Improvement of physico-chemical properties by addition of H2O2: An extensive case study on the RE-doped ceria system (RE = Gd, Sm)

2009 ◽  
Vol 24 (9) ◽  
pp. 2845-2854 ◽  
Author(s):  
Balaji P. Mandal ◽  
Vinita Grover ◽  
Mrinal R. Pai ◽  
Avesh K. Tyagi
Keyword(s):  
Surface Area ◽  
Photoelectron Spectroscopy ◽  
Chemical Properties ◽  
Doped Ceria ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Physico Chemical ◽  
Powder Properties ◽  
Temperature Programmed

Effect of H2O2 on synthesis and powder properties such as surface area and agglomerate size of nanocrystalline Ce0.8M0.2O1.90 (M: Sm, Gd) was explored by treating cerium nitrate and rare-earth nitrate with NaOH in the presence/absence of H2O2. The resultant products were characterized by x-ray diffraction, Raman spectroscopy, thermo-gravimetry–differential thermal analysis, dynamic light scattering, surface area analysis, high-resolution transmission electron microscopy, and x-ray photoelectron spectroscopy. The presence of H2O2 was found to have a profound effect on powder properties such as surface area and particle size of these doped ceria samples and results in smaller crystallite size, softer agglomerates, and larger surface area. A mechanism is proposed to explain the observed better powder properties of the samples. It was also shown that the samples prepared in the presence of H2O2 can lower the conversion temperature of CO to CO2, proving these to be better catalysts. Interestingly, temperature-programmed reduction studies on Sm3+-doped samples showed that the doping in conjunction with the use of H2O2 leads to enhanced reduction properties of the samples over multiple cycles.

Physico-Chemical and Morphological Changes of Sayong Kaolinite Clay Treated with Sulphuric Acid for Enzyme Immobilization

2013 ◽  
Vol 832 ◽  
pp. 589-595 ◽  
Author(s):  
N.A. Edama ◽  
A. Sulaiman ◽  
K.H. Ku Hamid ◽  
M.N. Muhd Rodhi ◽  
Mohibah Musa ◽  
...  
Keyword(s):  
Surface Area ◽  
Sulphuric Acid ◽  
Enzyme Immobilization ◽  
Morphological Changes ◽  
Chemical Properties ◽  
X Ray Diffraction ◽  
Kaolinite Clay ◽  
X Ray ◽  
Mineral Oxides ◽  
Physico Chemical

This study analyzed the effects of sulphuric acid (H2SO4) treatment on pysico-chemical properties and morphological changes of clay obtained from Sg. Sayong, Perak. The clay was ground and sieved to <150μm and treated with different concentrations of H2SO4. The treatment was completed by refluxing the clay with different concentration of H2SO4 (1M, 5M and 10M ) at 100 °C for 4 hours and followed by calcination at 500 °C for 1 hour. The physic-chemical properties and morphological changes of the untreated and treated clay were compared using Surface Area Analyser, X-Ray Diffraction (XRD), Field Emission Scanning Electron Micrograph (FESEM), X-Ray Diffraction (XRD) and Fourier Transformed Infrared Spectroscopy (FTIR). The results showed that acid treatment of 5M increased the surface area from 25 m2/g to 75 m2/g and the pore volume increased from 0.1518 cc/g to 0.3546 cc/g. The nanopore size of the clay decreased from 24.8 nm to 19.4 nm after treated with acid. This can be explained due to the elimination of the exchangeable cations and generation of microporosity. The results of XRF showed SiO2 increased from 58.34% to 74.52% and Al2O3 reduced from 34.6% to 18.31%. The mineral oxides such as Fe2O3, MgO, CaO, K2O and TiO2 also reduced. This concluded that H2SO4 treatment has led to significant removal of octahedral Al3+, Fe3+ cations and other impurities. In conclusion, this study showed the physico-chemical properties and morphology of Sayong clay were improved once treated with H2SO4 and therefore suggests better supporting material for enzyme immobilization.

scholarly journals Nanosized V-Ce Oxides Supported on TiO2 as a Superior Catalyst for the Selective Catalytic Reduction of NO

