scholarly journals A Structural Comparison of Ordered and Non-Ordered Ion Doped Silicate Bioactive Glasses

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 992
Author(s):  
Seray Schmitz ◽  
Ana M. Beltrán ◽  
Mark Cresswell ◽  
Aldo R. Boccaccini
Keyword(s):  
Metal Ion ◽  
Sol Gel ◽  
Glass Network ◽  
Textural Properties ◽  
Mesoporous Structure ◽  
Structure Directing Agent ◽  
Surface Areas ◽  
Pluronic P123 ◽  
Gel Glasses ◽  
The One

One of the key benefits of sol-gel-derived glasses is the presence of a mesoporous structure and the resulting increase in surface area. This enhancement in textural properties has a significant effect on the physicochemical properties of the materials. In this context the aim of this study was to investigate how sol-gel synthesis parameters can influence the textural and structural properties of mesoporous silicate glasses. We report the synthesis and characterization of metal ion doped sol-gel derived glasses with different dopants in the presence or absence of a surfactant (Pluronic P123) used as structure-directing templating agent. Characterization was done by several methods. Using a structure directing agent led to larger surface areas and highly ordered mesoporous structures. The chemical structure of the non-ordered glasses was modified to a larger extent than the one of the ordered glasses due to increased incorporation of dopant ions into the glass network. The results will help to further understand how the properties of sol-gel glasses can be controlled by incorporation of metal dopants, in conjunction with control over the textural properties, and will be important to optimize the properties of sol-gel glasses for specific applications, e.g., drug delivery, bone regeneration, wound healing, and antibacterial materials.

Sol–gel derived SiO2–B2O3–Na2O–ZnO–Al2O3 glass powder for glass-based composite

2019 ◽  
Vol 34 (04) ◽  
pp. 2050052
Author(s):  
Changxiu Wen ◽  
Xiaoxia Cui ◽  
Yantao Xu ◽  
Pengxiang Yang ◽  
Xiaozhang Wang ◽  
...  
Keyword(s):  
Glass Powder ◽  
Coefficient Of Thermal Expansion ◽  
Sol Gel ◽  
Glass Network ◽  
Treatment Temperature ◽  
Synthesis Conditions ◽  
Surface Areas ◽  
Ft Ir ◽  
The Fourier Transform ◽  
Gel Glasses

The glass powder with a relatively complicated composition of 64.02SiO2–10.05B2O3–7.84Na2O–14.07ZnO–4.02Al2O3 (in wt.%) was first synthesized via sol–gel route. The optimal synthesis conditions for the amorphous gel are obtained. The glass transition temperature [Formula: see text] of xerogel was detected as 552[Formula: see text]C and the glass network structure formed by the [SiO4], [BO4] and [AlO4] units were confirmed by the Fourier Transform-Infrared Spectroscopy (FT-IR). The phase structure and morphologies of glass powder were characterized by X-ray diffractometer (XRD) and Field Emission-Scanning Electron Microscope (FE-SEM), the xerogels and sol–gel glasses exhibit amorphous phase when the heat-treatment temperature increases from [Formula: see text]C to [Formula: see text]C. The prepared glass powder with high specific surface areas and a large amount of pores contribute to the synthesis of a composite of glass-mullite-[Formula: see text]-eucryptite at a relatively low sintering temperature of [Formula: see text]C, which present a relatively low coefficient of thermal expansion (CTE) and high mechanical strength.

scholarly journals Hydrocracking of Polyethylene to Jet Fuel Range Hydrocarbons over Bifunctional Catalysts Containing Pt- and Al-Modified MCM-48

Reactions ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 195-209
Author(s):  
Yanyong Liu
Keyword(s):  
Mesoporous Silica ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
Jet Fuel ◽  
Magic Angle Spinning ◽  
High Yield ◽  
Magic Angle ◽  
Surface Areas ◽  
Angle Spinning ◽  
Post Modification

