SBA-15 Host Research Articles

Enhancement of the dispersion and catalytic performances of copper in the hydrogenation of cinnamaldehyde by incorporation of aluminium into mesoporous SBA-15 silica

Copper is active in hydrogenation reactions, but it is a base metal difficult to disperse inside mesostructured supports, with adverse consequences on the catalytic properties. Incorporating aluminium into mesoporous SBA-15 silicas allows solving both problems of Cu dispersion and activity. The incorporation of 20 wt.% Al2O3 in the SBA-15 host structure leads to an increase of the copper metallic surface area by a factor 6 compared to the pure siliceous SBA-15-supported catalyst. The support also proves to be stable upon exposure to the impregnation aqueous solution used for copper introduction. The incorporation of Al provides Lewis acidic sites that favour the transformation of cinnamaldehyde into cinnamyl alcohol, a feature usually assigned to larger metal particles. As a consequence, the catalytic activity of Cu catalysts is enhanced compared to silica-supported Cu catalysts, while the chemoselectivity towards the unsaturated alcohol appears to be similar to that of a mesoporous alumina-supported system.

PY13FSI-Infiltrated SBA-15 as Nonflammable and High Ion-Conductive Ionogel Electrolytes for Quasi-Solid-State Sodium-Ion Batteries.

Exploring electrolytes of high safety is essential to pave the practical route for sodium-ion batteries (SIBs) toward their important applications in large-scale energy storage and power supplies. In this regard, ionogel electrolytes (IEs) have been highlighted owing to their high ionic conductivity, prominent electrochemical and thermal stability, and, more crucially, high interfacial wettability. However, present studies lack an understanding of the interaction of IEs, which determines the ion desolvation and migration. In this article, IEs comprising an SBA-15 host, an ionic liquid, sodium salt, and poly(vinylidene fluoride)-hexafluoro propylene (PVDF-HFP) have been proposed by mechanical ball milling and roller pressing. The component ratio has been optimized based on the balance between ionic conductivity and self-supporting capability of IEs. The optimal IEs showed sufficiently high ionic conductivity (2.48 × 10-3 S cm-1 at 30 °C), wide electrochemical window (up to 4.8 V vs Na+/Na), and high Na+ transference number (0.37). Due to the presence of SBA-15 and an ionic liquid, the IEs exhibited much improved thermal resistance than that of the conventional organic liquid electrolytes (OLEs). Furthermore, Fourier transform infrared (FT-IR) spectroscopy revealed the hydrogen bonding interaction between silanols and the dissolved salts, not only anchoring anions for immobilization but also promoting the dissociation of sodium salts. After being matched with the Na3V2(PO4)3 (NVP) cathode and metallic Na anode, the SIBs presented a specific discharge capacity of up to 110.7 mA h g-1 initially at room temperature with 92% capacity retention after 300 cycles. The improved safety and electrochemical performance provided insights into rationally regulating IEs and their interactions with the prospect of strengthening their practical applications in SIBs.

Nanostructured SBA-15 host applied in ketorolac tromethamine release system.

The ordered mesoporous silica SBA-15 has been applied in studies of ketorolac tromethamine adsorption and release. The SBA-15 materials with hexagonal and regular structure were obtained using a triblock copolymer Pluronic P123 as a template and TEOS as a silica source. Ketorolac tromethamine was adsorbed into SBA-15 silica nanochannels using ethanol as solvent. The physicochemical and textural properties of SBA-15 and ketorolac tromethamine/SBA-15 were characterized by X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, fourier transform infrared spectroscopy and BET surface studies. Drug release was evaluated by soaking the loaded silica mesoporous material into a solution of HCl (0.1 N) at initial time (0-2 h) and buffer pH 7 at high times at 37 °C under continuous stirring. Oral commercial Keto tablets (Dolten®) and Keto solution (Keto power) were study for the contrast. Release studies were performed in order to evaluate the required therapeutic efficacy. SBA-15 provides significant improvement in the controlled release of ketorolac tromethamine. Release profile of KETO from SBA-15/KETO and control releases.

