Showing papers on "MCM-41 published in 2014"
TL;DR: In this article, Ru catalysts with a wide range of dispersion on carbon, silica, alumina, and titania supports were synthesized, characterized and evaluated for hydrodeoxygenation (HDO) activity using phenol as a model compound.
Abstract: Substituted phenols are the most recalcitrant oxygenates in conventional pyrolysis oils and the dominant oxygenates in lower-oxygen content, formate-assisted pyrolysis oils (FAsP). Ru catalysts with a wide range of dispersion on carbon, silica, alumina, and titania supports were synthesized, characterized and evaluated for hydrodeoxygenation (HDO) activity using phenol as a model compound. Metal content, phase, and particle size were determined with ICP-OES, EXAFS/XANES, and CO pulse chemisorption, respectively. High dispersion of ruthenium on the supports converts more phenol to products. The majority of catalysts predominantly catalyze the hydrogenation (HYD) route typical of noble metal catalysts. A highly dispersed Ru/TiO2 catalyst shows unusually high selectivity toward direct deoxygenation (DDO) and outstanding activity. We suggest that the DDO pathway on titania involves a bifunctional catalyst, where hydrogen creates reduced titania sites, created by hydrogen spillover, that interact strongly with the phenol hydroxyl group.
142 citations
TL;DR: In this article, the effects of Ti on the catalytic properties of Ni2P/Ti-MCM-41 catalysts were investigated under a lower reduction temperature of 400°C.
130 citations
TL;DR: Tungsten-containing functional meso-materials WMCM-41 have been successfully synthesized and employed in the desulfurization of dibenzothiophene (DBT) as discussed by the authors.
98 citations
TL;DR: In this paper, a composite of polypyrrole/thiol-functionalized Beta/MCM-41 (PPy/SH-Beta/MCMC-41) was prepared, characterized by FE-SEM, FT-IR, XRD, TGA and BET analysis.
84 citations
TL;DR: A core-shell structural magnetically separable catalyst, with γ-Fe2O3 nanoparticles as the core layer and the copper and aluminum containing MCM-41 as the shell layer, has been fabricated to target the low catalytic activity and the inconvenient separation of copper loading nanocatalysts in heterogeneous Fenton-like reaction.
82 citations
TL;DR: In this paper, high-structured neat MCMMCM-41 mesoporous materials were synthesized using a simple, one-pot procedure at room temperature, and they were impregnated with 2.5, 5 and 10% Ni and catalytic performance was assessed for CO2 reforming of methane (CH4).
Abstract: Highly structured neat MCM-41, Na-form, and Al-incorporated MCM-41 mesoporous materials were synthesized using a simple, one-pot procedure at room temperature. The neat MCM-41 material possessed a surface area comparable with other MCM-41 materials prepared using more conventional higher temperature methods. Incorporating Al into the MCM-41 framework increased support acidity while entrapping Na ions in the MCM-41 pores lowered acidity. The neat MCM-41, Na-form, and Al-incorporated MCM-41 were impregnated with 2.5, 5 and 10% Ni and catalytic performance was assessed for CO2 reforming of methane (CH4). XRD, TEM and H2-TPR indicated at low loadings the Ni was highly dispersed on the support, whereby increasing the Ni loading encouraged the formation of larger Ni crystals on the external MCM-41 surface. 2.5% Ni catalysts supported on neat MCM-41 exhibited excellent catalytic activity invoking up to 98% CH4 conversion at 800 °C and 26% at 500 °C. Carbon accumulation on the catalyst was greater at higher Ni loadings although this was not to the detriment of activity over the reaction time-frame. This result coupled with variations in the H2/CO product ratio and CH4/CO2 conversion difference suggested increasing the Ni loading promoted the Boudouard, CH4 cracking and reverse water gas shift side reactions. Incorporating the MCM-41 with either Al or Na lowered catalyst performance with the promoters found to enhance or suppress the side reactions to varying degrees.
78 citations
TL;DR: In this article, the selective dehydration of glucose to hydroxymethylfurfural (HMF) in a biphasic medium (water/methylisobuthylketone) has been studied by using different catalysts based on mesoporous MCM-41 silica containing ZrO 2.