A low-density polyethylene was hydrocracked to liquid hydrocarbons in autoclave reactors over catalysts containing Pt- and Al-modified MCM-48. Two kinds of Al-modified MCM-48 were synthesized for the reaction: Al-MCM-48 was synthesized using a sol–gel method by mixing Al(iso-OC3H7)3 with Si(OC2H5)4 and surfactant in a basic aqueous solution before hydrothermal synthesis, and Al/MCM-48 was synthesized using a post-modification method by grafting Al3+ ions on the surface of calcined Al/MCM-48. X-ray diffraction (XRD) patterns indicated that both Al-MCM-48 and Al/MCM-48 had a cubic mesoporous structure. The Brunauer–Emmett–Teller (BET) surface areas of Al-MCM-48 and Al/MCM-48 were larger than 1000 m2/g. 27Al Magic Angle Spinning-NMR (MAS NMR) indicated that Al3+ in Al-MCM-48 was located inside the framework of mesoporous silica, but Al3+ in Al/MCM-48 was located outside the framework of mesoporous silica. The results of ammonia temperature-programmed desorption (NH3-TPD) showed that the acidic strength of various samples was in the order of H-Y > Al/MCM-48 > Al-MCM-48 > MCM-48. After 4 MPa H2 was charged in the autoclave at room temperature, 1 wt % Pt/Al/MCM-48 catalyst showed a high yield of C9−C15 jet fuel range hydrocarbons of 85.9% in the hydrocracking of polyethylene at 573 K for 4 h. Compared with the reaction results of Pt/Al/MCM-48, the yield of light hydrocarbons (C1−C8) increased over Pt/H-Y, and the yield of heavy hydrocarbons (C16−C21) increased over Pt/Al-MCM-48 in the hydrocracking of polyethylene. The yield of C9−C15 jet fuel range hydrocarbons over the used catalyst did not decrease compared to the fresh catalyst in the hydrocracking of polyethylene to jet fuel range hydrocarbons over Pt/Al/MCM-48.

Synthesis of Carbon Nanofiber-Titania-Cordierite Monolith Composite and its Application as Catalyst Support on Citral Hydrogenation

2012 ◽  
Vol 535-537 ◽  
pp. 178-185 ◽  
Author(s):  
Jie Zhu ◽  
Ming Shi Li ◽  
Mo Hong Lu
Keyword(s):  
Surface Area ◽  
Carbon Nanofiber ◽  
Sol Gel ◽  
Catalyst Support ◽  
Textural Properties ◽  
Mesoporous Structure ◽  
Catalytic Performance ◽  
Bet Surface Area ◽  
Tetrabutyl Titanate ◽  
Citral Hydrogenation

We reported the synthesis of a promising carbon nanofiber-titania-cordierite monolith composite (C/TiO2/monolith) and its application in citral hydrogenation. The composite was synthesized through two steps: TiO2 coating on the surface of the monolith with sol-gel method and the following carbon deposit by methane decomposition. C/TiO2/monolith was subsequently employed to prepare its supported palladium catalyst, Pd/C/TiO2/monolith and its catalytic performance was evaluated in selective hydrogenation of citral. Results revealed that 2.0 wt% tetrabutyl titanate sol in composite synthesis was the best in improving textural properties of C/TiO2/monolith. The optimal composite possessed a BET surface area of 39.4 m2/g and micropore area accounted for only 3.8% of its total BET surface area. It contained about 30 wt% of carbon, which was mainly composed of carbon nanofiber. Pd/C/TiO2/monolith exhibited the high citronellal selectivity (81%) at 90% citral conversion, which was attributed to the decrease of internal diffusion limitation due to its mesoporous structure.

A General Nonhydrolytic Sol‐Gel Route to Oxides

1994 ◽  
Vol 346 ◽  
Author(s):  
Sylvie Acosta ◽  
Pascal Arnal ◽  
Robert J.P. Corriu ◽  
Dominique Leclercq ◽  
P. Hubert Mutin ◽  
...  
Keyword(s):  
Nucleophilic Substitution ◽  
High Surface ◽  
Sol Gel ◽  
Metal Center ◽  
Binary Oxides ◽  
Surface Areas ◽  
Sol Gel Process ◽  
Silica Alumina ◽  
The One ◽  
Oxygen Donors

ABSTRACTA nonhydrolytic sol‐gel route based on the condensation between chlorides and oxygen donors such as ethers and alkoxides is presented. Four examples, silica, alumina, titania and binary oxides in the Al/Si system show that this is a general route. The mechanism of this condensation is completely different from the one of classical sol‐gel process, since it implies nucleophilic substitution at the carbon center instead of the metal center. As a consequence, the differences in reactivity between different metals are reduced. In addition, the structure of the precursors may be retained in the gel. Thus, the nonhydrolytic sol‐gel process is very efficient for the preparation of homogeneous bicomponent oxides. Futhermore, nonhydrated gels are formed, which allowed us to prepare amorphous aluminas with high surface areas.

scholarly journals Synthesis and Characterization of a Highly Ordered Mesoporous Bio-glass

