A. I. Gubanov

Bimetallic Rh-Co/ZrO2 catalysts for ethanol steam reforming into hydrogen-containing gas

The properties of supported bimetallic Rh-Co/ZrO2 catalysts in ethanol steam reforming into hydrogen-containing gas were studied. The particles of Rh-Co solid solutions on the catalyst surface were prepared by the thermal decomposition of the double complex salt [Co(NH3)6][Rh(NO2)6] and the solid solution Na3[RhCo(NO2)6]. It was found that the bimetallic Rh-Co/ZrO2 catalysts exhibited high activity in the reaction of ethanol steam reforming. The equilibrium composition of reaction products was attained at 500–700°C and a reaction mixture space velocity of 10000 h−1.

[Pd(NH3)4][Ir0.5Os0.5Cl6] Solid Solution: Synthesis and Properties

Abstract[Pd(NH3)4][Ir0.5Os0.5Cl6] solid solution, isomorphic to [Pd(NH3)4][IrCl6], is synthesized and studied by X-ray powder diffraction and elemental analyses, IR and Raman spectroscopies.

Three hexafluoridoiridates(IV), Ca[IrF6].2H2O, Sr[IrF6].2H2O and Ba[IrF6].

The structures of the hexafluoridoiridates(IV) of calcium, Ca[IrF(6)].2H(2)O [calcium hexafluoridoiridate(IV) dihydrate], strontium, Sr[IrF(6)].2H(2)O [strontium hexafluoridoiridate(IV) dihydrate], and barium, Ba[IrF(6)] [barium hexafluoridoiridate(IV)], have been determined by single-crystal X-ray analysis. The first two compounds are isomorphous. Their metal cations are eight-coordinated in a distorted square-antiprismatic coordination environment, and their anions are represented by an almost ideal octahedron. These two structures can be described as frameworks in which all atoms occupy general positions. Sr[RhF(6)] and Ba[RhF(6)] have a different space group (R\overline{3}m, from powder diffraction data) but similar cell dimensions. The structures are very close to that of Ba[IrF(6)]. The cation is in a cuboctahedral coordination. The metal atoms are located on special positions of \overline{3} symmetry, while the F atoms are in general positions.

Double complexes [Co(NH3)5(H2O)]2[Zr3F18]·6H2O and [Co(NH3)6]2[Zr3F18]·6H2O

The structures of orthorhombic bis[pentaammineaquacobalt(III)] tetra-mu(2)-fluorido-tetradecafluoridotrizirconium(IV) hexahydrate (space group Ibam), [Co(NH(3))(5)(H(2)O)](2)[Zr(3)F(18)].6H(2)O, (I), and bis[hexaamminecobalt(III)] tetra-mu(2)-fluorido-tetradecafluoridotrizirconium(IV) hexahydrate (space group Pnna), [Co(NH(3))(6)](2)[Zr(3)F(18)].6H(2)O, (II), consist of complex [Co(NH(3))(x)(H(2)O)(y)](3+) cations with either m [in (I)] or overline{1} and 2 [in (II)] symmetry, [Zr(3)F(18)](6-) anionic chains located on sites with 222 [in (I)] or 2 [in (II)] symmetry, and water molecules.

Synthesis conditions and sintered ZrW2O8 structure

This paper discusses synthesis condition effect on the structure and morphology of ZrW2O8 using thermal decomposition of precursor ZrW2O7(OH,Cl)2·2H2O prepared by hydrothermal method. It was observed that for hydrothermal precursor synthesis the optimal concentration of hydrochloric acid in the reaction mixture was about 2.3 M and sintering time amounted to 36 hours. The precursor morphology was in the form of needle-like particles and loose irregular shape agglomerates. The pure nanoscale ZrW2O8 powder was obtained by precursor heating at 570°C for 1 hour and has needle-like particles with an intrinsic block structure. The average block size was 50 nm. The average transverse size was less than 1 µm, the longitudinal particle size varied from 500 to 5000 nm.