78 citations
TL;DR: In this article, a molecular sieve was used using tetraethoxysilane and cetyltrimethylammonium bromide and used as an effective adsorbent for CO2.
72 citations
TL;DR: In this paper, the effect of Mo content on the activity of the catalyst was investigated for syngas methanation in a fixed-bed reactor, and the results showed that the addition of MoO3 could enhance the interaction between metal nickel and the support in the way of Ni-Mo alloy, which inhibited the catalyst sintering.
64 citations
TL;DR: Covalently linked amine functionalized MCM-41 catalysts were investigated as an efficient, heterogeneous and recyclable catalyst for the coupling of carbon dioxide (CO 2 ) and aziridines providing high conversion with excellent regioselectivity towards 5-aryl-2-oxazolidinones under mild and solvent free conditions.
Abstract: Covalently linked amine functionalized MCM-41 catalysts were investigated as an efficient, heterogeneous and recyclable catalyst for the coupling of carbon dioxide (CO 2 ) and aziridines providing high conversion with excellent regioselectivity towards 5-aryl-2-oxazolidinones under mild and solvent free conditions The effect of various reaction parameters, such as temperature, time, and CO 2 pressure for the synthesis of 5-aryl-2-oxazolidinones using amine functionalized MCM-41 catalyst was investigated The optimized protocol was applied to a wide variety of 1-alkyl-2-arylaziridines producing the corresponding 5-aryl-2-oxazolidinones with good yield and excellent regioselectivity Amine functionalized MCM-41 catalysts were characterized by FT-IR, TG/DTA, high and low angle XRD, and solid state 29 Si CPMAS NMR analysis Furthermore, the catalyst was effectively recycled for five consecutive cycles without any significant loss in its catalytic activity and selectivity under the described reaction conditions Readily available reagents, mild reaction conditions and effective catalyst recyclability make this protocol simple, convenient, practical and environmentally friendly
63 citations
TL;DR: MCM-41-type and MCM-48-type mesoporous silica have great promise as solid dispersion carriers for sustained and immediate release separately according to the drug loading efficiency and the maximum percent cumulative drug dissolution.
Abstract: Objective: To explore the suitable application of MCM-41 (Mobil Composition of Matter number forty-one)-type and MCM-48-type mesoporous silica in the oral water insoluble drug delivery system.Methods: Cilostazol (CLT) as a model drug was loaded into synthesized MCM-48 (Mobil Composition of Matter number forty-eight) and commercial MCM-41 by three common methods. The obtained MCM-41, MCM-48 and CLT-loaded samples were characterized by means of nitrogen adsorption, thermogravimetric analysis, ultraviolet-visible spectrophotometry, scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry and powder X-ray diffractometer.Results: It was found that solvent evaporation method was preferred according to the drug loading efficiency and the maximum percent cumulative drug dissolution. MCM-48 with 3D cubic pore structure and MCM-41 with 2D long tubular structure are nearly spherical particles in 300–500 nm. Nevertheless, the silica carriers with similar large specific...
TL;DR: In this article, the effects of pore characteristics of supports including unimodal and bimodal pore structures, loading amount of Fe, and reaction temperature on the catalytic performance were investigated.
TL;DR: Amine-functionalized MCM-41 was prepared for use as basic heterogeneous catalysts in trasesterification of soybean oil to produce biodiesel as discussed by the authors, achieving up to 99% yield in biodiesel at 70°C and 3h of reaction were obtained with the guanidine-derived catalyst.
TL;DR: In this paper, the isomerization of α-pinene oxide was carried out in toluene as a solvent at 70°C and the main properties influencing the activity and the selectivity are the acidic and structural properties of the tested catalysts.
