scholarly journals Characterization and carbon monoxide oxidation activity of La1.ySryCr1.xRuxO3 perovskites

2000 ◽  
Vol 65 (1) ◽  
pp. 15-25 ◽  
Author(s):  
A. Terlecki-Baricevic ◽  
S. Petrovic ◽  
D. Jovanovic ◽  
Lj. Karanovic ◽  
C. Marinova
Keyword(s):  
Activation Energy ◽  
Photoelectron Spectroscopy ◽  
Fluorescence Analysis ◽  
Kinetic Studies ◽  
Bet Surface Area ◽  
Specific Rate ◽  
X Ray Diffraction ◽  
Oxidation Activity ◽  
X Ray ◽  
Recycle Reactor

The oxidation of CO over La1-y Sr y Cr1-xRuxO3 perovskite type oxides with y=0.3 and 0 ?x ?0.100 have been studied. X-ray fluorescence analysis confirmed that content of elements in the bulk corresponds to the established nominal perovskite stoichiometry, indicating that no significant oxidation of ruthenium into volatile polyvalent oxides with their consequented escape from the sample occurred in air up to the temperature of 1000?C. According to X-ray diffraction analysis, all sampls achieved the perovskite hexagonal with the presence of some SrCrO4. X-ray photoelectron spectroscopy analysis of ruthenium samples shows higher Ru and Sr surface concentrations than in the bulk. The binding energy for Ru3p is virtually the same in all samples and consistent with that of Ru 4+ (463.6.464.3eV). Kinetic studies were performed in a differential recycle reactor with a recycling ratio 80. The results show that substitution of Ru 4+ for Cr 3+ in La1-y Sr y CrO3 leads to a significant increase in both the activity and the activation energy. The global CO oxidation rate, referred on the BET surface area, correlates with the surface Ru 4+ atomic concentration. Hence, the activity reflect the surface enrichment in ruthenium. Moreover, an identical apparent activation energy E = 93 kJ/mol and the same specific rate per ruthenium surface ion were obtained for samples with a Ru content x ? 0.05 suggest that exposed Ru 4+ ions mainly participate in the reaction.

scholarly journals Microwave-assisted preparation of ZnS and ZnSe nanocrystals with different morphologies for photodegradation process of organic dyes

2019 ◽  
Author(s):  
Katarzyna Matras-Postolek ◽  
A. Zaba ◽  
S. Sovinska ◽  
D. Bogdal
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Organic Dyes ◽  
Zinc Sulphide ◽  
Conventional Heating ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy

Zinc sulphide (ZnS) and zinc selenide (ZnSe) and manganese-doped and un-doped with different morphologies from 1D do 3D microflowers were successfully fabricated in only a few minutes by solvothermal reactions under microwave irradiation. In order to compare the effect of microwave heating on the properties of obtained  nanocrystals, additionally the synthesis under conventional heating was conducted additionally in similar conditions. The obtained nanocrystals were systematically characterized in terms of structural and optical properties using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV-Vis spectroscopy (DR UV-Vis), Fourier-transform infrared spectroscopy (FT-IR), photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) surface area analysis. The photocatalytic activity of ZnSe, ZnS, ZnS:Mn and ZnSe:Mn nanocrystals with different morphologies was evaluated by the degradation of methyl orange (MO) and Rhodamine 6G (R6G), respectively. The results show that Mn doped NCs samples had higher coefficient of degradation of organic dyes under ultraviolet irradiation (UV).

scholarly journals Vanadium Chemical Compounds Forms in Wastes of Vanadium Pentoxide Production

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4889
Author(s):  
Anton Volkov ◽  
Ulyana Kologrieva ◽  
Anatoly Kovalev ◽  
Dmitry Wainstein ◽  
Vladimir Vakhrushev
Keyword(s):  
Vanadium Pentoxide ◽  
Photoelectron Spectroscopy ◽  
Converter Slag ◽  
Fluorescence Analysis ◽  
Vanadium Content ◽  
X Ray Diffraction ◽  
Oxidation Degree ◽  
X Ray ◽  
Secondary Ions ◽  
Optimal Technology

