Authors:Ping Liu, Xingguang Zhang, Yue Yao, and Jun Wang
Alkaline earth metal (Mg, Ca, Sr and Ba) ions were exchanged into Hβ zeolite, which were used as the supports to load the
noble metal Pt to prepare bifunctional catalysts for hydroisomerization of n-heptane. The catalysts were characterized by ICP, XRD, BET, NH3-TPD, H2-TPR and H2-chemisorption techniques, and evaluated in an atmospheric fixed bed reactor. The catalysts promoted by the alkaline earth
metals are revealed to present much higher selectivity to isomerization than the counterpart Pt/Hβ. Moreover, the Ba-bearing
catalyst loaded with 0.4 wt% Pt and 5:1 molar ratio of Ba to Pt gives a very high selectivity to iso-heptanes 95.4% with a
considerable high conversion of n-heptane 61.7%. The promotion effect of alkaline earth metals is briefly discussed in relation to characterization data.
Authors:A. A. Opalovsky, V. E. Fedorov, and T. D. Fedotova
The thermal stability of alkaline earth metal hydrofluorides was studied by means of a Derivatograph. The values of the activation energy, reaction order and rate constant were determined. The comparison of the kinetic parameters of the decomposition process for the complete series of hydrofluorides studied led to a certain regularity in the differences in their thermal stabilities and its correlation with the strength of the hydrogen bond in their structure.
The distribution coefficients for alkali and alkaline earth metal ions on potassium cobalt hexacyanoferrate (II), K2CoFe(CN)6×1.4H2O, show high selectivity for cesium. The uptake values of the ions vary widely. The uptake is most probably an ion exchange process.
The separation of alkali and alkaline earth metals by means of an acyclic polyether, 1,13-bis(8-chinolinyl)-1, 4, 7, 10, 13-pentaoxatridecane
(CPOD), and cyclic polyethers, benzo-15-crown-5 (BC), dibenzo-18-crown-6 (DBC) and dicyclohexyl-18-crown-6 (DCHC), using extraction
chromatography has been studied. The alkali metals can be effectively separated using SCN− ions. Different elution sequences for these groups were observed using chloroform and mesitylene and diluents for the polyethers.
In order to reveal to what extent tritium (3H or T) can be incorporated into hydroxides, the isotope exchange reaction (OT-for-OH exchange reaction) between each alkaline earth metal hydroxide (M(OH)2), where M means alkaline earth metal (M=Ca, Sr or Ba) and HTO water was observed homogeneously at 30 °C under equilibrium after mixing. Consequently, the followings were obtained: (1) a quantitative relation between the electronegativity of each M ion and the ability (of the M ion) incorporating OT– into the M hydroxide can be found and the ability is small when the temperature is high, (2) the exchange rate for the OT-for-OH exchange reaction is small when the electronegativity of the M ion in the M hydroxide in great, (3) as for the dissociation of HTO water, it seems that fomula (HTOT++OH–) is more predominant than the fomula (HTOH++OT–) when the temperature is high and (4) the method used in this work is useful to estimate the reactivity of a certain alkaline material.
The thermo non-oxidative degradation of PVC and the effects of alkaline earth metal (Be, Mg, Ca, Ba) stearates were studied
by thermogravimetry in the temperature range 150 to 500°C. The alkaline earth metal stearates were observed effectively reduce
the dehydrochlorination of PVC. The synergistic effects of combinations of these salts with lead stearate were also studied
and are discussed. Kinetic parameters such as the activation energy, order of reaction and Arrhenius factor were calculated
by the Coats and Horowitz methods. The results showed that these metal stearates increase the activation energy required for
the dehydrochlorination of PVC.
Authors:R. Qadeer, J. Hanif, M. Saleem, and M. Afzal
Effects of alkali metals, alkaline earth metals and some lanthanides on the adsorption of uranium on activated charcoal from aqueous solutions have been studied. These effects are correlated with the ionic radii of metal ions present in the solutions. Adsorption capacity, Xm and binding energy contant, K for uranium adsorption were calculated from the Langmuir equätion. The mean energy of adsorption, Es was calculated from adsorption energy constant, K, values determined from the Dubinin-Radushkevich isotherm equation. Wavelength dispersive X-ray fluorescence spectrometry was used for measuring the uranium concentration.
montmorillonite for alkaline and alkalineearthmetals have been reported in numerous studies [ 20 – 22 ]. Furthermore, more work has been focused on the effects of interlayer cations on the physicochemical properties, such as cation exchange capacity, pore
The thermal decompositions of the salicylates of magnesium, calcium, strontium and barium were investigated using thermogravimetry and differential thermal analysis, together with the analysis of intermediate products formed during the decomposition processes. One intermediate product was isolated and identified during the decomposition of the magnesium salt, and two for each of the remaining metal salts.
Metal complexes of calcium with 5,7-dibromo, 7-iodo and 5-chloro-7-iodo-8-hydroxyquinolate were precipitated in aqueous ammonia
and acetone medium, except for the solid state compound with 5,7-dichloro-8-hydroxyquinoline which hasn"t been obtained under
these conditions. The complexes obtained through the mentioned precipitation are Ca[(C9H4ONBr2)2]3H2O, Ca[(C9H5ONI)2]2H2O and Ca[(C9H4ONICl)2]2.5H2O. Their intermediate from the thermal decomposition found through TG/DTA curves in air indicated the presence of different
kinds of calcium carbonates related to the reversibility and crystalline structure, depending on the original compounds. The
initial compounds and the intermediate from the thermal decomposition were also characterized through IR spectra and X-ray