Four-component reciprocal system Na,K∥Cl,CO<Subscript>3</Subscript>, WO<Subscript>4</Subscript>

The four-component reciprocal system Na,K∥Cl,CO₃,WO₄ has been studied using differential thermal analysis in combination with projective and differential geometry, the a priori prediction of the crystallization path (CP), and a computation-experimental method. The concentration and temperature coordinates of the four quaternary invariant points (IVPs) existing in the system have been determined.     

Five-component reciprocal systems Na,K∥Cl,CO<Subscript>3</Subscript>,MoO<Subscript>4</Subscript>,WO<Subscript>4</Subscript> and Na,K∥F,CO<Subscript>3</Subscript>,MoO<Subscript>4</Subscript>,WO<Subscript>4</Subscript>

Five-component reciprocal systems Na,K∥Cl,CO₃,MoO₄,WO₄ and Na,K∥F,CO₃,MO₄,WO₄ have been studied by differential thermal analysis (DTA) and X-ray powder diffraction (XPD). The systems have been triangulated to phase simplexes. The main reciprocal and complex-formation reactions have been revealed. The stability of [Na,K]₂CO₃, Na₂[Mo,W]O₄, and K₂[Mo,W]O₄ binary solid solutions and the nonexistence of quintuple invariant points in the title systems have been verified.     

Phase equilibria in the Na,K∥SO<Subscript>4</Subscript>, CO<Subscript>3</Subscript>, F-H<Subscript>2</Subscript>O system at 25°C

Phase equilibria in the Na, K∥SO₄, CO₃, F-H₂O system at 25°C are studied using the translation technique. Twenty four divariant fields, 22 univariant curves, and seven invariant points are found in the system. The complete phase diagram (the phase complex) of the system is designed on the basis of these data.     

A secant element of the Li,K||F,Br,VO<Subscript>3</Subscript>,MoO<Subscript>4</Subscript> five-component reciprocal system

The LiF–KBr–KVO₃–K₂MoO₄ secant tetrahedron of the Li,K||F,Br,VO₃,MoO₄ five-component reciprocal system was studied by differential thermal analysis. The composition corresponding to the quaternary eutectic was determined (mol %): LiF, 7.2; KBr, 16.8; KVO₃, 66.5; and K₂MoO₄, 9.5. The eutectic melting temperature was found to be 419°С.     

Topology of the Li‖F,Cl,CO<Subscript>3</Subscript>,MoO<Subscript>4</Subscript> four-component system

A computation-and-experiment technique and differential thermal analysis were used to study the Li‖F,CO₃,MoO₄ three-component system and Li‖F,Cl,CO₃,MoO₄ four-component system for the first time and to restudy the Li‖Cl,CO₃,MoO₄ and Li‖F,Cl,MoO₄ three-component systems.     

Li,Cs||F,NO<Subscript>3</Subscript> ternary reciprocal system

The Li, Cs||F, NO₃ ternary reciprocal system was for the first time described and experimentally studied by differential thermal analysis and differential scanning calorimetry. Phase equilibrium states were determined, and so were the compositions and melting points of two ternary eutectics. Reactions describing the chemical interaction in the system were presented.     

Solubility in the Na,Са||SO<Subscript>4</Subscript>,СО<Subscript>3</Subscript>–H<Subscript>2</Subscript>O system at 25°С

Solubility at the invariant points of the Na,Са||SO₄,СО₃–H₂O system at 25°C was studied, and a solubility diagram at this temperature constructed.     

Reactions of Cr atoms with NO,N<Subscript>2</Subscript>O,CO<Subscript>2</Subscript>, NO<Subscript>2</Subscript>, and SO<Subscript>2</Subscript> molecules

Experimental results on the interaction of Cr atoms with various oxygen-containing molecules (NO, N₂O, CO₂, NO₂, and SO₂) at high temperatures (>1000 K) are presented. It is demonstrated that activation barrier for spin-forbidden reactions is higher, all other things being equal. For the reaction of Cr atoms with N₂O, an interpolated temperature dependence of the rate constant, based on the high-temperature measurements conducted in the present work and the published low-temperature data, is proposed.     

