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1.
The phase diagrams of the binary system KF-AlF3 as well as the ternary system NaF-KF-AlF3 in the range up to 50 mol% AlF3, were measured using the thermal analysis method. In the system KF-AlF3 the coordinates of the eutectic points are: E
1: 8.0 mol% AlF3, 821.2°C, and E
2: 45.5 mol% AlF3, 565.0°C. In the investigated concentration range of the ternary system 2 eutectic points have been found with the calculated
coordinates: E
1: 36.3 mol% NaF, 62.7 mol% KF, 1.0 mol% AlF3; t=711.2°C; and E
2: 51.9 mol% NaF, 27.4 mol% KF, 20.7 mol% AlF3; t=734.5°C. Other eutectic points lie most probably beyond the investigated part of the system.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
Marián Kucharík František Šimko Vladimír Danielik Miroslav Boča Roman Vasiljev 《Monatshefte für Chemie / Chemical Monthly》2007,138(12):1211-1215
Summary. The phase diagram of the system Na3AlF6–NaVO3 was determined by means of thermal analysis. The system is a simple binary eutectic one. The eutectic point was estimated
at x(NaVO3) = 0.975 and t
eut = 617°C. The XRD patterns of samples after thermal analysis revealed the presence of cryolite and NaVO3 only supporting the above assumption of a simple eutectic binary system. 相似文献
3.
This study examines the alkylation of diphenylamine (DPA) with nonene (NON) in a liquid phase catalyzed by acid-treated clay-based catalysts from commercial suppliers (Fulcat 22B, Nobelin MM, and Jeltar 300). Alkylations were conducted to achieve the highest possible selectivity of diisononyldiphenylamine (DNDPA), low selectivity of monoisononyldiphenylamine, and a maximum triisononyldiphenylamine yield of 4%. This study also examines the reaction conditions to selectively form dialkylated diphenylamine from DPA and NON in a batch reactor. Repeated use of the catalyst during the alkylation of DPA with NON was also investigated. Catalyst deactivation takes place during the alkylation of each batch and intensifies with repeated catalyst use, resulting in low DNDPA selectivity. The regenerated catalyst was sufficiently active only until the regeneration of the first and second batches. After the third batch, the catalyst’s selectivity for DNDPA was very low, and its reuse in the alkylation of DPA with NON was not efficient. Therefore, to achieve the maximum length of catalyst activity, the fresh catalyst was gradually added to the used catalyst from a previous batch, thus maintaining a high activity of eight batches. The reduction in catalyst activity was probably caused by the irreversible adsorption of substances on the surface, a loss of microporous structure, and a loss of surface acidity. DPA or alkylated products are adsorbed on the surface oxygen of the catalyst through nitrogen and form nitro formations. The fresh and regenerated catalysts were characterized by their surface area, surface acidity, pore size distribution, and pore volume. 相似文献
4.
M. Boča V. Danielik Z. Ivanová E. Mikšíková B. Kubíková 《Journal of Thermal Analysis and Calorimetry》2007,90(1):159-165
The phase diagrams of the systems KF-K2TaF7 and KF-Ta2O5 were determined using the thermal analysis method. The phase diagrams were described by suitable thermodynamic model. In
the system KF-K2TaF7 eutectic points at x
KF=0.716 and t=725.4°C and at x
KF=0.214 and t=712.2°C has been calculated. It was suggested that K2TaF7 melts incongruently at around 743°C forming two immiscible liquids. The system KF-Ta2O5 have been measured up to 8 mol% of Ta2O5. The eutectic point was estimated to be at x
KF∼0.9 and t∼816°C. The formation of KTaO3 and K3TaO2F4 compounds has been observed in the solidified samples. 相似文献
5.
V. Dvořák V. Danielik O. Matal Marta Chrenková M. Boca 《Journal of Thermal Analysis and Calorimetry》2008,91(2):541-544
The phase diagram of the binary system NaF-SnF2 was determined by using the thermal analysis method. In addition to the crystallisation
fields of pure components the formation of three other crystallisation fields was observed and these were attributed to the
compounds: NaF·2SnF2, NaF·SnF2 and 2NaF·SnF2. The coordinates of the four eutectic points are: e
1: 70 mol% NaF, 30 mol% SnF2 and 255°C e
2: 58 mol% NaF, 42 mol% SnF2 and 238°C e
3: 44 mol% NaF, 56 mol% SnF2 and 246°C e
4: 18 mol% NaF, 82 mol% SnF2 and 191°C
The model independent on the real structure of the melt was applied for the calculation of phase diagram comprising the calculation
of excess molar Gibbs energy of mixing. The probable inaccuracy in the calculated phase diagram is σ=2.0°C. XRD analysis of
solidified mixtures was performed in order to confirm the formation of expected compounds. 相似文献
6.
