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1.
Geoffrey Lawrence Arun V Baskar Mohammed H El-Newehy Wang Soo Cha Salem S Al-Deyab Ajayan Vinu 《Science and Technology of Advanced Materials》2015,16(2)
Three-dimensional cage-like mesoporous FDU-12 materials with large tuneable pore sizes ranging from 9.9 to 15.6 nm were prepared by varying the synthesis temperature from 100 to 200 °C for the aging time of just 2 h using a tri-block copolymer F-127(EO106PO70EO106) as the surfactant and 1,3,5-trimethyl benzene as the swelling agent in an acidic condition. The mesoporous structure and textural features of FDU-12-HX (where H denotes the hydrothermal method and X denotes the synthesis temperature) samples were elucidated and probed using x-ray diffraction, N2 adsorption, 29Si magic angle spinning nuclear magnetic resonance, scanning electron microscopy and transmission electron microscopy. It has been demonstrated that the aging time can be significantly reduced from 72 to 2 h without affecting the structural order of the FDU-12 materials with a simple adjustment of the synthesis temperature from 100 to 200 °C. Among the materials prepared, the samples prepared at 200 °C had the highest pore volume and the largest pore diameter. Lysozyme adsorption experiments were conducted over FDU-12 samples prepared at different temperatures in order to understand their biomolecule adsorption capacity, where the FDU-12-HX samples displayed high adsorption performance of 29 μmol g−1 in spite of shortening the actual synthesis time from 72 to 2 h. Further, the influence of surface area, pore volume and pore diameter on the adsorption capacity of FDU-12-HX samples has been investigated and results are discussed in correlation with the textural parameters of the FDU-12-HX and other mesoporous adsorbents including SBA-15, MCM-41, KIT-5, KIT-6 and CMK-3. 相似文献
2.
Wen-Ting Qiao Guo-Wei Zhou Xiao-Tong Zhang Tian-Duo Li 《Materials science & engineering. C, Materials for biological applications》2009,29(4):1498-1502
TiO2–SBA-15 complex materials with highly ordered mesostructures have been prepared by a one-step hydrothermal synthesis method of titanium tetraisopropoxide (TTIP) and tetraethoxysilane (TEOS) in an acidic solution using surfactant P123 (EO20PO70EO20) as structure-directing reagent. The prepared materials were characterized by transmission electron microscopy (TEM), small-angle X-ray diffraction patterns (SAXRD), Fourier transformed infrared spectroscopy (FT-IR) and N2 adsorption–desorption experiments. The resulting TiO2–SBA-15 complex materials showed highly ordered mesoporous structure with uniform pore sizes of 5.95 and 8.24 nm, high specific surface areas SBET of 689 m2 g? 1 and 347 m2 g? 1 at different hydrothermal temperatures (100 °C and 130 °C). The photocatalytic activity of these TiO2–SBA-15 mesoporous materials has been studied by 4-chlorophenol decomposition under UV light irradiation. The TiO2–SBA-15 mesoporous materials prepared at the TiO2:SiO2 mass ratios of 25:75, 40:60 and 50:50 showed higher photocatalytic activity than that prepared at the TiO2:SiO2 mass ratio of 75:25. 相似文献
3.
Comparative research of matrix and bulk carbonization of some organic precursors (sucrose, acetonitrile) in silica mesoporous
materials SBA-15 and KIT-6 was conducted. X-ray diffraction, nitrogen adsorption analysis, Raman spectroscopy were used for
determination of the structural-sorption characteristics of the obtained materials. It was shown that the carbon mesoporous
materials CMK-8 obtained in the mesopores of KIT-6 had higher adsorption characteristics because of features of three-dimensional
cubic structure, larger pore volume and framework’s wall thickness. It was established that partially graphitized spatially
well-organized carbon materials were formed as a result of pyrolysis of acetonitrile in the silica matrices SBA-15 and KIT-6.
It was conditioned by the absence of considerable spatial limitations for growth of graphite structures on the initial stage
of the synthesis when the pores of the matrix were not filled up with the organic precursor. Product of bulk carbonization
of sucrose is compact carbon microporous framework with low sorption characteristics (micropore volume is 0.09 cm3/g). 相似文献
4.
