report for the application of MPc supported on γ-alumina for partial oxidation of cyclohexane with H 2 O 2 and TBHP. In this work, Fe, Mn and CoPc supported on γ-alumina were reported as catalysts for aerobic oxidation of cyclohexane to cyclohexanol and
Authors:Sumit Kumar, Aishwarya Kar, D. Bhattacharyya, and B. Tomar
LIII edge X-ray Absorption Fine Structure (XAFS) spectroscopic study of Eu(III) sorbed on γ-alumina from aqueous solutions of
different pH (values ranging from 6 to 8) has been carried out at XAFS beam line of Elettra Synchrotron facility, Italy, in
transmission mode. Extended X-ray Absorption Fine Structure spectra of reference compounds, namely, Eu2O3, Eu(OH)3 and Eu-aquo complex in solution, were also measured. The data were analyzed using the IFEFFIT suite of code. XAFS spectra
of the sorption samples is dominated by the Eu–O near neighbor co-ordination at distance 2.4 ± 0.1 Å. 8–9 oxygen atoms, coming
from both coordinating water molecule and oxygen atoms from alumina surface, surround the Eu(III) in the surface complex.
Next near neighbor atoms in all the sorption samples consist of Al at distance ~3.6 and 3.8 Å, which on comparison with literature
data indicates towards Eu(III) bidentate binding to apical oxygen of two different alumina octahedra on γ-alumina surface.
Authors:Yeqiang Chen, Shenfeng Yuan, Hong Yin, Zhirong Chen, and Chunqiang Mao
, deviation was generated.
In the present work, we investigated the kinetics of the process from natural aspects. Water produced was not removed and γ -alumina without drying was chosen as the catalyst, making the reaction a reversible one and
Authors:Mirabdullah Sadjadi, Amin Ebadi, and Karim Zare
The oxidation of alcohols with tert-butylhydroperoxide, in the presence of metallophthalocyanines supported on γ-alumina was investigated. These metallophthalocyanines
supported on γ-alumina were effective catalysts for the oxidation of alcohols such as cyclohexanol, benzyl alcohol and hexanol.
Authors:Viorel Chihaia, Karl Sohlberg, M. Scurtu, C. Hornoiu, M. Caldararu, C. Munteanu, G. Postole, N. I. Ionescu, T. Yuzhakova, and A. Redey
surface area like γ-alumina. Supported oxides are widely used in catalysis, the high surface area support allows the dispersion of the active phase significantly increases the extent of interaction with gaseous reactants and also improves stability under
Authors:R. Ozao, M. Ochiai, H. Yoshida, Y. Ichimura, and T. Inada
Gamma-alumina membrane was prepared from anodic (amorphous) alumina (AA) obtained in a sulphuric acid electrolyte. The transformation
scheme, i.e., the crystallization to form metastable alumina polymorphs and the final transition to α-Al2O3 with heating was studied by TG-DTA and X-ray diffraction (XRD) using fixed time (FT) method. When heating at a constant rate,
the crystallization occurred at 900C or higher and the final formation of α-Al2O3 occurred at 1250C or higher, which temperatures were higher than the case of using anodic (amorphous) alumina prepared from
oxalic acid electrolyte. Relative content of S of the products was obtained by transmission electron microscope (TEM)-energy
dispersive spectroscopy (EDS). The proposed thermal change of anodic alumina membrane prepared from sulphuric acid is as follows:
1. At temperatures lower than ca 910C: Formation of a quasi-crystalline phase or a polycrystalline phase (γ-, δ- and θ-Al2O3);
2. 910–960C: Progressive crystallization by the migration of S toward the surface within the amorphous or the quasi-crystalline
phase, forming S-rich region near the surface;
3. 960C: Change of membrane morphology and the quasi-crystalline phase due to the rapid discharge of gaseous SO2;
4. 960–1240C: Crystallization of γ-Al2O3 accompanying δ-Al2O3; and
5. 1240C: Transition from γ-Al2O3 (+tr. δ-Al2O3) into the stable α-Al2O3.
The amorphization which occurs by the exothermic and the subsequent endothermic reaction suggests the incorporation of SO3 groups in the quasi-crystalline structure.
The catalytic conversion of isopropanol was conducted over a poorly crystalline -alumina irradiated with different doses of -rays (25–150 Mrad). The catalytic reaction was carried out at 180–400°C in a flow technique under atmospheric pressure. The results showed that the dose of 25 Mrad resulted in a decrease of about 50% of the dehydration activity which suffered a further slight decrease upon irradiation at a dose of 50 Mrad. Increasing the dose in the range of 50–150 Mrad effected an increase in the dehydration activity reaching a maximum limit at 100 Mrad, then decreased abruptly by a dose of 150 Mrad. -irradiation led also to creation of some active sites contributing in dehydrogenation of isopropanol to producing acetone. These results were discussed in terms of removal of Brönsted acidity (25–50 Mrad), responsible for the dehydration reaction and to transformation of Lewis to Brönsted acidity (100 Mrad) by the action of liberated water from the dehydration reaction. The drop in dehydration activity due to irradiation at 150 Mrad might result from an efficient removal of the Brönsted acid sites created. The induced dehydrogenation activity of irradiated aluminas was attributed to creation of some electron-donor centers.
The acid-base character of vanadium pentoxide, V2O5/SiO2 and V2O5/γ-Al2O3 catalysts has been investigated by adsorption of ammonia and sulphur dioxide using microcalorimetry. By depositing vanadium
oxide on silica; new surface sites are formed which present more acid strength than bulk vanadium pentoxide and pure silica.
Alumina-supported vanadium catalysts can be regarded as acidic monolayers VOx. Sulphur dioxide was found to be selective for uncovered alumina.
Authors:Juan Mou, Chengjuan Li, Guoju Wang, and Wenxian Shi
The removal of heavy metal ion Co(II) from aqueous solution is studied using γ-Al2O3 by batch technique. The experiments are performed at T = 20 ± 2 °C, in 0.01 M NaNO3 solutions and under aerobic conditions. The effect of pH, ionic strength, fulvic acid (FA) and alumina concentration on the
sorption of Co(II) on alumina are also respectively investigated. The pH affects the sorption of Co(II) significantly as compared
with the effect of FA and ionic strength. The results indicate that strong chemical bonds are formed between Co(II) and the
bare or FA coated alumina surface, and a transition from the adsorption to surface-induced precipitation of Co(II) on alumina
surface takes place. The addition sequences of Co/FA on Co(II) sorption is also studied and the results indicate that the
sorption of Co(II) in ternary system is independent of addition sequences. The results also suggest that the sorption of metal
ions on mineral surface depends on the nature of mineral, nature of organic ligand and nature of metal ion.