Synthesis,characterization and catalytic properties of mesoporous Al-FSM-16 materials

Al-substituted mesoporous FSM-16 materials with different SiO₂/Al₂O₃ (28–452) ratios have been synthesized by intercalating kanemite using cetyltrimethylammonium bromide (CTMABr) as the intercalating agent and sodium aluminate as the aluminium source, and characterized by different physico-chemical characterization techniques. The XRD measurements revealed a slightly disordered hexagonal packing of channels in the Al-FSM-16 samples. The thermal stability of Al-FSM-16 samples was confirmed by DTA analysis, where no structural changes were observed in the temperature range of 600–900°C. No significant changes were observed in the morphology of kanemite and the Al-FSM-16 sample obtained from kanemite as revealed by the SEM analysis. This result clearly indicated that the Al-FSM-16 sample is formed via a folded sheet mechanism. Moreover, TEM measurements confirmed the presence of a slightly disordered hexagonal array of channels in Al-FSM-16 in agreement with the XRD results. The BET surface areas (638–788 m² g⁻¹) and pore volumes (0.57–0.87 cm³ g⁻¹) were indicative of the high porosity of the Al-FSM-16 samples. The Al-FSM-16 (SiO₂/Al₂O₃ = 49) sample exhibited excellent hydrothermal stability at 150°C. The Al-FSM-16 samples were found to catalyze the isomerization of m-xylene to p- and o-xylenes.     

Synthesis, characterization, and unique catalytic performance of the mesoporous material Fe-TUD-1 in Friedel–Crafts benzylation of benzene

Iron (Fe)-containing mesoporous TUD-1 catalysts (denoted as Fe-TUD-1) with different Si/Fe ratios (100, 50, 20 and 10) were synthesized using triethanolamine as a template. They were characterized by XRD, elemental analysis, N₂ ad/desorption measurements, HR-TEM, UV–vis, ²⁹Si NMR, and ⁵⁷Fe Mössbauer spectroscopies. Catalytic performance was tested in the Friedel–Crafts benzylation of benzene. Fe-TUD-1 showed excellent activity, with 100% conversion and 100% selectivity towards diphenylmethane, superior to other metal-containing TUD-1 (e.g. Ga, Sn, and Ti) or other Fe-containing mesoporous materials (e.g. Fe-MCM-41 and Fe-HMS).     

Vanadium-containing ordered mesoporous silicas: Synthesis, characterization and catalytic activity in the hydroxylation of biphenyl

A series of vanadium-containing ordered mesoporous MCM-41 materials (V-OMS) have been synthesized by direct hydrothermal (V-MCM-41) and grafting (V/MCM-41) methods using hexadecyl trimethyl ammonium bromide (HDTMABr) as the structure-directing agent. The physico-chemical properties of the vanadium-containing materials were characterized in detail by ICP-OES, XRD, FT-IR, N₂ adsorption–desorption, DRUV-VIS, TPR, XPS and SEM techniques. The redox performances of the vanadium-modified mesoporous materials were tested in the hydroxylation of biphenyl using aqueous H₂O₂ (30 wt.%) as oxidant. For a better exploitation of the catalytic activity, the reaction parameters are optimized in terms of temperature, solvent, oxidant, etc. A comparison between the catalytic activity values of the vanadium-containing mesoporous materials prepared by the two routes shows that vanadium-substituted (V-MCM-41) materials had increased activity and improved selectivity for mono hydroxyl products in the hydroxylation reaction of biphenyl compared to the V/MCM-41 catalysts. The heterogenity of the catalysts was verified by a series of leaching studies. Both the catalysts enhance the leaching of active vanadia species during the reaction; among them, V/MCM-41 shows the least heterogenity.     

