-1 zeolites were quantified. • 2D TS-1 zeolites have high density of isolated surface silanol and titanol groups. • Reactivity of external sites decreases with increasing mesoporosity in 2D TS-1. • Decrease in reactivity of external sites is caused by loss of partial confinement. • Kinetic decoupling of epoxidation pathways enabled catalytic behavior assessment. [ABSTRACT FROM AUTHOR]

Lead substituted hydroxyapatite (Pb-HAP) has been an active catalyst for oxidative coupling of methane (OCM) reactions. CO 3 2 − substituted HAP (HAP-CO 3 ) has showed enhanced oxide ion conductivity than bare HAP in high temperature solid oxide fuel cells. Substitutions for both cations and anions in HAP structure (Pb-HAP-CO 3 ) are promising to integrate the catalytic property of Pb-HAP and oxide ion conductive property of HAP-CO 3 into one apatite-based ceramic material that can be manufactured into membrane reactors for possessing CH 4 activation and O 2 permeation capabilities for efficient OCM reactions. In this work, the effects of substitutions for both cation (Pb 2+ ) and anion (CO 3 2 − ) in HAP structure on OCM reactions were studied. The composition and physicochemical properties of HAP catalysts were changed by the cation and anion substitutions, respectively, and as consequences, they influenced the catalytic performances of HAP structure in OCM reactions. The selectivity to C 2 (ethylene and ethane) products increased in the order of HAP-CO 3 < HAP < Pb-HAP-CO 3 < Pb-HAP, while Pb-HAP-CO 3 showed the best stability and comparable C 2 yield (under optimized reaction conditions) to Pb-HAP catalyst. Under different reaction temperature and/or CH 4 /O 2 ratio in the OCM reactions, the CH 4 conversion and C 2 or CO x (CO and CO 2 ) selectivity showed a strong dependence on the composition of HAP-based catalysts. The present study forms a basis for understanding of the correlations between the composition, structure, and catalytic performance of HAP and other apatite structured catalysts, which are potential membrane materials for OCM reactions in membrane reactors. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ag nanoparticles were incorporated into hydrogel, aerogel and film of NFC. [•] Addition of AgNO3 triggered hydrogelation of NFC. [•] The gelation mechanism of NFC by monovalent cations was explored. [•] The NFC-Ag aerogel had less BET surface area than the NFC aerogel. [•] Presence of Ag species reduced coalescence of NFC in the film formation. [Copyright &y& Elsevier]

Abstract The pillared MWW (PMWW or MCM-36) and pillared MFI (PMFI) are two prominent representatives of meso-/microporous lamellar zeolites, which are made by pillaring of layered MCM-22(P) and multilamellar MFI precursors, respectively. They both consist of a 10-membered ring sinusoidal micropore channel within each zeolitic layer and mesopore voids created by pillars between two adjacent zeolitic layers. Although catalytic activities of PMWW and PMFI have been compared, identification of mesopore differences between these two pillared lamellar zeolites has not been attempted. In this work, we report the differences in mesopore characteristics between PMWW and PMFI zeolites probed by atomic layer deposition (ALD) of titania (ALD-TiO 2) species and a combination of structural, textural, composition and catalytic property analyses of the samples before and after ALD treatment, respectively. The results suggest PMFI has cylindrical mesopores with uniform sizes from pore entrance to main body, while PMWW has ink-bottle mesopores with the neck size much smaller than pore body. The communication between micropore and mesopore in PMFI is direct, but no communication exists in PMWW zeolites. The ALD-TiO 2 process considerably modified external surface composition of PMFI and PMWW zeolites, which consequently led to a new application of the pillared lamellar zeolite materials, i.e., photo-catalytically active meso-/microporous zeolites for environmental remedy reactions. Graphical abstract Image 1 Highlights • Identification of mesopore differences between PMFI and PMWW was attempted. • Atomic layer deposition of titania was used as probe for mesopore differences. • PMFI has more uniform mesopores compared to PMWW zeolite. • Atomic layer deposition of titania enabled photocatalytic activity. [ABSTRACT FROM AUTHOR]

