The Performance of Au Nanoparticle Supported on Mesoporous TiO2 for Low-Temperature CO Oxidation

2013 ◽  
Vol 726-731 ◽  
pp. 720-724 ◽  
Author(s):  
Jian Hua Li ◽  
Meng Jie Feng ◽  
Mei Lin Jia
Keyword(s):  
Reduction Method ◽  
Catalyst Activity ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
Au Nanoparticle ◽  
Template Method ◽  
Oxidation Of Co ◽  
Low Temperature Co Oxidation ◽  
Xrd Patterns ◽  
Adsorption Desorption

A series of mesoporous TiO2 supports were synthesized by the sol-gel template method by using different surfactant and Au/TiO2 catalysts were prepared by the solution reduction method. The catalytic oxidation of CO was taken as the probe reaction for comparing the catalyst activity. Wide-angle XRD patterns and N2 adsorption–desorption isotherms revealed that the TiO2 with crystallized anatase and mesoporous structure can be synthesized after an optimized sol-gel template method. The results indicated that the pore size of TiO2 plays a key role in the catalyst activity. Among them the activity of Au/TiO2-F1 catalyst synthesized by using the F127 surfactant demonstrated superior activity to other catalysts. CO could be converted at 70 °C.

Preparation of catalyst as Au doped Mn1Co9Ox/ceramic system for total oxidation of CO

2021 ◽  
Vol 10 (4) ◽  
pp. 39-45
Author(s):  
Phuong Pham Thi Mai ◽  
Hoan Nguyen Quoc ◽  
Quan Do Quoc ◽  
Hung Nguyen Thanh
Keyword(s):  
Sol Gel ◽  
Active Phase ◽  
Catalyst System ◽  
Oxidation Of Co ◽  
Sem Images ◽  
Total Oxidation ◽  
Wet Impregnation ◽  
Modern Analysis ◽  
Catalyst Powder ◽  
Xrd Patterns

In this paper, the Au doped Mn1Co9Ox was investigated for total oxidation of CO. The sol-gel method was applied to prepare this catalyst and some modern analysis methods as XRD, EPR, TPx, SEM were utilized to characterize its properties. The XRD patterns showed only Co3O4 phase without any peaks belonging to Mn or Au. However, the presence of Au and Mn was confirmed by EPR and O2-TPD results. With the aim to further apply catalyst in reality, the Au doped Mn1Co9Ox was deposited on ceramic by sol-gel, wet impregnation. The SEM images displayed the successful coating of active phase on substrate. However, the complete catalyst system didn’t have the high activity in total CO oxidation like the catalyst powder because of large agglomerations on coatings.

Controllable Synthesis of Modified Porous Anatase TiO2 with High Photocatalytic Activity

2021 ◽  
Vol 21 (11) ◽  
pp. 5742-5748
Author(s):  
Mei-Qing Fan ◽  
Heng-Yi Yuan ◽  
Cheng Qiu ◽  
Hong-Xia Zhao ◽  
Xu Zeng ◽  
...  
Keyword(s):  
Phase Transition ◽  
Sol Gel ◽  
High Photocatalytic Activity ◽  
Degradation Efficiency ◽  
Crystal Phase ◽  
Template Method ◽  
X Ray Diffraction ◽  
Crystal Phase Transition ◽  
Adsorption Desorption ◽  
Synthesized Materials

In this study, we added ZrO2 and Y2O3 to stabilize the anatase TiO2 phase at higher temperatures. Composite mesoporous TiO2/ZrO2/Y2O3 (TZY) oxides were prepared by a sol-gel method, and triblockcopolymer P123 and PEG was used as templates. The properties of the synthesized materials were characterized using X-Ray diffraction (XRD), Raman scattering, N2 adsorption/desorption, and UV-Visible spectrophotometry (UV-Vis) methods et al. The samples prepared using P123 and PEG as double-template exhibited smaller particles and a higher specific surface area than the samples prepared using P123 and PEG as single-template. Furthermore, crystal phase transition from anatase to rutile occurred later in the case of the double-template method. After introducing ZrO 2and Y2O3, the crystal phase transition and the growth of crystallites were severely suppressed. The results indicated that the RhB degradation efficiency for the double-template method was 99.24%, while the RhB degradation efficiency with TZY/P123 and TZY/PEG samples was 97.43 and 98.18%, respectively.

