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Showing papers on "MCM-41 published in 2006"


Journal ArticleDOI
01 Oct 2006-Fuel
TL;DR: In this article, the mesopores of MCM-41 materials have been evaluated as potential catalysts in the catalytic biomass pyrolysis process and it was found that the presence of the MCM41 material alters significantly the quality of the pyrotechnic products.

292 citations


Journal ArticleDOI
TL;DR: In this paper, mesoporous silicas (SBA-15 and MCM-41) have been functionalized by two different methods: using the heterogeneous route, the silylating agent, 3-chloropropyltriethriethoxysilane, was initially immobilized onto the mesophorous silica surface to give the chlorinated mesoporus silica Cl-SBA 15 or Cl-MCM 41, and in a second reaction a multifunctionalized N, S donor compound (2-mercaptopyridine,

165 citations


Journal ArticleDOI
TL;DR: In this paper, a chiral Mn(III) salen complex supported onto modified mesoporous supports (MCM-41 and SBA-15) was prepared using 3-aminopropyltriethoxysilane as a reactive surface modifier by a covalent grafting method.

148 citations


Journal ArticleDOI
TL;DR: In this paper, a high-ordered iron-containing mesoporous material, Fe-MCM-41, with 0.5-4 Fe/Si mol% loading was prepared and characterization was performed using XRD, SEM/TEM, EDS, N2-sorption, and FT-IR and UV-vis spectroscopies.

132 citations


Journal ArticleDOI
TL;DR: In this article, the effects of several factors such as the state and content of Ti, surfactant/Si ratio and template removal technique on the physicochemical properties and catalytic activity of Ti-MCM-41 were investigated.
Abstract: Ti-containing mesoporous catalysts with MCM-41 structure have been successfully prepared by direct hydrothermal synthesis These mesoporous materials were compared with pure siliceous MCM-41 synthesized at the same conditions An extended and detailed study, which includes the effects of several factors such as the state and content of Ti, surfactant/Si ratio and template removal technique on the physicochemical properties and catalytic activity of Ti-MCM-41, is presented in this contribution Various techniques including XRD, FT-IR, DRUV–vis, ICP and N2 adsorption were employed for the materials characterization An optimum surfactant/Si molar ratio in the synthesis gel for the highest regularity of the formed mesostructure was found Both the structure stability and the local environment of Ti sites in mesostructures with different degrees of Ti loading (010–322 wt%) have been carefully investigated Based on a combined FT-IR and DRUV–vis study and ICP analysis, it was possible to conclude that Infrared spectroscopy can result a powerful tool to verify the Ti(IV) incorporation into the framework of MCM-41 Therefore, a simple and novel method for estimation of framework Ti content could be developed Also, these materials were catalytically tested in the oxidation of cyclohexene with aqueous hydrogen peroxide Finally, the catalysts could be regenerated without any loss in activity/selectivity

121 citations


Journal ArticleDOI
TL;DR: In this article, the dynamic adsorption of an organic dye, methylene blue, on mesoporous silica materials with different structures was investigated and it was found that dye adaption presents reversible or irreversible behavior in dye solution depending on the structure of mesopore materials.

118 citations


Journal ArticleDOI
TL;DR: In this paper, a mesoporous molecular sieves MCM-41 support was modified with organic silicanes and the organofunctionalized MCM41 was coordinated with cupric ions.

112 citations


Journal ArticleDOI
TL;DR: The release of the water-soluble drug Captopril is controlled by tailoring the surface properties of mesoporous silica via stepwise silylation and the drug-loading amount is correlated to the Brunauer-Emmett-Teller surface area and surface hydrophilicity/hydrophobicity of the mesoporus silica material.
Abstract: The release of the water-soluble drug Captopril is controlled by tailoring the surface properties of mesoporous silica via stepwise silylation. The degree of silylation is manipulated by adjusting the initial concentration of silylanizing reagent (trimethylchlorosilane, TMCS). The silylanized and drug-loaded samples are characterized by powder X-ray diffraction, Fourier transform IR spectroscopy, N2 adsorption and desorption,29Si cross-polarization magic angle spinning NMR spectroscopy, and transmission electron microscopy. The drug-loading amount is correlated to the Brunauer–Emmett–Teller surface area and surface hydrophilicity/hydrophobicity of the mesoporous silica material, while drug release profiles can be controlled by tailoring the surface properties and pore size.