A big amount of solid wastes or dump sludges is generated after leaching vanadium (V) from a roasted mixture. As the vanadium content in these tailings is comparable to its concentration in traditional vanadium sources such as titanomagnetite ores or a vanadium converter slag, these wastes could be recycled to extract additional vanadium. Therefore, this research was aimed on studies of vanadium-containing sludges resulting from hydrometallurgical production of vanadium pentoxide to find an optimal technology for V extraction. The material composition of industrial and synthetic sludge samples was studied by X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), secondary ions mass spectroscopy (SIMS), and X-ray photoelectron spectroscopy (XPS, ESCA). The paper demonstrates the presence of vanadium in sludges, not only in spinels in 3+ oxidation degree, but also in other compounds containing V4+ and V5+. It was found that vanadium substitutes a set of elements in minerals except spinel. The dependence between the content of insoluble vanadium compounds and V oxidation degree was determined.

scholarly journals Thermal CO Oxidation and Photocatalytic CO2 Reduction over Bare and M-Al2O3 (M = Co, Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au) Cotton-Like Nanosheets

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1278
Author(s):  
Heejung Yoon ◽  
Juhyun Yang ◽  
Sojeong Park ◽  
Youngku Sohn
Keyword(s):  
Electron Microscopy ◽  
Transition Metals ◽  
Co Oxidation ◽  
Photoelectron Spectroscopy ◽  
Co2 Reduction ◽  
Data Sets ◽  
X Ray Diffraction ◽  
Oxidation Activity ◽  
X Ray ◽  
Transmission Electron

Aluminum oxide (Al2O3) has abundantly been used as a catalyst, and its catalytic activity has been tailored by loading transition metals. Herein, γ-Al2O3 nanosheets were prepared by the solvothermal method, and transition metals (M = Co, Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au) were loaded onto the nanosheets. Big data sets of thermal CO oxidation and photocatalytic CO2 reduction activities were fully examined for the transition metal-loaded Al2O3 nanosheets. Their physicochemical properties were examined by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction crystallography, and X-ray photoelectron spectroscopy. It was found that Rh, Pd, Ir, and Pt-loading showed a great enhancement in CO oxidation activity while other metals negated the activity of bare Al2O3 nanosheets. Rh-Al2O3 showed the lowest CO oxidation onset temperature of 172 °C, 201 °C lower than that of bare γ-Al2O3. CO2 reduction experiments were also performed to show that CO, CH3OH, and CH4 were common products. Ag-Al2O3 nanosheets showed the highest performances with yields of 237.3 ppm for CO, 36.3 ppm for CH3OH, and 30.9 ppm for CH4, 2.2×, 1.2×, and 1.6× enhancements, respectively, compared with those for bare Al2O3. Hydrogen production was found to be maximized to 20.7 ppm during CO2 reduction for Rh-loaded Al2O3. The present unique pre-screening test results provided very useful information for the selection of transition metals on Al2O3-based energy and environmental catalysts.

Novel Homogeneous and Mesoporous MnOx-Doped Ceria Nanosheets as Catalysts for Low-Temperature Selective Catalytic Reduction

2019 ◽  
Vol 72 (9) ◽  
pp. 657
Author(s):  
Yan Yue ◽  
Yanhua Wang ◽  
Jun Ling ◽  
Weilin Sun ◽  
Zhiquan Shen
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Bet Surface Area ◽  
Homogeneous Distribution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Precipitation ◽  
Scr Of Nox

The development of a catalyst for the selective catalytic reduction (SCR) of NOx is essential for purifying air and the denitration of coal-burning exhaust. Herein, we prepare novel MnOx-CeO2 nanosheets with porous structures by a homogeneous coordination precipitation (HCP) method which exhibit a high NO removal efficiency above 90% in the SCR reaction at low temperature (150–240°C). The MnOx-CeO2(HCP) catalysts have a higher Brunauer–Emmett–Teller (BET) surface area and more homogeneous distribution of Mnx+ in the CeO2 lattice than those prepared by co-precipitation and precursor mixture combustion methods according to BET, X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy characterizations. Together with a higher ratio of Mn4+, Ce3+, and Oα, the above properties are responsible for the high catalytic performances of MnOx-CeO2(HCP) in the SCR of NOx.

