scholarly journals Lanthanum-Based Perovskite-Type Oxides La1−xCexBO3(B = Mn and Co) as Catalysts: Synthesis and Characterization

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Nyamdavaa Erdenee ◽  
Uyanga Enkhnaran ◽  
Sevjidsuren Galsan ◽  
Altantsog Pagvajav
Keyword(s):  
Catalytic Activity ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Reduction Behavior ◽  
Process Characterization ◽  
Lattice Geometry ◽  
Sol Gel Process ◽  
Ce Substitution ◽  
Crystallite Sizes ◽  
Perovskite Type

La1−xCexCoO3(x= 0, 0.2, 0.4) and La1−xCexMnO3(x= 0, 0.2) perovskite-type oxides were prepared by sol-gel process. Characterization techniques EDS, FTIR, XRD, BET, and XPS experiments were performed to survey the composition, bulk structure, and the surface properties of perovskites. The reduction behavior, thermal stability, and catalytic activity were studied by H2-TPR and catalytic performance. All synthesized samples showed well crystalline perovskite structure, 8–22 nm crystallite sizes, and SSA with 2–27 m2 g−1. The XRD results showed that the Ce substitution promoted the structural transformation for LaCoO3from rhombohedral into cubic and for LaMnO3no change in lattice geometry. Substitution with cerium (x= 0.2) showed smaller crystallite size, higher SSA, and the highest reducibility and catalytic activity for LaCoO3.

Synthesis by sol–gel process, characterization and catalytic activity of vanadia–silica mixed oxides

2005 ◽  
Vol 351 (46-48) ◽  
pp. 3624-3629 ◽  
Author(s):  
Mariza Alves Figueiredo ◽  
André Luiz de Faria ◽  
Marilda das Dores Assis ◽  
Herenilton Paulino Oliveira
Keyword(s):  
Catalytic Activity ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Process Characterization ◽  
Sol Gel Process

scholarly journals Nanostructured LiFe5O8 by a Biogenic Method for Applications from Electronics to Medicine

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 193
Author(s):  
Silvia Soreto Teixeira ◽  
Manuel P. F. Graça ◽  
José Lucas ◽  
Manuel Almeida Valente ◽  
Paula I. P. Soares ◽  
...  
Keyword(s):  
Spinel Ferrite ◽  
Sol Gel ◽  
Reaction Medium ◽  
Magnetic Hyperthermia ◽  
Magnetic Characteristics ◽  
Secondary Phases ◽  
Heat Treated ◽  
Structure Morphology ◽  
Sol Gel Process ◽  
Crystallite Sizes

The physical properties of the cubic and ferrimagnetic spinel ferrite LiFe5O8 has made it an attractive material for electronic and medical applications. In this work, LiFe5O8 nanosized crystallites were synthesized by a novel and eco-friendly sol-gel process, by using powder coconut water as a mediated reaction medium. The dried powders were heat-treated (HT) at temperatures between 400 and 1000 °C, and their structure, morphology, electrical and magnetic characteristics, cytotoxicity, and magnetic hyperthermia assays were performed. The heat treatment of the LiFe5O8 powder tunes the crystallite sizes between 50 nm and 200 nm. When increasing the temperature of the HT, secondary phases start to form. The dielectric analysis revealed, at 300 K and 10 kHz, an increase of ε′ (≈10 up to ≈14) with a tanδ almost constant (≈0.3) with the increase of the HT temperature. The cytotoxicity results reveal, for concentrations below 2.5 mg/mL, that all samples have a non-cytotoxicity property. The sample heat-treated at 1000 °C, which revealed hysteresis and magnetic saturation of 73 emu g−1 at 300 K, showed a heating profile adequate for magnetic hyperthermia applications, showing the potential for biomedical applications.

scholarly journals The Study on the Reaction Order and Kinetics of Total Oxidation Reaction of m-xylene over LaMnO3 Perovskite Catalyst

2018 ◽  
Vol 34 (3) ◽  
Author(s):  
Tran Thi Thu Huyen ◽  
Dang Thi Minh Hue ◽  
Nguyen Thi Tuyet Mai ◽  
Tran Thi Luyen ◽  
Nguyen Thi Lan
Keyword(s):  
Catalytic Activity ◽  
Reaction Order ◽  
Catalytic Properties ◽  
Sol Gel ◽  
Deep Oxidation ◽  
Perovskite Oxide ◽  
Mixed Metal Oxide ◽  
Total Oxidation ◽  
Kinetics Of ◽  
Perovskite Type