Stable tetrahedron of lithium bromide,metavanadate, and molybdate and potassium bromide in the Li,K || Br,VO<Subscript>3</Subscript>, MoO<Subscript>4</Subscript> quaternary reciprocal System

Phase equilibria in the LiBr–LiVO₃–Li₂MoO₄–KBr quaternary system (the stable tetrahedron of the quaternary reciprocal system Li, K || Br, VO₃, MoO₄) were studied by differential thermal analysis. The composition and melting point of a quaternary eutectic were determined: 56.7 mol % LiBr, 1.5 mol % LiVO₃, 4.9 mol % Li₂MoO₄, 36.9 mol % KBr, 321°C.     

Phase Equilibria in the K,Cа∥SO<Subscript>4</Subscript>,CO<Subscript>3</Subscript>,HCO<Subscript>3</Subscript>–H<Subscript>2</Subscript>O System at 25°С

Phase equilibria in the system K,Cа∥SO₄,CO₃,HCO₃–H₂O have been studied at 25°С. This system at 25°С involves 7 invariant points, 21 monovariant curves, and 22 divariant fields. The data gained served to plot the first phase diagram (phase complex) of the studied system at 25°С.     

Solubility of YF<Subscript>3</Subscript>, CeF<Subscript>3</Subscript>, PrF<Subscript>3</Subscript>, NdF<Subscript>3</Subscript>, and DyF<Subscript>3</Subscript> in solutions containing sulfuric and phosphoric acids

The solubility of YF₃, CeF₃, PrF₃, NdF₃, and DyF₃ in solutions containing 0–4.496% mol/L (0–35 wt %) of H₂SO₄ and 0–27.6 g/L of H₃PO₄ (0–20 g/L of P₂O₅) at 20 °C was determined. Higher solubility in sulfuric acid solutions compared to that in hydrochloric and phosphoric acid solutions was attributed to the formation of fluorosulfate complexes M₂(SO₄)F₄(M = Y, Ce, Pr, Nd, Dy). The effect of minor concentrations of the phosphate ions on the solubility of YF₃, CeF₃, PrF₃, NdF₃, and DyF₃ in sulfuric acid solutions and the effect of fluoride ions on the recovery of lanthanides during sulfuric acid leaching from the phosphohemihydrate were discussed.     

The interaction of CH<Subscript>3</Subscript>Cl,CH<Subscript>2</Subscript>Cl<Subscript>2</Subscript>, CHCl<Subscript>3</Subscript>, and CCl<Subscript>4</Subscript> with ozone on the surface of ice under stratospheric conditions

The interaction of ozone with chlorinated methanes adsorbed on a thin ice film was studied over the temperature range 77–292 K. Ozone was shown to oxidize chlorinated methanes starting with 210 K to produce chlorine oxides of various compositions. The products formed in the oxidation of chlorinated methanes with ozone over the temperature range 77–292 K were analyzed by IR Fourier transform spectroscopy. Along with carbon dioxide and water, chlorine oxides in high oxidation states were predominantly formed.     

Electronic energy structure of As<Subscript>2</Subscript>S<Subscript>3</Subscript>, AsSI,AgAsS<Subscript>2</Subscript>, and TiS<Subscript>2</Subscript> semiconductors

Quantum-mechanical calculations with the FEFF8 code were used to study the electronic energy structure of 200-atomic clusters of As₂S₃, AsSI, AgAsS₂, and TiS₂ semiconductor compounds. The calculated local partial densities of electronic states are compared with the sulfur K and L X-ray emission spectra and sulfur K absorption spectra for fine powders of these compounds. Good agreement between theory and experiment has been obtained.     

