Reactions of the gas-phase synthesis of tin vanadates, borates, and molybdates were studied. Standard enthalpies of formation and atomization of gaseous salts SnV 2 O 6 , SnB 2 O 4 , Sn 2 B 2 O 5 , SnMoO 4 , Sn 2 MoO 5 , and SnMo 2 O 7 were determined.

Knowledge of the structures of gaseous oxyacid salts of the M(m) XO(n) type is of interest for understanding the nature of chemical bonds. Gaseous VPO(2) and VPO(3) have been identified by Knudsen effusion mass spectrometry during the vaporization of mixtures of V(2)O(3) and alkali earth phosphates from molybdenum and tungsten effusion cells. The structures and molecular parameters of the gaseous vanadium phosphates under study were determined using quantum chemical calculations. On the basis of equilibrium constants measured for gas-phase reactions, the standard formation enthalpies were determined to be -273 ± 17 and -615 ± 16 kJ·mol(-1) for VPO(2) and VPO(3), respectively.

A number of gaseous oxyacid salts have been identified by Knudsen effusion mass spectrometry, while vaporizing Cr(2)O(3) and mixtures of Cr(2)O(3)+Nb(2)O(5), Cr(2)O(3)+Ta(2)O(5), Cr(2)O(3)+BaO, and Cr(2)O(3)+Mg(2)P(2)O(7) from molybdenum and tungsten cells. The stabilities of the gaseous molecules CrMoO(3), CrMoO(4), CrMoO(5), CrWO(3), CrWO(4), CrWO(5), CrNbO(3), CrTaO(3), CrPO(2), CrPO(3), BaCrO(2) and BaCrO(3) were deduced from the measurements. The thermodynamic properties of this gaseous chromium-containing species are summarized. Prediction is tentatively made of the stability of as-yet unstudied gaseous molecules.

The thermodynamic functions found in the Yb2O3-ZrO2 system at 2400 K, such as the activities of components and the Gibbs energy of formation, displayed negative deviation from ideality. Mutual agreement was observed between the experimental thermodynamic values and the results of calculations based on the CALPHAD approach.

A comparative study of metal − polymer complexes of Cu(I) with polybenzoxazinoneimide (PBOI) and its prepolymer imide-containing polyamic acid (PAA) as novel membrane materials for methyl tertiary butyl ether (MTBE) purification was undertaken. The structure, physical parameters and transport properties were characterized in detail to analyse the separation performance of the membranes and obtain new knowledge on the interdependence of the chemical structure and physical data with transport parameters. Thermally initiated conversion of PAA − Cu(I) to PBOI − Cu(I) was studied by TGA and DSC. The thermal conversion increases the polymer glass transition temperature and membrane density. Both polymers were applied to pervaporation separation of MTBE from methanol impurities. Membranes based on PAA are highly effective in MTBE purification and preferably permeate methanol. The transport properties of PAA − Cu(I) membrane are compared with those of known membranes.

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The stability of gaseous vanadium molybdate and vanadium tungstates was confirmed by high-temperature mass spectrometry. A number of gas-phase reactions involving vanadium-containing salts were studied. On the basis of equilibrium constants, the standard formation enthalpies of gaseous VMoO(4) (-676 ± 27 kJ/mol), VWO(3) (-331 ± 29 kJ/mol), and VWO(4) (-706 ± 23 kJ/mol) at 298 K were determined. A theoretical study of these salts revealed the structure with bidentate binding of the vanadium cation to the anion part to be the lowest-lying isomer, with a quartet spin state for VMoO(4) and VWO(4) molecules as well as a sextet spin state for the VWO(3) molecule. On the basis of critical analysis of the literature data concerning standard formation enthalpies of gaseous VO and VO(2), we adopted new values of Δ(f)H°(298) = 135 ± 10 kJ/mol for VO(g) and -185 ± 15.0 kJ/mol for VO(2)(g). Overall, the results obtained allowed us to estimate the standard formation enthalpy of VMoO(3) to be -318 kJ/mol with an accuracy near 40 kJ/mol.

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