Synthesis of Three-Dimensionally Interconnected Hierarchical Meso/Mesoporous Tb3+ Doped Titania with Enhanced Photocatalytic Activity

2013 ◽  
Vol 275-277 ◽  
pp. 1755-1761
Author(s):  
Wei Yin ◽  
Lei Shi ◽  
Dan Hua Zhao ◽  
Xiu Lian Zhang
Keyword(s):  
Photocatalytic Activity ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
Irradiation Condition ◽  
Sensitive Material ◽  
Transmission Electron ◽  
Ultrasonic Assisted ◽  
Width Distribution ◽  
Doped Titania ◽  
Adsorption Desorption

The precursor was prepared by cohydrolysis reactions of Ti(OC2H5)4and Tb(OC2H5)6around micelles of cetyltrimethylammonium bromide processed by ultrasonic before the cohydrolysis reactions. After calcined the precursor, Terbium doped anatase with a three-dimensionally interconnected hierarchical meso/mesoporous structure had been successfully prepared using an ultrasonic-assisted routine of sol-gel. The three-dimensionally interconnected hierarchical meso/mesoporous structure of the prepared material was proved by high resolution transmission electron microscopy and N2adsorption-desorption analysis. The material prepared displays a pore width distribution curve of single peak at 17.8 nm and displays a range from 6 nm to 42 nm, and possesses a BET area of 105 m2/g and a porosity of 0.65 cm3/g. The results of XPS analysis show that Ti exists in the Ti4+form and Ti-O-Tb/H and Ti-O-Ti bonds exist in the surface of the mesoporous material prepared. The terbium-doped sensitive material prepared possessing a three-dimensionally interconnected hierarchical meso/mesoporous structure is conducive mass-transferring and light-harvesting, and shows that a photocatalytic activity for phenol is about 4.9 times than that of commercial P25 titania under a very weak UV-Vis irradiation condition.

Preparation of Three-Dimensionally Interconnected Meso/Mesoporous Ho3+ Doped TiO2 Nanoparticles with Enhanced Photocatalytic Activity

2013 ◽  
Vol 652-654 ◽  
pp. 779-786
Author(s):  
Wei Yin
Keyword(s):  
Photocatalytic Activity ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
Titania Nanoparticles ◽  
Irradiation Condition ◽  
Transmission Electron ◽  
Prepared Material ◽  
Phenol Photodegradation ◽  
Doped Titania ◽  
Adsorption Desorption

Three-dimensionally interconnected meso/mesoporous holmium doped titania nanoparticles had been successfully prepared by a sol-gel routine. The precursors were prepared by cohydrolysis reactions of Ti(OC2H5)4/Ho(OC2H5)6coprecipitating around micells of cetyltrimethylammonium bromide processed by ultrasonic. The hierarchical meso/mesoporous material was proved by high resolution transmission electron microscopy and N2adsorption-desorption analysis. The results of selecting area electron diffraction pattern, Raman spectroscopy, and X-ray diffractometry in wide-angle range showed a crystal phase of anatase for the prepared material. The XPS spectroscopy analysis showed that Ti element exists in the Ti4+form and the bonds of Ti-O-Ho/H and Ti-O-Ti exist in the surface of Ho3+doped TiO2. Phenol photodegradation in an aqueous medium was employed as a probe reaction to evaluate the photocatalytic reactivity of the catalyst. The catalyst which possessed a hierarchical meso/mesoporous structure being conducive mass-transferring and light-harvesting showed that a photocatalytic activity for phenol is about 3.3 times than that of commercial P25 titania under a very weak UV-Vis irradiation condition.

scholarly journals Characterization of Bioactive Glass Synthesized by Sol-Gel Process in Hot Water

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 529 ◽  
Author(s):  
Tan Hiep Dang ◽  
Thi Hoa Bui ◽  
Elena V. Guseva ◽  
Anh Tuan Ta ◽  
Anh Tien Nguyen ◽  
...  
Keyword(s):  
Bioactive Glass ◽  
Sol Gel ◽  
Acid Catalyst ◽  
Mesoporous Structure ◽  
Hot Water ◽  
Spherical Particles ◽  
Average Pore ◽  
Amorphous Glass ◽  
Adsorption Desorption