Thermal behavior of LDH 2CuAl.CO<Subscript>3</Subscript> and 2CuAl.CO<Subscript>3</Subscript>/Pd

Cu/Al layered double hydroxide (LDH) can be used as a catalyst for important processes such as cross-coupling reactions. This property may be improved by adding palladium by either impregnation or intercalation. Therefore, the LDH matrix and its composites with Pd⁰ or [PdCl₄]^2? have been prepared. By powder X-ray diffraction, FT-infrared spectroscopy, thermogravimetric and elemental analysis it was determined the LDH formula Cu₄Al₂(OH)₁₂CO₃.4H₂O, with malachite as the second phase. The LDH thermal decomposition occurs between 120 and 600 °C, having as intermediates the double oxi-hydroxide and the mixed oxide phases. At 800 °C the residue is composed of CuO and CuAl₂O₄. The composites were obtained employing [PdCl₄]^2? and Pd₂(dba)₃ as precursors, and the solvent choice for this process was shown to be of significant importance: the materials obtained using DMF had Pd impregnated in the surface, while the usage of water promoted the intercalation of [PdCl₄]^2? in the LDH matrix. The thermogravimetric analysis was able to distinguish the mode of supporting palladium between the composites being a reliable characterization for such task.     

Conductivity of molten LiF-ZrF<Subscript>4</Subscript>, NaF-ZrF<Subscript>4</Subscript>, KF-ZrF<Subscript>4</Subscript>, RbF-ZrF<Subscript>4</Subscript>, and CsF-ZrF<Subscript>4</Subscript> systems

Specific conductivity of molten salt mixtures of the LiF-ZrF₄, NaF-ZrF₄, KF-ZrF₄, RbF-ZrF₄, and CsF-ZrF₄ systems is measured in the whole concentration range using the reference capillary technique. The results are presented in the form of equations of the χ = a + bT + cT ² [S m^?1] type. The concentration dependences of molar conductivity are calculated on the basis of the density data. The obtained regularities are explained in the terms of the complex model of ion melt structures.     

FT-IR study on CO<Subscript>2</Subscript> adsorbed species of CO<Subscript>2</Subscript> sorbents

The stability of amine-functionalized silica sorbents prepared through the incipient wetness technique with primary, secondary, and tertiary amino organosilanes was investigated. The prepared sorbents were exposed to different gaseous streams including CO₂/N₂, dry CO₂/air with varying concentration, and humid CO₂/air mixtures to demonstrate the effect of the gas conditions on the CO₂ adsorption capacity and the stability of the different amine structures. The primary and secondary amine-functionalized adsorbents exhibited CO₂ sorption capacity, while tertiary amine adsorbent hardly adsorbed any CO₂. The secondary amine adsorbent showed better stability than the primary amine sorbent in all the gas conditions, especially dry conditions. Deactivation species were evaluated using FT-IR spectra, and the presence of urea was confirmed to be the main deactivation product of the primary amine adsorbent under dry condition. Furthermore, it was found that the CO₂ concentration can affect the CO₂ sorption capacity as well as the extent of degradation of sorbents.     

Organometallic coordination polymers based on silver carboxylates: [AgCF<Subscript>3</Subscript>CO<Subscript>2</Subscript>(2,3-Et<Subscript>2</Subscript>Pyz)] and [AgCF<Subscript>3</Subscript>CO<Subscript>2</Subscript>(Bpeta)]

Coordination polymers [AgCF₃CO₂(2,3-Et₂Pyz)](I)(2,3-Et₂Pyz-C₈H₁₂N₂) and [AgCF₃CO₂(Bpeta)] (II) (Bpeta is 4′4-bipyridylethane, C₁₂H₁₂N₂) are synthesized. Their structures are determined. The crystals of compound I are monoclinic, space group P2(1)/n, a = 7.185(1), b = 14.754(1), c = 12.317(1)Å, β = 97.09(1)°, V = 1295.7(2) ų, ρ_calcd = 1.831 g/cm³, Z = 4. Structure I consists of infinite chains of doubled polymeric chains joined by silver carboxylate dimers [[Ag₂(CF₃CO₂)₂(Et₂Pyz)₂]_∞. The coordination polyhedron of Ag⁺ is a distorted tetrahedron. The crystals of compound II are orthorhombic, space group Pbca, a = 13.555(3), b = 13.991(3), c = 16.449(3) Å, V = 3119.5(11) ų, ρ_calcd = 1.725 g/cm³, Z = 8. Doubled polymeric chains with the Ag…Ag bond (3.16 Å) are also formed in structure II. Supramolecular layers are formed in the structure due to the weak π-π-stacking interaction between the aromatic groups of chains. The CF₃CO ₂ ^? anion is weakly bound to Ag⁺ (Ag-O_avg 2.790 Å).     

