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1.
For the first time, SBA‐15/cyclodextrin nanosponge adduct was synthesized through reaction of Cl‐functionalized SBA‐15 and amine‐functionalized cyclodextrin nanosponge (CDNS). This adduct, which benefits from features of both SBA‐15 and CDNS, was then used for immobilization of Ag(0) nanoparticles which were prepared and capped using a bio‐based approach. Ag@CDNS–SBA‐15 was applied as a heterogeneous catalyst for promoting the three‐component reaction of benzaldehydes, 4‐hydroxycoumarin and urea or thiourea under ultrasonic irradiation to furnish benzopyranopyrimidines. The reaction variables were optimized using response surface methodology. The catalytic activity of Ag@CDNS–SBA‐15 was higher than those of Ag@CDNS, Ag@SBA‐15 and Ag@SBA‐15 + CDNS, confirming the contribution of both components to catalysis as well as a synergistic effect between CDNS and SBA‐15. The role of CDNS was to accommodate the substrates and bring them to the vicinity of the Ag(0) nanoparticles. Notably the catalyst was reusable and could be recovered and reused for up to four reaction runs with slight Ag(0) leaching and loss of catalytic activity.  相似文献   

2.
A series of Keggin‐type heteropolyacid‐based heterogeneous catalysts (Co‐/Fe‐/Cu‐POM‐octyl‐NH3‐SBA‐15) were synthesized via immobilized transition metal mono‐ substituted phosphotungstic acids (Co‐/Fe‐/Cu‐POM) on octyl‐amino‐co‐functionalized mesoporous silica SBA‐15 (octyl‐NH2‐SBA‐15). Characterization results indicated that Co‐/Fe‐/Cu‐POM units were highly dispersed in mesochannels of SBA‐15, and both types of Brønsted and Lewis acid sites existed in Co‐/Fe‐/Cu‐POM‐octyl‐NH3‐SBA‐15 catalysts. Co‐POM‐octyl‐NH3‐SBA‐15 catalyst showed excellent catalytic performance in H2O2‐mediated cyclohexene epoxidation with 83.8% of cyclohexene conversion, 92.8% of cyclohexene oxide selectivity, and 98/2 of epoxidation/allylic oxidation selectivity. The order of catalytic activity was Co‐POM‐octyl‐NH3‐SBA‐15 > Fe‐POM‐octyl‐NH3‐SBA‐15 > Cu‐POM‐octyl‐NH3‐SBA‐15. In order to obtain insights into the role of ‐octyl moieties during catalysis, an octyl‐free catalyst (Co‐POM‐NH3‐SBA‐15) was also synthesized. In comparison with Co‐POM‐NH3‐SBA‐15, Co‐POM‐octyl‐NH3‐SBA‐15 showed enhanced catalytic properties (viz. activity and selectivity) in cyclohexene epoxidation. Strong chemical bonding between ‐NH3+ anchored on the surface of SBA‐15 and heteropolyanions resulted in excellent stability of Co‐POM‐octyl‐NH3‐SBA‐15 catalyst, and it could be reused six times without considerable loss of activity.  相似文献   

3.
Mesoporous silica SBA‐15 functionalized with N‐methylpyrrolidonium‐zinc chloride based deep eutectic solvent (DES) is found to be a more efficient and reusable catalyst for a convenient N‐formylation of a variety of amines at room temperature. N‐Formylation of primary, secondary as well as heterocyclic amines have been carried out in good to excellent yields by treatment with formic acid in low loading of DES/SBA‐15 an environmentally benign catalyst for the first time. The DES/SBA‐15 catalyst, which possesses both Brønsted and Lewis acidities as well as an active SBA‐15 support, makes this procedure quite simple, reusable, more convenient and practical. This catalyst was tolerant of a wide range of functional groups, and it can be reused for four runs without obvious deactivation.  相似文献   