Exploring polymeric surfactants as templates for synthesizing ordered mesoporous silicas has become increasingly important
for both academic interests and industrial applications. In this work, we employed C16EO40, a di-block copolymer polyethylene-poly(ethylene oxide), as template in an attempt to synthesize a modified 3-dimensional
wormhole mesoporous silicas (WMS-39). In addition, various synthesizing conditions were investigated, including pre-hydrolysis
time of TEOS, reaction temperatures and the ratios of TEOS to template. The products were characterized using powder XRD,
TEM, 29Si MAS NMR and nitrogen adsorption measurements. The characteristics of as-synthesized mesoporous silica were compared with
SBA-15, a highly ordered mesoporous silica, prepared using non-ionic tri-block copolymers of poly(ethylene oxide)–poly(propylene
oxide)–poly(ethylene oxide) as templates. The WMS-39 materials have a BET surface area of 600–970 m2/g and narrowly distributed pore diameter around 3.9 nm. The morphology of WMS-39 was found to be wormhole framework as indicated
in TEM diagrams. Thermal transformation of the as-synthesized mesoporous materials were carefully analyzed with TGA/DTA. Findings
obtained from this work enable us to propose a modified assembly mechanism of mesoporous silicas. 相似文献
5.
In this study, we report the pore expansion effect of gelatin, a common amphoteric biological protein, on the hexagonal mesoporous
silica materials. Tetraethyl orthosilicate (TEOS) was used as silica source and the nonionic surfactant P123 (EO20PO70EO20) as template. The microstructure characters of products were investigated by low-angle X-ray diffraction (LAXRD), transmission
electron microscope (TEM), and N2 adsorption–desorption measurements. The results show that the products prepared with gelatin have the mild expansion ratios
of 29–39% and 5–22% in pore diameter and pore volume, respectively. The specific surface area of products ranges from 445
to 590 m2 g−1. Moreover, it is revealed that the presence of gelatin did not change the intact 2D-hexagonal mesoporous structure of materials.
The ultraviolet–visible absorption spectroscopy (UV–Vis) analysis indicates that there is an interaction between the oxygen
atoms of P123 and gelatin molecules. The pore expansion may be because the gelatin can interact with the hydrophilic sides
of P123 micelles via hydrogen bonds interaction, which is different from the reported pore expansion mechanisms for other
systems. 相似文献
6.
Template‐Free Fabrication of Mesoporous Alumina Nanospheres Using Post‐Synthesis Water‐Ethanol Treatment of Monodispersed Aluminium Glycerate Nanospheres for Molybdenum Adsorption
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Indra Saptiama Yusuf Valentino Kaneti Yoshitaka Suzuki Kunihiko Tsuchiya Nobuyoshi Fukumitsu Takeji Sakae Jeonghun Kim Yong‐Mook Kang Katsuhiko Ariga Yusuke Yamauchi 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(21)
This work reports the template‐free fabrication of mesoporous Al2O3 nanospheres with greatly enhanced textural characteristics through a newly developed post‐synthesis “water‐ethanol” treatment of aluminium glycerate nanospheres followed by high temperature calcination. The proposed “water‐ethanol” treatment is highly advantageous as the resulting mesoporous Al2O3 nanospheres exhibit 2–4 times higher surface area (up to 251 m2 g?1), narrower pore size distribution, and significantly lower crystallization temperature than those obtained without any post‐synthesis treatment. To demonstrate the generality of the proposed strategy, a nearly identical post‐synthesis “water treatment” method is successfully used to prepare mesoporous monometallic (e.g., manganese oxide (MnO2)) and bimetallic oxide (e.g., CuCo2O4 and MnCo2O4) nanospheres assembled of nanosheets or nanoplates with highly enhanced textural characteristics from the corresponding monometallic and bimetallic glycerate nanospheres, respectively. When evaluated as molybdenum (Mo) adsorbents for potential use in molybdenum‐99/technetium‐99m (99Mo/99mTc) generators, the treated mesoporous Al2O3 nanospheres display higher molybdenum adsorption performance than non‐treated Al2O3 nanospheres and commercial Al2O3, thereby suggesting the effectiveness of the proposed strategy for improving the functional performance of oxide materials. It is expected that the proposed method can be utilized to prepare other mesoporous metal oxides with enhanced textural characteristics and functional performance. 相似文献
7.
