The valence state of chromium ions contained in the active sites of dehydrocylization of paraffin hydrocarbons on aluminochromium catalysts

1974 ◽  
Vol 23 (12) ◽  
pp. 2582-2585
Author(s):  
M. I. Rozengart ◽  
K. M. Gitis ◽  
V. G. Bryukhanov
Keyword(s):  
Valence State ◽  
Active Sites ◽  
Chromium Ions

Valence state and X-ray photoelectron 2p spectra of chromium ions in the La1–x Sr x CrO3 (x = 0, 0.1, 0.3, 0.5) system

2017 ◽  
Vol 81 (3) ◽  
pp. 331-333
Author(s):  
A. T. Kozakov ◽  
A. G. Kochur ◽  
A. V. Nikolskii ◽  
I. P. Raevskii
Keyword(s):  
Valence State ◽  
X Ray ◽  
Chromium Ions

Valence state of dopant chromium ions in calcium-gallium-germanium garnet crystals

1993 ◽  
Vol 58 (5-6) ◽  
pp. 413-417 ◽  
Author(s):  
A. E. Nosenko ◽  
L. V. Kostyk
Keyword(s):  
Valence State ◽  
Chromium Ions

scholarly journals Determination of chromium valence state in the CaO–SiO2–FeO–MgO–CrOx system by X-ray photoelectron spectroscopy

2020 ◽  
Vol 39 (1) ◽  
pp. 351-356
Author(s):  
Deman Liu ◽  
Jiang Diao ◽  
Yiyu Qiu ◽  
Guang Wang ◽  
Gang Li ◽  
...  
Keyword(s):  
High Temperature ◽  
Binding Energy ◽  
Oxygen Pressure ◽  
Photoelectron Spectroscopy ◽  
Valence State ◽  
Slag Basicity ◽  
X Ray ◽  
Chromium Ions ◽  
Valence States

AbstractThe chromium valence states in the CaO–SiO2–FeO–MgO–CrOx system were investigated by X-ray photoelectron spectroscopy (XPS). The results indicated that the XPS peaks of Cr 2p3/2 and Cr 2p1/2 locate at the binding energy of ∼577 and ∼586 eV, respectively. There are three kinds of chromium ions such as bivalent Cr(ii), trivalent Cr(iii), and hexavalent Cr(vi) in the CaO–SiO2–FeO–MgO–CrOx slag. Cr(iii) is the dominant valence state, and more than 77.99% Cr is trivalent Cr(iii). The fraction of Cr(ii)/Cr is in the range of 11.24–17.22%. The fraction of Cr(vi)/Cr is below 4.80%. The fraction of Cr(ii)/Cr decreases with increasing slag basicity, Cr2O3 content, temperature, or oxygen pressure log(PO2), while the fraction of Cr(iii)/Cr increases with increasing basicity, Cr2O3 content, temperature, or oxygen pressure. The trend of change is opposite. Low log(PO2), high Cr2O3 content, and high temperature are beneficial to reduce the toxic hexavalent Cr(vi). The slag basicity has little influence on the fraction of Cr(vi)/Cr.

scholarly journals ACTIVATED ADSORBENT PREPARED FROM BOVINE BONE WASTE: PHYSICO-CHEMICAL CHARACTERISTICS, ISOTHERM AND THERMODYNAMICS ADSORPTION OF CHROMIUM IONS IN WASTEWATER

2020 ◽  
Vol 7 (3) ◽  
pp. 1-11
Author(s):  
I Nengah Simpen ◽  
I Made Sutha Negara ◽  
Sofyan Dwi Jayanto
Keyword(s):  
Active Sites ◽  
Crystal Size ◽  
Physical Adsorption ◽  
Low Cost ◽  
Chemical Characteristics ◽  
Bovine Bone ◽  
Chromium Ions ◽  
Physico Chemical ◽  
Freundlich Adsorption Isotherm ◽  
Surface Active

The adsorption characteristics of chromium ions in chrome electroplating wastewater on low cost adsorbent have been conducted. Adsorbent was prepared from bovine bone waste of NaOH activated at various concentrations (0.2 to 0.8 M). Its adsorption such as adsorption isotherms and adsorption thermodynamics as well as adsorbent physico-chemical characteristics (surface active sites, crystallinity and crystal size, surface morphology and elementals composition). The result showed that amount of adsorbent surface active sites increased because of NaOH activated, the highest at 0.4 M NaOH concentration (AT0.4 adsorbent). X-ray diffraction patterns of the adsorbents showed a wide peaks and crystal size as nanocrystalline. The surface morfology was stack of aglomerates and leached of Ca and Mg due to increase Na. The adsorption result of adsorbents to chromium ions showed that the highest adsorption ability on AT0.4 adsorbent. It was suitable for Freundlich adsorption isotherm model as physical adsorption and endothermic but the tendency to be spontaneous process.

