scholarly journals Sol-Gel Processed Cobalt-Doped Methylated Silica Membranes Calcined under N2 Atmosphere: Microstructure and Hydrogen Perm-Selectivity

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4188
Author(s):  
Lunwei Wang ◽  
Jing Yang ◽  
Ruihua Mu ◽  
Yingming Guo ◽  
Haiyun Hou
Keyword(s):  
Average Pore Size ◽  
Sol Gel ◽  
Total Pore Volume ◽  
Molar Ratio ◽  
Average Pore ◽  
Silica Membranes ◽  
Physical Chemical ◽  
N2 Atmosphere ◽  
Coating Method ◽  
Gel Technique

Methyl-modified, cobalt-doped silica (Co/MSiO2) materials were synthesized by sol-gel technique calcined in N2 atmospheres, and membranes were made thereof by coating method. The effects of Co/Si molar ratio (nCo) on the physical-chemical constructions of Co/MSiO2 materials and microstructures of Co/MSiO2 membranes were systematically investigated. The gas permeance performance and hydrothermal stability of Co/MSiO2 membranes were also tested. The results show that the cobalt element in Co/MSiO2 material calcined at 400 °C exists not only as Si–O–Co bond but also as Co3O4 and CoO crystals. The introduction of metallic cobalt and methyl can enlarge the total pore volume and average pore size of the SiO2 membrane. The activation energy (Ea) values of H2, CO2, and N2 for Co/MSiO2 membranes are less than those for MSiO2 membranes. When operating at a pressure difference of 0.2 MPa and 200 °C compared with MSiO2 membrane, the permeances of H2, CO2, and N2 for Co/MSiO2 membrane with nCo = 0.08 increased by 1.17, 0.70, and 0.83 times, respectively, and the perm-selectivities of H2/CO2 and H2/N2 increased by 27.66% and 18.53%, respectively. After being steamed and thermally regenerated, the change of H2 permeance and H2 perm-selectivities for Co/MSiO2 membrane is much smaller than those for MSiO2 membrane.

Nanoporous TiO2/SiO2 Composite Prepared by a Combined Sol-Gel and Hybrid Method

2008 ◽  
Vol 368-372 ◽  
pp. 1497-1499 ◽  
Author(s):  
Wen Yuan Xu ◽  
Lu Bin Wei ◽  
Ming Biao Luo
Keyword(s):  
Phase Composition ◽  
Pore Size ◽  
Hybrid Method ◽  
Average Pore Size ◽  
Sol Gel ◽  
Molar Ratio ◽  
Tetrabutyl Titanate ◽  
Average Pore ◽  
Silica Nanocomposites ◽  
Surface Areas

Titania-silica nanocomposites with different TiO2/SiO2 compositions have been prepared by a sol-gel and hybrid method from tetraethylorthosilicate (TEOS) and tetrabutyl titanate(TBT) and β-Cyclodextrin as a pore-forming template. Drying and calcining of the hybrid xerogel can lead to the formation of nanoporous particles with surface areas in the range of 298-418 m2/g. The effect of the β-cyclodextrin concentration, the molar ratio of TiO2/SiO2 and the calcining temperature on the phase composition and structural properties of TiO2/SiO2 composites were also investigated. The results show that an increase in β-cyclodextrin concentration can lead to a decrease of the surface area and an increase of average pore size, which can be controlled by the amount of β- cyclodextrin in the hybrid sol.

Characterization of TiO2 Film Prepared by Sol-Gel Method Using Ti(OC4H9)4

2011 ◽  
Vol 298 ◽  
pp. 249-252 ◽  
Author(s):  
Li Li Yang ◽  
Jia Wei Bai ◽  
Wen Jie Zhang
Keyword(s):  
Pore Size ◽  
Tio2 Film ◽  
Average Pore Size ◽  
Sol Gel ◽  
Total Pore Volume ◽  
Source Surface ◽  
Average Pore ◽  
Tio2 Particles ◽  
Sol Gel Process

