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Nickel and cobalt salen complexes were simultaneously encapsulated in mesoporous zeolite A by flexible ligand method. The prepared catalyst NiCosalenA was investigated for its electrochemical behavior and electrocatalytic activity towards the oxidation of methanol on glassy carbon electrode in 0.1 M NaOH solution. Upon encapsulation in zeolite A, the NiCosalen complex exhibits the typical cyclic voltammetric response, which can be anticipated for the Ni 2+ Co 2+ (Salen)(OH) 2 /Ni 3+ Co 3+ (Salen)O(OH) redox couple. It also showed much higher electrocatalytic activity towards the oxidation of methanol than pure NisalenA, due to a synergetic effect that may originate from the interaction of Ni(salen) and Co(salen) and/or the formation of dinuclear salen complexes in adjacent or appropriate sites in a nano-cage through the lattice oxygen of the zeolitic host. The mechanism of electrocatalytic oxidation of methanol on NiCosalenA modified electrode was proposed to be EC process. In both the chronoamperometric and chronocoulometric studies, the reaction of methanol electrooxidation followed a Cottrellian behavior and similar diffusion coefficients ( D ) of methanol were found to be 3.82 × 10 −7 cm 2 s −1 and 3.91 × 10 −7 cm 2 s −1 , respectively. The catalytic rate constant ( k cat ) was also calculated to be 5.52 × 10 5 cm 3 mol −1 s −1 in the range of 0.005–2.0 M of methanol. [ABSTRACT FROM AUTHOR]

Nickel and manganese salen complexes were simultaneously encapsulated in the supercages of the mesoporous zeolite A by using the flexible ligand method. The electrochemical behavior and electrocatalytic activity toward the electrooxidation of methanol on glassy carbon electrode coated with NiMnsalenA (NiMnsalenA/GCE) in 0.1 M NaOH solution were studied by cyclic voltammetry (CV), chronoamperometry (CA) and AC electrochemical impedance spectroscopy (EIS). The results showed that the addition of small amounts of Mn species can give rise to much higher electrocatalytic activity than the pure NisalenA toward the oxidation of methanol, mainly due to a synergetic effect that may originate from the interaction of Ni(salen) and Mn(salen) and/or the formation of dinuclear salen complexes via the lattice oxygen of the zeolitic host. Kinetic parameters such as the electron transfer coefficient α , the rate constant k s of the electrode reaction and the charge transfer coefficient of the catalytic reaction, α n were determined to be 0.40, 1.898 s −1 and 0.43, respectively, and the detection limit was found to be 97.66 μM. The mechanism of electrocatalytic oxidation of methanol on NiMnsalenA/GCE was investigated and proposed to be done by reaction with Ni 3+ (salen)O(OH) and also direct electro-oxidation reaction. The impedance behaviors showed different patterns at different applied potentials, indicating the changes of the rate-determining step, from the methanol electrooxidation leading to the formation of intermediates on the surface of electrode gradually to the oxidation and removal of adsorbed intermediates. The influence of methanol concentration on the impedance behaviors was also studied and the results demonstrated that the semidiameters of the Nyquist diagrams decreased with the increase of methanol concentration, signifying the acceleration of the reaction rate of methanol electrooxidation. [ABSTRACT FROM AUTHOR]

A feasible approach was developed for the synthesis of ordered mesoporous SBA-15-type materials using coal fly ash (CFA) as raw material. In the proposed approach, CFA was, firstly, activated by subcritical water with the addition of NaOH, which allowed an efficient extraction of silicon species from CFA under strong acidic conditions at near room temperature. Subsequently, in the synthesis system, using silicon extraction solution as the silicon precursor, the introduction of anhydrous ethanol as a co-solvent effectively inhibited the polymerization of silanol species and promoted their collaborative self-assembly with surfactant molecules by enhancing the hydrogen bond interactions. The resultant SBA-15 material had a high purity, high specific surface area (1014 m2/g) and pore volume (1.08 cm3/g), and a highly ordered mesostructure, and, therefore, exhibited an excellent removal efficiency (90.5%) and adsorption capacity (160.8 mg/g) for methylene blue (MB) from simulated wastewater. Additionally, the generation of surface acid sites from the homogenous incorporation of Al atoms onto the mesoporous walls of SBA-15 combined with the perfect retention of the ordered mesostructure endowed the obtained Al-SBA-15 material with a further boost in the removal performance of MB. The MB removal efficiency can reach ~100%, along with a maximum adsorption capacity of 190.1 mg/g. [ABSTRACT FROM AUTHOR]