4.
Heavy metal ions are harmful to aquatic life and humans owing to their high toxicity and non‐biodegradability, so their removal from wastewater is an important task. Therefore, this work focuses on designing suitable, simple and economical nanosensors to detect and remove these metal ions with high selectivity and sensitivity. Based on this idea, different types of mesoporous materials such as hexagonal SBA‐15, cubic SBA‐16 and spherical MCM‐41, their chloro‐functionalized derivatives, as well as 4‐(4‐nitro‐phenylazo)‐naphthalen‐1‐ol (NPAN) azo dye have been synthesized, with the aim of designing some optical nanosensors for metal ions sensing applications. The mentioned azo dye has been anchored into the chloro‐functionalized mesoporous materials. The designed nanosensors were characterized using scanning and transmission electron microscopy as well as Fourier transform infrared and UV–visible spectral analysis, nitrogen adsorption–desorption isotherms, low‐angle X‐ray diffraction and thermogravimetric analyses. Their optical sensing to various toxic metal ions such as Cd (II), Hg (II), Mn (II), Fe (II), Zn (II) and Pb (II) at different values of pH (1.1, 4.9, 7 and 12) was investigated. The optimization of experimental conditions, including the effect of pH and metal ion concentration, was examined. The experimental results showed that the solution pH had a major impact on metal ion detection. The optical nanosensors respond well to the tested metal ions, as reflected by the enhancement in both absorption and emission spectra upon adding different concentrations of the metal salts and were fully reversible on adding ethylene diamine tetra acetic acid or citric acid to the formed complexes. High values of the binding constants for the designed nanosensors were observed at pHs 7 and 12, confirming the strong chelation of different metals to the nanosensor at these pHs. Also, high binding constants and sensitivity were observed for NPAN‐MCM‐41 as a nanosensor to detect the different metal ions. From the obtained results, we succeeded in transforming the harmful azo dye into an environmentally friendly form via designing of the optical nanosensors used to detect toxic metal ions in wastewater with high sensitivity.  相似文献   

5.
Silanol groups on a silica surface affect the activity of immobilized catalysts because they can influence the hydrophilicity/hydrophobicity, matter transfer, or even transition state in a catalytic reaction. Previously, these silanol groups have usually been passivated by using surface‐passivation reagents, such as alkoxysilanes, bis‐silylamine reagents, chlorosilanes, etc., and surface passivation has typically been found in mesoporous‐silicas‐supported molecular catalysts and heteroatomic catalysts. However, this property has rarely been reported in mesoporous‐silicas‐supported metal‐nanoparticle catalysts. Herein, we prepared an almost‐superhydrophobic SBA‐15‐supported gold‐nanoparticle catalyst by using surface passivation, in which the catalytic activity increased more than 14 times for the reduction of nitrobenzene compared with non‐passivated SBA‐15. In addition, this catalyst can selectively catalyze hydrophobic molecules under our experimental conditions, owing to its high (almost superhydrophobic) hydrophobic properties.  相似文献   

6.
Understanding the complex thermodynamic behavior of confined amphiphilic molecules in biological or mesoporous hosts requires detailed knowledge of the stacking structures. Here, we present detailed solid‐state NMR spectroscopic investigations on 1‐butanol molecules confined in the hydrophilic mesoporous SBA‐15 host. A range of NMR spectroscopic measurements comprising of 1H spin–lattice (T1), spin–spin (T2) relaxation, 13C cross‐polarization (CP), and 1H,1H two‐dimensional nuclear Overhauser enhancement spectroscopy (1H,1H 2D NOESY) with the magic angle spinning (MAS) technique as well as static wide‐line 2H NMR spectra have been used to investigate the dynamics and to observe the stacking structure of confined 1‐butanol in SBA‐15. The results suggest that not only the molecular reorientation but also the exchange motions of confined molecules of 1‐butanol are extremely restricted in the confined space of the SBA‐15 pores. The dynamics of the confined molecules of 1‐butanol imply that the 1H,1H 2D NOESY should be an appropriate technique to observe the stacking structure of confined amphiphilc molecules. This study is the first to observe that a significant part of confined 1‐butanol molecules are orientated as tilted bilayered structures on the surface of the host SBA‐15 pores in a time‐average state by solid‐state NMR spectroscopy with the 1H,1H 2D NOESY technique.  相似文献   