scholarly journals Synthesis and Catalytic Performance of Ni/SiO2for Hydrogenation of 2-Methylfuran to 2-Methyltetrahydrofuran

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Fu Ding ◽  
Yajing Zhang ◽  
Guijin Yuan ◽  
Kangjun Wang ◽  
Ileana Dragutan ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ni Content ◽  
Transmission Electron ◽  
Temperature Programmed ◽  
Ni Species

A series of Ni/SiO2catalysts with different Ni content were prepared by sol-gel method for application in the synthesis of 2-methyltetrahydrofuran (2-MTHF) by hydrogenation of 2-methylfuran (2-MF). The catalyst structure was investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and temperature programmed reduction (TPR). It is found that structures and catalytic performance of the catalysts were highly affected by the Ni content. The catalyst with a 25% Ni content had an appropriate size of the Ni species and larger BET surface area and produced a higher 2-MF conversion with enhanced selectivity in 2-MTHF.

Preparation of Gold Nanoparticles Supported on Montmorillonite and its Catalytic Activity for CO Oxidation

2014 ◽  
Vol 955-959 ◽  
pp. 51-55
Author(s):  
Ting Ting Hu ◽  
Lin Hua Zhu
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Oxidation Reaction ◽  
Fluorescence Analysis ◽  
X Ray Diffraction ◽  
Oxidation Activity ◽  
X Ray ◽  
Transmission Electron ◽  
Gold Precursor

Gold catalysts supported on Na-MMT and Al-PILM noted as Au/Na-MMT and Au/Al-PILM respectively were prepared using Au(en)2Cl3 as precursor, and the catalytic oxidation activity for CO oxidation was investigated. The influence of different carriers on the conversion of CO was discussed. The phase of catalysts, the actual gold loading and the morphology of gold nanoparticles were characterized by X-ray diffraction(XRD), X-ray fluorescence analysis(XRF) and Transmission electron microscopy(TEM). The results showed that Au/Al-PILM exhibited higher catalytic activity for the oxidation reaction of CO, and 100% conversion of CO was achieved at reaction temperature of 250°C when gold precursor was loaded on the Al-PILM carrier at 60°Cand calcined it at 450°C for 1h.

Solid-Phase Synthesis and Photocatalytic Property of Cobalt-Doped TiO2 Mesoporous Materials

2011 ◽  
Vol 217-218 ◽  
pp. 1462-1468 ◽  
Author(s):  
Shao You Liu ◽  
Qing Ge Feng
Keyword(s):  
Photoelectron Spectroscopy ◽  
Solid Phase ◽  
Photocatalytic Property ◽  
Textural Properties ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Bending Vibration ◽  
Toluene Oxidation ◽  
X Ray ◽  
Transmission Electron

Mesoporous cobalt-doped TiO2 (Co-TiO2) material has been synthesized by solid-state reaction route. The textural properties of the samples are monitored by the X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy(EDS), Raman spectroscopy, N2-physisorption, Fourier transform infrared spectroscopy (FT-IR), ultraviolet visible light spectroscopy (UV-Vis) and X-ray photoelectron spectroscopy(XPS). It is shown that the mesoporous Co-TiO2 is consisted of polycrystalline with some amorphous mixture and trace cobalt oxide. Cobalt has been incorporated into the framework of anatase TiO2. The bending vibration at 1124 cm-1 of Co-O-Ti bond in mesoporous Co-TiO2 material is confirmed. Interestingly, it possesses a large BET surface area (97.6 m2/g) and a narrow distribution of pore size presenting a better photocatalytic reactivity for toluene oxidation. Within 150 min irradiation, the maximum conversion (95 mol%) of toluene oxidation is obtained.

scholarly journals Experimental Design Modelling and Optimization of Triazine Herbicides Removal With Reduced Graphene Oxide Using Response Surface Method

