Sol-Gel Precursors and the Oxygen Storage Capacity of PrOy-ZrO2 Materials

1997 ◽  
Vol 497 ◽  
Author(s):  
C. K. Narula ◽  
K. L. Taylor ◽  
L. P. Haack ◽  
L. F. Allard ◽  
A. Datye ◽  
...  
Keyword(s):  
Single Phase ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Fluorite Structure ◽  
Oxygen Storage Capacity ◽  
Oxygen Storage ◽  
Molar Ratio ◽  
Metal Nitrates ◽  
Temperature Programmed

ABSTRACTThe gels derived from mixtures of Pr(OiC3H7)3 and Zr(OiC3H7)4•iC3H7OH, upon hydrolysis and pyrolysis, furnish single-phase PrOy-ZrO2 materials crystallized in the fluorite structure. These materials can be coated onto high-surface-area γ-alumina powders or deposited onto dense α-alumina coupons in the form of thin films from a solution of parent alkoxides modified with 2,4-pentanedione in THF. The fluorite structure of the PrOy-ZrO2 in the films appears to be thermally stable in air up to 1200°C. Temperature-programmed-reduction (TPR) measurements show that the bulk PrOy-ZrO2 material with a Pr. Zr molar ratio of 1:1 can store and release oxygen while that with a molar ratio of 1:3 cannot.The precursors play an important role in determining phase composition of the resulting PrOy-ZrO2 material. A mixture of monoclinic and cubic or tetragonal phases was found in PrOy-ZrO2 prepared from a new single-source heterometallic alkoxide, Pr2Zr6(μ4-O)2(μ-OAc)6(μ-OiPr)10(OiPr)10, whereas a mixture of cubic and tetragonal phases was present in PrOy-ZrO2 made previously by coprecipitation from aqueous solutions of the metal nitrates.

Oxygen Storage Capacity of CexZr1-xO2 (0.4≤x≤0.8) Solid Solution Using Thermogravimetric Analysis

2013 ◽  
Vol 747 ◽  
pp. 579-582 ◽  
Author(s):  
N. Shanmuga Priya ◽  
Chandramohan Somayaji ◽  
S. Kanagaraj
Keyword(s):  
Solid Solution ◽  
Storage Capacity ◽  
Mixed Oxides ◽  
High Surface ◽  
High Surface Area ◽  
Oxygen Storage Capacity ◽  
Oxygen Storage ◽  
Co Precipitation ◽  
Good Number ◽  
High Oxygen Storage Capacity

The property of high oxygen storage capacity (OSC) of Ceria is an important component in three-way catalysts (TWC), which depends on the low reduction temperature, high surface area and stable crystalline structure. These are required to be improved using mixed oxides for the increased OSC of TWC. Though a good number of literature is available in Ceria-Zirconia mixed oxides, optimization of the composition of oxides based on OSC is very much limited. Hence, an attempt was made to optimize the composition of CexZr1-xO2 (0.4 x 0.8) (CZ) based on the OSC using thermogravimetric technique. The CZ solid solution was prepared by co-precipitation (COP) method using Ceria nitrate, and Zirconia oxy-choloride precursors, where the freshly prepared metal hydroxide precipitates were continuously stirred at 45 °C for 60 minutes followed by washing and drying to obtain the nanosized CZ particles. The formation of single nanocrystallite with less than 8 nm size solid solution was identified by XRD, and the same was confirmed by Micro Raman studies. It is observed that the trend of OSC in CZ solid solution was based on the ratio of Ce to Zr in the starting aqueous solution, where the OSC was found to be maximum at 1.5 and the corresponding OSC of the compound was about 0.14 μmol per gram of Ceria.

Ce–Zr materials with a high surface area as catalyst supports for hydrogenation of CO2

2020 ◽  
Vol 13 (04) ◽  
pp. 2040004
Author(s):  
Nikolay D. Evdokimenko ◽  
Alexander L. Kustov ◽  
Konstantin O. Kim ◽  
Igor V. Mishin ◽  
Vera D. Nissenbaum ◽  
...  
Keyword(s):  
Surface Area ◽  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Oxygen Storage Capacity ◽  
Hydrogenation Reaction ◽  
Oxygen Storage ◽  
Hexadecyltrimethylammonium Bromide ◽  
Developed Surface ◽  
Direct Hydrogenation

The most promising way of CO2 utilization is its catalytic conversion into valuable products, in particular, the direct hydrogenation of CO2 on heterogeneous catalysts to obtain such products as synthesis gas, hydrocarbons, alcohols, esters, carboxylic acids, and some other organic molecules. Heterogeneous iron-based catalysts possess a special position among the promising candidates for the synthesis of CO2-based hydrocarbons. However, individual iron oxide catalysts have a fairly low surface area, which requires their deposition on the support or modification. CeO2 is rather attractive in catalysis because of its high oxygen storage capacity. The most effective thermal stabilizer of CeO2 is ZrO2. In this work, cerium–zirconium systems with various Ce to Zr ratios were synthesized by the method of coprecipitation in the absence and presence of the hexadecyltrimethylammonium bromide template. These systems were characterized by adsorption of N2, XRD, and DTA-TG-DTG and used as supports for 5% Fe catalysts. The activity of synthesized Fe-containing catalysts was investigated in the reaction of CO2 hydrogenation. The developed surface and the presence of cerium in the supports are the possible reasons for the high activity of Fe-containing catalysts in the hydrogenation reaction of CO2.