7.
SBA‐15 materials of different pore lengths and functionalized with various organic groups were synthesized by one‐pot co‐condensation and applied as adsorbents for the acid orange 12 (AO12) and acid red 73 (AR73) dyes. The materials were characterized by techniques such as X‐ray powder diffraction, nitrogen sorption isotherms, scanning electron microscopy, and infrared (FTIR) spectroscopy. The adsorption behaviors of the SBA‐15 materials toward AO12 and AR73 dyes were investigated by varying several factors including morphologies of adsorbents, pH of solution, functional groups on SBA‐15, and temperature. The equilibrium adsorption data agreed with Langmuir isotherms. The kinetic parameters were also calculated and the first‐order kinetic model fitted well for amino‐functionalized SBA‐15 material. The short channeling pores of the amino‐functionalized SBA‐15 platelets facilitated the diffusion of dye molecules inside the pores and prevented the aggregation of dye molecules from the blocking of the pores. To conclude, however, the adsorption capacity is dependent on the amount of amino‐loading and surface area of the SBA‐15 materials.  相似文献   

8.
The nanocomposite with polypyrrole (PPy) confined in ordered mesoporous silica SBA‐15 channels was synthesized by in situ electropolymerization. X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption/desorption, and FT‐IR studies indicated that the nanocomposite has the well‐ordered hexagonal structures and PPy was in situ polymerized into the channels instead of the outer surface of SBA‐15. Furthermore, the PPy/SBA‐15 nanocomposite was used as an electrode modifier. We found that the nanocomposite‐modified electrode exhibited good electrocatalytic activities for hydroquinone oxidation where PPy chains could facilitate the electron transfer between molecular sieves and electrode surface. Three dihydroxybenzene isomers (hydroquinone, catechol and resorcinol) have been successfully detected at PPy/SBA‐15 modified electrode by preconcentration of the analyte.  相似文献   

9.
A series of Mo‐based catalysts for 1‐butene metathesis to propene were prepared by supporting Mo species on SBA‐15 premodified with alumina. The effects of the method of introduction of the alumina guest to the host SBA‐15 on the location of the Mo species and the corresponding metathesis activity were studied. As revealed by N2 adsorption isotherms and TEM results, well‐dispersed alumina was formed on the pore walls of SBA‐15 if the ammonia/water vapor induced hydrolysis (NIH) method was employed. The Mo species preferentially interacted with alumina instead of SBA‐15, as evidenced by X‐ray photoelectron spectroscopy, time‐of‐flight secondary‐ion mass spectrometry, and IR spectroscopy of adsorbed pyridine. Furthermore, new Brønsted acid sites favorable for the dispersion of the Mo species and low‐temperature metathesis activity were generated as a result of the effective synergy between the alumina and SBA‐15. The Mo/Al2O3@SBA‐15 catalyst prepared by the NIH method showed higher metathesis activity and stability under the conditions of 120 °C, 0.1 MPa, and 1.5 h?1 than catalysts prepared by other methods.  相似文献   