Gases of m-xylene is one of the popurlar toxic pollutants in the exhaust gases, it is emitted into the environment from factories and engines because the fuel in the engine does not burn completely. The best solution in order to remove this toxic gases of m-xylene to protect the environment is transforming them completely into CO2 and H2O by catalysts. Perovskite of LaMnO3 is one of the catalysts that was synthesized and studied the catalytic properties in total oxidation of m-xylene in our previous report. Obtained results showed that the LaMnO3 perovskite has good catalytic characterizations such as large surface area and the amount of α-oxygen adsorbed on the catalyst is large too. So, it exhibits a good catalytic activity in total oxidation of m-xylene at relatively low reaction temperature. In present work, the reaction order  and kinetics of this reaction are determined. The obtained results demonstrated that the reaction order value with respect to m-xylene is equal to about 1, to oxygene is proximately equal to 0 and the order of reaction is equal to about 1. Based on reaction order data, it was thought that the pathway of m-xylene oxidation by air oxygen  over LaMnO3 may be followed through which the Langmuir - Hinshelwood mechanism. Keywords Catalyst, perovskite, oxidation, m-xylene, kinetics References [1] Penã M.A and Fierro J.L.G (2001), << Chemical Stuctures and Performance of Perovskite Oxide>>, Chem. Rev, 101, pp 1981-2018. [2] Seiyama T., Yamazoe N. and Eguchi K. (1985), <<Characterization and Activity of some Mixed Metal Oxide Catalysts>>, Ind. Eng. Chem. Prod. Res. Dev., 24, pp. 19-27.[3] [3] Van Santen R. A., Neurock M. (2006), Molecular Heterogeneous catalysis, Wiley – VCH, pp.62-244. [4] Petrovics, Terlecki - Baricevic A., Karanovic Lj., Kirilov - Stefanov P. , Zdujic M., Dondur V., Paneva D., Mitov I., Rakic V. (2008), <<LaMO3 (M = Mg, Ti, Fe) perovskite type oxides : Preparation, Characterization and Catalytic Properties in Methane deep Oxidation>>, Appl. Catal. B, Env., 79, pp. 186-198. [5] Spinicci R., Tofanari A., Faticanti M., Pettiti I. and Porta P. (2001), <<Hexane Total Oxidation on LaMO3 (M = Mn, Co, Fe) perovskite-type oxides>>, J. Mole. Catal., 176, pp. 247-252. [6] Trần Thị Thu Huyền, Nguyễn Thị Minh Hiền, Nguyễn Hữu Phú (2006), <<Study on the preparation of perovskite oxides La1-xSrxMnO3 (x = 0; 0,3; 0,5) by sol - gel citrate method and their catalytic activity for m-xylene toltal oxidation>>, Hội nghị xúc tác và hấp phụ toàn quốc lần thứ IV, Tp. Hồ Chí Minh, Tr. 477-482.[7] Trần Thị Thu Huyền, Nguyễn Thị Minh Hiền, Nguyễn Hữu Phú (2009), <<Nghiên cứu động học của phản ứng oxi hóa hoàn toàn m-xylen trên các xúc tác perovskit LaMnO3 và La0,7A0,3MnO3 (A = Sr, Ca, Mg)>>, Tạp chí Hóa học, T.47 (6A), Tr 132-136.[8] Geoffrey C. Bond, Catherine Louis, David T. Thompson (2006), <<Catalysis by Gold>>, Catalytic Science Series-Vol.6.

How does the Support Influence the Catalytic Activity of the Keggin Ion?

1996 ◽  
Vol 454 ◽  
Author(s):  
Zakiyyah Smith ◽  
Michael Palmieri ◽  
Nancy Buecheler ◽  
Susan A. Jansen
Keyword(s):  
Catalytic Activity ◽  
Carbon Materials ◽  
Solid Acid ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Heteropoly Acids ◽  
Keggin Ion ◽  
Oxide Substrates ◽  
Silica Matrices

AbstractHeteropoly acids, HPA are well known solid acid and oxidation catalysts that find application in hetergeneous and homogeneous reactions. In the former, surface area and stability problems are diminshed by supporting the HPA. Typical supports include oxide substrates and porous carbon materials. The HPA's show some instability on these supports however. In this work, we demonstrate that HPA encapsulated in sol-gel silica matrices show enhanced catalytic performance without compromising the catalytic activity of the HPA. In addition, the specific role of the support in the catalytic process is described as well.