Impact of structural features of SBA-15 host particles on activity of immobilized glucose oxidase enzyme and sensitivity of a glucose sensor

Glucose oxidase (GOD) enzyme immobilized mesoporous silica particles (SBA-15) have been developed as an amperometric glucose sensor. SBA-15 particles with fibre, rod and cuboid morphologies of decreasing aspect ratio (12.1, 4.6 and 1.1), and increasing mesopore diameter (6.8, 6.8 and 11.4 nm), respectively, were synthesized, to understand the role of these structural parameters on enzyme activity and sensor performance. Microscopy and gas sorption experiments confirm that, as required, GOD (~7 nm size) immobilizes inside mesopores. Amongst all forms, cuboid SBA-15 showed the highest normalized absolute activity and reusability for at least six cycles. Thus, compared to rod SBA-15, an electrode with GOD immobilized-cuboid SBA-15 showed ten times higher sensitivity of 0.53 µA/cm2/mM, with a linearity range of 1.0–7.7 mM glucose and a short response time (<5 s). Hence, structural features of the host could be directly related to the sensor performance. Therefore, in general, SBA-15 hosts with a smaller particle aspect ratio and a larger internal mesopore diameter (like cuboid), together with appropriate enzyme loading density and presence of ferrocene as an electron mediator, can ensure a superior biosensor performance.

Synthesis of lanthanide-based SBA-15 mesoporous hybrids by a novel route

AbstractThe ligand N

Mesoporous hard-templated Me–Co [Me = Cu, Fe] spinel oxides for water gas shift reaction

Copper–cobalt and iron–cobalt oxides, as well as a cobalt oxide sample, were synthesized through the hard template (HT) route by using SBA-15 silica as the HT. Copper- and iron-containing materials with a Me/(Co + Me) atomic ratio of 9 and 17 mol% were obtained and characterized as to their structure, morphology, texture and redox properties by X-ray diffraction, FTIR spectroscopy, transmission electron microscopy, N2-physisorption and H2-temperature programmed reduction, respectively. All the oxides were tested in a fixed-bed reactor for the water gas shift reaction in the 200–350 °C temperature range. All the catalysts showed a spinel structure, with the copper ions occupying exclusively the tetrahedral positions in the Cu–Co spinels and the iron ions being present in both tetrahedral and octahedral positions in the Fe–Co spinels. Segregation (to a minor extent) of maghemite phase was detected only for the high-concentration iron–cobalt oxide. The materials were replicas of the topological structure of the template, the channels being void replicas of the former walls of the SBA-15 host and the oxide appearing as nanorods, arranged in a highly ordered way in the case of Cu–Co oxides. Compared to Co3O4, the copper-containing and the iron-containing spinels were easier and harder to reduce, respectively. While the catalytic activity of cobalt and iron–cobalt spinels was rather poor, a remarkable water gas shift activity, accompanied (to a minor extent) by methanation, was observed over Cu–Co spinels. The influence of the reduction features on the catalytic performance is discussed.

Preparation and Luminescence of Host-Guest (SBA-15)-(Arsenano-III) Nanocomposite Materials

The nanosized channels of SBA-15 molecular sieves were used as template and arsenano-III (ASA-III) was trapped inside the SBA-15 molecular sieves by means of liquid grafting method. The prepared nanocomposite materials were characterized by the powder X-ray diffraction, low temperature nitrogen adsorption-desorption and solid diffuse reflectance absorption spectra. The powder X-ray diffraction indicated the structure of the (SBA-15)-(ASA-III) still remains two-dimensional hexagonal mesostructrure. The low temperature nitrogen adsorption-desorption research showed that the ASA-III was present on the inner surface and partially occupied the channels of the molecular sieve. The UV-Vis solid state diffuse reflectance absorption spectra of the prepared composite materials showed the steroconfinmment effect of the host SBA-15 channels on the guest ASA-III and the guest was in the channels of the SBA-15 host. Luminous spectra showed that the prepared (SBA-15)-(ASA-III) nanocomposite materials have the investigating optical properties.