10.
1,3‐Diphenyl‐1,3‐propanepione (DBM)‐functionalized SBA‐15 and SBA‐16 mesoporous hybrid materials (DBM‐SBA‐15 and DBM‐SBA‐16) are synthesized by co‐condensation of modified 1,3‐diphenyl‐1,3‐propanepione (DBM‐Si) and tetraethoxysilane (TEOS) in the presence of Pluronic P123 and Pluronic F127 as a template, respectively. The as‐synthesized mesoporous hybrid material DBM‐SBA‐15 and DBM‐SBA‐16 are used as the first precursor, and the second precursor poly(methylacrylic acid) (PMAA) is synthesized through the addition polymerization reaction of the monomer methacrylic acid. These precursors then coordinate to lanthanide ions simultaneously, and the final mesoporous polymeric hybrid materials Ln(DBM‐SBA‐15)3PMAA and Ln(DBM‐SBA‐16)3PMAA (Ln=Eu, Tb) are obtained by a sol‐gel process. For comparison, binary lanthanide SBA‐15 and SBA‐16 mesoporous hybrid materials (denoted as Ln(DBM‐SBA‐15)3 and Ln(DBM‐SBA‐16)3) are also synthesized. The luminescence properties of these resulting materials are characterized in detail, and the results reveal that ternary lanthanide mesoporous polymeric hybrid materials present stronger luminescence intensities, longer lifetimes, and higher luminescence quantum efficiencies than the binary lanthanide mesoporous hybrid materials. This indicates that the introduction of the organic polymer chain is a benefit for the luminescence properties of the overall hybrid system. In addition, the SBA‐15 mesoporous hybrids show an overall increase in luminescence lifetime and quantum efficiency compared with SBA‐16 mesoporous hybrids, indicating that SBA‐15 is a better host material for the lanthanide complex than mesoporous silica SBA‐16.  相似文献   

11.
Bismuth (Bi)‐containing SBA‐15 mesoporous silica catalysts, Bi/SBA‐15, with different Bi loadings were synthesized by a direct hydrothermal method. The materials were characterized in detail by various techniques. Powder‐X‐ray‐diffraction (PXRD), N2‐adsorption/desorption, and transmission‐electron‐microscopic (TEM) analyses revealed that the well‐ordered hexagonal structure of SBA‐15 is maintained after Bi incorporation. Diffuse‐reflectance UV/VIS, Raman, and X‐ray photoelectron spectroscopy (XPS) showed that the incorporated Bi‐atoms are highly dispersed, most of them entering the internal surface of SBA‐15. The new, very stable catalysts were found to be highly efficient for the oxidation of cyclohexane in a solvent‐free system, molecular oxygen (O2) being used as oxidant.  相似文献   

12.
以多羟基有机物α-或γ-环糊精为分散促进剂制备了Ni/SBA-15催化剂,通过N2吸附-脱附、X射线衍射、透射电镜、程序升温还原和热重等手段对该催化剂的物理化学性质进行了表征,并将其应用于甲烷二氧化碳重整(CRM)制合成气反应。结果显示,与采用传统浸渍法制备的Ni/SBA-15催化剂相比,采用α-或γ-环糊精改性法制备的催化剂具有更小的NiO颗粒,并在CRM中显示出更高的催化活性及更强的抗积碳性能。机理研究表明,采用传统浸渍法制备Ni/SBA-15催化剂时,浸渍液中的Ni2+主要在浓度梯度的作用下逐渐进入到SBA-15孔道内部, Ni2+水合物容易团聚,分散程度较低;而采用α-或γ-环糊精改性方法制备催化剂时,在水溶液中Ni2+与环糊精形成包覆物,环糊精携带Ni2+进入SBA-15孔道内,并且环糊精的存在使得Ni2+之间相互隔离,以高度分散形态存在于SBA-15孔道表面,有利于后续热处理中NiO在载体上较好地分散。  相似文献   

