Thermodynamic properties of compounds with kosnarite-type structure

350-356<span style="font-size: 9.0pt;mso-bidi-font-size:10.0pt;mso-bidi-font-weight:bold" lang="EN-US">Synthesis and thermodynamic properties of the<span style="font-size:9.0pt; mso-bidi-font-size:10.0pt" lang="EN-US"> crystalline kosnarite-type structure compounds, viz., A<i style="mso-bidi-font-style: normal">xMe2.25-0.25x(PO4)3 (A = Na, Cs; Me = Ti, Zr, Hf; x = 0, 1 and 5) are reported. The heat capacities of the phosphates have been measured between 6 and 650 K. Investigations on the isostructural solid-to-solid phase transitions of Na5Zr(PO4)3 and Na5Hf(PO4)3 show centering of the off-centered Me atoms in octahedral sites and Na+ occupation transfer between sodium sites. The transition temperatures (T<span style="mso-bidi-font-style: italic">0trs), enthalpy of transition (ΔtrsH0), entropy of transition (ΔtrsS0), molar heat capacities (C0p,m), enthalpy (H0(<i style="mso-bidi-font-style: normal">T) – H0(0)), entropy (S0(T)) and Gibbs) energy (G0(<i style="mso-bidi-font-style: normal">T) H0(0)) are calculated from the experimental data. Standard enthalpies of formation at T = 298.15 K for the phosphates Zr3(PO4)4, NaZr2(PO4)3, CsZr2(PO4)3 and Na5Zr(PO4)3 are estimated by solution reaction calorimetry. By combining the data obtained by the two techniques, their Gibbs energies of formation at 298.15 K have been obtained. Thermodynamic functions of the reactions for solid-state synthesis of the compounds of kosnarite-type structure are calculated. </span

Dehydration of butanols on copper-containing zirconium orthophosphates

The catalytic properties of ternary zirconium phosphates N a1-2xCuxZr2(PO4)3 in the transformations of butanols were been studied. It was found that the structure of alcohol and the copper content (x = 0, 0.15, 0.25, 0.35) affect the rate and selectivity of dehydration. The activity and selectivity changed as the content of copper that substitutes for sodium ions increased. The general conversion of alcohol and selectivity in dehydration decreased in the series butanol-2 →- isobutanol →- butanol-1, due probably to the change in the apparent activation energy of the reaction, depending on the stability of alcohol binding to the surface. © Pleiades Publishing, Ltd., 2010

Dehydration of butanols on copper-containing zirconium orthophosphates

The catalytic properties of ternary zirconium phosphates N a1-2xCuxZr2(PO4)3 in the transformations of butanols were been studied. It was found that the structure of alcohol and the copper content (x = 0, 0.15, 0.25, 0.35) affect the rate and selectivity of dehydration. The activity and selectivity changed as the content of copper that substitutes for sodium ions increased. The general conversion of alcohol and selectivity in dehydration decreased in the series butanol-2 →- isobutanol →- butanol-1, due probably to the change in the apparent activation energy of the reaction, depending on the stability of alcohol binding to the surface. © Pleiades Publishing, Ltd., 2010

The catalytic properties of new complex zirconium and iron orthophosphates

The catalytic properties of double zirconium and iron orthophosphates were studied for the example of the model reaction of isopropanol conversion. The structure of the orthophosphates and the procedures for their preparation are described

Catalytic activity and selectivity of combined zirconium-3d transition metal phosphates in isopropanol conversion

The isopropanol conversion catalytic activity of a family of crystalline M0.5Zr2(PO4)3 phosphates (M = Mn, Co, Ni, Cu, Zn), in which the negative charge of the anionic skeleton is compensated by 3d transition metal ions, was studied. It was found that isopropanol is simultaneously dehydrogenated and dehydrated irrespective of the composition of the catalyst. The chemical nature of the transition metal was shown to significantly affect the catalytic activity and, to a smaller degree, the selectivity of the orthophosphate. The effects of treatment of the catalysts with oxygen and with monochromatic light were also examined