Vinu A Miyahara M Hossain KZ Takahashi M Balasubramanian VV Mori T Ariga K 《Journal of nanoscience and nanotechnology》2007,7(3):828-832
In this paper, adsorption of lysozyme onto two kinds of mesoporous adsorbents (KIT-5 and AISBA-15) has been investigated and the results on the effects of pore geometry and stability of the adsorbents are also discussed. The KIT-5 mesoporous silica materials possess cage-type pore geometry while the AISBA-15 adsorbent has mesopores of cylindrical type with rather large diameter (9.7 nm). Adsorption of lysozyme onto AISBA-15 aluminosilicate obeys a Langmuir isotherm, resulting in pore occupation of 25 to 30%. In contrast, the KIT-5 adsorbents showed very small adsorption capacities for the lysozyme adsorption, typically falling in 6 to 13% of pore occupation. The cage-type KIT-5 adsorbents have narrow channel (4 to 6 nm) where penetration of the lysozyme (3 x 3 x 4.5 nm) might be restricted. The KIT-5 adsorbent tends to collapse after long-time immersion in water, as indicated by XRD patterns, while the AISBA-15 adsorbent retains its regular structure even after immersion in basic water for 4 days. These facts confirm superiority of the AISBA-15 as an adsorbent as compared with the KIT-5 mesoporous silicates. This research strikingly demonstrates the selection of mesoporous materials is crucial to achieve efficient immobilization of biomaterials in aqueous environment. 相似文献
8.
Chromium-substituted MCM-48-like large pore mesoporous silica with average pore size up to 10 nm was directly synthesized
by using P123 (EO20PO70EO20) as a template, n-butanol as an assistant, and chromic nitrate nonahydrate as a chromium source. The Cr species was doped by simply adjusting
the pH of the synthesis system with ammonia from strong acid to nearly neutral after crystallization for 24 h. The Si/Cr ratios
in the initial gel ranged from 10 to 80, and the actual weight percentage of Cr was analyzed by ICP. XRD pattern, high-resolution
TEM, and N2 adsorption–desorption isotherm were employed to investigate the pore structure properties of these materials. The results
showed that all the samples had Ia3d cubic structure and the pore channels were highly ordered. UV–vis, wide-angle XRD, and ESR spectra revealed that at lower
Cr content (Si/Cr > 30), only Cr (VI) and Cr(V) species existed in the mesoporous framework, and at higher Cr content, Cr
(III) species appeared. 相似文献
9.
Magdalena Kwaśny Anna Kowalewska Krystyna Wodnicka Mirosław Handke 《Journal of Materials Science》2013,48(15):5188-5195
Mesoporous silica, due to its porosity and morphological features, have been considered a fascinating material for many technological applications. In this report, we describe the preparation of a structurally stable mesoporous silica material using octahydridooctasilsesquioxane (T8 H). The structure and properties of final samples were determined by XRD, FT-IR, and TEM methods. Structural analysis has shown that the siliceous material is amorphous but mesoporous. BET surface area, pore volumes, and pore size distribution were measured using nitrogen sorption methods—data were collected from the adsorption branch using BJH method for mesopores and t-plot method for micropores. It was found that the cage-type structure of T8 H molecules and the process conditions determine the specific morphology of the cross-linked products. Completely inorganic, mesoporous silica of a narrow pore distribution was obtained. It was found that the materials have large surface area and pores in the meso range (2–5 nm). The amount of mesopores and the characteristic surface area of the prepared samples strongly depended on the reaction conditions. 相似文献
10.
《Materials Letters》2004,58(22-23):2872-2877
Large mesoporous aluminas have been prepared by the hydrolysis of aluminum tri-sec-butoxide in the presence of cetyltrimethylammonium bromide (CTAB) using oil-in-water microemulsion template. These resulting materials showed a disordered mesostructure with large mesopore frameworks. It is found to convert the intermediate phase (hydrated pseudoboehmite) into γ-Al2O3 at 268.7 °C. The large mesoporous alumina materials possess relative narrow mesoporous size distribution, high surface area (407.2 m2/g) and pore volumes (0.877 cm3/g). The prepared materials exhibited higher performance as catalyst support than that of the similar commercial γ-Al2O3 granules. 相似文献
11.