Ternary water-salt system Sm(CCl<Subscript>3</Subscript>COO)<Subscript>3</Subscript>-Er(CCl<Subscript>3</Subscript>COO)<Subscript>v</Subscript>-H<Subscript>2</Subscript>O at 298 K

The system of samarium and erbium trifluoroacetates and water has been studied by the isothermal solubility technique at 298 K. The composition of the solids has been determined using the Schreinemakers wet residue technique. The refractive indices, specific volumes, and viscosities of liquid phases and the refractive indices of solid residues have been determined. A continuous solid solution is found to form in the system. Some thermodynamic parameters have been determined for this solid solution.     

Structure and properties of Ce<Subscript>3</Subscript>Pd<Subscript>3</Subscript>Bi<Subscript>4</Subscript>, CePdBi,and CePd<Subscript>2</Subscript>Zn<Subscript>3</Subscript>

The intermetallic cerium compounds Ce₃-Pd₃Bi₄, CePdBi, and CePd₂Zn₃ were synthesized from the elements in sealed tantalum ampoules in an induction furnace. The compounds were characterized by X-ray powder and single crystal diffraction: CeCo₃B₂ type (ordered version of CaCu₅), P6/mmm, a = 538.4(4), c = 427.7(4) pm, wR2 = 0.0540, 115 F ² values, 9 variables for CePd₂Zn₃ and Y₃Au₃Sb₄ type, I \({\bar 4}\)3d, a = 1005.2(2) pm, w R2 = 0.0402, 264 F ² values, 9 variables for Ce₃Pd₃Bi₄, and MgAgAs type, a = 681.8(1) pm for CePdBi. The bismuthide structures are build up from three-dimensional networks of corner-sharing PdBi₄ tetrahedra with Pd–Bi distances of 281 (Ce₃Pd₃Bi₄) and 296?pm (CePdBi), respectively. The cerium atoms are located in larger voids of coordination number 12 (Ce₃Pd₃Bi₄) and 10 (CePdBi). In CePd₂Zn₃ the cerium atoms fill larger channels within the three-dimensional [Pd₂Zn₃] network with 18 (6 Pd + 12 Zn) nearest neighbors. The three compounds contain stable trivalent cerium with experimental magnetic moments of μ_eff = 2.70(2), 2.48(1), and 2.49(1) μ_B/Ce atom for CePd₂Zn₃, Ce₃Pd₃Bi₄, and CePdBi, respectively. Susceptibility and specific heat data gave no hint for magnetic ordering down to 2.1?K.     

A comparative study of Ir/Ga<Subscript>2</Subscript>O<Subscript>3</Subscript>, Pt/Ga<Subscript>2</Subscript>O<Subscript>3</Subscript>, and Ru/Ga<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts in selective hydrogenation of crotonaldehyde

Catalytic performance of gallia-supported iridium catalysts in the reaction of selective hydrogenation of crotonaldehyde in the gas phase was studied and compared to that of platinum and ruthenium catalysts. The best catalytic properties in terms of the selectivity to crotyl alcohol are shown by 5 wt % Pt/α-Ga₂O₃ and 5 wt % Ir/α-Ga₂O₃ catalysts prepared from nonchlorine precursors: Pt(acac)₂ and Ir(acac)₃, but for the 5 wt % Pt/α-Ga₂O₃ a very high selectivity of 75% at the high conversion (ca. 60%) is observed. A high selectivity of galia-supported iridium and platinum catalysts was explained by the surface reducibility of gallium oxide leading to covering (decoration) of platinum and iridium by gallium suboxides and the promoting effect of gallium.