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 202
Author(s):  
Long Lu ◽  
Xueman Wang ◽  
Chunhua Hu ◽  
Ying Liu ◽  
Xiongbo Chen ◽  
...  
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Redox Capacity ◽  
Scr Of No ◽  
Temperature Programmed

Nanosized V-Ce oxides supported on TiO2 (VCT) were prepared and utilized in the low-temperature selective catalytic reduction (SCR) of NO with NH3. Compared with the other V-Ce oxides-based catalysts supported on Al2O3, ZrO2, and ZSM-5, VCT showed the best SCR activity in a low-temperature range. The NOx conversion of 90% could be achieved at 220 °C. Characterizations including X-ray diffraction (XRD), scanning election micrograph (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption with NH3 (NH3-TPD), and temperature-programmed reduction with H2 (H2-TPR) showed that V1.05Ce1/TiO2 exhibited a good dispersion of V2O5, enrichment of surface Ce3+ and chemical-absorbed oxygen, and excellent redox capacity and acidity, which resulted in the best SCR performance at low temperature.

scholarly journals Influence of Intercalation-Exfoliation-Reduction Technique towards the Physico-Chemical of VPO Catalysts

2013 ◽  
Vol 2013 ◽  
pp. 1-8
Author(s):  
Y. C. Wong ◽  
Y. H. Taufiq-Yap
Keyword(s):  
Electron Microscope ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vpo Catalysts ◽  
Transmission Electron ◽  
Physico Chemical ◽  
Vpo Catalyst ◽  
Temperature Programmed ◽  
Lower Temperature ◽  
Synthesized Materials

Four VPO catalysts were synthesized through intercalation and exfoliation in various alcohols and subsequent reduction of the exfoliated VOPO4sheets with various alcohols to produce VOHPO4⋅0.5H2O. The resulting VOHPO4⋅0.5H2O that undergoes the intercalation-exfoliation-reduction (IER) process will be further activated into VPO catalysts, and addition of 1 mole % Bi(NO3)3⋅5H2O in the first stage of this experiment has also being investigated. The synthesized materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and temperature-programmed reduction (TPR) in H2. Catalytic evaluation of the IER-treated and Bi-doped VPO catalysts was also studied on microreactor. The VPO catalyst produced through IER using 2-butanol and ethanol with addition of Bi, IERC(2Bu-Et)RBi1, gave the highest MA selectivity due to reactive O2−species released from the additional crystalline V5+phase formed by doping 1% bismuth as promoter (O2−-V5+pair) at relative lower temperature. Nevertheless, the VPO catalyst produced through IER using isobutanol, IERC(isoBu), gave the highest activity due to high amount of reactive O−species released from V4+phase (O−-V4+pair) whereby the IERC(isoBu) catalyst synthesized consists of high percentage of V4+(93 %).

scholarly journals Structural and Chemical Properties of Geopolymer Gels Incorporated with Neodymium and Samarium

Gels ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 195
Author(s):  
Snežana S. S. Nenadović ◽  
Ljiljana M. Kljajević ◽  
Marija M. Ivanović ◽  
Miljana M. Mirković ◽  
Nadežda Radmilović ◽  
...  
Keyword(s):  
Rare Earth ◽  
Photoelectron Spectroscopy ◽  
Chemical Properties ◽  
Alkali Activation ◽  
Tetrahedral Coordination ◽  
X Ray Diffraction ◽  
Tem Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Na Ions

The present work was focused on doping of 1% and 5% both of Nd2O3 and Sm2O3 in geopolymer gels. One of the main goals was to determine the influence of the behavior of Nd and Sm as dopants and structural nanoparticles changes of the final geopolymer formed. It is shown that the disorder formed by alkali activation of metakaolin can accommodate the rare earth cations Nd3+ and Sm3+ into their aluminosilicate framework structure. The main geopolymerization product identified in gels is Al-rich (Na)-AS-H gel comprising Al and Si in tetrahedral coordination. Na+ ions were balancing the negative charge resulting from Al3+ in tetrahedral coordination. The changes in the structures of the final product (geopolymer/Nd2O3; Sm2O3), has been characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) analysis with energy dispersive spectrometry (EDS). Nucleation at the seed surfaces leads to the formation of phase-separated gels from rare earth phase early in the reaction process. It is confirmed that Nd and Sm have been shown to form unstable hydroxides Nd(OH)3 and Sm(OH)3 that are in equilibrium with the corresponding oxides.

