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Journal ArticleDOI

Preparation of highly ordered Fe-SBA-15 by physical-vapor-infiltration and their application to liquid phase selective oxidation of styrene

01 May 2007-Journal of Molecular Catalysis A-chemical (Elsevier)-Vol. 268, Iss: 1, pp 155-162
TL;DR: In this article, a simple physical-vapor-infiltration (PVI) method was applied to prepare highly ordered Fe-containing mesoporous silica SBA-15.
Abstract: A simple physical-vapor-infiltration (PVI) method was applied to prepare highly ordered Fe-containing mesoporous silica SBA-15. The loading amount of Fe in SBA-15 was very high (up to 24 mol%) and can be tuned by using different PVI time. The liquid phase selective oxidation of styrene with H 2 O 2 has been used to characterize their catalytic properties, the major product is benzaldehyde and the minor is styrene oxide. Independent of the Fe contents and the heat treatment temperature, the selectivity for benzaldehyde in the reaction at a mild temperature of 50 °C are all above 91%. At elevated temperature of 70 °C, the conversion rate of styrene increases beyond 36% and more significantly the selectivity for benzaldehyde can reach as high as 99%. Comparatively, another two different schemes (simple wet impregnation and incorporation using silane coupling agent) have been also applied to synthesize Fe-containing SBA-15 samples. Under the same condition, the styrene conversion on these two samples are both very low with minor product of phenylacetaldehyde and other styrene oxides.
Citations
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Journal ArticleDOI
TL;DR: Magnetoresponsive Therapy Nohyun Lee, Dongwon Yoo, Daishun Ling,†,‡,⊥ Mi Hyeon Cho, Taeghwan H Yeon,*,†,† and Jinwoo Cheon.
Abstract: Magnetoresponsive Therapy Nohyun Lee, Dongwon Yoo, Daishun Ling,†,‡,⊥ Mi Hyeon Cho, Taeghwan Hyeon,*,†,‡ and Jinwoo Cheon* †Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, Korea ‡School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Korea Department of Chemistry, Yonsei University, Seoul 120-749, Korea School of Advanced Materials Engineering, Kookmin University, Seoul 136-702, Korea Institute of Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, PR China

777 citations

Journal ArticleDOI
TL;DR: In this article, the authors focus mainly on mesoporous SBA-15 together with its application as support for various oxidation reactions in the field of catalysis, adsorption, separations, drug delivery systems and gas sensors.
Abstract: Ordered mesoporous materials are attracting wide concern because of their applications in the field of catalysis, adsorption, separations, drug delivery systems and gas sensors owing of their extremely high surface area combined with well-defined pore structures with narrow pore size distributions. Various mesoporous materials such as MCM-41, MCM-48, SBA-15 and SBA-16 have been reported in past two decades. Synthesis of mesoporous materials involves the concept of aggregation of surfactants as structure directing agents under acidic or basic conditions. The dimensions of these mesopores can be obtained by type of surfactant, auxiliary chemicals and synthesis conditions. At present, SBA-15 has attracted more attention among different mesoporous silica structures due to their desirable properties such as thick pore wall and hexagonal mesopores (4–12 nm), high surface area, ease of synthesis and functionalization and high thermal and mechanical stability. In last few years, great effort has been made on the development of various methods for the synthesis of mesoporous materials as support for oxidation reactions. The aim of this review article is to focus mainly on mesoporous SBA-15 together with its application as support for various oxidation reactions.

108 citations

Journal ArticleDOI
TL;DR: A unique mesoporous silica nanoparticles‐based theranostic platform with ultrasmall iron oxide nanoparticles confined within mesopore network has been developed by a facile but efficient physical‐vapor‐infiltration (PVI) method and provides a new promising MSNs‐based anti‐cancer nanomedicine for future biomedical application.
Abstract: A unique mesoporous silica nanoparticles (MSNs)-based theranostic platform with ultrasmall iron oxide nanoparticles (NPs) confined within mesopore network has been developed by a facile but efficient physical-vapor-infiltration (PVI) method. The highly dispersed Fe species within mesopore channels can synchronously function as the non-toxic contrast agents for highly efficient T1-weighted MR imaging, and as anchoring sites for anti-cancer drug molecule loading and pH-responsive release based on the special metal-ligand coordination bonding between the Fe species and drug molecules. Moreover, the obtained Fe-MSNs exhibit favorable biocompatibility, enhanced chemotherapeutic efficacy and concurrently diminished side effects due to the non-specific attack of chemotherapeutic drugs, as well as the capability in circumventing the multidrug resistance (MDR) of cancer cells and suppressing the metastasis of tumor cells in vitro and in vivo. This pH-resoponsive theranostic agent provides a new promising MSNs-based anti-cancer nanomedicine for future biomedical application.

