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Abstract The nitric oxide (NO) production for a series of aluminosilicate zeolites, prepared using the ADOR method, was investigated. Al-UTL and Al-IPC-2,-4 and −6 were prepared and characterised to determine their elemental composition. Positive trends were found to exist between zeolite pore size and the rate and total amount of NO produced. A trend between the number of acid sites and the initial rate of NO produced by the zeolite was also discovered. Graphical abstract Image 1 Highlights • ADOR synthesis of active Al-containing zeolites. • Demonstration of NO-production from nitrite substrate. • Relationship between pore size and reaction developed. [ABSTRACT FROM AUTHOR]

Abstract Up to date, hydrophobic hybrid zeolites (water contact angle > 120°) unexceptionally are prepared through post synthesis methods by using long-alkyl-chain organosilanes (C8∼C16) as organic Si source. In this work, organic-inorganic hybrid zeolite with exceptional hydrophobicity (WCA of 150°) has been firstly one-step synthesized by rotating dry gel conversion (rota-DGC) route in the present of short-alkyl-chain organosilanes (dimethyldiethoxysilane) without using any structure-directing agents. Not only the efficient utilization for carbon source has been achieved, but also the crystallization rate of hybrid zeolite has been fastened. Various analysis results and hydrophobic stability support the incorporation of Si(CH 3) 2 moiety into the zeolite framework. Thus-synthesized hybrid zeolite acts as excellent catalyst support for the phenol hydrogenation in aqueous medium at low temperature of 318 K. The hydrophobic/lipophilic property of the catalyst plays an important role in the formation of stable oil/water microenvironment on the surface of catalyst to accelerate the interfacial reactions, and the solubility difference of product and reactant at low temperature in water has promoted the complete conversion of reactant phenol and the high selectivity of cyclohexanol. Graphical abstract One-step rota-DGC synthesis of hybrid zeolite with exceptional hydrophobicity to accelerate the interfacial reaction at low temperature. Image 1 Highlights • One-step synthesis of organic-inorganic hybrid zeolite with exceptional hydrophobicity. • Methyl-functionalized hybrid zeolite with water contact angle of 150°. • Hydrophobic catalyst to accelerate the interfacial reactions at low temperature. • Highly efficient conversion of phenol to cyclohexanol. [ABSTRACT FROM AUTHOR]

Abstract The traditional methods for zeolite synthesis include use of various solvents that tend to produce pollutants. It is therefore necessary to find green and efficient routes for zeolite synthesis. Herein, we demonstrated a detailed way to synthesize MOR zeolite by a solvent-free method. The synthesized MOR zeolite was characterized by XRD, SEM, TEM, N 2 sorption, MAS NMR and UV-Raman spectroscopy. Compared with other routes, solvent-free method not only addresses pollution issues, but also significantly enhances the yield. A 650 g mass of MOR zeolite with good crystallinity was obtained in 1 L Teflon by one-time synthesis. The optimum conditions for fast synthesis of large amounts of high purity MOR zeolite crystals are the SiO 2 /Al 2 O 3 /Na 2 O = (7.5–25)/1/1, crystallization temperature and period at 200 °C for 24 h. Graphical abstract Image 1 Highlights • MOR zeolite is prepared by solvent-free grinding method. • Optimum synthesis conditions of MOR zeolite via the solvent-free route are examined in detail. • Significantly high product yield is obtained by solvent-free synthesis. • Mass production of high crystallization MOR zeolite can be achieved in laboratory. [ABSTRACT FROM AUTHOR]

Abstract In this work, the hierarchical Y zeolites are firstly obtained by etching NaY zeolites with different NH 4 HF 2 solutions. The morphology and microstructure, toluene adsorption property of as-prepared hierarchical Y zeolites are characterized. The results demonstrate that the mesoporous number and size, the n(SiO 2)/n(Al 2 O 3) value of hierarchical Y are increased with NH 4 HF 2 concentration. The 0.3M NH 4 HF 2 -etched NaY exhibits satisfactory crystallinity, suitable mesoporous content and better toluene adsorption performance. The NH 4 HF 2 -etched NaY is an excellent material for pressure swing adsorption. Furthermore, the synthesis mechanism of hierarchical Y has been elaborately demonstrated. The synergistic effect of H+ and F− is beneficial to dealumination as well as the introduction of mesoporous. The NH 4 HF 2 ionizes into positive H+ and negative F− at a very slow rate, which avoids the concentration of H+ and F− going up suddenly. Under the circumstances, the dealumination reaction between NH 4 HF 2 and NaY zeolites is more sustained and mild, and the crystallinity of hierarchical Y zeolites is higher than that of the HCl/NH 4 F-etched or HF/NH 4 F-etched NaY. This work presents an effective method to synthesize the hierarchical Y zeolites. Graphical abstract Image 1 Highlights • The hierarchical Y zeolites were obtained by etching NaY with NH 4 HF 2 in single-stage process. • The possible reaction equations between NaY and NH 4 HF 2 were given. • The synergistic effect of H+ and F− was more beneficial to dealumination as well as the introduction of mesoporous. • The crystallinity of NH 4 HF 2 -etched NaY zeolites was higher than that of the HCl/NH 4 F-etched or HF/NH 4 F-etched NaY. [ABSTRACT FROM AUTHOR]

Abstract An unconventional hydrothermal synthesis of high-silica zeolite starting from a highly concentrated silicate solution was examined. As a result, the novel zeolite YNU-5 (YFI), which contains a 12−12−8-ring pore system and isolated 8-ring straight channels, was synthesized using dimethyldipropylammonium, one of the simplest tetraalkylammonium compounds, as the organic structure-directing agent. Although several competing phases such as MCM-68 (MSE), ZSM-5 (MFI) and beta (* BEA) were observed during investigation, YNU-5 (YFI) was obtained as a pure phase within a narrow synthesis window. The dealumination behavior by post-synthesis treatment using nitric acid was investigated and the Si/Al molar ratios of YNU-5 were controlled in the range from 9 to >200 by tuning acid concentration and/or temperature. Thermal stability of the framework was enhanced under severer acid-treatment conditions, and the stabilized material exhibited better catalytic performance. Graphical abstract Image 1 Highlights • There was a significant effect of H 2 O/SiO 2 ratios on the zeolitic phase selections in the synthesis of novel zeolite YNU-5. • It is possible to skip the evaporation step for the YNU-5 synthesis; however, the aging process to obtain clear solution is still essential. • YNU-5 with desired Si/Al ratios can be obtained by tuning acid concentration and/or temperature when treated with nitric acid. • The framework was stabilized under severe acid-treatment conditions; the stabilized material showed better catalytic performance. • Si-migration plays important roles in the framework stabilization, and it occurs during nitric acid-treatment at 100 °C. [ABSTRACT FROM AUTHOR]