109 citations


Journal ArticleDOI
TL;DR: In this article, an original pathway for the reaction between low-cost Mo(VI) peroxo species and silica precursors (tetraethylorthosilicate), silica beads (pure SiO2) or precipitated silica in an acidic and peroxidic medium (peroxo route).
Abstract: Molybdenum(VI)-containing siliceous-MCM-41 and -SBA-15 mesoporous molecular sieves and silica-supported molybdenum(VI) complexes have been prepared according to an original pathway by the reaction between low-cost Mo(VI) peroxo species and silica precursors (tetraethylorthosilicate), silica beads (pure SiO2) or precipitated silica in an acidic and peroxidic medium (peroxo route). Hydrogen peroxide is added to avoid the formation of iso-(or hetero-)polyoxometalates in the direct one-pot synthesis of mesoporous solids, or in the case of pure SiO2. The resulting calcined materials have been characterized by chemical analysis, X-ray powder diffraction, nitrogen sorption isotherms, TEM and EDX analysis, UV–vis diffuse reflectance spectroscopy, Raman spectrometry and catalysis tests. The peroxo routes lead to inserted and/or supported molybdenum oxide zones which are restricted in size due to the porous structure of the silica-based materials and to the involment of low-condensed and even mononuclear oxoperoxo species. This allows to support MoOx species in a dispersion which cannot be achieved with the systems using heptamolybdate [Mo7O24]6− salts or heteropolyoxometalates, which favor the anchoring of MoO3 clusters. Catalysis tests show that the very dispersive structure of the MoOx-siliceous-MCM-41, -SBA-15 and MoOx/SiO2 promotes the generation of fairly active oxidation catalysts for liquid-phase olefin epoxidation (cyclooctene, R-(+)-limonene from ambient to 40 °C) using anhydrous tert-butylhydroperoxide (TBHP) as oxidant. Under specific conditions, leaching of redox-active species has been minimized (less than 2 ppm) especially with MoOx/SiO2 which is proposed as the simplest catalyst for these oxidations. MCM-41 and SBA-15 do not show clear advantages over silica in epoxidation reactions with TBHP.

91 citations


Journal ArticleDOI
TL;DR: In this article, a mesoporous Ce-MCM-41 catalysts were used for liquid phase oxidation of cyclohexane under mild reaction conditions, using aqueous hydrogen peroxide (30%) as oxidant and acetic acid as solvent without adding any initiator.
Abstract: Liquid phase oxidation of cyclohexane was carried out under mild reaction conditions over mesoporous Ce-MCM-41 catalysts using aqueous hydrogen peroxide (30%) as oxidant and acetic acid as solvent without adding any initiator. The catalysts exhibited high substrate conversion and good product (cyclohexanol) selectivity and it can be reused once with almost the same activity. The catalyst was characterized by a combination of various physicochemical techniques, such as N2 physisorption, diffuse reflectance UV–vis, X-ray diffraction and FT-IR.

80 citations


Journal ArticleDOI
TL;DR: In this article, an efficient, productive, and low-cost aerosol-assisted self-assembly process has been developed to produce organically modified mesoporous silica particles via a direct co-condensation of silicate species and organosilicates that contain nonhydrolyzable functional groups in the presence of templating surfactant molecules.
Abstract: An efficient, productive, and low-cost aerosol-assisted self-assembly process has been developed to produce organically modified mesoporous silica particles via a direct co-condensation of silicate species and organosilicates that contain nonhydrolyzable functional groups in the presence of templating surfactant molecules. Different surfactants including cetyltrimethylammonium bromide, nonionic surfactant Brij-56, and triblock copolymer P123 have been used as the structure-directing agents. The organosilanes used in this study include tridecafluoro-1,1,2,2-tetrahydrooctyltriethoxysilane, methytriethoxysilane, vinyltrimethoxysilane, and 3-(trimethoxysilyl)propyl methacrylate. X-ray diffraction and transmission electron microscopy studies indicate the formation of particles with various mesostructures. Fourier transform infrared and solid-state nuclear magnetic resonance spectra confirm the organic ligands are covalently bound to the surface of the silica framework. The porosity, pore size, and surface area...