The combination of two compositionally and/or structurally different zeolites into one single zeolite composite particle is a potential approach to integrate advantages of different zeolite structures for desirable properties and applications. In the present study, we report the overgrowth of lamellar mesoporous silicalite-1 on the commercial microporous MFI and BEA zeolites, respectively, to render hierarchical meso-/microporous lamellar silicalite-1/MFI (L-Si/MFI) and lamellar silicalite-1/BEA (L-Si/BEA) zeolite composites via hydrothermal crystallization of lamellar silicalite-1 with the assistance of a diquaternary ammonium template. Epitaxial growth of lamellar silicalite-1 on commercial bulk MFI was observed, resulting in the L-Si/MFI zeolite composite as porcupine sensory message ball with nerve-stimulating silicalite-1 bumps extended from the MFI particle. In the L-Si/BEA zeolite composite, the lamellar silicalite-1 was laid over the surface of or partially interdigitated into the commercial bulk BEA particle, forming a BEA nanosponge structure connected to lamellar silicalite-1 nanosheets. The resultant interconnected micro- and mesoporosity in the L-Si/MFI and L-Si/BEA composite zeolites allowed facile mass transport of bulky molecules. The acid sites sitting on the external surface of commercial MFI and BEA zeolites were partially passivated by the lamellar silicalite-1. The consequences of improved mass transport and passivation of external acid sites on the catalytic performance of these zeolite composites were tested in 2 wt% molybdenum (Mo) loaded L-Si/MFI and L-Si/BEA for direct non-oxidative methane aromatization reaction, which showed higher methane conversion and hydrocarbon product formation as well as higher selectivity to naphthalene and coke in comparison with 2 wt% Mo-loaded commercial MFI and BEA catalysts. [ABSTRACT FROM AUTHOR]

Direct non-oxidative methane coupling (NMC) is one of the promising pathways for methane upgrading into value-added olefin and aromatic hydrocarbons. The silica-supported iron (i.e., Fe/SiO 2) catalyst has been reported effective for NMC, but the effects of silica support on the catalyst property and NMC performance have rarely been explored. In this work, we prepared a vitreous silica-supported iron (Fe/SiO 2 -V) catalyst by flame fusion of a mixture of quartz silica and fayalite. The physicochemical properties and NMC performance of the as-prepared catalysts were measured. Compared to crystalline cristobalite support in Fe/SiO 2 catalyst that has been studied previously, vitreous silica support has disordered Si-O bonds and structural defects, enabling better iron dispersion and more vital metal-support interaction. The as-prepared Fe/SiO 2 -V catalyst had a shorter induction period in methane activation and lower coke yield in NMC. The increase in iron concentration in Fe/SiO 2 -V catalysts elongated the catalyst induction period and promoted aromatics and coke formation. The coke type of the spent Fe/SiO 2 -V catalyst is more uniform than the cristobalite-supported iron catalyst. [Display omitted] • Vitreous silica-supported iron catalysts were prepared by an oxyhydrogen flame fusion method. • The amorphous vitreous silica support contains disordered and defective Si-O bonds. • Iron has higher dispersion and more uniform bonding in the vitreous silica support. • Vitreous silica-supported iron enabled fast methane activation and low coking in NMC. • Increase in iron loading in vitreous silica support promoted aromatics formation. [ABSTRACT FROM AUTHOR]