Hierarchical ZSM‐5 zeolites were synthesized by in‐situ crystallization of mesoporous carbon‐silica composites with a well‐ordered SBA‐15 structure. The hierarchical ZSM‐5 zeolite possessed a rather high external surface area (205 m2/g) and pore volume (0.35 cm3/g) compared with the reference ZSM‐5 zeolite, as well as higher acid‐site accessibility to large molecules. In the naphthalene benzylation reaction, the hierarchical HZSM‐5 zeolite converted approximate 50 % of benzyl chloride in 100 minutes under mild conditions and showed a high stability, which could be ascribed to the improved diffusion ability and acid‐site accessibility. [ABSTRACT FROM AUTHOR]

Abstract Ordered mesoporous Mg Al composite oxide-supported K catalysts (x K/OMMA) were prepared and used for soybean oil transesterification with methanol. The prepared x K/OMMA demonstrated a much higher soybean oil conversion (up to 97.0%) along with a 99.8% selectivity to fatty acid methyl ester and a desirable reusability, compared with K-based catalysts prepared with the same K loading and using ordered mesoporous alumina or mesoporous Mg Al mixed oxide as support. The superior catalytic performance of x K/OMMA is associated with the excellent structural and surface properties of support OMMA, thus benefiting the generation of catalytically active sites and their highly homogenous dispersion. Graphical abstract Unlabelled Image Highlights • Ordered mesoporous Mg Al composite oxide-supported potassium for biodiesel production. • Excellent support properties benefiting the generation of basic K species. • A highly homogenous dispersion of catalytically active sites on the surface of support. • A superior catalytic activity for soybean oil conversion along with a desirable reusability. [ABSTRACT FROM AUTHOR]

Ordered mesoporous alumina (OMA)-supported vanadia catalysts with different vanadium loading (denoted as n V/OMA) were employed for ethylbenzene dehydrogenation to styrene with CO 2 as soft oxidant, and a commercial γ-Al 2 O 3 -supported vanadia catalyst for comparison. The catalytic behavior depends strongly on the vanadium loading and the support properties. With an optimal V loading of 0.8 mmol/g-support, 0.8 V/OMA catalyst exhibits superior catalytic performance than that of 0.8 V/γ-Al 2 O 3 , which can be attributed to the excellent structural, textual, and surface properties of OMA support. The important roles played by OMA lies in stabilizing highly dispersed V 5+ active species and preventing the coke formation. [ABSTRACT FROM AUTHOR]

Ordered macro-mesoporous Mg-Al composite oxides (denoted as OMM-MA-x) with tunable macropore size and highly homogenous distribution of Mg have been synthesized via a confined evaporation induced self-assembly method, in which triblock copolymer F127 and polystyrene colloidal crystals are utilized as templates for ordered mesoporous and macroporous structures, respectively. The resultant OMM-MA-x materials exhibit a much more ordered 2D hexagonal mesostructure constituting wall skeleton of ordered macropores and more excellent textural properties than those of ordered macro-mesoporous alumina materials. More importantly, both ordered mesostructure and macroporous structure of OMM-MA-x can be well maintained even after thermal treatment at 900 °C or pressure treatment at 15 MPa. [ABSTRACT FROM AUTHOR]

Mesoporous EU-1 zeolites with adjustable mesoporosity have been prepared by employing silanized silica into the starting synthesis gel, based on the hinder effect of organic moiety to crystal growth. The synthesized mesoporous EU-1 zeolites were characterized by XRD, NMR, SEM/TEM and N 2 adsorption/desorption at 77 K, showing the persistence of inherent microporous framework structure of EU-1 zeolite and the existence of additional mesopores within the range of 3–10 nm. The generation of mesoporosities is from the intercrystalline voids of nanocrystal aggregates. The introduction of mesopores in EU-1 zeolite increased the adsorption of mesitylene with the kinetics diameter larger than the micropore size, and made it possible for the diffusion pattern of n -heptane from one-dimensional in microporous EU-1 to three-dimensional in mesoporous EU-1. This result together with the enhanced accessibility of acidic sites of mesoporous EU-1 improved greatly the catalytic activity and product yields of cumene cracking reaction involving bulky molecules. [ABSTRACT FROM AUTHOR]