Journal ArticleDOI
TL;DR: In this paper, three catalysts with different chemical and physical properties were synthesized (one HZSM-5 zeolite and two ordered mesoporous aluminosilicates) and tested for the pyrolysis of four samples of commercial polymers (LDPE, PP, PS and EVA copolymer), using a thermobalance under nitrogen atmosphere at a heating rate of 10°C/min.
Abstract: In this work, three catalysts with different chemical and physical properties were synthesized (one HZSM-5 zeolite and two ordered mesoporous aluminosilicates—MCM-41a and MCM-41b) and tested for the pyrolysis of four samples of commercial polymers (LDPE, PP, PS and EVA copolymer), using a thermobalance under nitrogen atmosphere at a heating rate of 10 °C/min. The catalysts were characterized using X-ray powder diffraction, nitrogen adsorption at 77 K and 27 Al and 29 Si solid state nuclear magnetic resonance (NMR). The HZSM-5 zeolite showed the lowest activity in the catalytic pyrolysis of the four polymers. The two mesoporous catalysts, with a greater pore size, were the most active materials in the catalytic pyrolysis of the polymers, and the MCM-41b sample, with higher acidity, was the most active. The presence of MCM-41 samples during the pyrolysis of the high impact PS sample permits us to distinguish between different decomposition steps which are probably related to the pyrolysis of PS and polybutadiene domains. This processes separation was not observed in absence of the catalyst. Thus, catalytic pyrolysis of such samples in the presence of MCM-41 and other catalysts could be a promising technique to characterize this type of polymers.

Journal ArticleDOI
TL;DR: In this article, the adsorption of the basic amino acid, lysine, onto MCM-41, a siliceous mesoporous molecular sieve, has been investigated under a range of solution conditions.

Journal ArticleDOI
TL;DR: The Ta(CHtBu)(CH2tBu)3 complex reacts with the OH groups of a MCM-41 mesoporous silica dehydroxylated at 500 °C to form the monosiloxy surface species.

Journal ArticleDOI
TL;DR: In this article, transition metals (M = Ti, V, Cr) were incorporated into the MCM-41 framework by surfactant-assisted direct hydrothermal (DHT) methods and were characterized in detail by XRD, N2 adsorption-desorption, TG-DTG/DTA, SEM/TEM, DR UV-Vis, XPS and EPR.

Journal ArticleDOI
TL;DR: The result shows that mesoporous catalysts have exhibited the highest catalytic activity among these catalysts above, and the bimetallic Cu-Mn-MCM-41 supported catalyst shows higher oxidation activity than either single metal catalyst.
Abstract: Complete catalytic oxidation of toluene was investigated on Cu−Mn doped mesoporous and microporous catalysts, i.e., Cu−Mn/MCM-41, Cu−Mn/β-zeolite, Cu−Mn/ZSM-5 (where SiO2/Al2O3 is either 25 or 38), and Cu−Mn/porous silica, in the presence of excess oxygen. The result shows that mesoporous catalysts have exhibited the highest catalytic activity among these catalysts above. The less amount of coke formation due to the unique mesoporous structures could play a key role in the high activity on the mesoporous catalyst. In addition, the bimetallic Cu−Mn−MCM-41 supported catalyst shows higher oxidation activity than either single metal catalyst, i.e., Cu−MCM-41 and Mn−MCM-41. The highly dispersed Cu−Mn mixed oxides on mesoporous structures probably provide active sites for the complete oxidation of toluene on these mesoporous catalysts.