Ordered mesoporous silicas with different pore structures, including SBA-15, MCM-41, MCM-48 and KIT-6, were functionalized with phenyltriethoxysilane by a post-synthesis grafting approach. It was found that phenyl groups were covalently anchored onto the surface of mesoporous silicas, and the long-range ordering of the mesoporous channels was well retained after the surface functionalization. The static adsorption of benzene and the dynamic adsorption of single component (benzene) and bicomponent (benzene and cyclohexane) on the original and functionalized materials were investigated. As indicated by the adsorption study, the functionalized silicas exhibit improvement in the surface hydrophobicity and affinity for aromatic compounds as compared with the original silicas. Furthermore, the pore structure and the surface chemistry of materials can significantly influence adsorption performance. A larger pore diameter and cubic pore structure are favorable to surface functionalization and adsorption performance. In particular, the best adsorption performance observed with phenyl-grafted KIT-6 is probably related to the highest degree of surface functionalization, arising from the relatively large mesopores and bi-continuous cubic pore structure which allow great accessibility for the functional groups. In contrast, functionalized MCM-41 exhibits the lowest adsorption efficiency, probably owing to the small size of mesopores and 1D mesoporous channels. 相似文献
12.
《Materials Letters》2007,61(23-24):4569-4572
Highly 3D body centered cubic (Im3m) ordered mesoporous bioactive glasses (MBG) were synthesized by evaporation-induced self-assembly (EISA) in the presence of a nonionic triblock copolymer, EO100PO65EO100 (F127), template. The influence of the F127 concentration on the mesostructure was examined. MBG calcined at 600 °C possessed a large specific surface area (∼ 520 m2 g− 1) and pore volume (0.51 cm3 g− 1) and a uniformly distributed pore size (5.4 nm). In vitro bioactivity studies were carried out in simulated body fluid (SBF). 相似文献
13.
Industrial TiOSO4 solution was used as inorganic precursor to prepare mesoporous titania via composite template route, using cetyl-trimethylammonium bromide (CTAB) and tri-block copolymer EO20PO70EO20 (P-123) as structure-directing agents (SDA) under high acidic conditions. Mesoporous TiO2 with high thermal stability was obtained via controlling the hydrolysis and condensation rate of industrial TiOSO4 solution by adjusting the pH value and post hydrothermal treating. The as-prepared materials were characterized by XRD, nitrogen adsorption-desorption, SEM and HRTEM. The powder calcined at 723 K for 2 h showed higher thermal stability, with BET specific surface area of 218.7 m2/g and an average pore diameter of 3.63 nm. 相似文献
14.
《Materials Letters》2007,61(19-20):4137-4139
Novel monolithic mesoporous silica was synthesized with a new SDA (Structure-Directing Agent) of PE6400 (EO13PO30EO13). The monolithic silica was found possessing special “oriented block” structure at nano-scale where pore channels' orientations were the same in a single block but not always the same in different blocks. Pore channels of a single oriented block were well ordered hexagonally oriented. Moreover, the average pore diameter, the average wall thickness, the specific surface area and the pore volume of the obtained monolithic silica were 3.5 nm, 3.3 nm, 777.5 m2/g and 0.44 m3/g, respectively. 相似文献
15.
We have examined the effect of solution acidity on the textural characteristics of silica gels prepared by sol–gel synthesis using tetraethyl orthosilicate (TEOS) as a silica precursor and cetyltrimethylammonium bromide (CTAB) as a template. Using IR spectroscopy, we have studied micellar TEOS solutions and the synthesized silica gel samples. The results demonstrate that, in an alkaline medium in a water–ethanol solution, SiO2 experiences short-range ordering on the surface of micelles formed by CTAB molecules, whereas in an acid medium the process is not influenced by the presence of CTAB. Nitrogen porosimetry and electron microscopy data indicate that the silica gel obtained at pH 2 is microporous, with an average pore size of 2 nm. In an alkaline medium at pH 10, we obtained mesoporous SiO2 (18 nm) with a narrow pore size distribution and a specific surface area of 110 m2/g. 相似文献
16.
Narges Habibi Yuan Wang Hamidreza Arandiyan Mehran Rezaei 《Advanced Powder Technology》2017,28(4):1249-1257
A simple, template-free and scalable modified sol-gel route was developed for the synthesis of mesoporous flake-like magnesium aluminate spinel (MgAl2O4) at low temperature (700 °C) with high surface area (281 m2 g?1). The obtained spinel materials were characterized by means of physicochemical techniques including X-ray diffraction, thermogravimetric analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and N2 adsorption-desorption analysis. The propylene oxide was used as gelation and pore forming agent in the sol-gel process. Different morphologies and sizes of flake were generated by the varied synthesis conditions. The result materials reveal that the textural properties of the MgAl2O4 product are strongly associated with the nature and amount of addictive solvent and calcination temperatures. It shows that the BET surface area decrease as the increase of calcination temperature and the optimal temperature of 700 °C result in the pure phase of MgAl2O4 spinel. This synthesis strategy offers a feasible approach for scalable fabrication of mixed metal oxides for various catalytic reactions or catalyst supports due to the large surface area. 相似文献
17.