Bioactive glass 70SiO2-30CaO (mol.%) was successfully synthesized by modified sol–gel in hot water without using an acid catalyst. TG-DSC analysis showed that the amorphous glass could be synthesized by sintering the sample at 700 °C for three hours. The N2 adsorption/desorption and TEM investigations highlighted that the synthetic glass had a mesoporous structure, consisting of spherical particles with sizes in the range of 11–20 nm. The specific surface area, pore volume, and average pore diameter of synthetic glass were 150.13 m2/g, 0.37 cm3/g, and 11.84 nm, respectively. Moreover, synthetic bioactive glass presented interesting bioactivity and good biocompatibility after in vitro experiments in simulated body fluid (SBF) and in cellular medium.

scholarly journals Enhanced Photocatalytic Activity of Hierarchical Macro-Mesoporous Anatase byZrO2Incorporation

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
M. L. García-Benjume ◽  
M. I. Espitia-Cabrera ◽  
M. E. Contreras-García
Keyword(s):  
Photocatalytic Activity ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Mesoporous Structure ◽  
Tween 20 ◽  
X Ray Diffraction ◽  
Surface Areas ◽  
Photocatalytic Effect ◽  
Different Temperatures ◽  
Adsorption Desorption

The effect of the addition of zirconia in the photocatalytic behaviour of titania is analysed. In order to increase the ways for reagent and product diffusion in the material, a sol-gel hydrothermal synthesis route using Tween-20 as a directing agent to obtain a hierarchical macro-mesoporous structure is proposed. Nanostructured macro-mesoporous TiO2/ZrO2photocatalyst with 0, 10, 20, 30, and 100% mol of ZrO2were obtained and calcined at different temperatures. The crystalline structure was analyzed by X-ray diffraction and TEM. The porosity was confirmed by SEM, TEM, and nitrogen adsorption-desorption isotherms. The worm-like mesoporous structure was confirmed by TEM. The specific surface areas obtained by Brunauer-Emmet-Teller method (BET) ranged from 125 to 180 m2/g. The Tween-20 total elimination from the structure by thermal treatment was confirmed by infrared spectroscopy and thermogravimetric analysis. Additionally, the photocatalytic effect of the zirconia addition was studied in the methylene blue (MB) degradation reaction, and the best photocatalytic activity was obtained in the sample with 10% mol of ZrO2, degrading up to 92% the MB.

The Effects of Calcination Temperatures in the Synthesis of Nanocrystalline Magnesium Oxide via Sol-Gel Technique

2017 ◽  
Vol 865 ◽  
pp. 36-42
Author(s):  
Hanis Mohd Yusoff ◽  
Faridatul Akmar Rafit ◽  
Fatin Izwani Mohamad ◽  
Norhafiefa Hassan ◽  
Adibah Izzati Daud
Keyword(s):  
Magnesium Oxide ◽  
Sol Gel ◽  
Combustion Method ◽  
Metal Nitrate ◽  
Complexing Agent ◽  
Sem Images ◽  
Calcination Temperatures ◽  
Xrd Patterns ◽  
Adsorption Desorption ◽  
Nanocrystalline Magnesium Oxide

This study highlights on a convenient and optimised method for the preparation of nanocrystalline magnesium oxide (MgO) catalyst via sol-gel combustion method. Nanocrystalline MgO was prepared by using polyvinyl alcohol (PVA) as a complexing agent and metal nitrate (Mg (NO 3 )2.6H2O) as a precursor. The obtained MgO powder was calcined at 200 °C, 400 °C, 600 °C and 800 °C. All the MgO calcined samples including commercial MgO were characterised using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-Ray diffraction (XRD) and N2 adsorption-desorption Brunauer–Emmett–Teller (BET). From FTIR analysis, the appearance of a peak at 3700 cm-1 represent the O-H stretching bonded with Mg and the broad absorption peak at 3421 cm-1 indicates O-H stretching band which is due to the absorption of moisture from the surrounding. (BET) results indicate the MgO sample that has been calcined at 400 °C shows the largest surface area. SEM images show there is porosity in all MgO powder. While XRD patterns revealed that higher temperature of calcination gives higher crystallinity of the MgO samples.