Graphical abstract Construction of hierarchical porous Al-KIL-2 via kinetic regulation. Highlights • Hierarchical aluminosilicates were synthesized via kinetic regulation method. • Hierarchical Al-KIL-2 possessed well distributed bimodal mesopores. • Composition of framework Al and non-framework Al was analyzed by XPS. • Adjustable porous and acidic properties can face to adsorption of various molecules. Abstract Novel hierarchical Al-KIL-2 aluminosilicates with bimodal mesoporous distribution were successfully synthesized via a feasible and cost-effective kinetic regulation method. The molar ratio of Si/Al, the kinetics of Al-Si polyanions growth and its following oriented-attachment on KIL-2 matrix were regulated aiming at various porous and acidic properties. The hierarchical Al-KIL-2 samples were characterized, and their adsorption capacities were tested by adsorptive denitrogenation for model fuels containing pyridine and quinoline. It was revealed that the branching epitaxial growth behavior originating from Al-zoning on KIL-2 matrix contributed to fabrication of the hierarchical porous structures. In addition, introduction of Al endowed KIL-2 with rich Lewis acid sites for the adsorption of basic contaminants. Hierarchical Al-KIL-2 obtained considerable adsorption efficiencies of pyridine and quinoline, the regularities of which relied on the appropriate kinetic regulation conditions during materials synthesis. The adsorption isotherms and adsorption thermodynamics research essentially presented the feature of this adsorptive denitrogenation system over hierarchical Al-KIL-2 for its potential industrial applications. [ABSTRACT FROM AUTHOR]

A synthetic strategy is reported here for the selective containment of oxide nanoparticles of base metals within zeolitic voids of molecular dimensions. The technique, though generally applicable, is specifically illustrated to encapsulate Ni, Co, and Fe oxides within LTA, MFI, and FAU zeolites through hydrothermal framework crystallization in the presence of ligand-protected metal cations. Such ligands contain bidentate amine groups that preclude the precipitation of metal precursors in alkaline synthesis gels, and alkoxysilane moieties that form covalent linkages with nucleating zeolite precursors to enforce metal uptake into crystallized solids. These ligands are removed by subsequent oxidative treatments that nucleate oxide nanoparticles without structural degradation of the zeolites. The clusters are small (<2.5 nm) and uniformly distributed in size, reflecting their constrained growth within zeolite crystals. In contrast with exchange strategies for encapsulation, which lead to grafted cations and dense metal aluminosilicates, these methods form oxide nanoparticles, evident from infrared spectra of samples exposed to CO. Oxide nanoparticles undergo more facile redox cycles than grafted cations or dense aluminosilicates, thus rendering oxide domains more effective oxidation catalysts. The dynamics and stoichiometry of nanoparticle reduction in H 2 confirmed the presence of NiO, Co 3 O 4 , and Fe 2 O 3 clusters and their more facile reducibility relative to metal aluminosilicates. Ethanol oxidation rates on these clusters were essentially unaffected by exposure to bulky thiol poisons that titrate metal oxide surfaces, reflecting the selective placement of the oxide nanoparticles within the confines of microporous voids, where they are protected from contact by large molecules. These synthetic strategies and guiding principles circumvent long-standing hurdles in the selective encapsulation of base metals, and provide enabling routes for the synthesis of the many metal-zeolite systems that confront similar hurdles. [ABSTRACT FROM AUTHOR]

Abstract Halloysite Nanotubes (HNTs) are clay minerals that possess unique chemical composition and a tubular structure due to which, they have recently emerged as a potential nanomaterial for umpteen applications. Over the years, the myriad applications of HNT have been realized through the surface modification of HNT, which involves the modification of nanotube's inner lumen and the outer surface with different functional compounds. The presence of aluminum and silica groups on the inner and outer surface of HNT enhance the interfacial relationship of the nanotube with different functional agents. Compounds such as alkalis, organosilanes, polymers, compounds of biological origin, surfactants and nanomaterials have been used for the modification of the inner lumen and the outer surface of HNT. The strategies change the constitution of HNT's surface either through micro-disintegration of the surface or by introducing additional functional groups on the surface, which further enhances their potential to be used as a flexible interface for different applications. In this review, the different surface modification strategies of the outer surface and the inner lumen that have been employed over the years have been discussed. The biological, environmental and catalytic applications of these surface modified HNTs with such versatile interface in the past two years have been elaborately discussed as well. Graphical abstract Unlabelled Image Highlights • Halloysite Nanotubes are clay-based and of aluminosilicate composition. • Surface modification of inner lumen and outer surface are discussed. • Outer surface modified by change in morphology/addition of functional groups. • Inner lumen modification in infancy, presents an opportunity for myriad uses. • Surface modified Halloysite Nanotubes are used in different applications. [ABSTRACT FROM AUTHOR]

Data on the synthesis and sorption properties of natural calcium aluminosilicates modified by poly-1-vinyl imidazole (PVIm) and poly-4-vinyl pyridine (PVP) are presented. The fullest recovery of nickel (II) ions from low-concentration solutions is observed for PVP-modified aluminosilicates. Adsorption of nickel (II) ions by PVIm-modified aluminosilicates is best described by the Freundlich adsorption model. In the case of PVP-modified aluminosilicates, the Langmuir model is more adequate. The free adsorption energy values indicate that the interaction between nickel (II) ions and modified aluminosilicates is of a chemical nature. [ABSTRACT FROM AUTHOR]