TiO2 film was dip-coated on glass substrate by a sol-gel process. Ti(OC4H9)4 was used as the titanium source. Surface morphology, crystallite phase, UV-Vis transmittance spectrum and pore size distribution of TiO2 powder prepared under the same conditions of the film were investigated. Surface of TiO2 film is fairly smooth with very slight roughness. No obvious hole or pore is found on the surface of the film. The strongest diffraction peak situated at 2θ=25.3o is the characteristic of anatase TiO2. The absorption edge of the TiO2 film is around 350 nm, while the transmittance fluctuates between 50% and 90%. The average pore size of the TiO2 particles calculated by BJH method is 23 nm. The total pore volume and specific surface area are 0.16 ml/g and 27 m2/g, respectively.

scholarly journals Indium doping in sol-gel synthesis of In-Sm co-doped xIn-0.05%Sm-TiO2 composite photocatalyst

2018 ◽  
Vol 25 (4) ◽  
pp. 817-824 ◽  
Author(s):  
Wenjie Zhang ◽  
Yuxuan Liu ◽  
Xiaobei Pei ◽  
Jiao Yang
Keyword(s):  
Methyl Orange ◽  
Anatase Phase ◽  
Average Pore Size ◽  
Sol Gel ◽  
Total Pore Volume ◽  
Far Infrared ◽  
Crystal Formation ◽  
Average Pore ◽  
Indium Doping ◽  
Co Doped

Abstract Sol-gel method was used to prepare a novel In-Sm co-doped TiO2 photocatalyst. The materials were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared/far infrared, UV-Vis diffuse reflectance, and N2 adsorption-desorption analyses. Anatase phase TiO2 is formed in the pure and doped TiO2 samples. Anatase TiO2 crystal formation and growing are disturbed by the dopants. The substitution of smaller Ti4+ ions by the larger Sm3+ and In3+ ions causes the expansion of TiO2 cell. The doping of indium and samarium ions has no noticeable influence on the bonding characters of TiO2. A continuous red shift of the absorption edge of xIn-0.05%Sm-TiO2 occurs at increasing indium doping content. Brunauer-Emmett-Teller surface area, average pore size, and total pore volume are enhanced after doping of samarium and indium. The adsorption of methyl orange on the surface of xIn-0.05%Sm-TiO2 increases with rising indium content. The 5%In-0.05%Sm-TiO2 has the maximum photocatalytic activity. About 97.7% of the initial methyl orange is decolorized on 5%In-0.05%Sm-TiO2 after 45 min of irradiation.

Study on Environmental Materials with Pore Size and Photocatalytic Activity of Porous TiO2-Al2O3 Photocatalyst

2013 ◽  
Vol 700 ◽  
pp. 67-70 ◽  
Author(s):  
Rui Ma ◽  
Wen Jie Zhang
Keyword(s):  
Methyl Orange ◽  
Photocatalytic Degradation ◽  
Pore Size ◽  
Pore Volume ◽  
Average Pore Size ◽  
Sol Gel ◽  
Total Pore Volume ◽  
Degradation Process ◽  
Order Kinetic ◽  
Average Pore

A novel porous TiO2-Al2O3 composite as a kind of environmental material was prepared by sol-gel method. The pore size distribution is not even in the whole pore size range. When pore size is 7.049 nm, the maximum pore volume of the material is 0.06627 cm3·g-1. The average pore size for the material is 14.56 nm and the total pore volume is 0.3945 cm3·g-1, as calculated from BJH method. Photocatalytic degradation of methyl orange can be regarded as following first order kinetic reaction. After 90 min of reaction, methyl orange degradation on the material was 77.0% and the total dye decoloration rate was 95.1%, containing both adsorption and photocatalytic degradation. The intensities of both peaks in visible and UV regions decreased sharply during photocatalytic degradation process.

scholarly journals Preparation of High-Performance Activated Carbon from Coffee Grounds after Extraction of Bio-Oil

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 257
Author(s):  
Jie Ren ◽  
Nanwei Chen ◽  
Li Wan ◽  
Guojian Li ◽  
Tao Chen ◽  
...  
Keyword(s):  
Activated Carbon ◽  
High Performance ◽  
Average Pore Size ◽  
Total Pore Volume ◽  
Micropore Volume ◽  
Bet Surface Area ◽  
Average Pore ◽  
Activation Temperature ◽  
Coffee Grounds ◽  
Bio Oil