Composition-Dependent Morphostructural Properties of Ni–Cu Oxide Nanoparticles Confined within the Channels of Ordered Mesoporous SBA-15 Silica

NiO and NiO-CuO polycrystalline rodlike nanoparticles were confined and stabilized within the channels of ordered mesoporous SBA-15 silica by a simple and viable approach consisting in incipient wetness impregnation of the calcined support with aqueous solutions of metal nitrates followed by a mild drying step at 25 °C and calcination. As revealed by low- and high-angle XRD, N2 adsorption/desorption, HRTEM/EDXS and H2 TPR analyses, the morphostructural properties of NiO-CuO nanoparticles can be controlled by adjusting their chemical composition, creating the prerequisites to obtain high performance bimetallic catalysts. Experimental evidence by in situ XRD monitoring during the thermoprogrammed reduction indicates that the confined NiO-CuO nanoparticles evolve into thermostable and well-dispersed Ni-Cu heterostructures. The strong Cu-Ni and Ni-support interactions demonstrated by TPR and XPS were put forward to explain the formation of these new bimetallic structures. The optimal Ni-Cu/SBA-15 catalyst (i.e., Cu/(Cu+Ni) atomic ratio of 0.2) proved a greatly enhanced reducibility and H2 chemisorption capacity, and an improved activity in the hydrogenation of cinnamaldehyde, as compared with the monometallic Ni/SBA-15 or Cu/SBA-15 counterparts, which can be associated with the synergism between nickel and copper and high dispersion of active components on the SBA-15 host. The unique structure and controllable properties of both oxidic and metallic forms of Ni-Cu/SBA-15 materials make them very attractive for both fundamental research and practical catalytic applications.

Preparation of Stable Pt Nanoparticles Supported by Mesoporous Silica SBA-15

A simple two-step procedure towards the Pt nanoparticles and mesoporou silicate SBA-15 composite was developed in this work. The ultrasonic irradiation and the calcinations involved in the preparation did not destroy the size and morphology of prepared Pt nanoparticles, and no agglomeration of Pt nanoparticles was observed, thus stable Pt nanoparticles supported by SBA-15 host were formed. The hexagonal ordered structure of SBA-15 also remained. This stable composite are mainly used as the starting material in fabricating stable Pt nanoparticles doped glass.

Pt nanoparticles supported on highly dispersed TiO2 coated on SBA-15 as an efficient and recyclable catalyst for liquid-phase hydrogenation

A series of TiO2@SBA-15 composites with different TiO2 loadings have been synthesized through hydrolysis of tetrabutyl orthotitanate via a facile sol–gel method in the presence of SBA-15 mesoporous silica. The TiO2@SBA-15 composites retain the mesostructure of the SBA-15 host, and TiO2 is highly dispersed and uniformly coated. The TiO2@SBA-15 composites serve as remarkable supports for Pt nanoparticles, which can be applied efficiently to the liquid-phase hydrogenation of benzaldehyde, its derivatives, and other unsaturated compounds under mild conditions. Of particular note is that the Pt/TiO2@SBA-15 catalysts can be reused several times without distinct loss in activity or selectivity. The more electron-deficient surface state, together with the structural and physicochemical features of Pt/TiO2@SBA-15 catalysts, would improve the catalytic activity and reusability toward the liquid-phase hydrogenation of unsaturated compounds.

Synthesis, characterization and sustaining controlled release effect of mesoporous SBA-15/ramipril composite drug

A loading of ramipril in SBA-15 (Santa Barbara Amorphous) mesoporous material was studied. (SBA-15)-ramipril composite material was characterized by chemical analysis, infrared spectroscopy, powder X-ray diffraction, low temperature N2 adsorption–desorption at 77 K characterization techniques. Ramipril drug release processes from SBA-15 host to simulated body fluid (SBF), simulated gastric juice (SGJ), simulated intestinal fluid (SIF) were monitored in a simulated way and actions of the sustained release of (SBA-15)-ramipril was studied. The results showed that the loading amount of ramipril drug in SBA-15 was 90.30 mg/g. The cumulative sustained release rate of ramipril composite drug in SBF achieved 99.7 % after 27 h. When the sustained release of composite drug in SGJ was 8 h, the maximum cumulative sustained release ratio achieved 54.9 %. When the sustained release of composite drug was 9 h in SIF, the maximum cumulative sustained release ratio achieved 34.9 %. The method described in this study is suitable for carrying ramipril drug on SBA-15, and a new carrier to load ramipril drug was found. Meanwhile, the efficacy of ramipril drug and time efficacy could be improved.