We report for the first time, a novel one-pot protocol for the synthesis of large-pore AlMCM-41 aluminosilica materials (i.e. LP-AlMCM-41(y), where y = Si/Al ratio). Assisted by a pore-expansion agent, i.e. N,N -dimethylhexadecylamine (DMHA) and the self-assembly process, aluminum incorporation and pore-enlargement were achieved in a single step, eliminating costly post-synthesis treatments. The LP-AlMCM-41s and the corresponding protonated materials, i.e. LP-H-AlMCM-41, were thoroughly characterized by ICP, N 2 adsorption-desorption, TEM, 27 Al MAS NMR and FT-IR of adsorbed pyridine. The LP-AlMCM-41 materials exhibited relatively sharp and uniform pore size distribution profiles, BET surface areas of around 1000 m 2 /g and average pore diameters of 6–7 nm. No dealumination or structural degradation was observed upon pore-enlargement of AlMCM-41, which is a unique feature of this methodology. As opposed to purely siliceous LP-MCM-41, the LP-AlMCM-41(20) showed structural stability toward prolonged exposure to boiling water and steam. Thus, it is anticipated to be a good candidate for adsorption applications in aqueous media as well in processes utilizing steam for regeneration. Upon protonation, the catalytic activity of LP-H-AlMCM-41s was investigated in the acid-catalyzed reaction of furfural with 2-methylfuran to produce 2,2’-(2-furylmethylene)bis(5-methylfuran) (FMBM). A superior catalytic performance was observed in the presence of LP-H-AlMCM-41(20), showing 49% furfural conversion with 71% selectivity to FMBM. Owing to the high BET surface areas and pore volumes as well as the large and uniform pore diameters preserved after protonation, these LP-H-AlMCM-41 aluminosilicates can be potential candidates for catalytic processes involving complex molecular structures such as petroleum heavy oil and biomass. [ABSTRACT FROM AUTHOR]

Although NH 3 has recently been regarded as a renewable and carbon-free energy source, NH 3 fuel has a high ignition temperature and its use results in the production of N 2 O/NO x . To overcome these issues, in this work, we focused on a novel catalytic combustion system and copper oxides (CuO x ) catalysts supported on aluminum silicates (Al 6 O 13 Si 2 , 3Al 2 O 3 ·2SiO 2 , 3A2S) and silicon oxides (SiO 2 ). The preparation methods for 3A2S as a support material were optimized to achieve high catalytic NH 3 combustion activity and high N 2 (low N 2 O/NO) selectivity. Because the CuO x supported on 3A2S prepared by an alkoxide method and subsequent calcination at 1200 °C for 5 h in air exhibited high catalytic performance for NH 3 combustion, the properties of the catalyst in addition to CuO x /SiO 2 thermally aged at 900 °C for 100 h in air were also evaluated using high-angle annular dark-field scanning transmission electron microscopy, energy-dispersive X-ray mapping, operando X-ray absorption fine structure analysis, X-ray photoelectron spectroscopy, and gas adsorption techniques. Our findings suggest that the catalytic NH 3 combustion activity, NO selectivity, and N 2 O selectivity are closely associated with the reducibility (dispersion) of CuO x , local structures around Cu, fraction of the oxidation state (Cu 2+ ), and adsorption species of NH 3 (NH, imide). Finally, we propose a reaction mechanism for catalytic NH 3 combustion over not only CuO x /3A2S but also CuO x /SiO 2 . [ABSTRACT FROM AUTHOR]

The temperature dependent behaviour of a complex aluminosilicate glass (SiO 2 -Al 2 O 3 -ZnO-Na 2 O system), which is a reference for ceramic glaze technology, has been determined, by combining techniques that cover a scale ranging from atomistic to macroscopic. The system shows a linear thermal expansion up to about 600 °C. The glass transition temperature is at 620 °C, as observed from Differential Scanning Calorimetry. Ex situ synchrotron diffraction experiments found a further transformation consisting of albite crystallization above 810 °C. This reaction is very slow and induces permanent structural modifications in the material at both intermediate and short ranges, as shown by in situ synchrotron diffraction experiments. These observations explain why ceramic glaze technology still faces challenges for large scale manufacturing and show the critical thermal range where interventions should be focussed. Eventually, melting takes place at 1190 °C, from hot stage microscopy. [ABSTRACT FROM AUTHOR]

The CHA-type aluminosilicate zeolites were synthesized in the presence of the N,N,N-trimethyl-1-adamantammonium cation from different starting materials, including fumed silica, aluminum hydroxide and the FAU-type zeolite, with their proportions varied. In this work, the proportion of "Q4(nAl)", Si(OSi)4-n(OAl)n and "Q3(nAl)", Si(OSi)3-n(OH)(OAl)n, in the total framework Si atoms, which can be estimated by the solid-state 29Si MAS NMR technique, has been applied to an index for Al distribution. When the proportion of the Al source derived from the FAU-type zeolite was increased, the proportion of Q4(2Al) was increased. Thus, we found a facile method for controlling the Al distribution in the CHA-type zeolite by varying the starting materials. Finally, the impacts of the Al distribution on the hydrothermal stability and catalytic properties in the methanol to olefins (MTO) reaction were investigated. [ABSTRACT FROM AUTHOR]

The crystal structures are determined for KDy[AlSi4O12]·0.41H2O and KTb[AlSi4O12]·0.32 H2O compounds synthesized under hydrothermal conditions, which crystallize in the space group C2/c with the unit cell parameters a = 26.6956(6) Å and 26.619(1) Å, b = 7.2477(2) Å and 7.2553(3) Å, c = 14.7705 Å and 14.8200(6) Å, β = 123.7721° and 123.5149° for KDy and KTb aluminosilicates respectively. Tetrahedral layers in the structures of the studied crystals differ in their packing order and can be matched in space with a twofold rotational symmetry axis. In the studied phases Dy and Tb present in a trivalent form. [ABSTRACT FROM AUTHOR]

The foaming index of the CaO-SiO-MO (MO = MgO, FeO, or AlO) ternary slag system with a fixed CaO/SiO ratio is measured to understand the effect of the ionic structure. At 1773 K (1500 °C), the foaming index of the slag increases with AlO addition and decreases with MgO or FeO addition at a fixed CaO/SiO ratio. It is verified that the previous correlation between the foaming index and the physical properties could also be valid for the CaO-SiO-(MgO or AlO) system. Raman spectroscopy for the CaO/SiO = 1.0 slag is applied to explain the foaming behavior from an ionic structural perspective. From the ionic structural viewpoint, the fractional change in each silicate anion unit is identified by de-convoluted Raman spectra. The Raman spectra indicate that the silicate network structure is polymerized with AlO as an aluminosilicate structure; in contrast, de-polymerization occurs by MgO or FeO addition. Furthermore, the relationship between the silicate structure and the thermodynamic stability function is discussed. Since the ionic structure of the molten slag affects various physical/thermodynamic properties, the foaming behavior could be successfully interpreted from the ionic structural viewpoint. [ABSTRACT FROM AUTHOR]