scholarly journals Synthesis of High Surface Area Mesoporous Silica Powder Using Anionic Surfactant

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Sang-wook Ui ◽  
In-seok Choi ◽  
Sung-churl Choi
Keyword(s):  
Mesoporous Silica ◽  
Surface Area ◽  
High Surface ◽  
Sol Gel ◽  
Sodium Dodecyl ◽  
High Surface Area ◽  
Molar Ratio ◽  
Silica Powder ◽  
Gel Method ◽  
Sol Gel Method

Over the past several years, synthesized mesoporous nanosilica (SiO2) powders have been developed by many different methods. The methods include precipitation and microemulsion, the Stöber method, chemistry, and technology. In this study, mesoporous silica powders are synthesized by the sol-gel method. The sol-gel method obtains a high purity silica powder; however, the process yields a low percentage. Past syntheses of SiO2 powder precursors are expensive, but this study needs to find a replacement precursor for low cost alternatives. A high surface area was used to form an anion surfactant sodium dodecyl sulfate, which regulates the molar concentration. The particles size variability was changed by the precursor molar ratio of the sodium silicate solution with hydrochloric acid.

High-Surface-Area Alumina-Silica Nanocatalysts Prepared by a Hybrid Sol-Gel Route Using a Boehmite Precursor

2010 ◽  
Vol 93 (12) ◽  
pp. 4047-4052 ◽  
Author(s):  
Padmaja Parameswaran Nampi ◽  
Padmanabhan Moothetty ◽  
Wilfried Wunderlich ◽  
Frank John Berry ◽  
Michael Mortimer ◽  
...  
Keyword(s):  
Surface Area ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area

Synthesis and structural characteristics of high surface area TiO2 aerogels by ultrasonic-assisted sol–gel method

2018 ◽  
Vol 29 (7) ◽  
pp. 075702 ◽  
Author(s):  
Feng Qingge ◽  
Cai Huidong ◽  
Lin Haiying ◽  
Qin Siying ◽  
Liu Zheng ◽  
...  
Keyword(s):  
Surface Area ◽  
Structural Characteristics ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Gel Method ◽  
Sol Gel Method ◽  
Ultrasonic Assisted

Texture Evaluation of Sol-Gel Derived Mesoporous Bioactive Glass

2013 ◽  
Vol 284-287 ◽  
pp. 230-234
Author(s):  
Yu Jen Chou ◽  
Chi Jen Shih ◽  
Shao Ju Shih
Keyword(s):  
Surface Area ◽  
Calcination Temperature ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
Bioactive Glasses ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Adsorption Desorption

Recent years mesoporous bioactive glasses (MBGs) have become important biomaterials because of their high surface area and the superior bioactivity. Various studies have reported that when MBGs implanted in a human body, hydroxyl apatite layers, constituting the main inorganic components of human bones, will form on the MBG surfaces to increase the bioactivity. Therefore, MBGs have been widely applied in the fields of tissue regeneration and drug delivery. The sol-gel process has replaced the conventional glasses process for MBG synthesis because of the advantages of low contamination, chemical flexibility and lower calcination temperature. In the sol-gel process, several types of surfactants were mixed with MBG precursor solutions to generate micelle structures. Afterwards, these micelles decompose to form porous structures after calcination. Although calcination is significant for contamination, crystalline and surface area in MBG, to the best of the authors’ knowledge, only few systematic studies related to calcination were reported. This study correlated the calcination parameters and the microstructure of MBGs. Microstructure evaluation was characterized by transmission electron microscopy and nitrogen adsorption/desorption. The experimental results show that the surface area and the pore size of MBGs decreased with the increasing of the calcination temperature, and decreased dramatically at 800°C due to the formation of crystalline phases.