Co-MCM-48的制备及其对烯烃环氧化催化性能的研究

通过水热合成法合成了掺杂过渡金属元素Co的介孔材料MCM-48,然后通过傅里叶变换红外(FT-IR)波谱、X-射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、N_2吸附-脱附等温线对其进行了表征,并以环己烯为底物,分别用w(过氧化氢)=30%和过氧乙酸作氧源对其烯烃环氧化的催化性能作了研究。催化剂的表征结果表明,合成的介孔材料结构规整。将合成的杂原子分子筛用于催化烯烃的环氧化反应,反应结果表明,w(过氧化氢)=30%和过氧乙酸相比,w(过氧化氢)=30%使反应达到了更好的转化率,但对环氧化物的选择性远远不如过氧乙酸,几乎没有目标产物环氧化物的生成。这可能是由于w(过氧化氢)=30%更容易被活化,但是也更容易发生环氧化物进一步的开环反应,从而导致极少目标产物环氧化物的生成。     

Synthesis,characterization, and applications of organic-inorganic hybrid mesoporous silica

Organic-inorganic hybrid mesoporous materials composed of homogeneously distributed ethane group in a silica framework were prepared by using 1,2 bis(trimethoxysilyl) ethane (BTME) as a precursor and alkyltrimethylammoniumchloride or -bromide surfactant as a structure directing agent with or without the presence of a swelling agent, mesitylene. Characterization of the materials was performed by XRD, TEM/SEM,^29Si-/^13C-solid state NMR, and N₂-adsorption. Testing of the hybrid material as a reversed phase HPLC column stationary phase after C18 surfacefunctionalization demonstrated a promising result, which closely approaches the performance of a commercial product. Mn-salen complex tethering on the hybrid material produced a catalyst with somewhat enhanced performance in liquid phase etherification with tert-butyl hydroperoxide as oxidant. This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University.     

Synthesis and characterization of mesoporous silicon carbide

A modified sol–gel method is proposed for the preparation of mesoporous silicon carbide. In this method, tetraethoxysilane (TEOS) and phenolic resin are used for preparing a binary carbonaceous silicon xerogel, and nickel nitrate is employed in the sol–gel process as a pore-adjusting reagent. SiC was produced in the carbothermal reduction of the binary xerogel at 1250 °C in an argon flow (40 cm³ min⁻¹) and purified by removing excess silica, carbon and other impurities. The purified SiC sample was characterized by XRD, SEM, TEM, and N₂ adsorption, and the results showed that the SiC sample had a surface area of 112 m² g⁻¹ (BET) and an average pore diameter of about 10 nm.     

Synthesis, characterization and catalytic applications of mesoporous γ-alumina from boehmite sol

In this study, boehmite sols were used as aluminum precursors for preparing mesoporous alumina (MA) having crystalline framework walls in the presence of non-ionic surfactants as structure directing agents. Nitrogen physisorption showed that aluminas prepared in this way displayed very rich porosities with large mesopores, and both the pore volumes and the pore sizes increased with the surfactant concentration. The improved textural parameters in the samples should be attributed to the three-dimensional interconnected scaffold-like channels, which were formed by randomly ordered stacking and condensing of rigid boehmite nanoparticles with the aid of the surfactant. TEM observations revealed that the precursor morphology had an important effect on the textural properties of the mesoporous alumina. The sample with a corrugated platelet-like morphology exhibited a large surface area of 463 m²/g, which was reduced to 81 m²/g after calcination at 1200 °C, indicating a strong resistance to sintering. This material, with its improved textural properties, crystalline framework walls and high thermal stability, not only could increase the dispersion of the active catalytic species, but also could enhance the diffusion efficiency and mass transfer of reactant molecules when employed as catalyst supports. As examples, our MA samples demonstrated a remarkable enhancement in the catalytic performances for both reactions of SO₂ catalytic reduction by CO and catalytic combustion of methane.     