Zeolites containing Zn in their frameworks are promising materials for ion-exchange and catalysis because of their unique ion-exchange capabilities and characteristic Lewis acidity. However, expensive organic compounds often required in their synthesis can prevent their practical uses. Here, a facile organic-free synthesis route for new zincoaluminosilicate zeolites having MOR topology, in which both Zn and Al are substituted in the framework, is demonstrated for the first time. The use of homogeneous zincoaluminosilicate gels prepared by a co-precipitation technique as raw materials is vital for the successful incorporation of both Zn and Al into the zeolite frameworks as revealed by several characterization techniques including solid-state NMR and UV-vis spectroscopy, and ion-exchange experiments. The obtained zincoaluminosilicate zeolites had high Zn contents comparable to those in the initial zincoaluminosilicate gels. In contrast, the uses of conventional sources of Si, Al, and Zn resulted in zeolites with very low contents of framework Zn or zeolites with extra-framework zinc oxide-species. FT-IR measurements using probe molecules and ion-exchange experiments suggested that there are two different environments of Zn in the zeolite frameworks. The obtained zincoaluminosilicate zeolites showed a higher ion-exchange efficiency for divalent cations such as nickel compared to the aluminosilicate analog. It is expected that the present co-precipitation technique is efficient for the incorporation of Zn (and other metals) into a variety of zeolite frameworks. To show its extended applicable scope, the synthesis of zincoaluminosilicate *BEA zeolite is also demonstrated. [ABSTRACT FROM AUTHOR]

The data on synthesizing nanosized potassium aluminosilicates (PAS) with a ratio of Si/Al of 1-5 obtained in the KOH-Al(SO) · 18HO-SiO · nHO-HO multicomponent system have been presented. Their composition, morphology, and IR and NMR spectra have been studied. [ABSTRACT FROM AUTHOR]

Self-assembly of block copolymer and zeolite Y precursors is an important way to prepare well-ordered mesoporous aluminosilicates (MAs). However, when the concentration of block copolymer is high (low amount of water), the cooperative templating mechanism (which bases the coordination of the inorganic precursor with micelles) is disturbed and well-ordered mesoporous structures will not form. A means to obtain hydrothermally stable MAs with decreased water amount is remains a challenging goal. Here, we report a urea additive method to solve this problem. In this procedure, the addition of urea could increase the hydrophilic strength of poly(ethylene oxide) (PEO) moieties of P123 micelles, which would strengthen their assembly ability. As a result, mesostructured ordering would be improved with greatly decreased water amount. Meanwhile, the P123 utilization efficiency rises. This strategy provides a facile route to synthesize MAs with reduced consumption of water and high P123 utilization efficiency, which is beneficial to industrial application. [ABSTRACT FROM AUTHOR]

Catalytic performance in the methanol-to-olefins reaction was studied on four 8-ring silicoaluminophosphate (SAPO) molecular sieves with different framework topologies and cavity-windows of various dimensions: SAPO-35 (LEV), SAPO-56 (AFX), STA-7 (SAV), and SAPO-42 (LTA). The four catalysts were compared with the widely investigated SAPO-34 (CHA) and showed remarkable differences in lifetime and products selectivity. In particular, the STA-7 catalyst gave higher selectivity to C3–C4 olefins, while it had methanol conversion capacity similar to that of a SAPO-34 catalyst with similar crystal size and acidity. Organic species retained in the cavities of partially deactivated catalysts were analyzed at different times on stream. The changes in composition of trapped compounds were correlated with those of the effluent products to elucidate the reaction mechanism and the deactivation pathway. The differences in effluent product distribution and trapped coke species suggest that framework topology has a great influence not only on the stability of the materials but also on the products distribution. [ABSTRACT FROM AUTHOR]

Improving concrete sustainability by increasing durability requires a detailed knowledge about microstructural properties. Due to the nanoscale nature of hydrate phases that determine concrete properties, microstructural characterization remains a challenge. Analytical electron microscopy offers promising techniques to characterize cement hydrates. In this study, electron microscopy imaging, diffraction, and energy dispersive X-ray spectroscopic information are combined in order to compare the structural properties of calcium silicate hydrate (C-S-H) and calcium aluminum silicate hydrate (C-A-S-H) phases. Results are shown for 28 days hydrated C-(A)-S-H of portland cement and cement containing ground granulated blast-furnace slag (GGFBS). Electron diffraction patterns of single fibrous C-S-H and foil-like C-A-S-H phases reveal a nanocrystalline structure. Also, it is shown by electron diffraction pattern that the crystal structures of C-S-H and C-A-S-H phases are similar. It is confirmed that the crystal structure of 14 Å tobermorite serves as good base for the structure of C-S-H. The electron diffraction patterns of fibrous C-S-H show streaks which indicate stacking faults, proofing that polymerization of silicate chains in C-S-H is limited. Here, we demonstrate for the first time that the dreierketten silicate chains contained in the C-S-H structure are oriented in parallel to the long axis of C-S-H fibers. This finding should be implemented in modeling of crystal growth of C-S-H. [ABSTRACT FROM AUTHOR]

The mechanical behavior, physical behavior, microstructural characteristics, and corrosion behavior of AA2014/silicon carbide (SiC)/carbonized eggshell hybrid green metal matrix composites (MMCs) were investigated. Twenty-five samples of hybrid composite with different combinations of SiC and carbonized eggshell particles in AA2014 matrix alloy were prepared. Microstructure presents that the reinforcement particles (SiC and eggshells) are uniformly distributed in the matrix AA2014 alloy. Transmission electron microscope image shows proper wettability between SiC, carbonized eggshell, and AA2014 aluminum alloy. The tensile strength and the fatigue strength for the composites containing 2.5 wt.% SiC up to 7.5 wt.% carbonized eggshell were observed to be higher than that of the other selected composites. The hardness values for the composites containing 12.5 wt.% SiC and 2.5 wt.% carbonized eggshell were in all cases higher than that of the other composites. The results show that toughness decreases with the increase in the weight ratio of SiC and carbonized eggshell in the composites. The results reveal that the sample of AA2014/2.5% SiC/12.5% carbonized eggshell shows minimum corrosion rate among all the selected samples. Density, porosity, and overall cost of hybrid metal matrix composites were also calculated to see the effects of carbonized eggshell and SiC addition in AA2014 matrix alloy. [ABSTRACT FROM AUTHOR]