Synthesis, characterization, and enhanced luminescence of CaWO4:Eu3+/SBA-15 composites

Considering the combination of lanthanide-doped CaWO4 nanophosphor and mesoporous matrix may contribute to superior luminescent properties, CaWO4:Eu3+/SBA-15 composites were successfully synthesized in a mild condition. The physicochemical properties of the resultant composites were carefully characterized by X-ray diffraction, high-resolution transmission electron microscopy, inductive coupled plasma optical emission spectroscopy (ICP), N2 adsorption–desorption, Fourier transform infrared spectroscopy, and luminescence spectra. It’s found that the incorporation of CaWO4:Eu3+ showed no obvious impact on the ordered mesostructure of the host matrix SBA-15, which, however, led to a decrease of BET surface area from 836 to 187 m2 g−1 for pure SBA-15 and CES (0.5), respectively. ICP results indicated that the real loaded amount of CaWO4:Eu3+ in SBA-15 host was lower than the initial molar ratios (x) of CaWO4:Eu3+ to SBA-15 for all samples. The maximum loaded level of CaWO4:Eu3+ in SBA-15 is about 27.3 %. Moreover, the real Eu3+ dopant concentration increased with the initial molar ratios (x), which showed a maximum of about 6.51 % at x = 0.25. The resultant CaWO4:Eu3+/SBA-15 composites exhibited enhanced-luminescent properties than that of pure CaWO4:Eu3+ nanoparticles, which can be mainly attributed to the variation of Eu3+ dopant concentration and the host-protect effect through interaction between guest molecules and host matrix. The available large surface area, pore volume, and superior luminescent properties would facilitate future applications for the composites.

Metallic inorganic/organic hybrid system through functionalized Schiff-base linkage: Molecular assembly, characterization and luminescence

In this paper, two Schiff-base compounds (N,N′-bis(salicylidene)-1,3-ethylenediamine (BSEA) and N,N′N″-tris(salicylidene)-(2-aminoethyl) amine (TSAEA)) are modified with a crosslinking reagent isocyanate propyl triethoxysilane (TESPIC) to achieve two linkages (BSEASi and TSAEASi). Then metallic (Ni 2+, Mn 2+, Co 2+) inorganic/organic hybrids with functionalized Schiff-base linkages are prepared with coordination bonding. Then the corresponding mesoporous hybrids with BSEASi functionalized SBA15 host are assembled. All these hybrids are characterized in detail and particularly the photoluminescence of them shows that they all show the luminescence of the organically bonded host and metal ions that only disturb it.

PH‐Responsive Release of Acetal‐Linked Melittin from SBA‐15 Mesoporous Silica

Free to go: A pH-labile immobilization of the melittin peptide with acetal linkers in the pore system of a SBA-15 host allows release of the peptide upon decrease of the pH value from 7.4 to 5.5. Such a release is shown by melittin-induced lysis of mouse erythrocytes. The method could be used to prepare new silica-based peptide delivery systems for targeted cancer therapy.

Stacking Structure of Confined 1‐Butanol in SBA‐15 Investigated by Solid‐State NMR Spectroscopy

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 (1)H spin-lattice (T(1)), spin-spin (T(2)) relaxation, (13)C cross-polarization (CP), and (1)H,(1)H two-dimensional nuclear Overhauser enhancement spectroscopy ((1)H,(1)H 2D NOESY) with the magic angle spinning (MAS) technique as well as static wide-line (2)H 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 (1)H,(1)H 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 (1)H,(1)H 2D NOESY technique.

Synthesis and Characterization of Biopolymer Composites from the Inside Out

The metal catalyzed ring-opening polymerization of d,l-lactide monomer inside the nanometer-sized channels of MCM-41 and SBA-15 hosts, creating an organic−inorganic hybrid polymeric material, is described. Detailed characterization of the polylactide/mesoporous silica organic−inorganic composite by multiple spectroscopic, microscopy, and calorimetric methods, as well as solvent extraction, reveals that the resulting in situ synthesized composite is unique relative to physical or solution-cast mixtures of polylactide and the mesoporous host. In this contribution, we focus on the incorporation of the stannous octanoate (Sn2+) catalyst inside the mesoporous host channels prior to monomer introduction and subsequent polymerization and specifically target the differentiation of polymerization chemistry that occurs inside the host channels versus less desirable reactions on the exterior surface of the mesoporous host crystallites.