Abstract: α-Pinene oxide, an oxygenated derivative of α-pinene, can be converted into various valuable substances useful as flavour, fragrance and pharmaceutical compounds. Campholenic aldehyde is one of the most desired products of α-pinene oxide isomerization being a valuable intermediate for the production of sandalwood-like fragrances. Iron modified zeolites Beta-75 and ZSM-5, mesoporous material MCM-41, silica and alumina were prepared by two methods (impregnation and solid-state ion exchange) and tested for selective preparation of campholenic aldehyde by isomerization of α-pinene oxide. The characterization of tested catalyst was carried out using scanning electron microscope analysis, nitrogen adsorption measurements, pyridine adsorption–desorption with FTIR, X-ray absorption spectroscopy measurements, XPS-analysis, 29Si MAS NMR and 27Al MAS NMR and X-ray diffraction. The isomerization of α-pinene oxide was carried out in toluene as a solvent at 70 °C. The main properties influencing the activity and the selectivity are the acidic and structural properties of the tested catalysts. The highest selectivity of 66% was achieved at complete conversion of α-pinene oxide with Fe-MCM-41.
TL;DR: In this paper, a simple covalently linked amine functionalized MCM-41 compound was investigated using mesoporous catalytic protocols as a highly efficient, heterogeneous and recyclable catalyst for the synthesis of a wide variety of quinazoline-2,4(1H,3H)-dione derivatives from 2-aminobenzonitriles and carbon dioxide in aqueous reaction medium.
TL;DR: In this article, synthetic procedures for anchoring N-(3-(trimethoxysilyl)-propylethylenediamine on the surface of the mesoporous silica, MCM-41 (MCM41-N), were described.
Abstract: Synthetic procedures are described for anchoring of N-(3-(trimethoxysilyl)-propylethylenediamine on the surface of the mesoporous silica, MCM-41 (MCM-41-N). The condensation of 4-hydroxysalicylidene with MCM-41-N creates the new MCM-41-N-Hdhba Schiff-base. The synthesis and characterization of the new palladium (II) complex, [Pd(MCM-41-N-(Hdhba)2(dhba)Cl(H2O)], is also described. The structure and morphology of the Schiff-base and the Pd(II) complex have been examined using spectroscopic (IR, Raman, XPS, UV–vis and solid state 13C and 90Si NMR), morphological (low angle XRD, and HRTEM-EDS), elemental analysis, N2 physisorption and thermal measurements. The heterogeneous catalytic epoxidations of n-octene, cyclooctene and styrene were achieved by employing the new Pd(II) complex as a catalyst in the presence of aqueous 30% H2O2–0.2 M NaHCO3 at atmospheric pressure and 353 K. The influence of pH, temperature, time and amount of catalyst has also been investigated. The catalyst can be readily separated from the epoxidation reactions mixtures and can be recovered after several catalytic cycles.
TL;DR: A facile synthetic method for MCM-41 mesoporous material at room temperature using iron ore tailing and cetyltrimethylammonium bromide (CTAB) as a silicon source and a structure-directing agent, respectively, was reported in this article.
TL;DR: In this paper, a new hybrid materials of vanadium-substituted phosphotungstic acids (VHPW) immobilized on amine-functionalized mesoporous MCM-41 are prepared and characterized by FT-IR, XRD, N 2 adsorption, elemental analysis, SEM and TEM for their structural integrity and physicochemical properties.
TL;DR: In this article, a novel synthesis procedure to prepare a highly active bimetallic AgCo/APTES@MCM-41 catalyst was reported, and the complete oxidation of formaldehyde was achieved at temperature as low as 90°C over the Bimetallic catalysts with Ag/Co = 3/1 (mass ratio).
Abstract: We reported here a novel synthesis procedure to prepare a highly active bimetallic AgCo/APTES@MCM-41 catalyst. Complete oxidation of formaldehyde was achieved at temperature as low as 90 °C over the bimetallic catalysts with Ag/Co = 3/1 (mass ratio). N2 isotherms, small-angle XRD results suggested that both Ag and Co species were well dispersed on the support, and the pore structure of the support was not destroyed after introducing the active metal. The formation of the strong metal–metal interaction (SMMI) between Ag and Co in the bimetallic catalysts due to the electron transfer between each other resulted in the high Co3+/Co2+ ratio and good low-temperature reducibility. And more surface active oxygen species (Osurf) formed on the surface of the bimetallic catalysts. All these factors gave rise to the high formaldehyde catalytic oxidation activity in AgCo bimetallic catalysts. The possible structure changes of bimetallic catalysts and the reaction path for the complete oxidation of formaldehyde over AgCo bimetallic catalyst was also proposed.