A new intrinsic hydrolysis method was employed, for the first-time, to synthesize well-ordered H-AlSBA-15 with trivalent aluminium exclusively in the tetrahedral framework structure of SBA-15. Unlike other methods, which involve incorporation of aluminium ions in both the framework (Brønsted) and non-framework (Lewis) sites of the silicate matrix, the intrinsic hydrolysis method isomorphously substitutes aluminium ions in the tetrahedral network even at high aluminium content. This unique approach relies mainly on the hydrolysis rates of the inorganic (silicon and aluminium) precursors used for the preparation in such a way that the condensation occurs simultaneously so as to overcome the usually encountered difficulties in stabilizing aluminium ions in the silicate matrix. In this way, we could successfully synthesize high quality Brønsted acidic H-AlSBA-15, hitherto not reported. The synthesized materials were systematically characterized by various analytical, spectroscopic, and imaging techniques, including XRD, Brunauer-Emmett-Teller (BET) surface area measurements, TEM, SEM, 29Si and 27Al magic angle spinning NMR spectroscopy, X-ray fluorescence (XRF), and NH3 temperature-programmed desorption (TPD). The characterization results reveal the presence of a highly porous structure (with narrow pores) and tetrahedrally coordinated trivalent aluminium in the silicate matrix with more medium to strong Brønsted acid sites. The resulting high quality catalysts exhibit excellent activity for tert-butylation of phenol with high selectivity towards para-tert-butyl phenol and 2,4 -di -tert-butyl phenol. [ABSTRACT FROM AUTHOR]

Montesommaite-type aluminosilicate was synthesized for the first time by the steaming of lithosite-type aluminosilicate which had been previously synthesized under solvothermal conditions. The montesommaite-type aluminosilicate samples obtained were pseudomorphs of the lithosite-type crystals and euhedral octahedral particles. Owing to the structural similarity, the montesommaite-type crystal could be grown hetero-epitaxially on the lithosite-type one. In addition, the montesommaite-type zeolite was predominantly crystallized at temperatures higher than 150 °C. The optimum duration of steaming for obtaining a single phase of montesommaite-type aluminosilicate changed with both the steaming temperature and initial K/Si ratio in the initial lithosite-type aluminosilicate. Since the lattice parameter of lithosite-type aluminosilicate sample changed with potassium content, which gradually changed with steaming, it was suggested that the steaming treatment caused the crystallization of montesommaite-phase not only by the destruction of the lithosite-type crystal, but also by changing the lattice parameter of the –LIT structure as the substrate. [ABSTRACT FROM AUTHOR]

Two synthesized mesoporous aluminosilicate catalysts were tested for their performance in the lignin hydrothermal cracking to benzenediol derivatives, and especially to catechol (1,2-benzenediol), compared to non-catalytic cracking. In this study, Al-doped MCM-41 catalysts were synthesized by direct and post-synthesis methods while Al-doped SBA-15 was prepared by post-synthesis method. The catalytic performance of these synthesized mesoporous aluminosilicate catalysts was compared with microporous HZSM-5 in terms of their selectivity for catechol production. All the tested catalysts gave markedly higher catechol selectivity than the non-catalytic reaction. The acidity and porosity of the catalyst played an important role in the selectivity for catechol. The highest selectivity for catechol (35.5%) was achieved from lignin hydrothermal cracking at a low temperature (300 °C) for 30 min with the Al-MCM-41 catalyst prepared by post-synthesis method, and at a catalyst to lignin weight ratio of 0.75. [ABSTRACT FROM AUTHOR]

Hybrid chitosan (CS)/calcium aluminosilicate nanocomposites thin films and membranes were prepared using a sol–gel method with three different concentrations of Al 2 O 3 (5, 7 and 10 mol. %). The prepared nanocomposites were characterized by transmission electron microscopy, X-ray diffraction and Fourier Transform Infrared spectroscopy. The optical properties of the prepared samples were analyzed by UV/Vis spectrophotometry and photoluminescence (PL) spectroscopy. The optical parameters revealed an increase in both the refractive index and band gap of the nanocomposites with increasing Al concentration. In addition, the PL spectra revealed a blue shift that was consistent with an increase in the optical band gap. These results suggest that CS/calcium aluminosilicate in two different forms can be a good candidate for optical sensors applications. [ABSTRACT FROM AUTHOR]

Nb-based intermetallics are, generally, low-density high-temperature materials used for structural applications or cryogenic superconductors. In this work, we report the development of an Al(96)-Nb(2)-B(2) master alloy where in situ-formed micrometric Nb-based intermetallics (i.e. NbB and AlNb) are used for a completely different purpose: to promote the refinement of Al-Si alloys by taking advantage of enhanced heterogeneous nucleation. Nb-based intermetallics have the right characteristics, like low density, stability at high temperature and good lattice match, to be used as heterogeneous nucleation substrates. It was found that the addition of these Nb-based intermetallics permits the significant refinement of the microstructural features of the Al-Si alloy studied. The enhanced heterogeneous nucleation makes the grain size of the material far less dependent on the cooling rate, which is one of the critical parameters influencing the variation of the properties of the alloy. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the influence of the conditions of low-temperature sequential dual template synthesis of micro-mesoporous aluminosilicates based on precursors of ZSM-5 on their phase composition, structure, sorption properties, and acidity. The methods of X-ray powder diffraction and volumetric adsorption (N, 77 K) analysis, dynamic light scattering (for characterization of sol-precursors), IR-spectroscopy, energy-dispersive X-ray spectroscopy, scanning and transmission electron microscopy, solid-state Si MAS NMR and Si{1H} cross-polarization MAS NMR spectroscopy, temperature-programmed desorption of ammonia, ad(de)sorption of pyridine and 2,6-di- tert-butylpyridine with IR-spectral control were used for characterization of the obtained micro-mesoporous aluminosilicates. It was shown that the convergence of compositions of the reaction mixtures and conditions of formation of zeolites and mesoporous molecular sieves, in particular, the use of alkali-free reaction medium and relatively low temperature of hydrothermal treatment (100 °C) allowed to obtain the X-ray amorphous and partially zeolitized micro-mesoporous aluminosilicates. Such aluminosilicates have appropriate structural and sorption properties and the acidity inherent to ZSM-5 and MCM-41, including the Brønsted and Lewis acid sites which are accessible for bulk molecules of organic substances. The possibility of purposeful regulation of characteristics of micro-mesoporous aluminosilicates depending on the conditions of their preparation was confirmed. Herewith the investigated aluminosilicates possess the sorption and acidic properties which are different from the mechanical mixture of two phases. [ABSTRACT FROM AUTHOR]