Journal ArticleDOI
TL;DR: A chiral BINOL ligand covalently anchored on silica and mesoporous MCM-41 was synthesized and characterized by powder XRD, FT-IR, N2 adsorption-desorption measurements, TGA and elemental analysis as discussed by the authors.
Abstract: A chiral BINOL ligand covalently anchored on silica and mesoporous MCM-41 was synthesized and characterized by powder XRD, FT-IR, N2 adsorption–desorption measurements, TGA and elemental analysis. These anchored ligands were then used to prepare La–Li–BINOL–silica 1a and La–Li–BINOL–MCM-41 1b complexes. The immobilized catalysts having lanthanum content around 0.12–0.18 mmol/g were tested as enantioselective catalyst for Henry reaction and ee 55–84% were found which were comparable to its homogeneous counterpart. The solid catalysts can be reused by simple filtration and recycled several times without much loss in performance.

Journal ArticleDOI
TL;DR: In this article, Ionic liquids (ILs) and immobilized ionic liquids were used as acid catalysts for the liquid phase alkylation of raffinate II and isobutane.
Abstract: Ionic liquids (ILs) and immobilized ionic liquids were used as acid catalysts for the liquid phase alkylation of raffinate II and isobutane. The influences of reactant concentration (molar ratio of iC4/C4 ), time, temperature and acid strength of the ionic liquids were studied. Using a step-up design under batch conditions with a very dilute mixture of isobutane and alkene, the conversion for a variety of ionic liquids was found to follow a pattern based on acid strength of the catalyst. Imidazolium based ILs were found to be superior to phosphonium based ILs. Novel Lewis-Acid Catalysts II (NLAC II, immobilization by grafting on siliceous MCM 41 or on silica FK 700) are better than other solid acid catalysts tested, such as SAC 13, zeolite H-Beta (Si/Al = 14) and NLAC I (impregnation of ILs on silica FK 700). Possible leaching of the ionic liquid from the catalyst surface was followed by ICP measurements of the catalyst after reaction and of the reaction mixture.

Journal ArticleDOI
TL;DR: In this article, the swelling agent (toluene) was used as a transport medium to inject the Pt precursor, Pt(acetylacetonate)2, directly into the inner core of the surfactant micelles.
Abstract: Platinum-containing MCM-41 was synthesized in a one step approach. In this new procedure, the swelling agent (toluene) was used as a transport medium to inject the Pt precursor, Pt(acetylacetonate)2, directly into the inner core of the surfactant micelles. A 1 wt % metal loading was achieved without the loss of pore ordering, while samples with 2 wt % loading showed a less ordered structure. A total of 80−100% of the Pt precursor was incorporated in the porous host matrix depending on the precursor concentration and final loading. During the calcination process, platinum acts as a catalyst for the oxidative removal of the surfactant molecules, allowing one to decrease the calcination temperature significantly. The calcined material had a high surface area (1000−1200 m2 g-1). Platinum particles could be detected using transmission electron microscopy confirming also the absence of large particles outside the mesopore system. The in situ approach was also applied to prepare other metal/MCM-41 or oxide/MCM-4...

Journal ArticleDOI
01 Jan 2006-Carbon
TL;DR: In this article, the Co-MCM-41 catalysts were used as catalysts for the synthesis of uniform diameter single wall carbon nanotubes (SWNT) by CO disproportionation (Boudouard reaction).