A double-chain quaternary ammonium salt of dioctyl dimethyl ammonium chloride (DDAC8) was first used as a low-cost template to prepare the mesostructured zirconia nanomaterials in an alcohol-thermal system. The material was calcinated to obtain pure tetragonal crystalline zirconia ( t -zirconia) and thus has significantly improved original structure properties, including a narrow pore size distribution of 4–7 nm and a high surface area of 195 m 2 /g. The t -zirconia hierarchical nanoparticle aggregate material is different from the smooth microsphere material obtained using the single chain quaternary ammonium salt template. The characteristic rough surface morphology results from the grid distribution form of the DDAC8 micelles in the ethanol solution and caused the formation of more defect sites, which demonstrate the potential for possible catalytic applications. A formation mechanism of the mesoporous zirconia nanomaterial in the alcohol-thermal system of the surfactants is reasonably explained. The synthesis system may provide a new approach to the preparation of mesoporous nanomaterials. [ABSTRACT FROM AUTHOR]

Highly ordered mesoporous magnesium-aluminium composite oxides (denoted as OMMA-x) with a variety of n Al / n Mg ratios have been successfully synthesized via a facile strategy, and a salt effect was proposed to explain the formation mechanism. The incorporation of Mg can significantly improve the structural and surface properties of ordered mesoporous alumina (OMA) material. The resultant OMMA-x exhibited a much more ordered 2-D hexagonal mesostructure, a narrower pore size distribution, a higher specific surface area and pore volume, and a stronger basicity than those of OMA. More importantly, the highly homogeneous incorporation of Mg at the atomic level and the formation of framework Mg O Al bonds could effectively suppress the formation of crystalline alumina during the calcination process. As a result, OMMA-x demonstrated a superior thermal stability. For example, the ordered mesostructure of OMMA-8 could be well maintained with a high surface area of 182 m 2 /g even after thermal treatment at 1000 °C. [ABSTRACT FROM AUTHOR]

By using the inexpensive aluminum nitrate as precursor, a highly ordered mesoporous alumina with high thermal stability has been synthesized successfully via an evaporation-induced self-assembly pathway associated with solvothermal pre-hydrolysis process. The resultant mesoporous alumina maintains the ordered hexagonal mesostructure, narrow pore-size distribution, high BET surface area and large pore volume even after thermal treatment at 900 °C. [ABSTRACT FROM AUTHOR]

Microspherical MFI mesoporous zeolites (MMZ-5) with different mesopore volumes and similar silica-alumina ratios were prepared by the bond-blocking principle and confirmed by physical methods. The zeolite materials with high external surface areas contained inter- and intra-crystalline mesostructures. NH-TPD and in situ FT-IR spectra techniques were used to characterize the acidic properties of the mesoporous zeolites. The results showed that the Py-Brönsted acid sites of the MMZ-5 samples are very similar to that of the conventional ZSM-5 zeolite, but the latter Py-Lewis acid sites are greatly larger than the former. Further, the concentration of DMPy-Brönsted acid sites in the mesoporous zeolites arrived at 70 μmol/g, namely, the 2,6-dimethylpyridine (DMPy) molecule can probe 97 % of the Py-Brönsted acid sites in the MMZ-5 zeolites. The introduction of the mesoporous structure into the MMZ-5 zeolites increased strongly the accessibility of the more bulky molecules, such as the DTBPy molecules. As expected, HMMZ-5-2 sample as an acid catalyst displayed a high reaction activity and an uniform product selectivity in the benzylation of p-xylene with benzyl chloride. Graphical Abstract: [Figure not available: see fulltext.]. [ABSTRACT FROM AUTHOR]

Abstract: The Mg2+ and Ca2+ exchange properties in the meso-zeolite LTA were investigated. These meso-zeolite materials with intracrystalline mesopores ca. 3nm were prepared using organic functioned fumed silica as silica source. The Dual-site Langmuir (D-L) expression appropriately describes the equilibrium data for the Ca2+ and Mg2+ exchange. The fitting results with D-L model suggest that two kinds of ion-exchange sites in the meso-zeolites exist, one in the part of intrinsic micropore structure (internal surface area) and the other one in the part of established mesopore structure (external surface area). The latter site has lower enthalpy values of Ca2+ or Mg2+ exchanges than the former one. Ca2+ or Mg2+ exchange kinetics is conducted at 273K, 288K and 308K. The results show the emergence of mesopores lowering the activation energy of ion exchange and accelerating Mg2+ exchange extremely in the materials. The diffusion rate of hydrated Mg2+ in the meso-zeolite LTA increases by 17.5 times, higher than that of conventional LTA at 273K. And the meso-zeolite LTA possesses large Mg2+ competitive ability in a solution containing Ca2+ and Mg2+. These properties make the meso-zeolite LTA a suitable material which could be used effectively in hard water softening and detergent building for Mg2+ removing. [Copyright &y& Elsevier]