Fe, Co and Cu-incorporated TUD-1: Synthesis, characterization and catalytic performance in N2O decomposition and cyclohexane oxidation

Fe, Co and Cu-TUD-1 were prepared with different metal loadings (Si/M ratio = 100, 50, 20 and 10). As a function of increasing metal loading either isolated metal atoms, nano-particles of M-oxide and/or bulk M-oxide crystals in the silicate matrix were obtained, respectively. The materials were fully characterized by means of XRD, UV–vis, elemental analysis, N₂ sorption measurements and HR-TEM. The catalytic performance of the prepared materials was tested in gas phase N₂O decomposition and in liquid phase oxidation of cyclohexane. Results of N₂O decomposition showed that a low M-loading is beneficial for the catalysis and leads to a high TOF, Co-TUD-1 being the most active catalyst. This suggests that the nano-particles observed in many catalysts are not dominating the N₂O decomposition rate, and that active phase entities ranging from isolated to polynuclear sites are the most active. The performance of the TUD-1 catalysts is significantly lower than reported for the microporous Fe, Co and Cu analogues. In the oxidation of cyclohexane with TBHP, Cu-TUD-1 showed the highest activity but also significant leaching. Co-TUD-1 did not show any leaching and is thus the best applicable catalyst in cyclohexane oxidation.     

Synthesis and characterization of mesoporous molecular sieve nanoparticles

Mesoporous molecular sieve was prepared hydrothermally by a two-step method with materials of cetyltrimethyl ammonium bromide (CTAB), as a template, and sodium metaaluminate (NaAlO₂) and sodium silicate (Na₂SiO₃·9H₂O), as aluminum and silicon sources, respectively. The mesoporous molecular sieves are well ordered and have high thermal and hydrothermal stabilities. The as-prepared samples were characterized by powder X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM), thermogravimetry-differential scanning calorimetry (TG/DSC), Fourier transform infrared spectroscopy (FT-IR) and nitrogen adsorption experiments. Particle size distribution was in the 30–50 nm range, BET surface area was more than 800 m²/g, thermal stability was higher than 1023 K, the mesoporous structure was not entirely damaged at a calcination temperature of 1123 K and there was no clear change in ordering degree, pore size, and surface area of the mesoporous molecular sieve after hydrothermal treatment at 373 K for 10 days. The activity and selectivity of benzene hydrogenation to cyclohexane by mesoporous molecular sieve-supported Pt was up to 100%. The catalytic activity didn’t decline in a reaction period of 30 h.     

Synthesis and characterization of highly ordered mesoporous YSZ by tri-block copolymer

A highly ordered mesoporous yttria-stabilized zirconia (YSZ) has been successfully prepared by evaporation-induced self-assembly method (EISA) using tri-block copolymer Pluronic F127 as a structure-directing agent and inorganic chlorides as precursors in a non-aqueous medium. The characterization of the mesoporous YSZ materials was carried out by using small angle X-ray diffraction (SAXRD), transmission electron microscopy (TEM) and N₂ adsorption/desorption. The well ordered mesoporous YSZ is thermally stable up to 600^∘C with an average pore size of 5.4 nm and specific surface area of 90 m²/g. The walls of mesoporous YSZ are composed of ∼6.5 nm nano-crystalline domains.     

Synthesis and catalytic properties of sulfonic acid-functionalized monodispersed mesoporous silica spheres

A new type of sulfonic acid-functionalized monodispersed mesoporous silica spheres (MMSS) were synthesized directly by co-condensation and subsequent oxidation. By changing the methanol ratio, sulfonic acid-functionalized MMSS with different particle diameters (390–830 nm) and the same mesopore sizes were successfully synthesized. TEM observations revealed that the mesopores were aligned radially from the center towards the outside of the spheres, even in the sulfonic acid-functionalized MMSS. The catalytic activities of the sulfonic acid-functionalized MMSS were studied in condensation reactions between 2-methylfuran and acetone, and it was found that their catalytic activities are highly dependent on the particle diameters. In addition, the catalytic activity of MMSS was much higher than that of other forms of mesoporous silica due to its radially-aligned mesopores.     