TL;DR: In this article, a luminescent platinum(II) complex platinum 5,10,15,20-tetra{4-[(N-carbazyl)butyloxyphenyl]}porphyrin (PtTCBPyP) has been synthesized and characterized by H-1 NMR, elemental analysis, IR and UV-vis.
Abstract: A novel luminescent platinum(II) complex platinum 5,10,15,20-tetra{4-[(N-carbazyl)butyloxyphenyl]}porphyrin (PtTCBPyP) has been synthesized and characterized by H-1 NMR, elemental analysis, IR and UV-vis. The platinum porphyrin is assembled with mesoporous silica SBA-15 and MCM-41 resulting in the assembly materials PtTCBPyP/SBA-15 and PtTCBPyP/MCM-41. The luminescence of platinum porphyrin complex/silicate assemble materials can be quenched by molecular oxygen with very high response (I-0/I-100 > 8700 for PtTCBPyP/SBA-15(20 mg/g) and I-0/I-100 > 3800 for PtTCBPyP/MCM-41(20 mg/g)), indicating that platinum porphyrin complex/silicate systems can be employed to develop high performance oxygen sensors. Among this assembly system, PtTCBPyP/SBA-15(20 mg/g) exhibits the highest response of platinum porphyrin complex/silica. (C) 2013 Elsevier B.V. All rights reserved.
TL;DR: A series of alkali metal and nickel-exchanged Al-MCM-41 catalysts were prepared via aqueous ion exchange and then investigated for gas-phase oligomerization of propene at 453 K and near ambient pressures as discussed by the authors.
Abstract: A series of alkali metal- and nickel-exchanged Al-MCM-41 catalysts were prepared via aqueous ion exchange and then investigated for gas-phase oligomerization of propene at 453 K and near ambient pressures. All catalysts were active and produced oligomers with >98% selectivity. The highest activities per Ni2+ cation were observed when the cations were highly dispersed as a consequence of either lowering the Ni loading for a fixed MCM-41 Si/Al ratio or by decreasing the concentration of exchangeable sites within the material by increasing the MCM-41 Si/Al ratio at a fixed Ni loading. The identity of the alkali metal cation had no significant effect on the catalytic activity or degree of dimer branching, except for the sample containing Cs+ cations, where the decreased pore volume resulted in a lower catalyst activity and slightly more linear dimer products. Comparison of Ni-MCM-41 prepared with and without Na+ cations showed that a higher yield of oligomers could be achieved when Na+ cations are present bec...
TL;DR: In this article, two Ga-MCM-41 materials with nanosized particles (<150nm) were prepared according to two new synthesis methods. The structural and textural properties of the materials were characterized by XRD, N2-physisorption, TEM, SEM and EDX, while 71Ga MAS-NMR was employed to monitor the coordination of the gallium atoms.
TL;DR: This study showed that melting a mixture of Ibu and MCM is a much more efficient method of confining the drug in the pores compared to incipient wetness, and clearly demonstrates that existing methods used to encapsulate drugs in mesoporous silica nanoparticles (MSNs) require reevaluation.
Abstract: In this work, we compared two methods (incipient wetness and melting) for the encapsulation of ibuprofen in the pores of Mobil Crystalline Material 41 (MCM-41) through NMR (nuclear magnetic resonance) spectroscopy. (1)H NMR spectra were recorded under very fast MAS (sample spinning 60 kHz) conditions in both 1D and 2D mode (NOESY sequence). We also performed (13)C cross-polarization magic angle spinning (CP/MAS) experiments, (13)C single pulse experiments (SPE), and (1)H-(13)C HSQC HR/MAS (heteronuclear single quantum coherence high resolution) HR/MAS correlations. Evaluation of the encapsulation methods included an analysis of the filling factor of the drug into the pores. The stability of Ibu/MCM in an environment of ethanol or water vapor was tested. Our study showed that melting a mixture of Ibu and MCM is a much more efficient method of confining the drug in the pores compared to incipient wetness. The optimal experiments for the former method achieved a filling factor of approximately 60%. We concluded that the major limitation to the applicability of the incipient wetness method (filling factor ca. 20%) is the high affinity of solvent (typically ethanol) for MCM-41. We found that even ethanol vapor can remove Ibu from the pores. When a sample of Ibu/MCM was stored for a few hours in a closed vessel with ethanol vapor, Ibu was transported from the pores to the outer walls of MCM. We observed a similar phenomenon with water vapor, although this process is slower compared to the analogous procedure using ethanol. Our study clearly demonstrates that existing methods used to encapsulate drugs in mesoporous silica nanoparticles (MSNs) require reevaluation.
