scholarly journals A Photocatalytic Active Adsorbent for Gas Cleaning in a Fixed Bed Reactor

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
Peter Pucher ◽  
Rabah Azouani ◽  
Andrei Kanaev ◽  
Gernot Krammer
Keyword(s):  
Sol Gel ◽  
Fixed Bed ◽  
Porous Silica ◽  
Active Surface ◽  
Fixed Bed Reactor ◽  
Total Oxidation ◽  
Gas Cleaning ◽  
Silica Substrate ◽  
Sol Gel Process ◽  
Highly Porous

Efficient photocatalysis for gas cleaning purposes requires a large accessible, illuminated active surface in a simple and compact reactor. Conventional concepts use powdered catalysts, which are nontransparent. Hence a uniform distribution of light is difficult to be attained. Our approach is based on a coarse granular, UV-A light transparent, and highly porous adsorbent that can be used in a simple fixed bed reactor. A novel sol-gel process with rapid micro mixing is used to coat a porous silica substrate withTiO2-based nanoparticles. The resulting material posses a high adsorption capacity and a photocatalytic activity under UV-A illumination (PCAA = photocatalytic active adsorbent). Its photocatalytic performance was studied on the oxidation of trichloroethylene (TCE) in a fixed bed reactor setup in continuous and discontinuous operation modes. Continuous operation resulted in a higher conversion rate due to less slip while discontinuous operation is superior for a total oxidation toCO2due to a user-defined longer residence time.

Porous Silica: A Potential Material for Low Dielectric Constant Applications

1998 ◽  
Vol 511 ◽  
Author(s):  
Edward D. Birdsell ◽  
Rosario A. Gerhardt
Keyword(s):  
Spin Coating ◽  
Colloidal Silica ◽  
Sol Gel ◽  
Gelation Time ◽  
Porous Silica ◽  
Low Dielectric Constant ◽  
Low Dielectric ◽  
Sol Gel Process ◽  
Gel Composition ◽  
Highly Porous

ABSTRACTHighly porous (15% dense) silica thin films with k < 2.2 have been produced using a colloidal sol-gel process. This process uses relatively inexpensive, commercially available colloidal silica and potassium silicate. These films were deposited by spin coating. The parameters for spin coating (spin speed, gelation time, gel composition, etc.) have been optimized and coherent films with thicknesses ranging from 0.7–2.0 μm can be reproducibly fabricated. Preliminary work shows that the porosity of these films ranges from a few rn to < 1 μm. The dielectric properties were examined for frequencies up to 1 MHz. Compatibility of the films with IC processing was also investigated.

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.

Preparation of Porous Silica by Microemulsion Coupling with Sol-Gel Method

2010 ◽  
Vol 113-116 ◽  
pp. 2266-2270
Author(s):  
Jing Li ◽  
Wei Xue ◽  
Yong Zhao ◽  
Zhi Miao Wang
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Tetraethyl Orthosilicate ◽  
Large Specific Surface Area ◽  
Silicon Source ◽  
Effect Of Solvent ◽  
Texture Properties ◽  
Sol Gel Process ◽  
Novel Method ◽  
Hcl Concentration

A novel method of microemulsion coupling with sol–gel process was used for preparation of porous silica using tetraethyl orthosilicate as silicon source. Effect of solvent and catalyst on the surface texture properties was investigated respectively. The results showed that porous silica with large specific surface area (738.65 m2/g) and high pore volume (2.01 cm3/g) was obtained. However, the mesopores in silica were arranged in disorder and showed great ununiformity in shape and arrangement. To obtain porous silica with desired texture properties, an appropriate dosage of ethanol and higher HCl concentration were needed.

Textural characterization of porous silica films prepared by the sol–gel process

2004 ◽  
pp. 227-231
Author(s):  
G. L. T. Nascimento ◽  
L. M. Seara ◽  
B. R. A. Neves ◽  
N. D. S. Mohallem
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Silica Films ◽  
Textural Characterization ◽  
Sol Gel Process

Synthesis of bimodal porous silica from rice husk ash via sol–gel process using chitosan as template

2008 ◽  
Vol 62 (10-11) ◽  
pp. 1476-1479 ◽  
Author(s):  
T. Witoon ◽  
M. Chareonpanich ◽  
J. Limtrakul
Keyword(s):  
Rice Husk ◽  
Rice Husk Ash ◽  
Sol Gel ◽  
Porous Silica ◽  
Sol Gel Process

Highly Porous (TiO2−SiO2−TeO2)/Al2O3/TiO2Composite Nanostructures on Glass with Enhanced Photocatalysis Fabricated by Anodization and Sol−Gel Process