Journal ArticleDOI
TL;DR: The liquid phase oligomerization of 1-hexene at 200°C and 5MPa using n-octane as solvent towards hydrocarbon mixtures useful as fuels (gasoline and diesel) was tested over several acid catalysts: micrometer (μ-) and nanocrystalline (n-) HZSM-5 zeolites, mesoporous hydrothermal Al-MCM-41, and sol-gel Al-MTS and Al-SBA-15 catalysts as mentioned in this paper.
Abstract: The liquid phase oligomerization of 1-hexene at 200 °C and 5 MPa using n-octane as solvent towards hydrocarbon mixtures useful as fuels (gasoline and diesel) was tested over several acid catalysts: micrometer (μ-) and nanocrystalline (n-) HZSM-5 zeolites, mesoporous hydrothermal Al-MCM-41, and sol–gel Al-MTS and Al-SBA-15 catalysts. The conversion was always above 75% except for μ-HZSM-5 (just 8.4%) due to its low external surface area (5 m2 g−1) and the fast deactivation in the reaction conditions used in this work. The total selectivity towards oligomers was around 95% and the highest share of C9–C12 dimers (47%), C13–C18 trimers (33%) and heavy C19–C30 compounds (33%) were yielded over Al-SBA-15, n-HZSM-5 and sol–gel Al-MTS, respectively. The remarkable oligomerization performance of n-HZSM-5 was ascribed to its high external surface area (102 m2 g−1) and for the mesoporous catalysts, to their large BET surface area. In particular, Al-MTS showed the best behaviour due to its higher BET surface area and slightly weaker acidity. All the catalysts exhibited steady-state performance with time on stream (TOS) without drastic changes in activity up to 180 min. Simulated distillation analyses proved that the lighter fuel (gasoline + diesel) was obtained over Al-MTS (final distillation temperature = 463 °C; C26–C32 = 8.4%) while the heaviest was obtained over n-HZSM-5 zeolite (final distillation temperature = 524 °C; C28–C40 = 11.7%), probably related to its stronger acidity and microporous nature. The similar nature of hydrocarbons compounds retained over the catalysts after reaction proved by FTIR spectroscopy together with the thermogravimetric analyses results, showed the stronger adsorption of the reaction products promoted by the microporous nature of zeolites.

Journal ArticleDOI
TL;DR: In this paper, the synthesis and surface characterization of a Zr-modified mesoporous MCM-41 solid with an ordered hexagonal arrangement, prepared through a templated synthesis route, using cetyltrimethylammonium chloride as the template.

Journal ArticleDOI
TL;DR: Si-MCM-41 molecular sieves, which are largely used in a number of acid and redox catalyzed reactions, as reported by the literature, were used as basic catalyst for the Knoevenagel condensation.
Abstract: Si-MCM-41 molecular sieves, which are largely used in a number of acid and redox catalyzed reactions, as reported by the literature, were used as basic catalyst for the Knoevenagel condensation. This reaction involves the condensation of carbonyl compounds with active methylene compounds to generate unsaturated products. The catalyst, which pores were occluded by the organic template, provided high activity in mild conditions, even under 10 °C. The high activity is due to the presence of siloxy anions, of high basicity, located in the pore cavity of the hexagonally ordered mesopores. Ion exchange procedures evidenced the presence of these high basic sites as a consequence of the high pH increase of the solution containing tetramethylammonium chloride, or the high H + consumption, added to a the medium as HCl, to keep constant pH. O 1s XPS and 29 Si CP/MAS NMR measurements confirmed the existence of only ≡SiO − CTA + ionic pair, which is the basic site itself.

Journal ArticleDOI
TL;DR: In this paper, a new mesoporous material with semiconducting polypyrrole (PPy) encapsulated in the channels of MCM-41 was synthesized and used as dispersed phase for electrorheological (ER) fluids.

Journal ArticleDOI
TL;DR: In this article, the authors used poly(methacrylic acid) and mesoporous molecular sieve Al-MCM-41 with Si/Al = 20 as supports for the encapsulation of bulky iron(III)-5,10,15,20,20-tetra-(4-pyridyl)porphyrin (Fe-TPyP).

Journal ArticleDOI
TL;DR: In this paper, the catalytic activity of MCM-41 molecular sieves in the Si/Al ratios 25, 50, 75 and 100 were characterised using powder X-ray diffraction (XRD), FT-IR and BET surface area analyser.
Abstract: Mesoporous Al-MCM-41 molecular sieves in the Si/Al ratios 25, 50, 75 and 100 were synthesized under hydrothermal condition. They were characterised using powder X-ray diffraction (XRD), FT-IR and BET surface area analyser. The catalytic activity of these materials was tested for the slurry phase acetalization of cyclohexanone with methanol (MET), ethylene glycol (EG) and pentaerythritol (PEN) at 40–120 °C. MET conversion was found to be higher than that of EG and PEN. Hydrophobic property of catalyst and alcohols and also the steric properties of alcohols were suggested to play an important role in the acetalization. For MET and EG, Al-MCM-41 (100) was found to be more active than other catalyst but for PEN, Al-MCM-41 (25) was found to be more active. The reaction was also studied over H 3 PW 12 O 40 supported MCM-41, commercially available heteropolyacid (H 3 PW 12 O 40 · n H 2 O) and zeolites (HM, Hβ and ZSM-5). Zeolites showed less activity for EG, PEN but comparable activity to MET. The requirement of Bronsted acid sites for the reaction was clearly established by running the reaction in the absence of catalyst.