Synthesis and Oxygen Sensing Properties of Ti1-xSnxO2 Solid Solutions Nanoparticles

2013 ◽  
Vol 575-576 ◽  
pp. 45-49
Author(s):  
Ai Qing Wu ◽  
Xin Zuo Fang ◽  
Xin Hua Lin ◽  
Huan Qin Wang ◽  
Ying Xian Wang ◽  
...  
Keyword(s):  
Hydrothermal Method ◽  
Solid Solutions ◽  
Sol Gel ◽  
Hydrothermal Process ◽  
Typical Sample ◽  
Sol Gel Process ◽  
Crystallite Sizes ◽  
Hybrid Alkoxides ◽  
Xrd And Tem ◽  
High Temperature Calcination

Rutile Ti1xSnxO2(0.2x<1) solid solutions had been prepared using a sol-hydrothermal method, which combined the conventional sol-gel process with hydrothermal method. Hybrid alkoxides of Ti4+and Sn4+were used as precursors in the sol-gel process and Sn4+served as crystal-inducing agent during the formation of rutile crystal lattice in the hydrothermal process at 200°C. The microstructures and morphologies of nanoparticles were detected with XRD and TEM. Rutile Ti1xSnxO2solid solutions nanoparticles with well-distributed crystallite sizes about 10nm were obtained with Sn4+content above 20mol% without any high temperature calcination. The oxygen sensitivity properties of Ti1xSnxO2solid solutions had also been investigated. It is proved Ti1xSnxO2solid solutions exhibited higher oxygen responses than single TiO2or SnO2. A typical sample of Ti0.5Sn0.5O2presented the best sensitivity is approximately 6 under 400°C.

Immobilization of a Quinonoid Rhodium Catalyst on Silica Gel by the Surface Sol−Gel Process and Catalytic Activity for Phenylacetylene Polymerization

2009 ◽  
Vol 28 (10) ◽  
pp. 3000-3003 ◽  
Author(s):  
Sang Bok Kim ◽  
Chen Cai ◽  
William C. Trenkle ◽  
Dwight A. Sweigart
Keyword(s):  
Catalytic Activity ◽  
Silica Gel ◽  
Sol Gel ◽  
Rhodium Catalyst ◽  
Sol Gel Process

Microstructural characteristics and photoluminescence performance of nanograined thermally treated CeO2-TiO2 xerogels

2007 ◽  
Vol 22 (5) ◽  
pp. 1182-1187
Author(s):  
Amita Verma ◽  
A.K. Srivastava ◽  
N. Karar ◽  
Harish Chander ◽  
S.A. Agnihotry
Keyword(s):  
Electron Microscopy ◽  
Crystallite Size ◽  
Sol Gel ◽  
Structural Features ◽  
X Ray Diffraction ◽  
Molar Ratios ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Crystallite Sizes ◽  
Thermally Treated

Nanostructured thermally treated xerogels have been synthesized using a sol-gel process involving cerium (Ce) chloride heptahydrate and titanium (Ti) propoxide mixed in different Ce:Ti molar ratios. Structural features of the xerogels have been correlated with their photoluminescence (PL) response. The crystallite sizes in the samples lie in the nanorange. The x-ray diffraction and transmission electron microscopy results have confirmed the coexistence of CeO2 and TiO2 nanocrystallites in these xerogels. In general, a decrease in the CeO2 crystallite size and an increase in the TiO2 crystallite size are observed in the xerogels as a function of Ti content. Scanning electron microscopy results have evidenced the evolution of ordered structure in the xerogels as a function of TiO2 content. Although both of the phases (CeO2 and TiO2) have exhibited PL in ultraviolet and visible regions, the major luminescence contribution has been made by the CeO2 phase. The largest sized CeO2 crystallites in 1:1 thermally treated xerogel have led to its highest PL response. PL emission in the xerogels is assigned to their nanocrystalline nature and oxygen vacancy-related defects.