TL;DR: Magnetite nanoparticles were used as a core for a mesoporous MCM-41 shell to provide a core-shell solid acid catalyst (Fe3O4@MCM41-OSO3H) as discussed by the authors.
Abstract: Magnetite nanoparticles were used as a core for –OSO3H functionalized mesoporous MCM-41 shell to provide a core–shell solid acid catalyst (Fe3O4@MCM-41-OSO3H). The catalyst was characterized by transmission electron microscopy (TEM), infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and a vibrating sample magnetometer (VSM). The obtained nano-magnetic catalyst was used in the three-component reaction of indoles, aldehydes and thiols to furnish the desired 3-[(aryl)(arylthio)methyl]-1H-indoles in good yields under very mild reaction conditions. The unique feature of the reaction was the ease of work-up and catalyst recovery. The recovered catalyst maintained catalytic activity for five successive runs.
TL;DR: The polyoxometalate (POM) as mentioned in this paper was introduced into the pores of both as-synthesized (I) and amine functionalized MCM-41 (II) and the resultant catalysts were characterized with powder X-ray diffraction, nitrogen sorption, and diffuse-reflectance UV-vis spectroscopy.
Abstract: The polyoxometalate (POM) catalyst, [γ-SiW10O34(H2O)2]4−, was introduced into the pores of both as-synthesized (I) and amine functionalized MCM-41 (II). The resultant catalysts were characterized with powder X-ray diffraction, nitrogen sorption, and diffuse-reflectance UV–vis spectroscopy. Both catalysts were tested for reusability through repeated catalytic conversions of methyl phenyl sulfide to methyl phenyl sulfone with hydrogen peroxide. While the physisorbed catalyst (I) exhibits steadily decreasing turnover frequency (TOF), the POM catalyst supported on MCM-41 functionalized with a protonated amine (II) exhibits markedly improved reusability. This chemisorbed catalyst effectively showed no change in TOF between the second (21) and the sixth reactions (22). Additionally, sulfoxidations with catalyst II were investigated with a small set of substrates focusing on compounds including dibenzothiophene, which serves as a model refractory sulfide.
05 Mar 2014
TL;DR: In this article, the structural evolution from natural halloysite to mesoporous material Al-MCM-41 at the atomic level was clarified at the molecular level using X-ray diffraction, transmission electron microscopy and N2 adsorption-desorption measurements.
Abstract: Aluminum-containing hexagonally ordered mesoporous silica (Al-MCM-41) with specific surface area of 509.4 m2/g was first synthesized using natural halloysite as source material by hydrothermal treatment, without addition of silica or aluminum regents. The samples were characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption–desorption measurements, and Fourier transform infrared spectra techniques. The results indicate that process parameters, including calcination temperature, pH value, n(SiO2)/n(CTAB)/n(H2O) ratio, and hydrothermal reaction time, show moderate effects on the preparation of Al-MCM-41. SiO2/Al2O3 molar ratio could be effectively modulated by the calcination temperature for halloysite. Furthermore, we first clarified the structural evolution from natural halloysite to mesoporous material Al-MCM-41 at the atomic level.
TL;DR: In this paper, the catalytic etherification of glycerol using calcium-lanthanum oxide supported on MCM-41 as a stable heterogeneous basic catalyst was investigated.