Magnetization of aminated lignin and characterization

TAPPI Journal ◽  
2019 ◽  
Vol 18 (01) ◽  
pp. 21-27 ◽  
Author(s):  
Xueqing Qiu ◽  
Yingzhi Ma ◽  
Dafeng Zheng
Keyword(s):  
Fourier Transform ◽  
Photoelectron Spectroscopy ◽  
Chemical Properties ◽  
Total Pore Volume ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Physico Chemical ◽  
Bet Method ◽  
Scanning Electron

A magnetic lignin-based nanomaterial (MLN) was prepared from alkaline lignin through an amination and precipitation strategy and characterized with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TG), Brunauer-Emmett-Teller (BET) method, scanning electron microscope (SEM), dynamic light scattering (DLS), and vibrating sample magnetometer (VSM). The results illustrated that MLN was thermostable and had an extensive degree of aminated lignin coating. The specific surface area of MLN was 65.43 m2/g, with the total pore volume of 0.311 cm3/g. The zeta potential of MLN was positive when pH was less than 2.9, and the saturation magnetization was 50.8 emu/g. The characterization data discovered that the physico-chemical properties of MLN were helpful for the adsorption application.

scholarly journals Evolution of Copper Supported on Fe3O4 Nanorods for WGS Reaction

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 415 ◽  
Author(s):  
Lingjuan Ma ◽  
Hongbin Ma ◽  
Dawei Han ◽  
Mingyue Qiu ◽  
Yafei Guan ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Phase Evolution ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Xrd ◽  
Wgs Reaction ◽  
Transmission Electron ◽  
Temperature Programmed

Rod-shaped Cu1Fe9Ox precursor was successfully prepared through an aqueous precipitation method. The shape and phase composition were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that Cu1Fe9Ox is composed of CuFe2O4 and Fe2O3. The reduction performance of Cu1Fe9Ox was studied by in situ XRD and H2 temperature-programmed reduction (H2-TPR). Cu/Fe3O4 nanorod catalyst is obtained through the controllable reduction of Cu1Fe9Ox nanorod, and the formed Cu/Fe3O4 nanorod catalyst does not have low-temperature water gas shift (WGS) activity, but exhibits high-temperature WGS reaction activity. Ambient pressure X-ray photoelectron spectroscopy (AP-XPS) studies showed that the main species of copper is Cu+ during the WGS reaction. The interaction between Cu and Fe3O4 rod and phase evolution of Cu species are quite different from Cu/Fe3O4 nanoparticles.

Characterization of Y/TiO2 Nanoparticles and their Reactivity for CO2 Photoreduction

2011 ◽  
Vol 55-57 ◽  
pp. 1506-1510 ◽  
Author(s):  
Jing Wei ◽  
Xin Tan ◽  
Tao Yu ◽  
Lin Zhao
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Chemical Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Uv Illumination ◽  
Transmission Electron ◽  
And Chemical Properties

A series of Y/TiO2nanoparticles (NPs) were synthesized via sol-gel method. The crystal structures, morphologies and chemical properties were characterized using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). We investigated the effects of different doping amounts of Y on the reaction of CO2photoreduction. The results shown that 0.1 wt.%Y/TiO2(0.1YT) performed the highest photocatalytic activity, which yielded 384.62 µmol/g∙cat. formaldehyde after 6 h of UV illumination.

scholarly journals Structural Characterizations of Palladium Clusters Prepared by Polyol Reduction of [PdCl4]2−Ions