62 citations

Journal ArticleDOI
TL;DR: In this paper, a co-impregnation method for the chemoselective hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG) was proposed.
Abstract: Mesoporous silica SBA-15-supported bimetallic silver–nickel catalysts (Ag–Ni/SBA-15) were prepared by a co-impregnation method for the chemoselective hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG). The structure and physicochemical properties of the catalysts were characterized using N 2 adsorption–desorption, X-ray fluorescence spectroscopy, transmission electron microscopy, H 2 -temperature-programmed reduction, UV–vis light diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, fourier-transform infrared spectroscopy and ester temperature-programed desorption. Compared with monometallic Ag or Ni catalyst, the bimetallic Ag–Ni/SBA-15 catalysts exhibited enhanced catalytic performance for the chemoselective hydrogenation of DMO to MG. The optimized Ag–Ni/SBA-15 catalyst with a Ni/Ag atomic ratio of 0.2 presented the highest MG yield and excellent catalytic stability during the hydrogenation of DMO to MG for longer than 140 h. The characterization results suggested that the Ag and Ni bimetallic nanoparticles on the catalyst surfaces likely formed a segregation structure with more Ni species in the core and more Ag in the shell, and electron transfer from Ni to Ag possibly occurred. The interactions between the Ag and Ni species generated more active/adsorption sites and prevented the transmigration of bimetallic nanoparticles during hydrogenation.

49 citations

Journal ArticleDOI
Xiaoli Gu1, Cheng Kanghua1, He Ming1, Yijun Shi1, Zhongzheng Li1 
TL;DR: In this paper, the inuence of organosolv beech wood lignin (LOB) on its oxidative conver- sion to high added-value phenolic aldehydes is discussed.
Abstract: In this manuscript, the inuence of organosolv beech wood lignin (LOB) on its oxidative conver- sion to high added-value phenolic aldehydes is discussed. Environmental friendly and low-cost H 2 O 2 was used as the oxygen atom donor. � e catalyst was prepared by immobilizing Lanthanum com- pounds onto the periodic mesoporous channels of siliceous SBA-15. � e activity of the La/SBA-15 was investigated towards oxidation of LOB in the presence of hydrogen peroxide as oxidant with microwave irradiation. Considering the characteristics of LOB, an unexpected low syringaldehyde concentration at 10min of reaction time (1.47 g/L, corresponding to 15.66% yield) was obtained; the other major product was vanillin at 25min (0.78 g/L, i.e., 9.94% yield). � e high reactivity of syringyl nuclei may be pointed out as the main reason for the faster production and degradation of syringaldehyde in oxida- tion. Other low molecular weight phenolic products were found: vanillic acid, syringic acid and minor quantities of aceto-derivatives. � e prole of products concentration with the reaction time of catalytic oxidation with microwave irradiation are shown and discussed with reference to the investigated lignin features. � e mechanism of the microwave catalytic oxidation for LOB under alkaline conditions was proposed.

45 citations


Cites background from "Preparation of highly ordered Fe-SB..."

  • ...Moreover, SBA-15 and Metal/SBA-15 catalyst are known to show interesting activities in the synthetic transformations, such as selective oxidation of styrene, cyclohexane and total oxidation of toluene (Reddy et al. 2009, Bendahou et al. 2008, Zhang et al. 2007)....

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References
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Journal ArticleDOI
TL;DR: In this paper, a family of highly ordered mesoporous (20−300 A) structures have been synthesized by the use of commercially available nonionic alkyl poly(ethylene oxide) (PEO) oligomeric surfactants and poly(alkylene oxide) block copolymers in acid media.
Abstract: A family of highly ordered mesoporous (20−300 A) silica structures have been synthesized by the use of commercially available nonionic alkyl poly(ethylene oxide) (PEO) oligomeric surfactants and poly(alkylene oxide) block copolymers in acid media. Periodic arrangements of mescoscopically ordered pores with cubic Im3m, cubic Pm3m (or others), 3-d hexagonal (P63/mmc), 2-d hexagonal (p6mm), and lamellar (Lα) symmetries have been prepared. Under acidic conditions at room temperature, the nonionic oligomeric surfactants frequently form cubic or 3-d hexagonal mesoporous silica structures, while the nonionic triblock copolymers tend to form hexagonal (p6mm) mesoporous silica structures. A cubic mesoporous silica structure (SBA-11) with Pm3m diffraction symmetry has been synthesized in the presence of C16H33(OCH2CH2)10OH (C16EO10) surfactant species, while a 3-d hexagonal (P63/mmc) mesoporous silica structure (SBA-12) results when C18EO10 is used. Surfactants with short EO segments tend to form lamellar mesost...