2021 ◽  
Author(s):  
Martina Foschi ◽  
Paola Capasso ◽  
Maria Anna Maggi ◽  
Fabrizio Ruggieri ◽  
Giulia Fioravanti
Keyword(s):  
Graphene Oxide ◽  
Response Surface ◽  
Photoelectron Spectroscopy ◽  
Bet Surface Area ◽  
Maximum Adsorption Capacity ◽  
Pristine Graphene ◽  
X Ray Diffraction ◽  
Freundlich Model ◽  
X Ray ◽  
Reduced Graphene

Abstract In this work, triazines were chosen as the organic micropollutants model, to develop a useful method for the removal of triazine products, using a reduced derivative of graphene oxide as adsorbent material. The pristine graphene oxide and its thermally reduced derivatives under mild conditions were tested, optimizing the GO reduction conditions by means of DOE coupled with the response surface methodology. For the reduction it was decided to choose the mildest and simplest conditions possible, using an air heat treatment in a common laboratory oven. The optimal reduction conditions deduced from the response surface were calculated at a reduction temperature of 110 °C maintained for 24 hours and rGO sample was employed in the adsorption of the triazines. All the adsorbent materials have been characterized before use, by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett- Teller (BET) surface area analysis. Triazine analyses were performed by HPLC. The data obtained from the adsorption isotherms have been fitted with the Langmuir and Freundlich models, and the Freundlich model was the best one, especially for the Atraton and the Prometryn. The maximum adsorption capacity obtained was 4.4 mg/g for Atrazine, 19.4 mg/g for Atraton and 18.4 mg/g for Prometryn, at room temperature.

scholarly journals Facile Template In-Situ Fabrication of ZnCo2O4 Nanoparticles with Highly Photocatalytic Activities under Visible-Light Irradiation

2019 ◽  
Vol 14 (2) ◽  
pp. 404 ◽  
Author(s):  
Vu T. Tan ◽  
La The Vinh ◽  
Tran Ngoc Khiem ◽  
Huynh Dang Chinh
Keyword(s):  
Electron Microscopy ◽  
Methylene Blue ◽  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
High Specific Surface Area ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Fabrication ◽  
Transmission Electron

High specific surface area ZnCo2O4 nanoparticles were prepared via a sacrificial template accelerated hydrolysis by using nanoparticles of ZnO with highly polar properties as a template. The obtained ZnCo2O4 nanoparticles were characterized by the method of scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area measurements, Transmission electron microscopy (TEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The obtained nanoparticles were performed as a photocatalyst for the degradation of methylene blue in aqueous solution under visible irradiation. The photocatalytic degradation rate of methylene blue onto the synthesized ZnCo2O4 was higher than that of commercial ZnO and synthesized ZnO template. Copyright © 2019 BCREC Group. All rights reserved. 

Investigation of the Effect of Uv-Assisted Oxidation and Nitridation of Hafnium Metal Films

2003 ◽  
Vol 780 ◽  
Author(s):  
C. Essary ◽  
V. Craciun ◽  
J. M. Howard ◽  
R. K. Singh
Keyword(s):  
Uv Radiation ◽  
Photoelectron Spectroscopy ◽  
Grazing Angle ◽  
X Ray Diffraction ◽  
Metal Thin Films ◽  
X Ray ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Silicon Interface

AbstractHf metal thin films were deposited on Si substrates using a pulsed laser deposition technique in vacuum and in ammonia ambients. The films were then oxidized at 400 °C in 300 Torr of O2. Half the samples were oxidized in the presence of ultraviolet (UV) radiation from a Hg lamp array. X-ray photoelectron spectroscopy, atomic force microscopy, and grazing angle X-ray diffraction were used to compare the crystallinity, roughness, and composition of the films. It has been found that UV radiation causes roughening of the films and also promotes crystallization at lower temperatures.Furthermore, increased silicon oxidation at the interface was noted with the UVirradiated samples and was shown to be in the form of a mixed layer using angle-resolved X-ray photoelectron spectroscopy. Incorporation of nitrogen into the film reduces the oxidation of the silicon interface.

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