Large-pore microporous materials are of great interest to process bulky hydrocarbon and biomass-derived molecules. ITQ-27 (IWV) has a two-dimensional pore system bounded by 12-membered rings (MRs) that lead to internal cross-sections containing 14 MRs. Investigations into the catalytic behavior of aluminosilicate (zeolite) materials with this framework structure have been limited until now due to barriers in synthesis. The facile synthesis of aluminosilicate IWV in both hydroxide and fluoride media is reported herein using simple, diquaternary organic structure-directing agents (OSDAs) that are based on tetramethylimidazole. In hydroxide media, a zeolite product with Si/Al=14.8-23.2 is obtained, while in fluoride media an aluminosilicate product with Si/Al up to 82 is synthesized. The material produced in hydroxide media is tested for the hydroisomerization of n-hexane, and results from this test reaction suggest that the effective pore size of zeolites with the IWV framework structure is similar to but slightly larger than that of ZSM-12 (MTW), in fairly good agreement with crystallographic data. [ABSTRACT FROM AUTHOR]

Aluminosilicate systems with high mechanical strength have been prepared by a rapid ambient pressure drying. A special nanocomposite structure results in the good mechanical properties and strengthens the aluminosilicate system for a rapid ambient pressure drying technique. The nanocomposite consists of an amorphous aluminosilicate network and an Al-containing nanocrystalline, reinforcement phase. The reinforcement phase and the gel network develop simultaneously from the starting solution in the gelation process. The nanocomposite structure can only be achieved at a limited molar ratio of Al/Si. The wet precursor system of drying has been synthesized by sol–gel technique from low cost water glass and environmental saving Al acetate. The bond system, the structure, the morphology, and the mechanical property were investigated in the function of Al/Si molar ratio. [ABSTRACT FROM AUTHOR]

A Ca/Na-aluminosilicate was synthesized from kaolin and limestone via the hydrothermal reaction and was used for CO 2 capture from a gas stream. Synthesis was performed at several combinations of temperature, pressure, kaolinite to limestone mass ratio, and the reaction time. The products were characterized by determining the crystalinity, surface morphology, surface area, and the pore size distribution. When the reaction temperature and pressure are increased, the sodium hydroxide concentration has a significant effect on the formation of novel Ca/Na-aluminosilicate phases. X-ray diffraction shows that a mixture of Gehlenite Ca 2 Al(Al 1.22 Si 0.78 O 6.78 )OH 0.22 (43 wt %) and Stilbite Na 5.76 Ca 4.96 (Al 15.68 Si 56.32 O 144 ) (57 wt%) is produced in 36 M NaOH at 200 °C and 15 bar. The adsorption capacity of the above product for CO 2 from a gas stream increased with temperature, reaching a CO 2 uptake of 294.7 mg/g at an equilibrium pressure of 45 bar and a temperature of 150 °C. Thermodynamic studies show spontaneous and endothermic adsorption behavior with a Δ H ads of 4.64 kJ/mol , Δ S ads of 25.25 J/mol.K, and Δ G ads of −6.09 kJ/mol obtained at 150 °C. The CO 2 adsorption/cycling process were repeated and it was found that the capacity of the novel adsorbent decreases in the second cycle and remains constant after that. This suggests chemisorption process took place on the fresh adsorbent and physical adsorption occurred at higher cycles. [ABSTRACT FROM AUTHOR]

The transformation of kaolin to amorphous mesoporous aluminosilicate was investigated in this study. We demonstrated the use of koalin as silica and alumina sources without prior pretreatment. Two steps synthesis method were carried out; hydrothermal reaction at 80 °C, followed by addition of mesoporogen cetyltrimethylammonium bromide (CTABr) surfactant. We observed that prolonging the synthesis period improves the surface area of the aluminosilicate with enhances mesopore volume and surface acidity. [ABSTRACT FROM AUTHOR]

Aluminosilicate materials were obtained by sol-gel method, using different Al2O3 and SiO2 precursors in order to prepare sols based on water and organic solvents. As SiO2 precursors, Aerosil 200ι and tetraethoxysilane TEOS: Si(OC2H5)4 were applied, while DisperalTM and aluminium secondary butoxide ATSB: Al(OC4H9)3 were used for Al2O3 ones. Bulk samples were obtained by heating gels at 500 °C, 850 °C and at 1150 °C in air, while thin films were synthesized on carbon, steel and alundum (representing porous ceramics) substrates by the dip coating method. Thin films were annealed in air (steel and alundum) and in argon (carbon) at different temperatures, depending on the substrate type. The samples were synthesized as gels and coatings of the composition corresponding the that of 3Al2O3γ2SiO2 mullite because of the specific valuable properties of this material. The structure of the annealed bulk samples and coatings was studied by FT-IR spectroscopy and XRD method (in standard and GID configurations). Additionally, the electron microscopy (SEM) together with EDS microanalysis were applied to describe the morphology and the chemical composition of thin films. The analysis of FT-IR spectra and X-ray diffraction patterns of bulk samples revealed the presence of -Al2O3 and γ-Al2O3 phases, together with the small amount of SiO2 in the particulate samples. This observation was confirmed by the bands due to vibrations of Al-O bonds occurring in -Al2O3 and δ-Al2O3 structures, in the range of 400 to 900 cm-1. The same phases (γ-Al2O3 and γ-Al2O) were observed in the deposited coatings, but the presence of particulate ones strongly depended on the type of Al2O3 and SiO2 precursor and on the heat treatment temperature. All thin films contained considerable amounts of amorphous phase. [ABSTRACT FROM AUTHOR]