Synthesis, characterization and catalytic activity of ruthenium-doped cobalt catalysts

Cobalt-based catalysts doped with different amounts of ruthenium supported on Zr-MSU type materials were studied in the hydrogenation and hydrogenolysis/hydrocracking of tetralin at different temperatures. The catalytic tests were carried out in a high-pressure fixed-bed continuous-flow stainless steel catalytic reactor operating at a pressure of 6.0 MPa. Textural, structural, acidic and metallic properties were studied by XRD, XPS, H₂-TPR, NH₃-TPD and Elemental Chemical Analysis. Five catalysts were prepared with 10 wt% of cobalt and a ruthenium loading ranging from 0.5 to 5 wt%, along with a monometallic ruthenium catalyst with 3 wt% of metal, for comparison. From catalysts characterization, no interaction between cobalt and ruthenium can be established, however, the presence of ruthenium influences the reducibility of cobalt.

Ruthenium-doped catalysts not only improve the catalytic activity of monometallic cobalt and ruthenium ones, but also ruthenium acts as a trap for sulphur organic molecules, preserving cobalt particles from sulphur poisoning and thus maintaining their high hydrogenation activity. The catalyst with a ruthenium loading of 3 wt% is found to be the most active, both, with or without sulphur in the feed. The most striking improvement of ruthenium-doped catalyst properties is their greater resistance to sulphur molecules than in the case of monometallic cobalt catalysts, which are otherwise rapidly deactivated under the same experimental conditions.     

Synthesis and characterization of hybrid nano-crystallites inside self-ordered mesoporous carbon

The design and construction of nano-crystallites inside ordered mesoporous carbon is of great interest for potential applications in many fields. One of the main challenges is how to control hybrid nano-crystallites formed inside the pores. We describe a synthesis strategy of impregnation/hydrothermal method for incorporation of hybrid nano-crystallites Ru_0.3Cr_0.7O₂ inside CMK-3 with the average size of the nano-crystallites around 2.8–3.05 nm. The texture/structures of the resultant materials have been characterized by X-ray diffraction, transmission electron microscope, and nitrogen adsorption/desorption measurements. No nano-crystallites are observed to be generated on the external surface of CMK-3. The resultant material exhibits a high specific capacitance of approximately 226 F g⁻¹. This approach is expected to be applied to other hybrid metals oxides synthesized inside CMK-3 with specific structures and properties. Furthermore, it provides a versatile route for expanding the application of ordered mesoporous carbon with diverse pore arrangements.     

Preparation of copper-containing mesoporous manganese oxides and their catalytic performance for CO oxidation

Copper-containing mesoporous manganese oxides were prepared by the sol–gel method. The samples obtained were characterized by XRD, N₂ adsorption–desorption, ICP, CO-TPD, redox measurement and XPS. After calcination at 300 °C, amorphous structure was shown by XRD for all the samples. All the samples had mesopores of about 6 nm and high surface areas of 170–230 m² g⁻¹. Using these samples as catalysts, CO oxidation was carried out as a model reaction. Copper-containing mesoporous manganese oxide prepared by the sol–gel method showed a very high activity. On the other hand, copper-supported manganese oxide prepared by the impregnation method using copper sulfate showed a low activity. Differences in activities were correlated with the mobility of lattice oxygen.     

Synthesis, structural characterization and photocatalytic activity of Ti-MCM-41 mesoporous molecular sieves

This paper reports the applicability of hydrothermal synthesis in alkaline medium for preparation of Ti-containing mesoporous MCM-41 materials. The influence of different parameters was investigated, such as the Ti source, the molar ratio between Si and Ti and also the synthesis temperature. Structural analysis shows that the high specific surface area, large pore size and well ordered mesostructure, are partially retained in the titania containing materials. Modifying synthesis temperature, it was shown that MCM-41 isotherms are different for temperatures above or under 140°C. UV-VisDR spectroscopy was used to investigate the local environment of Ti sites. The obtained materials were evaluated for the photocatalytic degradation of Rhodamine 6G in aqueous medium. The best photocatalytic activity was found for the sample prepared at higher ageing temperature of 160°C, at which anatase particles were formed.     