Lamellar MFI zeolite and lamellar MFI zeolite supported nickel were synthesized and examined for ex-situ catalytic upgrading of the vapors (without using any fluidized gases such as N 2 and H 2) resulted from fast pyrolysis of wood chips in comparison to its commercial MFI zeolite and its supported nickel counterparts. Pyrolysis tests were carried out using a catalytic augur reactor at atmospheric pressure, while pyrolysis unit was operating at 450 °C and upgrading unit at 420 °C, respectively. The introduction of nickel with a high dispersion over the zeolitic supports caused a significant increase in the products of aromatic compounds. Moreover, the addition of nickel to zeolite supports changed their acidity and decreased the total number of acid sites and the ratio of Brønsted to Lewis acid sites as determined by pyridine-FTIR spectroscopy. The use of lamellar zeolite catalysts increased the efficiency of catalytic cracking of pyrolysis vapors and their modification with nickel helped tuning the Lewis acidity to further increase catalytic cracking which resulted in a higher yield of the low molecular weight aromatics present in the bio-oil. • Lamellar catalysts are synthesized and extensively characterized. • Ex-situ catalytic fast pyrolysis without fluidizing gas can lead to a low bio-oil deoxygenation. • Lamellar catalysts are found to enhance catalytic cracking of pyrolysis oil vapors. • Lamellar catalysts show no loss in activity after multiple uses. [ABSTRACT FROM AUTHOR]

• Characteristics of the coke deposits on lamellar metal (Ga or Zn)-modified zeolites were studied. • Mesoporous lamellar structure decreases the coke formation by facilitating the external coke deposition. • Metal modification decreases the coke formation by changing the acidity of zeolite. • Highest fraction of light coke is obtained for Zn-modified lamellar zeolite. • Both zeolite structure and metal-modified acidity affect the coke formation. The effects of meso-/microporous structure and metal-additive (Ga or Zn) of lamellar MFI catalysts on the characteristics of coke deposits during ethylene-to-aromatic liquids conversion were investigated. The nature, composition, and location of coke deposits in spent lamellar catalysts were analyzed and compared to those on the microporous MFI counterparts, using FTIR, UV–Vis, GC–MS, and argon adsorption-desorption. The total amount of coke and the changes in coke nature during catalyst regeneration were studied by MS/FTIR combined with temperature programmed oxidation. The lamellar meso-/microporous structure of MFI reduces the coke quantity and the heavy coke fractions. The coke preferentially deposites on external surface of lamellar zeolite due to the lower diffusion limitation for bulky coke precursors. Metal-additive changes the catalyst acidity and decreases the coke formation rate, especially when zinc is used. Therefore, the coke formation on zeolite can be tuned by modulating the textural and acidity properties of the metal-modified catalyst. [ABSTRACT FROM AUTHOR]

• Catalytic performance of metal (Ga or Zn)-loaded mesoporous lamellar zeolites was evaluated. • Mesoporous lamellar structure is pivotal in determining metal dispersion in zeolite catalyst. • Metal loading changes the acidity of the zeolite catalyst and effect of Zn is more pronounced compared to Ga. • Higher liquid aromatics yield and selectivity for mono-benzene alkylated aromatics was observed while less coke was formed. • Both zeolite structure (mesoporosity) and type of metal dopant affect the catalytic performance of catalyst. The effects of meso-/microporous structure and metal-modification with gallium or zinc on catalytic performances of lamellar MFI zeolites in ethylene conversion reaction to liquid aromatics were investigated. TEM, XRD, Ar adsorption-desorption, UV-Visible spectroscopy, and H 2 -TPR measurements showed that the zeolite structure is a pivotal factor for controlling the type of metal dopant species forming on zeolite, their size, and their distribution. Adding metal dopants to zeolite structure decreased the Brønsted to Lewis (B/L) acid site ratio in the zeolites and improved their catalytic performance. As a result, metal-modified lamellar MFI zeolites showed higher liquid aromatics yield and selectivity for mono-benzene alkylated aromatics and lower coke formation rate compared to their microporous commercial MFI analogies. Zinc-loaded lamellar MFI had the most efficient catalytic performance among all studied catalysts. This phenomenon can be explained by higher accessibility of reactants to active sites and facilitated transport of products from lamellar structure of this zeolite and the low B/L acid site ratio of this catalyst provided by metal-modification, which is more suitable for ethylene aromatization. A bifunctional reaction mechanism has been proposed based on the analysis results of reaction product distributions that demonstrates the effect of both zeolite acid sites and metal sites in conversion of ethylene to liquid aromatics over MFI zeolite catalysts. [ABSTRACT FROM AUTHOR]