A novel synthesis route for topaz (Al 2 SiO 4 (OH,F) 2 ) by chemical vapor deposition (CVD) using Na 2 SiF 6 as solid precursor was developed. Synthesis tests were conducted with and without a flow of nitrogen, positioning the Al(OH) 3 substrate at 0° and 90° with respect to the gas flow direction, at 700 and 750 °C, for 60 and 90 min, respectively. It was found that topaz is synthesized through two pathways, directly and indirectly, involving a series of endothermic and exothermic, heterogeneous and homogeneous reactions between Al(OH) 3 and SiF 4 (g). Analytical structural determination confirmed existence of orthorhombic polycrystals with lattice parameters of a =4.6558 Å, b =8.8451 Å and c =8.4069 Å. According to ANOVA, while temperature, time and interaction of substrate angular position with atmosphere ( P × A ) are the parameters that most significantly influence the variability in the amount of topaz formed – equivalent contributions of 31% – topaz lattice parameters are mostly impacted by the same factors ( T , t , P , A ), but without the interaction factor. The projected amount of topaz is in good agreement with that obtained in confirmation tests under optimal conditions: Al(OH) 3 substrate compact placed at 0°, treated at 750 °C for 90 min in the absence of N 2 . [ABSTRACT FROM AUTHOR]

A template-free sol-gel synthesis method has been developed for obtaining mesoporous alumino-silicates with a narrow pore size distribution. The effect of the synthesis conditions on the formation of the porous structure and on the phase composition and surface acidity of the aluminosilicates has been elucidated. The catalytic properties of the synthesized aluminosilicates with SiO/AlO = 20 in the oligomerization of α-methylstyrene and 1-octene have been investigated. The highest oligomerization activity is shown by the aluminosilicate synthesized in two steps. The mesoporous aluminosilicates far exceed zeolite H-Beta (SiO/AlO = 18) in activity and in selectivity toward products with a higher degree of oligomerization. [ABSTRACT FROM AUTHOR]

Aluminum-containing hexagonally ordered mesoporous silica, Al-MCM-41, was successfully synthesized for the first time using natural clay from low-grade potash ores of a salt lake in Qinghai, China, through liquid-phase transport. Synthesis involved the use of impure natural clay, the principal components of which are kaolin and quartz, as a starting material to produce Al-MCM-41 directly without sedimentation processing; no additional silica or aluminum reagents were required in this process. The resultant product was characterized by X-ray fluorescence, X-ray diffraction, Fourier-transform infrared spectroscopy, N 2 adsorption/desorption isotherms, transmission electron microscopy, and 27 Al magic-angle spinning NMR. The adsorption capacity of the final product for removing octadecylamine in synthetic salt lake brine was also investigated. Results suggested that salt lake clay is a promising low-cost precursor for the industrial production of mesoporous aluminosilicate. [ABSTRACT FROM AUTHOR]

The article focuses on various articles published in several sister journals of the periodical "ChemPlusChem," on topics including chemical binding in crystalline ammonium chloride, cellulose hydrolysis in supercritical water, and synthesis of hexagonal mesoporous aluminosilicates.

We report a facile strategy for synthesis of hydrothermally stable mesoporous aluminosilicates (MAs) from zeolite Y precursors by adding small amount of Tween-20. By the addition of suitable amount of Tween-20, P123-Tween complex micelles formed due to the interaction between hydrophobic chain of Tween and PPO units of P123. The hydrophilicity of the complex micelles was enhanced due to the incorporation of PEO units of Tween. As a result of this, the micelles could be well dispersed and MAs with reduced particle size could be readily obtained. [ABSTRACT FROM AUTHOR]

The catalysts analysed in the current work are variations of MCM-41. The properties of these highly ordered mesoporous aluminosilicates were adjusted by an isomorphous substitution of Si by a trivalent cation, in this case Al3+, generating catalysts of the AlMCM-41 type. The materials were synthesized with a silicon/aluminium ratio of 40, through two methods of impregnation of the metal: conventional and post-synthesis alumination. With the aim of determining the density of the acid sites of the Al40MCM-41 prepared by post-synthesis and conventional alumination, studies of the adsorption of n-butylamine probe molecule were carried out. Further, the studied material was characterized by thermogravimetry measurements, providing the profile of decomposition of the samples, which allowed calculation of the densities of the acid sites. The model-free kinetic algorithms were applied in order to determinate conversion and apparent activation energy. Comparison of energy-dispersive X-ray fluorescence and X-ray photoelectron spectroscopy measurements indicated that the post-synthesis method was more favourable based on the metal positioning, 'anchored' in the surface of the catalyst. The textural properties of the calcined Al40MCM-41 prepared by post-synthesis and conventional alumination were characterized by X-ray diffraction, N2 isothermal adsorption measurements (Brunauer -- Emmett -- Teller and Barrett -- Joyner -- Halenda), transmission electron microscopy, and X-ray photoelectron spectroscopy. [ABSTRACT FROM AUTHOR]

Ordered mesoporous SBA-15 analogs with different Si/Al ratios were successfully prepared in a two-step process from self-assembly of ZSM-5 nanoseeds at high temperature in mildly acidic media (473 K, pH 3.5). The obtained products were characterized as SAXS, XRD, N2 sorption, FTIR, TEM, NH3-TPD, AAS and ICP. The results show that the initial Si/Al molar ratio of ZSM-5 precursors strongly affects the final materials' properties. A highly condensed, well-ordered mesoporous SBA-15 analog with improved hydrothermal stability and acidic properties can be prepared from low aluminum containing ZSM-5 precursors (Si/Al ≥ 20). Reducing the initial Si/Al molar ratio to 10, however, leads to the formation of a disordered mesoporous SBA-15 type material accompanied by degraded textural and acidic properties. The gas phase cracking of cumene, carried out as probe reaction to evaluate Bransted acidity, reveals that an increased density of Bransted acid sites has been achieved over the SBA-15 analogs compared to conventional Al-SBA-15 due to the preservation of zeolite building units in the mesopore walls of the SBA-15 analogs. [ABSTRACT FROM AUTHOR]

The influence of H3BO3 on the crystallization of hybrid organic-inorganic aluminosilicates denoted as Eni Carbon Silicates (ECS's) was investigated. Syntheses were carried out at 100 °C under different experimental conditions, using bridged silsesquioxanes of general formula (EtO)3Si-R-Si(OEt)3 (R = -C6H4- (BTEB), -C10H6- (BTEN) and -C6H4-C6H4- (BTEBP)), in the presence of equimolar concentrations of NaAlO2 and H3BO3. The study, involving the synthesis of three different but structurally related phases (ECS-14 from BTEB, ECS-13 here described for the first time from BTEN, and ECS-5 from BTEBP), confirmed a catalytic role for H3BO3 which in general increased the crystallization rate and improved the product quality in terms of amount of crystallized phase (crystallinity), size of the crystallites and phase purity, while it was weakly incorporated in trace amounts in the framework of ECS's. [ABSTRACT FROM AUTHOR]