2020 ◽  
Vol 36 (1) ◽  
Author(s):  
Bui Xuan Vuong ◽  
Ngo Thi My Thanh
Keyword(s):  
Body Fluid ◽  
Glass Powder ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
In Vitro Experiment ◽  
Pluronic P123 ◽  
Ordered Mesoporous ◽  
Synthetic Biomaterial

A highly ordered mesoporous bio-glass has been successfully prepared by the sol-gel method, in which copolymer pluronic P123 was used as a structure-creating template. The obtained material has the mesoporous structure with the high value of specific surface area (395.6 m2 /g) and the 2D hexagonal pore architecture with the pore sizes from 5.5 to 7 nm. The ‘‘in vitro’’ experiment was effectuated by soaking the bio-glass powder in the simulated body fluid (SBF). The obtained results confirmed the bioactivity of the synthetic biomaterial through the quick formation of a hydroxyapatite layer after 1 day of immersion. Keywords: Bio-glass, pore size, mesoporous, bioactivity, ‘‘in vitro’’.  

scholarly journals Ni-containing catalysts based on ordered mesoporous MgO–Al2O3for methane dry reforming

2018 ◽  
Vol 5 (1) ◽  
pp. 59-66 ◽  
Author(s):  
Svetlana Pavlova ◽  
Yuliya Fedorova ◽  
Arkadii Ishchenko ◽  
Maxim Melgunov ◽  
Elena Melgunova ◽  
...  
Keyword(s):  
Self Assembly ◽  
Mesoporous Structure ◽  
Dry Reforming ◽  
One Pot ◽  
Methane Dry Reforming ◽  
Pluronic P123 ◽  
Ordered Mesoporous ◽  
Evaporation Induced Self Assembly ◽  
The One ◽  
Adsorption Desorption

Abstract The ordered mesoporous Mg- and Ni-Mg-alumina samples of general formula xwt%Mg-Al2O3 and ywt%Nixwt% Mg-Al2O3(x, y = 5, 10 % wt) have been prepared by the one-pot evaporation induced self-assembly (EISA) method using Pluronic P123 as a template. The textural and structural properties of the prepared samples have been characterized by N2adsorption-desorption analysis, BET, XRD, TEM with EDX, HAADF-STEM, and H2-TPR. The samples calcined at 700°C had an ordered mesoporous structure with a SSA of 170-250 m2/g, a pore volume of 0.5-0.64 cm3/g and a narrow distribution of the pore size (mean 12-16 nm). For the catalysts prepared by the one-pot EISA method, the size of the metal Ni particles was in the range of 3-12 nm and was conditioned by their confinement in the mesopores and the interaction with MgO and Al2O3. Testing in methane dry reforming in the 15v.% CH4+ 15v.%CO2feed, with He balance, at 650-750°C and the contact time of 0.015 s has shown the higher activity and stability of the ordered mesoporous 10w%Ni- 10w%Mg-Al2O3catalysts prepared by the one-pot method as compared with the catalyst of the same composition obtained by impregnation.

Fabrication of Three-Dimensionally Ordered Macro-/Mesoporous Titania Monoliths by a Dual-Templating Approach

2011 ◽  
Vol 1352 ◽  
Author(s):  
Zhiyan Hu ◽  
Zhongjiong Hua ◽  
Shaohua Cai ◽  
Jianfeng Chen ◽  
Yushan Yan ◽  
...  
Keyword(s):  
Colloidal Crystal ◽  
High Surface ◽  
High Surface Area ◽  
Mesoporous Structure ◽  
Titanium Tetraisopropoxide ◽  
Structure Directing Agent ◽  
Pluronic P123 ◽  
Surfactant Templating ◽  
Mesopore Structure ◽  
Colloidal Crystal Templating

ABSTRACTThree-dimensionally ordered macro-/mesoporous (3DOM/m) TiO2 monoliths were fabricated by a dual-templating synthesis approach employing a combination of both colloidal crystal templating (hard-templating) and surfactant templating (soft-templating) techniques. Titania precursor, consisting of amphiphilic triblock copolymer Pluronic P123 as a mesopore-structure-directing agent and titanium tetraisopropoxide as a titanium source, was infiltrated into the void spaces of the poly(methyl methacrylate) (PMMA) colloidal crystal monolith. Subsequent thermal treatment produced 3DOM/m TiO2 monolith. The macropore walls of the prepared 3DOM/m TiO2 exhibit a well-defined mesoporous structure with narrow pore size distribution, and the mesopore walls are composed of nanocrystalline anatase TiO2. The material also shows a high surface area (171 m2/g), and large pore volume (0.402 cm3/g).