Journal ArticleDOI
TL;DR: In this paper, the structural properties of mesoporous silica materials modified by manganese have been investigated using surfactants containing different numbers of carbon atoms, and it has been found that structural properties are strongly related to the type of surfactant used, the amounts and the way of Mn introduction.

Journal ArticleDOI
TL;DR: In this article, stable V-MCM-41 mesoporous materials have been synthesized by hydrothermal method, using hexadecyl-trimethyl-ammonium bromide as template, and industrial Na2O·(3.3-3.5)SiO2 as the source of much cheaper silica instead of conventional expensive organic precursors.
Abstract: Stable V-MCM-41 mesoporous materials have been synthesized by hydrothermal method, using hexadecyl-trimethyl-ammonium bromide as template, and industrial Na2O·(3.3–3.5)SiO2 as the source of much cheaper silica instead of conventional expensive organic precursors. Several modern techniques like XRD, N2 adsorption, FT-IR, UV–vis and SEM have been utilized to characterize the framework structure and texture of the samples. The results of N2 adsorption and X-ray diffraction showed that the synthesized samples had a high ordered hexagonal structure, good hydrothermal stability and thermal stability. The selective oxidation of styrene using hydrogen peroxide as oxidant over V-MCM-41 samples showed a good catalytic performance of partial oxidation, the phenylacetic acid was the principal product (the selectivity value was 49.4%). Even after a thermal treatment at 900 °C in air for 12 h or a hydrothermal treatment in boiling water for 8 days, each of the two resultant materials could retain the ordered channels and a high BET surface area. UV–vis spectra provided strong evidences that most of vanadium ions were incorporated into the framework of siliceous MCM-41 sample.

Journal ArticleDOI
TL;DR: In this article, nano-scale silver supported mesoporous molecular sieve Ag/MCM-41 was directly prepared by one-pot synthesis method and the prepared sample was characterized by XRD, TEM, and N2 sorption.
Abstract: Nano-scale silver supported mesoporous molecular sieve Ag/MCM-41 was directly prepared by one-pot synthesis method. The prepared sample was characterized by XRD, TEM, and N2 sorption. The results showed that the sample of Ag/MCM-41 had no appreciable incorporation of silver into the mesoporous matrix of MCM-41 with good crystallinity, and silver nanoparticles were dispersed inside or outside of the channels in the mesoporous host. The catalytic performance of the sample for the cyclohexane liquid-phase oxidation into cyclohexanone and cyclohexanol by oxygen in the absence of solvents without inducing agents was investigated. The 83.4% selectivity to cyclohexanol and cyclohexanone at 10.7% conversion of cyclohexane was obtained over Ag/MCM-41 catalyst at 428 K for 3 h. The turn over numbers (TONs) of Ag/MCM-41 was up to 2946. The catalytic activity of Ag/MCM-41 was also compared with Ag/TS-1 as well as Ag/Al2O3. The results indicated that Ag/MCM-41 showed superior activity to both Ag/TS-1 and Ag/Al2O3. A calcined Ag/MCM-41 was found to be an efficient catalyst for the cyclohexane oxidation into cyclohexanol and cyclohexanone using oxygen as oxidant.

Journal ArticleDOI
TL;DR: In this article, all the catalysts studied were active in the NO decomposition reaction and were characterized by X-ray diffraction, BET, SEM, UV-DRS and hydrogen chemisorption.
Abstract: Palladium catalysts supported on SiO2, MCM-41, [Al]-MCM-41 and on Al2O3-thin-layer- modified SiO2 and MCM-41 were investigated for the direct decomposition of nitric oxide. The catalysts were characterized by X-ray diffraction, BET, SEM, UV-DRS and hydrogen chemisorption. All the catalysts studied were active in the NO decomposition reaction.