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Loredana Schiavo ◽  
Lucrezia Aversa ◽  
Roberta Tatti ◽  
Roberto Verucchi ◽  
Gianfranco Carotenuto
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Properties ◽  
Nucleating Agent ◽  
X Ray Diffraction ◽  
Palladium Clusters ◽  
X Ray ◽  
Transmission Electron ◽  
Hydrogen Technology ◽  
Physical And Chemical

Palladium nanoparticles are of great interest in many industrial fields, ranging from catalysis and hydrogen technology to microelectronics, thanks to their unique physical and chemical properties. In this work, palladium clusters have been prepared by reduction of [PdCl4]2−ions with ethylene glycol, in the presence of poly(N-vinyl-2-pyrrolidone) (PVP) as stabilizer. The stabilizer performs the important role of nucleating agent for the Pd atoms with a fast phase separation, since palladium atoms coordinated to the polymer side-groups are forced at short distances during nucleation. Quasispherical palladium clusters with a diameter of ca. 2.6 nm were obtained by reaction in air at 90°C for 2 hours. An extensive materials characterization by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and other characterizations (TGA, SEM, EDS-SEM, and UV-Vis) has been performed in order to evaluate the structure and oxidation state of nanopalladium.

scholarly journals Surface Properties and Denitrification Performance of Impurity-Removed Rare Earth Concentrate

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 580
Author(s):  
Kai Zhang ◽  
Yuze Bai ◽  
Zhijun Gong ◽  
Zengwu Zhao ◽  
Baowei Li ◽  
...  
Keyword(s):  
Rare Earth ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Chemical Properties ◽  
Acid Leaching ◽  
X Ray Diffraction ◽  
Acid Base ◽  
X Ray ◽  
Temperature Programmed ◽  
Physical And Chemical

Acid leaching and alkali roasting were used to remove impurities such as Ca and Si in Baiyun Obo rare earth concentrate. The effects of acid–base treatment on the physical and chemical properties of the samples were analyzed by scanning electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller characterization, X-ray photoelectron spectroscopy, H2-temperature-programmed reduction, NH3-temperature-programmed desorption (TPD), and NO-TPD. Results showed that the content of Ce7O12 in the rare earth concentrates increased and the dispersion was uniform. The grains became smaller, the specific surface area of rare earth concentrates increased, and the active sites were more exposed. Ce coexisted in the form of Ce3+ and Ce4+, whereas Fe coexisted in the form of Fe3+ and Fe2+. The content of Fe3+ was increased. The acid–base-treated rare earth concentrates had a denitration efficiency of 87.4% at a reaction temperature of 400 °C.

scholarly journals Characteristics and activity of Ni/CeO2 catalyst modified by Cr2O3 in combined steam and CO2 reforming of CH4

2021 ◽  
Vol 10 (1) ◽  
pp. 104-108
Author(s):  
Phuong Phan Hong ◽  
Anh Nguyen Phung ◽  
Huy Tran Anh ◽  
Tri Nguyen ◽  
Loc Luu Cam
Keyword(s):  
Chemical Properties ◽  
Catalytic Performance ◽  
Molar Ratio ◽  
Impregnation Method ◽  
Co2 Reforming ◽  
X Ray ◽  
Co2 Reforming Of Ch4 ◽  
Transmission Electron ◽  
Physico Chemical ◽  
Temperature Programmed

A series of 10%wtNiO/CeO2-nanorod catalyst without and with Cr2O3 additive was prepared by simultaneous impregnation method. Several techniques, including N2 physisorption measurements, X-ray powder diffraction (XRD), temperature-programmed reduction using H2 (H2-TPR), CO2 temperature-programmed desorption (CO2-TPD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) were used to investigate catalysts’ physico-chemical properties. The activity of the catalysts in combined steam and CO2 reforming of CH4 (BRM) was investigated at temperature range of 550-800 °C. The results showed that 10%NiO0.1%Cr2O3/CeO2 catalyst had the best catalytic performance due to a better reducibility and basicity. At 700 °C and CH4:CO2:H2O molar ratio in feed stream of 3:1.2:2.4, both conversion of CH4 and CO2 on this catalyst reached 98.5%.

Sign in / Sign up

Export Citation Format

Share Document