Roland Marschall Inga Bannat Armin Feldhoff Lianzhou Wang Gao Qing Lu Michael Wark 《Small (Weinheim an der Bergstrasse, Germany)》2009,5(7):854-859
Nanometer‐sized mesoporous silica particles of around 100‐nm diameter functionalized with a large amount of sulfonic acid groups are prepared using a simple and fast in situ co‐condensation procedure. A highly ordered hexagonal pore structure is established by applying a pre‐hydrolysis step in a high‐dilution synthesis approach, followed by adding the functionalization agent to the reaction mixture. The high‐dilution approach is advantageous for the in situ functionalization since no secondary reagents for an effective particle and framework formation are needed. Structural data are determined via electron microscopy, nitrogen adsorption, and X‐ray diffraction, proton conductivity values of the functionalized samples are measured via impedance spectroscopy. The obtained mesoporous SO3H‐MCM‐41 nanoparticles demonstrate superior proton conductivity than their equally loaded micrometer‐sized counterparts, up to 5 × 10?2 S cm?1. The mesoporosity of the particles turns out to be very important for effective proton transport since non‐porous silica nanoparticles exhibit worse efficient proton transport, and the obtained particle size dependence might open up a new route in rational design of highly proton conductive materials. 相似文献
18.
The multicomponent materials La–Ce–Co–Zr–O were first prepared by using mixed surfactants comprised of p-octyl polyethylene
glycol phenyl ether (OP) and cetyltrimethyl-ammonium bromide (CTAB) as co-templates, which show large specific surface areas
(up to 163 m2/g) and uniform pore size distributions (3.4–3.6 nm) after calcination at 500 °C. High-resolution transmission electron microscopy
(HR-TEM) image shows that these materials possess wormhole-like mesoporous structures. N2 adsorption/desorption indicates that the coexistence of La and Ce in a proper atomic ratio is very crucial to improve the
thermal stability of these mesoporous materials. The catalyst with La/Ce atomic ratio of 1/16 exhibits the best thermal stability.
After calcination at 700 °C, its specific surface area is still up to 54 m2/g, much larger than those for the most reported LaCoO3-related perovskite. Temperature-programed reduction (H2-TPR) results show that the coexistence of La and Ce in a ratio of 1/16 can bring more profound Co–Ce interaction and the
highest mobility of Co–O bond in the catalyst calcined at 700 °C. The mesoporous material La–Ce–Co–Zr–O with La/Ce atomic
ratio of 1/16 exhibits not only high-thermal stability, but also novel catalytic activity for CO oxidation. 相似文献
19.
《Materials Letters》2006,60(21-22):2682-2685
The preparation of a Al-MCM-41 mesoporous materials has been carried out using silica-gel and pseudoboehmite as silica and aluminum sources, respectively, and surfactant cetyltrimethylammonium bromide as structure template. The textural properties of the calcined Al-MCM-41 were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and N2 isothermal adsorption measurements. The hexagonal structure parameter ao was calculated based on d(100) XRD reflection as 4.75 nm. TEM images revealed the formation of a well-ordered Al-MCM-41. Accordingly, nitrogen adsorption measurements (BJH) showed a material with very narrow distribution and medium pore diameter of 3.14 nm. Mesopore volume based on adsorbed nitrogen was 0.51 cm3 g− 1. Through a combination of XRD and N2 adsorption data, the thickness of the channel walls of 1.61 nm could be calculated. 相似文献
20.
Zr-based MCM-41 mesoporous molecular sieves (ZrMCM-41) were successfully synthesized by microwave irradiation method and hydrothermal
method, respectively. The obtained samples were characterized by XRD, TEM, FT-IR and N2 physical adsorption. The results show that the samples synthesized by the two different methods both possess typical hexagonal
mesoporous structure of MCM-41 and high specific surface areas (over 800 m2/g). After calcination at 750°C for 3 h or hydrothermal treatment at 100°C for 6 days, the mesoporous structure of the samples
still retained, however, the mesoporous ordering is poor. Under the comparable conditions, the reaction time required in the
synthesis of ZrMCM-41 by microwave irradiation method was greatly reduced, and microwave irradiation method is eco-friendly
and is easy to operate. 相似文献