Abstract: The catalytic etherification of glycerol using calcium–lanthanum oxide supported on MCM-41 as a stable heterogeneous basic catalyst was investigated. Stable heterogeneous mesoporous basic catalysts were synthesized by wet impregnation of MCM-41 with calcium nitrate and lanthanum nitrate. The surface and structural properties of the prepared catalysts were when characterized using different techniques. MCM-41 and modified MCM-41 were used in the solventless etherification of glycerol to produce diglycerol as the desired product. The reaction was performed at 250 °C for 8 h, and catalyst activity was evaluated. Catalytic etherification over the 20%Ca1.6La0.6/MCM-41 catalyst resulted in the highest glycerol conversion of 91% at the diglycerol yield of 43%. The distribution of diglycerol isomer in the etherification of glycerol was studied, and the value of the sum of two dimers (ββ′ + αβ = 67%) was found to be higher than that of αα′ dimer (33%) after 8 h of reaction. Thus, the major reaction occurred inside the porous area instead of the external surface area.
TL;DR: Magnetic α-Fe2O3-MCM-41 mesoporous material functionalized by dual acidic ionic liquid (DAIL) was prepared through a two-step approach as a novel powerful acidic catalyst which provides high ionic media for reactions, by means of post-surface grafting of the mesochannels of α -Fe 2O3 -MCM41 materials with 3-sulfobutyl-1-(3-propyltrimethoxysilane)imidazolium hydrogen sulfate as DAIL as mentioned in this paper.
Abstract: Magnetic α-Fe2O3–MCM-41 mesoporous material functionalized by dual acidic ionic liquid (DAIL) was prepared through a two-step approach as a novel powerful acidic catalyst which provides high ionic media for reactions, by means of post-surface grafting of the mesochannels of α-Fe2O3–MCM-41 materials with 3-sulfobutyl-1-(3-propyltrimethoxysilane)imidazolium hydrogen sulfate as DAIL. Mesoporous MCM-41 was simply packed on the surface of ferric oxide nanoparticles and DAIL was efficiently incorporated into the mesochannels of MCM-41 generating Lewis and Bronsted acidic sites. The catalyst was characterized by FT-IR, X-ray powder diffraction, HRTEM, vibrating sample magnetometer, X-ray energy diffraction spectra, thermogravimetric and differential thermal analyses, and N2 adsorption–desorption measurements. The synthesized hybrid acidic MCM-41 showed good catalytic performance in the one-pot synthesis of pyrimido[4,5-d]pyrimidine derivatives using 6-aminouracil, aldehyde, and urea or thiourea under solvent free conditions. Moreover, it was proved that under this condition, the use of such a hybrid material as a catalyst plays the role of rendering the reactions while neither the α-Fe2O3–MCM-41 nor the 3-methyl-1-(4-sulfonic acid)butylimidazolium hydrogen sulfate were able to promote this reaction.
TL;DR: In this article, the thermal stability of NH2-MCM-41 hybrid material under different atmospheres (nitrogen and air) was investigated and it was found out that the temperature stability varied greatly in different environments.
Abstract: In the present work, we report on the thermal stability of NH2-MCM-41 hybrid material under different atmospheres (nitrogen and air) The thermal stability of this hybrid material is very important because of its common use in catalysis, adsorption, biomedical and biotechnological applications, based on mesoporous and aminopropyl functionalities Samples were prepared by one pot co-condensation method with different loadings of 3-aminopropyltriethoxysilane (APTES) The thermal stability of hybrid samples (NH2-MCM-41) heat treated in nitrogen and air at 30–800 °C has been investigated Samples were synthesized under basic media in the presence of cetyltrimethylammonium bromide (CTABr) as structure-directing agent, tetraethyl orthosilicate as silica source, and APTES as functionalizing agent with molar composition of 0055 CTABr:045 SiO2:0054 APTES:532 NH4OH:1499 H2O at 50 °C for 24 h at pH 124 The obtained hybrid materials have been characterized by thermogravimetric analysis (TG), derivative thermogravimetric analysis, differential scanning calorimetry, X-ray powder diffraction, Fourier-transform infrared spectroscopy, transmission electron microscopy, and surface area determination by the BET method Based on TG measurements of the treated samples, it was found out that the thermal stability varied greatly in different atmospheres
TL;DR: In this paper, a multi-component reaction of various types of aldehydes, 2-aminopyridines and trimethylsilyl cyanide was carried out in the presence of MCM-41 supported boron trifluoride (BF3/MCM41) as a nanostructured solid acid catalyst for the synthesis of 3-iminoaryl-imidazo[1,2-a]pyridine derivatives.