Properties of iron-based mesoporous silica for the CWPO of phenol: A comparison between impregnation and co-condensation routes

Iron-based mesoporous silica materials were prepared according to different impregnation and co-condensation procedures. Several complementary techniques, including XRD, TEM/EDX and nitrogen sorption isotherms were used to evaluate the final structural and textural properties of the calcined Fe/SBA-15 materials. While Fe 2O 3 isolated particles of which the size is close to the silica pore diameter (∼7–8 nm) were obtained using classical wet impregnation procedure, smaller iron oxide particles (∼2–4 nm) homogeneously dispersed within the hexagonal pore structure of the SBA15 host support were generated by self-combustion of an impregnated iron-glycinic complex. By contrast, the various co-condensation routes used in this work were less efficient to generate iron oxide nanoparticles inside the silica mesopores. Catalytic performances of the materials were evaluated in the case of total phenol oxidation by H 2O 2 in aqueous solution at ambient conditions. Large differences in terms of catalytic activity and iron species stability were observed. While the impregnated solids proved to be the most active catalysts (highest Fe 2O 3 nanoparticles dispersion), iron leaching was observed in aqueous solution, accounting for a homogeneous catalytic contribution. In contrast, the co-condensed samples exhibiting larger iron oxide clusters stabilized over the silica surface proved more efficient as active sites in Fenton catalysis.

Capturing 1,3-butadiene by the highly ordered Al-containing SBA-15

This investigation examined the instantaneous adsorption of 1,3-butadiene by aluminum-modified mesoporous silica SBA-15 at ambient temperature. To efficiently trap the 1,3-butadiene pollutant in environment, alumina was incorporated in SBA-15 through various pathways such as one-pot synthesis, solid state grinding and impregnation, and the property–function relation of resulting composites were characterized with XRD, N 2 adsorption–desorption, FTIR and NH 3-TPD techniques. Adsorption of N-nitrosopyrrolidine (NPYR) was employed for the first time to reveal the difference between the mesoporous silica with the same Al-content but prepared with different methods, providing a potential method for the delicate characterization. Modification with alumina significantly increased the capability of SBA-15 to adsorb 1,3-butadiene, and the one-pot synthesized sample exhibited a higher activity than the post-modified samples, resulting from the formation of Brønsted acidic sites and reservation of silianol groups on SBA-15 host.

Synthesis and Characterization of Noble Metal (Pd, Pt, Au, Ag) Nanostructured Materials Confined in the Channels of Mesoporous SBA-15

Highly dispersed metal (Pd, Pt) nanoparticles and uniformly distributed metal (Au, Ag) nanowires have been synthesized in ordered mesoporous silica SBA-15 via conventional incipient wetness impregnation followed by novel glow discharge plasma reduction. N2 adsorption−desorption isotherms and the low-angle X-ray diffraction (XRD) patterns indicate that the parent ordered mesoporous structure was well-maintained during the synthesis process. The wide-angle XRD patterns and transmission electron microscope images demonstrate that spherical Pd and Pt nanoparticles as well as rodlike Au and Ag nanowires were fabricated within the channels of SBA-15. The diameters of the metal nanoparticles and the metal nanowires were effectively controlled by the mesopores of the SBA-15 host. The population of the metal nanoparticles and the length of the metal nanowires can be tuned by the metal loading amount. In particular, the novel plasma reduction at ambient temperature is green, economical, and non-time-consuming, show...

Effect of pore diffusional resistance on biocatalytic activity of Burkholderia cepacia lipase immobilized on SBA-15 hosts

The present study was focused on elucidating the effects of nanopore diffusional resistance on the activity of Burkholderia cepacia (BC lipase) lipase immobilized in ordered mesoporous silica hosts. BC lipase was immobilized in ordered SBA-15 hosts possessing 55 and 240 A ˚ diameter pores by physical adsorption. A colorimetric assay of p-nitrophenyl acetate was employed to determine the lipase catalytic activity. The effect of diffusional resistance on catalytic activity of lipase immobilized in SBA-15 hosts was investigated by determining the effective substrate diffusivity as a function of pore size of the SBA-15 host and enzyme loading. Lipase immobilized in SBA-15- 55 A ˚ exhibited 20–30% of free lipase activity and the activity was further reduced with enzyme loading due to limited accessibility of substrate to the enzyme active sites. Lipase immobilized in SBA-15- 240 A ˚ hosts showed catalytic activity similar to free lipase activity suggesting that diffusional limitations were minimal. Large pore SBA-15 hosts provided an improved environment for BC lipase to retain its catalytic activity.