In this study, a new method for economical utilization of coffee grounds was developed and tested. The resulting materials were characterized by proximate and elemental analyses, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and N2 adsorption–desorption at 77 K. The experimental data show bio-oil yields reaching 42.3%. The optimal activated carbon was obtained under vacuum pyrolysis self-activation at an operating temperature of 450 °C, an activation temperature of 600 °C, an activation time of 30 min, and an impregnation ratio with phosphoric acid of 150 wt.%. Under these conditions, the yield of activated carbon reached 27.4% with a BET surface area of 1420 m2·g−1, an average pore size of 2.1 nm, a total pore volume of 0.747 cm3·g−1, and a t-Plot micropore volume of 0.428 cm3·g−1. In addition, the surface of activated carbon looked relatively rough, containing mesopores and micropores with large amounts of corrosion pits.

Silica Sol-Gel Supported Nickel Nano-Catalyst for Hydrogen Production Using Microreactors

2005 ◽  
Vol 885 ◽  
Author(s):  
Krithi Shetty ◽  
Shihuai Zhao ◽  
Wei Cao ◽  
Naidu V. Seetala ◽  
Debasish Kuila
Keyword(s):  
Steam Reforming ◽  
Average Pore Size ◽  
Sol Gel ◽  
Supported Catalyst ◽  
Silica Sol ◽  
Average Pore ◽  
Steam Reforming Of Methanol ◽  
Nano Catalyst ◽  
Before And After ◽  
Reforming Reactions

ABSTRACTThe goal of this research is to investigate the activities of a non-noble nano-catalyst (Ni/SiO2) using Si-microreactors for steam reforming of methanol to produce hydrogen for fuel cells. The supported catalyst was synthesized by sol-gel method using Ni (II) salts and Si(C2H5O)4 as starting materials. EDX results indicate that the actual loading of Ni (5-6%) is lower than the intended loading of 12 %. The specific surface area of the silica sol-gel encapsulated Ni nano-catalyst is 452 m2/g with an average pore size of ∼ 3 nm. Steam reforming reactions have been carried out in a microreactor with 50 µm channels in the temperature range of 180-240 °C and atmospheric pressure. Results show 53% conversion of methanol with a selectivity of 74 % to hydrogen at 5 l/min and 200 °C. The magnetic properties of the catalysts were performed using a Vibrating Sample Magnetometer (VSM) to study the activity of the catalysts before and after the steam reforming reactions. The VSM results indicate much higher activity in the microreactor compared to macro-reactor and Ni forms non-ferromagnetic species faster in the microreactor.

Sol-Gel Derived Silica Layers for Low-k Dielectrics Applications

2000 ◽  
Vol 612 ◽  
Author(s):  
Sylvie Acosta ◽  
André Ayral ◽  
Christian Guizard ◽  
Charles Lecornec ◽  
Gérard Passemard ◽  
...  
Keyword(s):  
Average Pore Size ◽  
Sol Gel ◽  
Porous Silica ◽  
Thin Layers ◽  
Gaseous Ammonia ◽  
Potential Candidate ◽  
Average Pore ◽  
Synthesis Strategy ◽  
Silica Layers ◽  
Highly Porous

AbstractPorous silica exhibits attractive dielectric properties, which make it a potential candidate for use as insulator into interconnect structures. A new way of preparation of highly porous silica layers by the sol-gel route was investigated and is presented. The synthesis strategy was based on the use of common and low toxicity reagents and on the development of a simple process without gaseous ammonia post-treatment or supercritical drying step. Defect free layers were deposited by spin coating on 200 mm silicon wafers and characterized. Thin layers with a total porosity larger than 70% and an average pore size of 5 nm were produced. The dielectric constant measured under nitrogen flow on these highly porous layers is equal to ∼ 2.5, which can be compared to the value calculated from the measured porosity, ∼ 1.9. This difference is explained by the presence of water adsorbed on the hydrophilic surface of the unmodified silica.