Preparation of La1-xCexNiO3 (x= 0 ~ 0.4) Perovskite-Type Oxide by Sol-Gel Using Polyvinyl Alcohol

2010 ◽  
Vol 434-435 ◽  
pp. 442-445 ◽  
Author(s):  
Kanit Soongprasit ◽  
Duangdao Aht-Ong ◽  
Viboon Sricharoenchaikul ◽  
Duangduen Atong
Keyword(s):  
Metal Ion ◽  
Sol Gel ◽  
Complexing Agent ◽  
Air Oxidation ◽  
X Ray Diffraction ◽  
Wet Air Oxidation ◽  
Energy Dispersion Spectroscopy ◽  
Sol Gel Process ◽  
Synthesized Materials ◽  
Perovskite Type

Perovskite-type oxides catalyst are of interest for various application such as auto-thermal reforming (ART), catalytic wet air oxidation (CWOA) and piezoelectric (PZT). In this paper, La1-xCexNiO3 (x= 0-0.4) perovskite-type oxides have been prepared b sol-gel process using PVA. The precursor was mixed metal ion and PVA with a mole ratio of 1:1 and 1:2. The decomposition during the calcinations process was evaluated by thermogravimetric analysis and differential thermal analysis. Phase of synthesized materials were characterized with X-ray diffraction. Morphological analysis and elemental composition of catalysts was determined by Scanning electron microscope and energy dispersion spectroscopy. The characterization results show that highly crystalline and homogeneous phase of these perovskite oxides were successfully synthesized by the sol-gel method via PVA as a complexing agent.

Preparation and Characterization of Cu1-xKxFe2O4 Fibers and the Catalytic Activity for Diesel Engine Exhaust Removal

2010 ◽  
Vol 96 ◽  
pp. 135-139
Author(s):  
Cai Rong Gong ◽  
Hai Feng Chen ◽  
Guo Liang Fan ◽  
Chong Lin Song ◽  
Gang Lv
Keyword(s):  
Catalytic Activity ◽  
Sol Gel ◽  
Complex Oxide ◽  
Average Diameter ◽  
Partial Substitution ◽  
High Catalytic Activity ◽  
Engine Exhaust ◽  
Sol Gel Process ◽  
Temperature Programmed ◽  
Temperature Programmed Reaction

A series of complex oxide Cu1-xKxFe2O4 fibers have been prepared via a sol-gel process related electron-spinning procedure, in which x is among 0, 0.05, 0.1 and 0.2 corresponding to the quantity of Cu2+ partial substitution by K+. The average diameter of the fiber was 500 nm. The catalytic activity of the catalysts in removal of NOx and carbon black from diesel exhaust gases were examined in detail using temperature-programmed reaction technique. The results show that after partial substitution of Cu2+ with K+, the catalytic activities have been improved. Cu0.95K0.05Fe2O4 as an optimal catalyst can significantly decrease the ignition temperature (Tig) of the PM, and has high catalytic activity on the removal of NOx.

The Effect of Sodium Hydroxide Concentration on the Structure of Iron Oxides@Bacterial Cellulose and their Catalytic Activity for Methylene Blue Degradation in Solution

2021 ◽  
Vol 891 ◽  
pp. 62-67
Author(s):  
Maradhana Agung Marsudi ◽  
Fakhri Arsyi Hawari ◽  
Ade Wahyu Y.P. Parmita ◽  
Untung Triadhi ◽  
Husaini Ardy ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Catalytic Activity ◽  
Sodium Hydroxide ◽  
Bacterial Cellulose ◽  
Large Scale ◽  
Sol Gel ◽  
Catalyst Support ◽  
Catalytic Performance ◽  
Main Crystalline Phase ◽  
Blue Solution

Heterogeneous fenton , although offering promises for large scale wastewater treatment, is still hindered in its practicality due to its modest catalytic activity. The usage of catalyst supportas been demonstrated previously toecrease the overall particle size to improve its catalytic performance. In this demonstration, fenton catalysts were prepared using the sol-gel method and bacterial cellulose (BC) as catalyst support, with varying sodium hydroxide (NaOH) concentrations (0.01; 0.1 and 1 M). NaCl impurities' presence was successfully eliminated by reducing NaOH concentration relative to the previous 4 M concentration. Lower NaOH concentration leads to a more favorable condition for the formation of smaller non-agglomerated particles and magnetite (Fe3O4) as its main crystalline phase. It was found that the best performing catalyst was produced using 1 M NaOH and was able to degrade Methylene blue solution up to 53.8% remaining dye concentration within two hours.

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