Structure of complex salts [Co(NH3)6][Rh(NO2)6] and [Co(NH3)6][(NO2)3Rh(μ-NO2)1+x(μ-OH)2−xRh(NO2)3]·(2-x)(H2O), x = 0.17

The structures of two salts [Co(NH3)6][Rh(NO2)6] (I) and [Co(NH3)6][(NO2)3Rh(μ-NO2)1+x(μ-OH)2−x Rh(NO2)3]·(2−x)(H2O), x = 0.17 (II) are solved. Single crystals of the salts are obtained by the counter diffusion method through the gel of aqueous solutions of [Co(NH3)6]Cl3 and Na3[Rh(NO2)6]. The structure of [Co(NH3)6][Rh(NO2)6] is consistent with the diffraction data for a polycrystalline sample of poorly soluble fine salt formed in the exchange reaction between aqueous solutions of [Co(NH3)6]Cl3 and Na3[Rh(NO2)6]. The structure of [Co(NH3)6][(NO2)3Rh(μ-NO2)1+x(μ-OH)2−xRh(NO2)3]·(2−x)(H2O), x = 0.17 exhibits the stabilizing effect of a large cation in the formation of novel, unknown previously coordination ions: [(NO2)3Rh(μ-NO2)(μ-OH)2Rh(NO2)3]3− and [(NO2)3Rh(μ-NO2)2(μ-OH)Rh(NO2)3]3−.

Synthesis of nanosize Co-Rh systems and study of their properties

Precursor compounds [Co(NH3)6][Rh(NO2)6] and [Co(NH3)6][Co(NO2)6], solid solutions [Co(NH3)6] [Rh(NO2)6]1−x[Co(NO2)6]x, and solid solutions Na3[Rh1−xCox(NO2)6] were synthesized and studied by IR spectroscopy and elemental, X-ray phase, X-ray diffraction, and thermogravimetric analyses. X-ray phase analysis was employed to examine products of thermal decomposition of precursors in the atmospheres of hydrogen and helium. Catalysts with a Co-Rh active system, supported by ZrO2, were prepared and tested in the reaction of steam conversion of ethanol.

[Pd(NH3)4][IrBr6] Complex: Synthesis, X-ray Powder Diffraction Analysis, and Thermal Decomposition

The complex salt [Pd(NH3)4][IrBr6] was synthesized and studied using X-ray powder diffraction, thermal and elemental analyses, and IR and Raman spectroscopy methods. Crystallographic parameters: a= 11.999 Å, b= 11.290 Å, c= 10.802 Å, V= 1463.3 Å3, Z= 4, space group Cmca, ρ(calcd) = 3.841 g/cm3. Thermolysis in an inert atmosphere runs through four stages to yield an equiatomic Pd–Ir solid solution as the final product.

X-ray diffraction investigations of Ag2ReCl6 and Ag2OsCl6

Complex salts Ag2ReCl6 and Ag2OsCl6 were synthesized and characterized by X-ray powder diffraction analysis, elemental analysis, and IR spectroscopy. The resulting compounds were demonstrated to be isostructural. It was found that the principal structural motif of the compounds under study is similar to that of K2ReCl6.

Preparation of Zr(Mo,W) 2 O 8 with a larger negative thermal expansion by controlling the thermal decomposition of Zr(Mo,W) 2 (OH,Cl) 2 ∙2H 2 O

Solid solutions of Zr(Mo,W)2O7(OH,Cl)2∙2H2O with a preset ratio of components were prepared by a hydrothermal method. The chemical composition of the solutions was determined by energy dispersive X-ray spectroscopy (EDX). For all the samples of ZrMoxW2−xO7(OH,Cl)2∙2H2O (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0), TGA and in situ powder X-ray diffraction (PXRD) studies (300–1100 K) were conducted. For each case, the boundaries of the transformations were determined: Zr(Mo,W)2O7(OH,Cl)2∙2H2O → orthorhombic-ZrMoxW2−xO8 (425–525 K), orthorhombic-ZrMoxW2−xO8 → cubic-ZrMoxW2−xO8 (700–850 K), cubic-ZrMoxW2−xO8 → trigonal-ZrMoxW2−xO8 (800–1050 K for x > 1) and cubic-ZrMoxW2−xO8 → oxides (1000–1075 K for x ≤ 1). The cell parameters of the disordered cubic-ZrMoxW2−xO8 (space group Pa-3) were measured within 300–900 K, and the thermal expansion coefficients were calculated: −3.5∙10−6 – −4.5∙10−6 K−1. For the ordered ZrMo1.8W0.2O8 (space group P213), a negative thermal expansion (NTE) coefficient −9.6∙10−6 K−1 (300-400 K) was calculated. Orthorhombic-ZrW2O8 is formed upon the decomposition of ZrW2O7(OH,Cl)2∙2H2O within 500–800 K.