Synthesis, characterization and electrochemical performance of mesoporous FePO4 as cathode material for rechargeable lithium batteries

Mesoporous FePO₄ could deliver enhanced specific capacity of 160 mAh g⁻¹ at first discharge process, 90% of theoretical capacity of pure FePO₄, and 135 mAh g⁻¹ in the following cycles at 0.1 C rate. At 1 and 3 C rates, the capacities are 110 and 85 mAh g⁻¹, respectively, which is much higher than that of previously reported for modified FePO₄ materials. Electrochemical impedance spectroscopy (EIS) tests proved that mesoporous structure in FePO₄ materials enhanced the lithium ion intercalation/deintercalation kinetics as indicated by smaller charge transfer resistance (R_ct) of these materials. These results revealed that this mesoporous electrode material can be a potential candidate for high-power energy conversion devices.     

含钛介孔分子筛的合成与催化性能

论述了含钛介孔分子筛的水热合成、室温合成、微波合成和选择不同模板剂与嫁接法等合成方法及其特点。对含钛介孔分子筛的表面修饰与改性技术进行了概述。总结了含钛介孔分子筛在催化氧化、烯烃环氧化、羟基化和光催化等反应中的催化性能。指出今后的研究方向是:高水热稳定性含钛介孔分子筛的合成方法;通过对含钛介孔分子筛进行表面修饰,制备出具有独特性能的催化材料;含钛介孔分子筛在光催化及其他催化反应中的催化作用机理。     

Synthesis and catalytic cracking performance of mesoporous zeolite Y

Mesoporous zeolite Y (denoted as meso-Y) was synthesized using hydrothermal synthesis method using pluronic P123 block copolymer as template. Furthermore, stabilized Y (USY) was prepared through ion exchange and ultra-stabilization process of the meso-Y. The catalysts were prepared and characterized by XRD, SEM, TEM, N₂ adsorption–desorption, NH₃-TPD and Py-IR. These catalysts were evaluated by determining the micro-activity using the light diesel oil as sample. The results showed that the Meso-CAT-3 catalyst had the highest micro-activity and lowest coke yield. It could be ascribed to the mesoporous structure which is known to improve the mass transfer of the larger molecules.     

Cobalt and iron oxide modified mesoporous zirconia: Preparation, characterization and catalytic behaviour in methanol conversion

Mesoporous zirconia materials with different textural characteristics and degrees of crystallinity were obtained by various procedures and modified with cobalt and iron oxide nanoparticles. The obtained materials were characterized by N₂-physisorption, XRD, TEM, FTIR, Mössbauer spectroscopy, TPR-TG and methanol conversion as a catalytic test. Formation of finely dispersed iron and cobalt oxide species, hosted in the zirconia matrix, was observed after the modification. The obtained composites possess higher catalytic activity and different in comparison with the corresponding zirconia supports dehydration and dehydrogenation ability. It was demonstrated that the variations in the textural and surface features of zirconia support and the deposition of different metal oxides on it provided a great opportunity for the preparation of catalysts with tunable bi-functional acidic and redox properties.     

Water-soluble,mesoporous Fe3O4: Synthesis,characterization, and properties

Water-soluble, mesoporous Fe₃O₄ nanopowder is successfully prepared by one-step thermal decomposition of an iron-urea complex ([Fe(NH₂CONH₂)₆](NO₃)₃) in triethylene glycol (TEG). The formation of Fe₃O₄ is confirmed from X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and selected area electron diffraction (SAED) measurements. The morphological and structural properties of the Fe₃O₄ nanopowder are characterized by transmission electron microscopy (TEM), nitrogen adsorption–desorption, and thermogravimetric analysis (TGA). Monodisperse, nearly spherical and highly crystalline Fe₃O₄ nanoparticles are obtained by this method. The Fe₃O₄ nanopowder is well dispersed in water and ethanol with a mesoporous structure, average pore size of 3.6 nm, and Brunauner–Emmett–Teller (BET) surface area of 122 m²/g. The room temperature magnetization hysteresis curve exhibits barely measurable values for coercivity and remanence, suggesting that the Fe₃O₄ nanopowder possesses superparamagnetic characteristics.