Marta Ambrová Jana Jurišová Alexandra Sýkorová Dalibor Uher Vladimír Danielik Ján Híveš 《Chemical Papers》2008,62(2):154-159
The electrochemical behaviour of the LiF-La2O3 and LiF-CaF2-La2O3 systems was investigated by means of cyclic voltammetry. Several types of working electrodes (spectrographic pure graphite,
W, Mo, Ni, Cu) were used. It was found that chemical reactions take place in the system during the dissolution of lanthanum
oxide. The reduction of lithium cations occurred at the most positive potential from the species formed in the melt on ‘inert’
cathodes (W, Mo). The reactive cathodes (Cu, Ni) allowed the lanthanum deposition with depolarisation. 相似文献
7.
The reactivity of flue gas desulphurization gypsum with ammonium carbonate has been studied in the temperature range (20–50) °C. Mechanism of this reaction was suggested and the kinetics parameters characterizing the reaction were determined. A mathematical model suitable for the prediction of the conversion of gypsum was proposed. The reaction is of the second order. Influence of the size of gypsum particles on the relationship between the surface and volume of the particles is not significant. From the obtained experimental results, it follows that the reaction does not proceed at the surface of the solid gypsum particles, but in the liquid phase between dissolved gypsum and ammonium carbonate. The diffusion of the dissolved gypsum through the liquid film formed at the surface of the solid gypsum particles is the rate-limiting step of the conversion reaction. 相似文献
8.
The electrochemical behaviour of lanthanum fluoride dissolved in molten lithium fluoride and in eutectic mixture LiF-CaF2 was investigated by cyclic voltammetry and laboratory electrolysis. The cyclic voltammetry experiments were carried out at
900°C and 800°C, respectively, in a graphite crucible (counter electrode). Several types of working electrodes (Mo, W, Ni
and Cu) were used. Ni/Ni(II) was used as a reference electrode. Laboratory electrolysis was carried out in the system LiF-CaF2-LaF3 at 800°C in galvanostatic (j
c = −0.21 A cm−2) and potentiostatic (E = 0.87 V) regimes. In both cases, nickel served as the cathode and graphite as the anode. It was found that no new separate
reduction peak occurred on the molybdenum or tungsten electrodes in the investigated systems. When copper or nickel electrodes
were used, new peaks corresponding to the reduction of lanthanum(III) to lanthanum metal appeared. This can be explained by
the formation of alloys or intermetallic compounds of lanthanum with copper or nickel. X-ray microanalysis showed that lanthanum
was electrodeposited together with calcium under formation of intermetallic compounds with the electrode materials in the
galvanostatic regime. In the potentiostatic regime, mainly lanthanum was deposited, which enabled its separation. 相似文献
9.
Zuzana?NetriováEmail author M.?Bo?a V.?Danielik Eva?Mik?íková 《Journal of Thermal Analysis and Calorimetry》2009,96(1):111-115
As an asymmetric organic molecular crystal, p-N,N-dimethylaminobenzaldehyde (DAB) exhibits peculiar optical property. It was first grown by solution technique adopting slow
evaporation method at room temperature using CCl4 as growth medium. The solubility of DAB increases with temperature. Good quality transparent crystals of p-N,N-dimethylaminobenzaldehyde were carefully collected and subjected various characterization studies such as UV, FTIR, 1H and 13CNMR spectral studies and thermal (TG-DTG) studies to determine the purity and application oriented properties of the grown
crystals. 相似文献
10.
The freezing point depression of cryolite (Na3AlF6) by the addition of Al2S3 and FeS was investigated. It was found that for contents of up to 10 wt.% Al2S3, it brings into the melt three new species. X-ray analysis of solidified melts of the system Na3AlF6–Al2S3 showed that it contained chiolite, Na5Al3F14 and Na2S. Chiolite originates from a reaction between Na3AlF6 and AlF3. This suggests that the system Na3AlF6–Al2S3 is a part of the reciprocal system NaF, AlF3//Na2S, Al2S3. The solubility of FeS in cryolite melt is so low that it cannot be determined by the thermal analysis. When FeO is added to the Na3AlF6–Al2S3 melt, Fe2+ cations and S2− anions react under the formation of solid FeS. A similar reaction was observed for Ni2+ and S2− ions. 相似文献