Surfactant Effect on the Synthesis of Mesoporous TiO2-SiO2 Coatings Using Sol-Gel Technology

2018 ◽  
Vol 762 ◽  
pp. 263-267
Author(s):  
Margarita Karpe
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
Titanium Isopropoxide ◽  
Water Contact ◽  
Separation Membranes ◽  
Mesoporous Thin Films ◽  
Potential Applications ◽  
Triblock Copolymer Surfactant ◽  
Xrd Patterns

The aim of the research was to develop the area of mesoporous thin films of a binary TiO2–SiO2 system. Sol was synthesized from tetraethylorthosilicate as the silica source and titanium isopropoxide solution as the TiO2 source, while triblock copolymer surfactant (Pluronic F 127 (10% solution in water, (P))) was used as the mesostructure-directing agent. In this paper we present sol-gel obtained TiO2–SiO2 with a mesoporous structure. The effects of added titanium on the mesostructure and on the porosity are presented and discussed. Four different molar percentage ratios of Ti: Si were used for the synthesis of mixed TiO2–SiO2 mesoporous thin films on glass substrate. The mesoporous structure of thin films was characterized by X-ray diffraction (XRD) patterns, atomic force microscopy (AFM), scanning electron microscopy (SEM) and the water contact angle. These mesoporous TiO2–SiO2 thin films could have many potential applications in many areas such as separation membranes, catalysis, optics, and self-cleaning surfaces.

The High Stability Mesoporous MgO-ZrO2 Materials as CO2 Adsorbents

2012 ◽  
Vol 490-495 ◽  
pp. 3797-3801
Author(s):  
Xin Fu
Keyword(s):  
Thermal Stability ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
High Thermal Stability ◽  
Surface Basicity ◽  
Temperature Application ◽  
The Stability ◽  
Co2 Adsorption Capacity ◽  
Adsorption Desorption ◽  
Thermal Stability Of

A novel CO2 absorbent, MgO-ZrO2 nanocomposite was synthesized via appropriate sol-gel process. The structure and surface properties of the as-prepared materials were characterized by XRD, N2 adsorption-desorption and CO2-TPD techniques. It was found the as-prepared materials showed high thermal stability, and their mesoporous framework was well preserved even after calcinations at 700oC. In addition, the nanocomposites exhibited appropriate basic strength and the basic sites were tightly anchored to the substrate, which greatly improved the stability of the surface basicity. Owing to the advantages of the mesoporous structure and the surface basicity, the as-prepared MgO-ZrO2 nanocomposites showed high CO2 adsorption capacity. Moreover, the high thermal stability of MgO-ZrO2 could greatly increase their performance in high-temperature application, which remarkably overcame the poor thermal stability of those organic group grafted porous silicas.

Modification of Silica Gel by Heteropolyacids

2016 ◽  
Vol 689 ◽  
pp. 126-132
Author(s):  
Opeyemi Adetola ◽  
Leonid Golovko ◽  
Aleksey Vasiliev
Keyword(s):  
Sol Gel ◽  
Mesoporous Structure ◽  
High Ratio ◽  
Silica Gels ◽  
Silica Network ◽  
Synthesis Conditions ◽  
Ft Ir ◽  
Gel Technique ◽  
Xrd Patterns ◽  
Modified Silica Gels

Silica gels containing incorporated heteropolyacids (HPAs) were synthesized in acidic media by co-condensation of tetraethoxysilane (TEOS) with phosphotungstic or phosphomolybdic acids using the sol-gel technique. The effect of the synthesis conditions on their structure and morphology was studied. Yields of modified materials were somewhat lower compared to non-modified silica gels. All materials were mesoporous but contained micropores in their structures. Presence of bands of Keggin’s structures in FT-IR spectra along with absence of XRD patterns of crystalline HPAs confirmed their fine incorporation into silica network. Particle sizes of modified materials were 500-1100 nm except for the W-containing sample obtained with trimethylstearylammonium chloride, which was significantly lower. This unusual effect was attributed to stabilization of primary silica nanoparticles by interactions between the surfactant and HPA. High ratio HPA/TEOS resulted in partial loss of porosity. Obtained results might be used for optimization of synthesis of effective catalysts and adsorbents containing HPAs in mesoporous structure.

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