Nano-Engineering Silica Aerogel Structure to Determine the Property-Structure Relationship

2009 ◽  
Author(s):  
Gitogo Churu ◽  
Hongbing Lu ◽  
Nicholas Leventis
Keyword(s):  
Silica Aerogel ◽  
Sol Gel ◽  
Mechanical Analysis ◽  
Honeycomb Structure ◽  
Material Point ◽  
Compression Tests ◽  
Structure Directing Agent ◽  
Static Compression ◽  
Pluronic P123 ◽  
Structure Relationship

We characterize mechanically strong nano/meso-porous cross-linked templated silica aerogels that were synthesized through the sol gel process and reinforced by nano casting a 4–10nm thick conformal layer of isocynate derived polymer. Tri-block co-polymer (pluronic P123) was used as a structure directing agent to produce ordered mesoporous walls while 1, 3, 5 trimethylbenzene (TMB) was added as micelle-swelling reagent to regulate the size of the pores. The shape and size of the micro and meso pores were nano engineered by varying the amount of chemical surfactant as well as the concentration of the cross-linking solution used to form the polymer nano layer. In so doing we manipulated the structure at the molecular level to develop an optimized structure that closely resembles the honeycomb structure found in nature. Dynamic mechanical analysis (DMA) test results established that the material had an α-grass transition temperature of about 130°C while quasi-static compression tests showed that the optimized nano-structured silica aerogel had a Young’s modulus of about 800MPa. We present the synthesis protocol as well as chemical, physical and mechanical characterization of cross-linked templated silica aerogel (CTSA). ). In addition, material point method (MPM) simulation results are highlighted.

Hierarchical Macro-Mesoporous Silica Monolith

2004 ◽  
Vol 847 ◽  
Author(s):  
Tomohiko Amatani ◽  
Kazuki Nakanishi ◽  
Kazuyuki Hirao ◽  
Tetsuya Kodaira
Keyword(s):  
Self Assembly ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
Silica Gels ◽  
Polymerization Reaction ◽  
Structure Directing Agent ◽  
Swelling Agent ◽  
Pure Silica ◽  
Inorganic Species ◽  
Hexagonal Arrays

ABSTRACTMonolithic pure silica gels with hierarchical macro-mesoporous structure have been synthesized via spontaneous sol-gel process from silicon alkoxide using a structure-directing agent and a micelle-swelling agent. Monolithic body with well-defined co-continuous macropores is a result of concurrent phase separation and sol-gel transition induced by the polymerization reaction, whereas the mesopores are templated by the cooperative self-assembly of inorganic species, a structure-directing agent and a micelle-swelling agent. The following removal of surfactants by heat-treatment gives silica gels with hierarchical and fully accessible pores in discrete size ranges of micrometers and nanometers. The highly ordered 2D-hexagonal arrays of mesopores have been confirmed by X-ray diffraction measurements and FE-SEM observations. Furthermore, by further additions of the micelle-swelling agent, the mesostructural transition from well-ordered 2D-hexagonal arrays to mesostructured cellular foams (MCF) have been induced accompanied by minor modifications of the micrometer-range structure.

scholarly journals REMOVAL OF NORFLOXACIN BY TiO2-SBA-15 PHOTOCATALYST

2020 ◽  
Vol 58 (3A) ◽  
pp. 13
Author(s):  
Nguyễn Thị Thu Trang ◽  
Trần Quang Vinh ◽  
Nguyễn Thành Đồng ◽  
Phạm Tuấn Linh ◽  
Nguyễn Viết Hoàng ◽  
...  
Keyword(s):  
Uv Light ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Surface Areas ◽  
Pluronic P123 ◽  
Adsorption Capacities ◽  
Transmission Electron ◽  
Photocatalytic Activities ◽  
Adsorption Desorption ◽  
Synthesized Materials

Ordered SBA-15 mesoporous silica support was synthesized by a sol-gel method using triblock copolymer Pluronic P123 and immobilized with different amounts of photocatalyst TiO2. The synthesized composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and N2 adsorption-desorption isotherms. The synthesized materials possessed specific surface areas SBET of 768 m2/g, 544 m2/g, 421 m2/g and 333 m2/g at the TiO2:SiO2 ratio of 0, 0.25, 1.0 and 5.0, respectively. The adsorption capacities and photocatalytic activities under UV light irradiation of these materials were evaluated for Norfloxacin degradation. Experimental results indicate that the highest activity was observed on the sample with TiO2:SiO2 ratio of 1.

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