6,274 citations

Journal ArticleDOI
11 Jul 2002-Nature
TL;DR: X-ray diffraction and absorption is used to show that LaFe0.05O3, one of the perovskite-based catalysts investigated for catalytic converter applications since the early 1970s, retains its high metal dispersion owing to structural responses to the fluctuations in exhaust-gas composition that occur in state-of-the-art petrol engines.
Abstract: Catalytic converters are widely used to reduce the amounts of nitrogen oxides, carbon monoxide and unburned hydrocarbons in automotive emissions. The catalysts are finely divided precious-metal particles dispersed on a solid support. During vehicle use, the converter is exposed to heat, which causes the metal particles to agglomerate and grow, and their overall surface area to decrease. As a result, catalyst activity deteriorates. The problem has been exacerbated in recent years by the trend to install catalytic converters closer to the engine, which ensures immediate activation of the catalyst on engine start-up, but also places demanding requirements on the catalyst's heat resistance. Conventional catalyst systems thus incorporate a sufficient excess of precious metal to guarantee continuous catalytic activity for vehicle use over 50,000 miles (80,000 km). Here we use X-ray diffraction and absorption to show that LaFe0.57Co0.38Pd0.05O3, one of the perovskite-based catalysts investigated1,2,3,4 for catalytic converter applications since the early 1970s, retains its high metal dispersion owing to structural responses to the fluctuations in exhaust-gas composition that occur in state-of-the-art petrol engines5. We find that as the catalyst is cycled between oxidative and reductive atmospheres typically encountered in exhaust gas, palladium (Pd) reversibly moves into and out of the perovskite lattice. This movement appears to suppress the growth of metallic Pd particles, and hence explains the retention of high catalyst activity during long-term use and ageing.

971 citations

Journal ArticleDOI
TL;DR: In this paper, Nanosized ZnS has been prepared inside MCM-41 hosts by two related schemes, both of which are derived from surface modification methods, and the results showed that the presence of ZnSS inside the hosts resulted in a considerable decrease in surface area, pore diameter, and pore volume, and a massive blue shift in the UV−vis spectra.
Abstract: Nanosized ZnS has been prepared inside MCM-41 hosts by two related schemes, both of which are derived from surface modification methods. The ZnS-containing MCM-41 samples with and without the functional groups (ethylenediamine groups in this case) were designated as ZnS−ED−MCM-41 and ZnS−MCM-41(cal), respectively. The ZnS−MCM-41 composites were characterized by powder X-ray diffraction patterns, transmission electron microscopy, energy disperse spectra, N2 adsorption−desorption isotherms, UV−vis diffuse reflectance spectra, and photoluminescence (PL) spectra. The ZnS was mainly formed and retained in the channels of the MCM-41 host, and its growth was controlled by the channels. In contrast, the amount of ZnS on the external surface is much smaller. The existence of ZnS inside the MCM-41 hosts resulted in a considerable decrease in surface area, pore diameter, and pore volume, and a massive blue shift in the UV−vis spectra was observed. In comparison with the ZnS−MCM-41(cal) sample, a dramatic increase in...

209 citations

Journal ArticleDOI
TL;DR: A review of the recent developments in nanomaterials preparation and properties from ordered mesoporous materials over the last five years, focusing on materials preparation methodology and special properties is presented in this article.
Abstract: The size distribution and dispersion of nanomaterials, in addition to their dimensions, are crucial for their performance. Ordered mesoporous materials (OMMs), due to their periodic and size-controllable pore channels (2–10 nm) and high surface areas, have been regarded as “a natural micro-reactor” to construct novel ordered and well dispersed nanocomposites with controlled size and size distribution. In this review, we overview the recent developments in nanomaterials preparation and properties from ordered mesoporous materials over the last five years, focusing on materials preparation methodology and special properties. Finally, the present and future research interests of nanocomposites from OMMs will also be discussed.

189 citations