MgO-codoping-induced change in the site distribution and valence state of chromium ions in LiNbO3

1997 ◽  
Vol 72-74 ◽  
pp. 177-178
Author(s):  
J. Díaz-Caro ◽  
J. García-Solé ◽  
H. Murrieta ◽  
F. Jaque
Keyword(s):  
Valence State ◽  
Chromium Ions ◽  
Site Distribution

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

Valence state analysis of elements by EPMA and its application

1990 ◽  
Vol 48 (2) ◽  
pp. 230-231
Author(s):  
Chen Liqing ◽  
Liu Zuqin ◽  
Zhang Wei
Keyword(s):  
Valence State ◽  
Line Intensities ◽  
Valence States ◽  
Valence Electrons ◽  
Fe And Mn ◽  
Intensity Ratios ◽  
State Analysis

Valence state analyses of Fe and Mn in oxides by EPMA have been reported in literature. In this paper, the effects of valence state on intensity ratios ILα/IKα and ILα/ILβ of Cu, Ni, Co, Fe, Mn, Cr and their oxides, and on intensity ratios ILβ2/ILα1 and ILγ1/ILα1 of Mo, Nb, Zr and their oxides were studied. It was observed that intensity ratios change with valence states in accordance with some regularities, and these effects could be utilized for analyzing the valence states of catalysts.Valence state analysis of elements by EPMA is based on the fact that changes in the states of valence electrons in the outer shells of an atom cause corresponding changes in line intensities. The M electrons of Cu, Ni, Co, Fe, Mn, Cr and the N electrons of Mo, Nb, Zr are valence electrons. Line Kα1,2 and six lines of L are produced from the transitions of K-L2,3 and L-M or L-N respectively.

Scanning luminescence x-ray microscopy: Progress toward selective staining using microspheres

1994 ◽  
Vol 52 ◽  
pp. 74-75
Author(s):  
C. Jacobsen ◽  
J. Fu ◽  
S. Mayer ◽  
Y. Wang ◽  
S. Williams
Keyword(s):  
Visible Light ◽  
Active Sites ◽  
Light Emission ◽  
Chinese Hamster ◽  
Polystyrene Spheres ◽  
Good Resistance ◽  
X Ray ◽  
Selective Staining ◽  
Visible Light Emission ◽  
Specific Labelling

In scanning luminescence x-ray microscopy (SLXM), a high resolution x-ray probe is used to excite visible light emission (see Figs. 1 and 2). The technique has been developed with a goal of localizing dye-tagged biochemically active sites and structures at 50 nm resolution in thick, hydrated biological specimens. Following our initial efforts, Moronne et al. have begun to develop probes based on biotinylated terbium; we report here our progress towards using microspheres for tagging.Our initial experiments with microspheres were based on commercially-available carboxyl latex spheres which emitted ~ 5 visible light photons per x-ray absorbed, and which showed good resistance to bleaching under x-ray irradiation. Other work (such as that by Guo et al.) has shown that such spheres can be used for a variety of specific labelling applications. Our first efforts have been aimed at labelling ƒ actin in Chinese hamster ovarian (CHO) cells. By using a detergent/fixative protocol to load spheres into cells with permeabilized membranes and preserved morphology, we have succeeded in using commercial dye-loaded, spreptavidin-coated 0.03μm polystyrene spheres linked to biotin phalloidon to label f actin (see Fig. 3).

The design and catalytic performance of molybdenum active sites on an MCM-41 framework for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

2019 ◽  
Vol 9 (3) ◽  
pp. 811-821 ◽  
Author(s):  
Zhao-Meng Wang ◽  
Li-Juan Liu ◽  
Bo Xiang ◽  
Yue Wang ◽  
Ya-Jing Lyu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Aerobic Oxidation ◽  
Catalytic Performance ◽  
Mcm 41

The catalytic activity decreases as –(SiO)3Mo(OH)(O) > –(SiO)2Mo(O)2 > –(O)4–MoO.

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