Abstract: By using zirconia as promoter, a highly ordered mesoporous alumina with extremely high thermal and hydrothermal stability has been synthesized successfully via an evaporation-induced self-assembly (EISA) pathway associated with thermal treatment. In comparison to pure mesoporous alumina, the resultant mesoporous zirconia–alumina nanomaterials maintain the ordered hexagonal mesostructure, narrow pore-size distribution, high BET surface area and pore volume even after thermal treatment at 1000°C or boiling water treatment for 6h. Our contribution provides an important approach to synthesize ordered mesoporous Zr–Al nanomaterials with high thermal and hydrothermal stability, which can find potential application for the catalytic applications in the petroleum industry. [Copyright &y& Elsevier]

Diffusion properties of mesostructured zeolite 5A were investigated by employing n-alkanes as probe molecules using the zero length column (ZLC) method. The mesopores were found to enhance molecule diffusion. Moreover, the effective diffusion time constant ( D/ R) increased with mesoporosity in the zeolites between 308 K and 393 K, whereas the activation energy decreased with increasing mesopore volume. The effective diffusivity values of n-alkanes in mesoporous zeolite 5A were generally higher than that the microporous zeolite 5A sample. This clearly implied the important role of the mesopore in zeolites crystals in facilitating the transport of reaction molecules due to shorter average diffusion path length and less steric hindrance. [ABSTRACT FROM AUTHOR]

A high-acidity HUSY zeolite with mesoporous structure was prepared by alumination with a dilute aqueous NaAlO solution and characterized by XRD, N adsorption, IR framework vibration and Si MAS NMR methods. The results indicated the extra-framework aluminum was reinserted into the tetrahedral framework through isomorphic substitution of framework Si (0Al) sites by Al ions, whereas the crystal and micropore structure were unaltered. FTIR spectra of hydroxyl vibrations and pyridine adsorbed on realuminated zeolites showed that the number of Brønsted acid sites and strong Lewis acid sites increased whereas weak Lewis acid sites decreased twice. The mesoporous structure composed of inter-and intra-crystalline pores in the aluminated HUSY increased the external surface area of the zeolite, improving accessibility of molecules to the active sites and enhancing its catalytic ability. The realuminated HUSY zeolite supported with Ru catalyst exhibited a higher catalytic activity for benzene hydrogenation than the parent HUSY zeolite; the reaction rate in comparison to the mesozeolite increased by 5.5 times. [ABSTRACT FROM AUTHOR]

Abstract: Chiral complex (1S,2S)-DPEN-RuCl2(TPP)2 (DPEN=1,2-diphenylethylenediamine; TPP=triphenylphosphine) was successfully encapsulated in the mesoporous cage of SBA-16 modified with phenyltrimethoxysilane. This was verified by ICP, powder XRD, N2 adsorption, FTIR, DRS and TEM analysis. The encapsulated chiral Ru complex gave high catalytic activity and excellent enantioselectivity like its homogeneous counterpart in asymmetric hydrogenation of various aromatic ketones. The encapsulated complex also showed high stability and could be recycled without significant loss of activity and enantioselectivity. [Copyright &y& Elsevier]

Abstract: Organotin compounds of (MeO)2ClSi(CH2)3SnCl3 have been grafted on a series of mesosporous silicas, as proved by XRD, N2 adsorption/desorption experiments and FTIR, diffuse reflectance UV–vis and 13C CP/MAS NMR spectroscopies. A further substitution of Cl− bonded to Sn4+ by CH3O− led to the formation of a series of active heterogeneous catalysts for the direct synthesis of dimethyl carbonate from methanol and CO2. The catalytic properties of these catalysts depended on the structure, crystal size and surface properties of mesoporous silicas. SBA-15 as a host was superior to SBA-16 and large-pore Ia3d. In addition, the methods used for removing surfactants occluded in mesoporous silicas had strong influences on the catalytic performance as a result of significantly affecting the surface areas and the concentrations of surface hydroxyl groups of the mesoporous silicas. The extraction of surfactants by an ethanol–HCl solution should be available. An increase in the reaction time, reaction temperature, methanol amount and CO2 pressure significantly increased the dimethyl carbonate yield before reaching thermodynamic equilibrium. The dimethyl carbonate yield could also be increased by adding dehydration agents to the reaction system. 2,2-Dimethoxypropane gave a much higher dimethyl carbonate yield than 3A molecular sieve and tetramethyl orthorsilicate. The prepared organotin/mesoporous silica catalysts were highly stable, as corroborated by the findings that the dimethyl carbonate yield obtained over the SBA-15-immoilized organotin compound did not decrease within six repeated runs with regeneration under the same reaction conditions and that the tetrahedral coordination state of Sn species was maintained after reaction. [Copyright &y& Elsevier]