13.
A site‐selective controlled delivery system for controlled drug release is fabricated through the in situ assembly of stimuli‐responsive ordered SBA‐15 and magnetic particles. This approach is based on the formation of ordered mesoporous silica with magnetic particles formed from Fe(CO)5 via the surfactant‐template sol‐gel method and control of transport through polymerization of N‐isopropyl acrylamide inside the pores. Hydrophobic Fe(CO)5 acts as a swelling agent as well as being the source of the magnetic particles. The obtained system demonstrates a high pore diameter (7.1 nm) and pore volume (0.41 cm3 g?1), which improves drug storage for relatively large molecules. Controlled drug release through the porous network is demonstrated by measuring the uptake and release of ibuprofen (IBU). The delivery system displays a high IBU storage capacity of 71.5 wt %, which is almost twice as large as the highest value based on SBA‐15 ever reported. In vitro testing of IBU loading and release exhibits a pronounced transition at around 32 °C, indicating a typical thermosensitive controlled release.  相似文献   

14.
A novel type of oxovanadium(IV) 8‐hydroxyquinoline (8‐Q) complex and oxovanadium(IV) acetylacetonate (acac) complex were synchronously anchored on to amino‐modified SBA‐15 (named VO(acac:8‐Q)‐SBA‐15) and examined as a catalyst for styrene oxidation. The structure of the synthesized catalyst was characterized by means of X‐ray diffraction (XRD), FT‐IR, diffusion reflection UV–visible, inductively coupled plasma atomic emission spectroscopy (ICP‐AES), scanning electron microscopy (SEM), and thermogravimetric analysis (TG). Characterizations with FT‐IR, diffusion reflection UV‐visible, ICP‐AES and TG suggested the incorporation of oxovanadium(IV) complex in amino‐modified SBA‐15. XRD and SEM results indicated that SBA‐15 remained intact throughout the grafting procedure. It was found that VO(acac:8‐Q)‐SBA‐15 catalyst was more active than single‐ligand catalysts VO(acac)2‐SBA‐15 and VO(8‐Q)2‐SBA‐15 and that the product selectivity varied in cases of different oxidants. The catalyst VO(acac:8‐Q)‐SBA‐15 with two different ligands showed high yield of styrene oxide (45.8%) and good recoverability when using air as oxidant. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

15.
《中国化学》2017,35(10):1619-1626
A series of SBA‐15‐supported chromia‐ceria catalysts with 3% Cr and 1%–5% Ce (3Cr‐Ce/SBA) were prepared using an incipient wetness impregnation method. The catalysts were characterized by XRD, N2 adsorption, SEM, TEM‐EDX, Raman spectroscopy, UV–vis spectroscopy, XPS and H2‐TPR, and their catalytic performance for isobutane dehydrogenation with CO2 was tested. The addition of ceria to SBA‐15‐supported chromia improves the dispersion of chromium species. 3Cr‐Ce/SBA catalysts are more active than SBA‐15‐supported chromia (3Cr/SBA), which is due to a higher concentration of Cr6+ species present on the former catalysts. The 3Cr‐3Ce/SBA catalyst shows the highest activity, which gives 35.4% isobutane conversion and 89.6% isobutene selectivity at 570 °C after 10 min of the reaction.  相似文献   

16.
Mesoporous SBA‐15 was synthesized and modified with 3‐chloropropyltrimethoxysilane and then used in immobilization of creatinine groups, which were employed to introduce Y3+ and Ce3+ to give rise to two novel yttrium and cerium catalysts: SBA‐15@Creatinine@M (M = Y and Ce). The structures of the SBA‐15@Creatinine@M catalysts were determined using various techniques. These catalysts offered outstanding catalytic performances in the oxidation of sulfides to sulfoxides and in the preparation of 5‐substituted 1H‐tetrazoles. An important characteristic of the SBA‐15@Creatinine@M catalysts is that they are very stable without a considerable decrease in their catalytic performance lasting seven cycles.  相似文献   