2003 ◽  
Vol 107 (27) ◽  
pp. 6586-6589 ◽  
Author(s):  
Song-Zhu Chu ◽  
Satoru Inoue ◽  
Kenji Wada ◽  
Di Li ◽  
Hajime Haneda ◽  
...  
Keyword(s):  
Sol Gel ◽  
Porous Tio2 ◽  
Sol Gel Process ◽  
Highly Porous

Highly Porous Silica Nanoaerogels for Ultrafast Nonlinear Optical Applications

2005 ◽  
Vol 287 ◽  
pp. 352-357 ◽  
Author(s):  
Jae Tae Seo ◽  
S.M. Ma ◽  
K. Lee ◽  
H. Brown ◽  
A. Jackson ◽  
...  
Keyword(s):  
Apparent Density ◽  
Homeland Security ◽  
Sol Gel ◽  
Nonlinear Refraction ◽  
Porous Silica ◽  
Signal Beam ◽  
Supercritical Fluid Drying ◽  
Optical Applications ◽  
Nonlinear Optical Applications ◽  
Highly Porous

Highly porous silica nanoaerogels with low apparent density of ~0.1 g/cm3 and ~0.07 g/cm3 were synthesized through two-step sol-gel processing and low temperature supercritical fluid drying. The nonlinear refraction (γ) of silica nanoaerogels was estimated to be ~ -3.4 x 10-16 m2/W for ~0.1 g/cm3 and ~0.07 g/cm3 apparent densities with a signal-beam femtosecond z-scan spectroscopy. The third-order nonlinear refraction coefficient of nanostructure silica nanoaerogels was almost four orders larger than that of bulk silica materials. The large nonlinearrefraction with high nonlinear figure of merit (γ/βλ, β~2×10-10 m/W for 0.07 g/cm3 apparent density, β~6×10-10 m/W for 0.1 g/cm3 apparent density, λ~0.775 µm) is an ideal optical property for nonlinear applications of homeland security, battlefield enhancement, and industrial uses.

Simulation Studies of Steam Reforming of Methane using Ni-Al2O3 Catalysts

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Giane Gonçalves Lenzi ◽  
Ervin Kaminski Lenzi ◽  
Cláudio Vilas Boas Fávero ◽  
Marcelo Kaminski Lenzi ◽  
Regina Maria Matos Jorge ◽  
...  
Keyword(s):  
Sol Gel ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Co2 Production ◽  
Simulation Studies ◽  
One Dimensional ◽  
Wgs Reaction ◽  
Different Characteristics ◽  
Water Gas ◽  
Al2o3 Catalyst

This paper reports the results of reforming methane into synthesis gas using industrial Ni-Al2O3 catalyst (75% NiO wt.) and Ni-Al2O3 produced by the sol gel method (8% Ni wt.). A mathematical investigation on the performance of a one-dimensional model of catalytic conventional fixed-bed reactor was developed and implemented for the process. The results indicated that the industrial catalyst favored the water gas shift (WGS) reaction increasing CO2 production. However in temperatures of 773 and 973 K the yield (H2/CH4,reacted) was more efficient for the sol-gel catalyst. This result is possibly due to the different characteristics as specific surface area and temperature reduction. The model validation for the adjustment parameters U and a1 was more efficient for temperature profiles (2% error) than for mole fraction (10% error).

Synthesis of CeO2 Supported BaCoO3 Perovskites for Chemical-Looping Methane Reforming to Syngas and Hydrogen

2017 ◽  
Author(s):  
Haoran Ding ◽  
Yongqing Xu ◽  
Linyi Xiang ◽  
Qiyao Wang ◽  
Cheng Shen ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Fixed Bed ◽  
Gas Production ◽  
Fixed Bed Reactor ◽  
Methane Reforming ◽  
Chemical Looping ◽  
X Ray ◽  
Syngas Production ◽  
Fuel Reactor

In order to reduce the hotspots in partial oxidation of methane, CeO2 supported BaCoO3 perogvskite-type oxides were synthesized using a sol-gel method and applied in chemical-looping steam methane reforming (CL-SMR). The synthesized BaCoO3-CeO2 was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD and XPS results suggested that the obtained BaCoO3 was pure crystalline perovskite, its crystalline structure and lattice oxygen could regenerate after calcining. The reactivity of perovskite-type oxides in CL-SMR was evaluated using a fixed-bed reactor. Gas production rates and H2/CO ratios showed that the optimal reaction temperature was about 860 °C and the properly reaction time in fuel reactor was about 180s when Weight Hourly Space Velocity (WHSV) was 23.57 h−1. The syngas production in fuel reactor were 265.11 ml/g, hydrogen production in reforming reactor were 82.53 ml/g. (CSPE)

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