Preparation of Silica-Supported Nickel Molybdenum Phosphides by Temperature-Programmed Reduction Technique

2007 ◽  
Vol 124-126 ◽  
pp. 1765-1768 ◽  
Author(s):  
So Yeon Lee ◽  
Yong Kul Lee ◽  
S.Ted Oyama ◽  
Seok Hee Lee ◽  
Hee Chul Woo
Keyword(s):  
Single Phase ◽  
Reduction Rate ◽  
Reduction Reaction ◽  
Molar Ratio ◽  
Infrared Spectrometry ◽  
Molybdenum Oxides ◽  
Temperature Programmed Reduction ◽  
X Ray Diffraction ◽  
Ammonium Hydrogen ◽  
Temperature Programmed

Silica supported nickel molybdenum phosphides (NiMoP/SiO2) were successfully prepared by temperature-programmed reduction (TPR) reaction of phosphorous-impregnated nickel molybdenum oxides (NiMoO4) precursors with hydrogen at relatively low temperatures (530 – 590 oC) and characterized by Fourier transform-Infrared spectrometry (FT-IR), X-ray diffraction (XRD), Electron probe microanalysis (EPMA) and Temperature-programmed reduction reaction (TPR). The process of solid transformation and properties of materials prepared from ammonium hydrogen phosphate (AMP)-impregnated samples were compared with those of phosphide made from phosphoric acid (PAC)-impregnated samples. Results show that the formation of a single NiMoP phase on silica significantly depends on reduction rates, phosphorous sources and phosphorous loadings. A single phase of NiMoP on SiO2 was particularly promoted at a below 5 oC/min of reduction rate and the starting molar ratio of Ni/Mo/P=1/1/1. A single phase of crystalline NiMoP on silica was produced from AMP-impregnated samples, while other phases of MoP, Ni2P, or NiMoP2 were appeared from PAC-impregnated samples with loading. The new phase of NiMoP2 was occurred with increasing phosphorous loading (above Ni/Mo/P=1/1/2.5) as a result of facilitated contact on the surface between the Ni-Mo bimetallic component and the phosphorous reagent

scholarly journals Recent Advances in Applications of Ceramic Nanofibers

2021 ◽  
Author(s):  
Nuray Kizildag
Keyword(s):  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Ceramic Materials ◽  
Water Remediation ◽  
Mechanical And Thermal Properties ◽  
Chemical Erosion ◽  
Recent Advances ◽  
Wide Range ◽  
Ceramic Nanofibers

Ceramic materials are well known for their hardness, inertness, superior mechanical and thermal properties, resistance against chemical erosion and corrosion. Ceramic nanofibers were first manufactured through a combination of electrospinning with sol–gel method in 2002. The electrospun ceramic nanofibers display unprecedented properties such as high surface area, length, thermo-mechanical properties, and hierarchically porous structure which make them candidates for a wide range of applications such as tissue engineering, sensors, water remediation, energy storage, electromagnetic shielding, thermal insulation materials, etc. This chapter focuses on the most recent advances in the applications of ceramic nanofibers.

Aqueous colloidal sol–gel route to synthesize nanosized ceria-doped titania having high surface area and increased anatase phase stability

2007 ◽  
Vol 43 (3) ◽  
pp. 299-304 ◽  
Author(s):  
Pradeepan Periyat ◽  
K. V. Baiju ◽  
P. Mukundan ◽  
P. Krishna Pillai ◽  
K. G. K. Warrier
Keyword(s):  
Surface Area ◽  
Phase Stability ◽  
Anatase Phase ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Doped Titania

scholarly journals Synthesis of Fe2SiO4-Fe7Co3 Nanocomposite Dispersed in the Mesoporous SBA-15: Application as Magnetically Separable Adsorbent

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 1016 ◽  
Author(s):  
Monickarla da Silva ◽  
Felipe Barbosa ◽  
Marco Morales Torre ◽  
Jhonny Villarroel-Rocha ◽  
Karim Sapag ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
High Surface ◽  
High Surface Area ◽  
Dye Adsorption ◽  
Santa Barbara ◽  
Mesoporous Support ◽  
Magnetically Separable ◽  
Temperature Programmed ◽  
Positive Effect ◽  
Isolated Species

The mixture containing alloy and oxide with iron-based phases has shown interesting properties compared to the isolated species and the synergy between the phases has shown positive effect on dye adsorption. This paper describes the synthesis of Fe2SiO4-Fe7Co3-based nanocomposite dispersed in Santa Barbara Amorphous (SBA)-15 and its application in dye adsorption followed by magnetic separation. Thus, it was studied the variation of reduction temperature and amount of hydrogen used in synthesis and the effect of these parameters on the physicochemical properties of the iron and cobalt based oxide/alloy mixture, as well as the methylene blue adsorption capacity. The XRD and Mössbauer results, along with the temperature-programmed reduction (TPR) profiles, confirmed the formation of Fe2SiO4-Fe7Co3-based nanocomposites. Low-angle XRD, N2 isotherms, and TEM images show the formation of the SBA-15 based mesoporous support with a high surface area (640 m2/g). Adsorption tests confirmed that the material reduced at 700 °C using 2% of H2 presented the highest adsorption capacity (49 mg/g). The nanocomposites can be easily separated from the dispersion by applying an external magnetic field. The interaction between the dye and the nanocomposite occurs mainly by π-π interactions and the mixture of the Fe2SiO4 and Fe7Co3 leads to a synergistic effect, which favor the adsorption.

Sign in / Sign up

Export Citation Format

Share Document