17.
Water pollution by polychlorinated aromatic hydrocarbons has always been a global issue. In this work, we reported a synthesis of supported palladium catalysts Pd/C, Pd/CeO2, Pd/SBA‐15, Pd/ZrO2,Pd/SiO2, and Pd/Al2O3 as well as their catalytic activities on hydrodechlorination (HDC) of 1,2,4,5‐tetrachlorobenzene (TeCB). These Pd catalysts were characterized by Brunauer‐Emmett‐Teller (BET) specific surface area, Transmission electron microscopy (TEM), X‐ray diffraction (XRD), energy Dispersive X‐ray Fluorescence (EDXRF), CO‐chemisorption, and H2‐temperature programmed reduction (H2‐TPR) analysis. Pd/C, Pd/CeO2 and Pd/SBA‐15 catalysts showed relatively high catalytic activities. The catalytic activities were associated with dispersion of Pd, metal surface area, and reaction temperature, etc.  相似文献   

18.
《先进技术聚合物》2018,29(4):1322-1333
This work aims to develop novel composites from a poly(L ‐lactide‐co‐trimethylene carbonate‐co‐glycolide) (PLTG) terpolymer and mesoporous silica (SBA‐15) nanofillers surface modified by post‐synthetic functionalization. SBA‐15 first reacts with a silane coupling agent, γ‐aminopropyl‐trimethoxysilane to introduce ammonium group. PLLA chains were then grafted on the surface of SBA‐15 through ammonium initiated ring‐opening polymerization of L ‐lactide. Composites were prepared via solution mixing of PLTG terpolymer and surface modified SBA‐15. The structures and properties of pure SBA‐15, γ‐aminopropyl‐trimethoxysilane modified SBA‐15 (H2N‐SBA‐15), PLLA modified SBA‐15 (PLLA‐NH‐SBA‐15), and PLTG/PLLA‐NH‐SBA‐15 composites were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, N2 adsorption‐desorption, differential scanning calorimetry, contact angle measurement, and mechanical testing. The results demonstrated that PLLA chains were successfully grafted onto the surface of SBA‐15 with grafting amounts up to 16 wt.%. The PLTG/PLLA‐NH‐SBA‐15 composites exhibit good mechanical properties. The tensile strength, Young's modulus, and elongation at break of the composite containing 5 wt.% of PLLA‐NH‐SBA‐15 were 39.9 MPa, 1.3 GPa, and 273.6%, respectively, which were all higher than those of neat PLTG or of the composite containing 5 wt.% of pure SBA‐15. Cytocompatibility tests showed that the composites present very low cytotoxicity.  相似文献   

19.
Using high‐resolution transmission electronic micrograph (HR‐TEM) observation, one can clearly see the pore geometry of the MCM‐41 and SBA‐15 mesoporous silicas to determine that their pore shapes are hexagonal and round, respectively. With the perpendicular orientations of the nanochannels to the electron beam, parallel line images of the (100) and (110) repeating spacings were observed. In the SBA‐15 mesoporous silicas, there are byproducts of the granular silica and disordered mesostructures, attributed to the weak hydrogen interactions between Pluronic 123 blockcopolymer and the silica species. There are also many different and significant +π disclination defects in SBA‐15 and MCM‐41 surfactant‐silica composites. The SBA‐15 with a thicker silica wall is more stable under irradiation by high‐energy electron beams compared to MCM‐41, which has thinner wall thickness. Some carbon nanostructure impurities were found in some carbon films on the metal grids.  相似文献   

20.
A novel strategy to synthesize a functional mesoporous material for efficient removal of cesium is reported. Specifically, Prussian blue derivate‐modified SBA‐15 (SBA‐15@FC) was prepared by photoinitiated thiol–ene reaction between thiol‐modified SBA‐15 and pentacyano(4‐vinyl pyridine)ferrate complex. The effects of weight percentage of the Prussian blue derivate, pH, adsorbent dose, co‐existing ions, and initial concentration were evaluated on the adsorption of cesium ions. The adsorption kinetically follows a pseudo‐second‐order model and reaches equilibrium within 2 h with a high adsorption capacity of about 13.90 mg Cs g?1, which indicates that SBA‐15@FC is a promising adsorbent to effectively remove cesium from aqueous solutions.  相似文献   

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