In this work, a highly crystallized SSZ-13 (STM-24) was successfully synthesized with sodium silicate as silica source in the co-existence of seeds and a small amount of N,N,N- trimethyl-1-adamantanamine hydroxide (TMAdaOH, TMAdaOH/SiO 2 = 0.02). The TMAdaOH amount is about one-seventh of that used in the conventional synthesis method. The SSZ-13 samples synthesized by this method were characterized by XRD, SEM, N 2 adsorption/desorption, ICP, FT-IR, UV-Raman, NH 3 -TPD, 27Al and 29Si NMR, and compared with SSZ-13 synthesized by conventional method at TMAdaOH/SiO 2 = 0.14 (TMA-0.14-48). The results show that STM-24 and TMA-0.14-48 have comparable textural properties and acidity, except STM-24 shows a smaller particle size than TMA-0.14-48. Moreover, the SiO 2 /Al 2 O 3 ratios of SSZ-13 synthesized by this method are controllable in a wide range of 7.3–21.5. The synergistic effect between seeds and a small amount TMAdaOH is the key to successful synthesis of SSZ-13. Additionally, Cu-STM-24 and Cu-TMA-0.14-48 catalysts show similar catalytic performances in SCR reaction. The synthesis method reported in this work provides a new and alternative way for a low-cost and efficient synthesis of SSZ-13. [Display omitted] • SSZ-13 was synthesized in the presence of seeds and a small amount of TMAdaOH. • TMAdaOH amount in this method is just 1/7 of that used in the conventional method. • There is a synergistic effect between the seeds and a small amount TMAdaOH. • The synergistic effect is the key to successful synthesis of SSZ-13. [ABSTRACT FROM AUTHOR]

Abstract: A series of nanosized ZSM-5 zeolite samples with intracrystalline mesopores has been synthesized using organosilane functioned fumed silica as silica source and tetrapropylammonium hydroxide as microporous structure directing agent. The organic moiety linked on the surface of fumed silica blocks the growth of zeolite crystal, forming the nanosized zeolite crystal and intracrystalline defects inside the nano-crystal. The formation of the mesopores is by bond-blocking function in crystallization. The XRD results indicate that the samples are high crystalline ZSM-5 and the TEM images show that the samples are nanosized with the size ca. 20nm and the intracrystalline mesopores about 3nm exist inside the nanosized crystal. [Copyright &y& Elsevier]

Ordered mesoporous Zr-Al composite oxide materials (denoted as OMZA-x) with different Zr contents have been synthesized by a solvent evaporation-inducing self-assembly procedure associated with a thermal treatment at 100 °C. A cooperative co-assembly process of amphiphilic triblock copolymer F127 molecules and inorganic hydroxyl species originated from the hydrolysis of Zr and Al precursors was proposed to explain the synthesis of OMZA-x. Compared to ordered mesoporous alumina prepared without introducing Zr species, the resultant OMZA-x exhibited a much more ordered mesostructure combined with a distinct increase in the pore volume and specific surface area. The highly homogenous doping of Zr into the mesopore walls together with the formation of Zr-O-Al bonds can effectively enhance the thermal and hydrothermal stability of OMZA-x. For instance, the ordered mesostructure and excellent textural properties of OMZA-6 prepared with the optimum atomic ratio of Al to Zr of 6 could be well maintained even after a high-temperature treatment at 1000 °C for 1 h or a hydrothermal treatment at 100 °C for 6 h. [ABSTRACT FROM AUTHOR]

• Well-crystallized zeolite Y assembled by nanocrystals with intercrystal mesopores. • The nanocrystal zeolite Y lying on both gel formation and aging at low temperature. • Presence of CTAB improving the assemblies of zeolite Y nanocrystals. • Highly active accessibility and rapid diffusion in the zeolite Y to bulk molecules. Zeolite Y nanocrystal assembly was synthesized by using cetyltrimethyl ammonium bromide (CTAB) under low gelling and aging temperature in the hydrothermal system. XRD, SEM, N 2 adsorption/desorption isotherms, 29Si and 27Al MAS NMR spectra as well as NH 3 -TPD demonstrated that the synthesized zeolite Y is a mesoporous zeolite composed of well-developed nanocrystals with high external surface area, intercrystal mesoporosity and acidity. The conversions of 1,3,5-trimethylbenzene (TMB) and 1,3,5-triisopropylbenzene (TIPB) reflect its superior features for isomerization, selectivity of bulky molecule and catalytic stability. [ABSTRACT FROM AUTHOR]