PHOTOCATALYTIC REMOVAL OF PHENOL OVER MESOPOROUS ZnO/TiO2 COMPOSITES

2018 ◽  
Vol 80 (2) ◽  
Author(s):  
Klinsmann Cheong Lee Khang ◽  
Mohd Hayrie Mohd Hatta ◽  
Siew Ling Lee ◽  
Leny Yuliati
Keyword(s):  
Pore Size ◽  
Uv Light ◽  
Average Pore Size ◽  
Anatase Tio2 ◽  
Light Irradiation ◽  
Molar Ratio ◽  
Average Pore ◽  
Uv Light Irradiation ◽  
Photocatalytic Removal ◽  
Mesoporous Zno

A series of mesoporous ZnO/TiO2 composites were successfully synthesized using cetyltrimethylammonium bromide surfactant. The composites of different Zn:Ti molar ratios (0.5:1, 0.75:1, and 1:1) were prepared by impregnating ZnO onto mesoporous TiO2. XRD results verified co-existence of both anatase TiO2 and hexagonal wurtzite ZnO in the ZnO/TiO2 composites. Based on the Tauc plots, all the composites showed almost the same band gap energy of approximately 3.21 eV. The fourier transform infrared spectroscopy results successful covering of ZnO on the surface of the TiO2 as the hydrophilicity property of TiO2 decreased remarkably with the loading of ZnO in the composites. N2 adsorption-desorption isotherms of the samples exhibited type-IV isotherm with a hysteresis loop. The Barrett-Joyner-Halenda pore size distribution revealed that the average pore size of the composites was around 3.6 nm, indicating the formation of mesopores dominantly in the samples. The photocatalytic removal of phenol over the samples under UV light irradiation after 3 h decreased in the order: ZnO/TiO2 composites > anatase TiO2 (with surfactant) > anatase TiO2 (without surfactant) > ZnO. The composite with Zn:Ti molar ratio of 0.75:1 has achieved the highest photocatalytic activity of 36.5% in the removal of phenol under UV light irradiation for 3 h.

Metal organic framework MIL-101 coated fiber for headspace solid phase microextraction of volatile aromatic compounds

2015 ◽  
Vol 7 (3) ◽  
pp. 918-923 ◽  
Author(s):  
Xiaohuan Zang ◽  
Guijiang Zhang ◽  
Qingyun Chang ◽  
Xi Zhang ◽  
Chun Wang ◽  
...  
Keyword(s):  
Solid Phase Microextraction ◽  
Solid Phase ◽  
Steel Wire ◽  
Metal Organic Framework ◽  
Sol Gel ◽  
Metal Organic Frameworks ◽  
Coating Method ◽  
Metal Organic ◽  
Gel Technique ◽  
Volatile Aromatic Compounds

The sol–gel technique was applied as a novel coating method in the preparation of metal organic frameworks (MOFs)-based solid phase microextraction (SPME) fibers by coating MIL-101 onto a stainless steel wire.

scholarly journals Evaluation of dolomite as catalyst in the transesterification reaction using palm oil (RBD)

DYNA ◽  
2019 ◽  
Vol 86 (209) ◽  
pp. 180-187
Author(s):  
Stephanie Alexa Ñústez Castaño ◽  
Duvan Oswaldo Villamizar Castro ◽  
Edgar Mauricio Vargas Solano
Keyword(s):  
Palm Oil ◽  
Batch Reactor ◽  
Methyl Esters ◽  
Average Pore Size ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Average Pore ◽  
X Ray ◽  
Rbd Palm Oil ◽  
Methyl Ester Content

In this study, the catalytic activity of dolomite was evaluated for the transesterification of Colombian RBD palm oil with methanol, carried out in a batch reactor at 333,15K and 600rpm. The activated dolomites (calcined at 1073.15K for 2h) were characterized by scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), Hammett indicators method, and quantification of the surface area, average pore size and average pore volume BET. The influence of reaction variables such as catalyst amount (%wt /wt) and methanol / palm oil molar ratio (mole/mole) was investigated. Under the suitable reaction conditions, the amount of calcined dolomite equal to 4% (wt /wt) based on the weight of oil, the methanol-oil molar ratio equal to 9:1, and the reaction time = 1h, the methyl ester content of 82.67% of fatty acid methyl esters (FAME) can be achieved.

Sign in / Sign up

Export Citation Format

Share Document