Highlights: [•] The SFH-type aluminosilicate zeolites were synthesized by direct- and post-synthesis methods. [•] The directly prepared SFH-type aluminosilicate zeolite exhibited a higher catalytic performance. [•] The Al distribution in the framework is remarkably affected by the preparation method. [ABSTRACT FROM AUTHOR]

Highlights: [•] A flat aluminosilicate framework composed mostly of hexagonal prisms was grown using a Ru(0001) surface as a template. [•] It is an incomplete framework forming a two-dimensional percolated network. [•] It has large voids in the structure in the mesoporous scale range leaving Ru exposed. [•] The structure is different from what was found for pure-silicate frameworks produced under the same conditions. [ABSTRACT FROM AUTHOR]

Abstract: The alkali activation of aluminosilicates is a procedure for obtaining new binders with many of the same properties as traditional portland cement. The type and characteristics of the products formed, however, and consequently their mechanical performance, are conditioned by a number of parameters. The present study explored the potential reactivity of synthetic alkaline silicoaluminates alkali-activated at high temperatures by analysing parameters such as the chemical composition of the starting material and the vitreous phase content. When alkali-activated, the glass produced in the laboratory developed high mechanical strength, while the performance of the resulting binders was conditioned by the SiO2/Al2O3 ratio in the starting materials. The optimal values were observed to lie between 3 and 4. [Copyright &y& Elsevier]

Highlights: [•] Mesoporous aluminosilicate with acidity and hydrothermal stability was developed. [•] Hydrothermal stability was improved by Beta zeolite precursors in zeolite walls. [•] Al was introduced into the mesophases, and thus the acidity was improved. [•] Bimodal zeolites demonstrated superior catalytic properties for heavy oil FCC. [Copyright &y& Elsevier]

Abstract: Two Tunisian clays, kaolinitic from the Tabarka (Clay T) region and illito-kaolinitic rich in hematite from the Medenine (Clay M) region, are tested as potential aluminosilicate sources for the synthesis of geopolymers. The raw clays and clays calcined at 700, 800, 850 and 900°C were characterized using XRD, DTA/TG, and FTIR spectroscopy and 29Si and 27Al MAS NMR measurements. It was demonstrated that samples based on Clay M present more reactivity than those based on the Clay T because of the amorphization of clay minerals. The structural evolution on calcination is studied in detail to predict the behavior of the clay during geopolymerization. Despite its lower content in kaolinite than Clay T, Clay M is capable of providing geopolymers. [Copyright &y& Elsevier]

Thermal barrier coatings (TBC) in service are prone to the attack by molten calcium–magnesium aluminosilicates (CMAS) resulting from the ingestion of siliceous minerals (dust, sand, volcanic ash) by the aeroengines. As CMAS deposits observed on ex-service parts present complex and highly variable compositions, progress in the understanding of the interaction mechanism between CMAS and TBC has been mostly obtained during laboratory experiments using simplified CMAS compositions. This paper consists in a microstructural characterization of the isothermal chemical interaction between a synthetic calcium aluminosilicate (CAS) and a standard 8YPSZ EB-PVD coating deposited on alumina substrates. The chosen CAS is the lowest melting temperature eutectic (1170°C) in the ternary (CaO–Al2O3–SiO2) system and it is prepared as a glass. The evolution of the reaction zone morphology and chemistry is studied after 1200°C treatments from 15min to 100h. The CAS/TBC interaction is governed by the classical mechanism of dissolution/reprecipitation with formation of Y-lean zirconia and Ca2Zr(Y)Si4O12. Ca2Zr(Y)Si4O12 formation induces local variation in the CAS composition leading to CaAl2Si2O8 (anorthite) precipitation. Y2O3 depletion in the YSZ regions infiltrated by CAS is attested using X-ray compositional mapping and the association of EDS and EBSD clearly illustrates that the morphological transformation from porous initial YSZ to dense globular Y-lean YSZ is associated with the structural transformation from initial tetragonal t′ to tetragonal Y-lean zirconia transforming into monoclinic during cooling. The degradation of the TBC columns increases with the duration of the 1200°C heat-treatment. The interfacial Ca2Zr(Y)Si4O12 phase forms on an increasing amount of columns and is finally observed on all the columns. Interfacial phase formation is discussed and compared to other phase assemblages reported in the literature. [ABSTRACT FROM AUTHOR]

Abstract: This study presents the synthesis of alkali aluminosilicates based on the stoichiometry of KAlSiO4 by a hydrothermal treatment followed by a sintering step. The aim was to create formed porous samples which could be a potential material in high temperature applications with alkali corrosive conditions. The material composition was adjusted using analysis of variance (ANOVA) to reach resistance to alkali corrosion of the synthesized material. A casting process was established replacing a part of the raw materials by pre-sintered material to produce porous samples. The final samples were characterized with regard to bulk density, refractoriness under load, cold crushing strength and thermal conductivity. The results showed similar properties compared to conventional materials. [Copyright &y& Elsevier]

Supplementary cementitious materials ( SCMs) are widely used to partially replace portland clinker in blended cements. Reducing clinker contents further without compromising the development of early strength necessitates a better assessment and enhancement of the reactivity of the available SCMs. To this purpose, the reactivity of synthesized calcium aluminosilicate glasses covering a compositional range from blast-furnace slags (BFS) over fly ashes to silica fume was analyzed by dissolution experiments. Initial glass dissolution rates were measured at 20°C and pH 13, and with varying initial concentrations of aqueous Al, Ca, and Si. At pH 13, glass dissolution rates were observed to scale linearly with the glass Ca/( Al + Si) molar ratio. Ca-rich blast-furnace type glass dissolution was shown to be up to one order of magnitude faster than tectosilicate fly ash and silica fume type glass dissolution, supporting different pathways to dissolution. In solutions that are strongly undersaturated with respect to hydrous glass and hydration products, glass dissolution rates are independent of changes in solution undersaturation and aqueous Si activity. In contrast, dissolution rates decrease with aqueous Ca concentration for all glasses and with aqueous Al concentration for tectosilicate-type glasses. The insights gained are instrumental in finding ways to enhance SCM reactivity. [ABSTRACT FROM AUTHOR]