P. Cafarelli

Intercalation compounds of α-zirconium hydrogen phosphate with RhIII ions and RhIII-diamine complexes. Part 1.—Preparation, thermal behaviour and X-ray photoelectron spectroscopy investigation

Rhodium(III) can be exchanged between the layers of α-zirconium phosphate by employing the pre-swelled diethanol intercalate, α-Zr(HPO4)2(ethanol)2. During the Rh3+/H+ exchange, four rhodium-containing phases are formed with different interlayer distances. However, only the fully Rh-exchanged compound, α-ZrRh0.66(PO4)2.4H2O, is obtained as a pure phase. Rhodium(III) can also be exchanged into the layered intercalation compounds α-Zr(HPO4)2(bipy)0.251.5H2O (bipy = 2,2′-bipyridyl), α-Zr(HPO4)2(phen)0.52H2O (phen = 1,10-phenanthroline) and aZr(HPO4)2(dmp)0.5·2.5H2O (dmp = 2,9-α-dimethyl-1,10-phenanthroline). Exchange is accompanied by a partial elution of the diamine for the phen and dmp derivatives. Various materials are obtained and their thermal properties discussed. X-Ray photoelectron spectroscopy (XPS) gives evidence that RhIII-diamine complex species mixed N- and O-coordinated RhIII are formed in the interlayer region of the three intercalation compounds.

Synthesis and chemical-physical characterization of palladium and rhodium new materials derived from octadecyltrimethylammonium cationic surfactant intercalated into zirconium and titanium dihydrogen phosphate

Abstract The intercalation of octadecyltrimethylammonium ion into group IV phosphates α- and γ-zirconium and γ-titanium has been investigated. These host matrices exchange cationic surfactant to give organo-inorganic composite materials. The obtained materials have an interlayer distance d notably increased with respect to the precursors, and are stable up to 200°C. These intercalated materials can, in turn, exchange transition metal ions, as Pd (II) and Rh (III) to give composite materials that can be used in heterogeneous catalysis. After metal exchange, partial surfactant elution does not remarkably modify the XRPD. The IR spectra confirm insertion of metals: competition of the metal with the amine for the P—OH bonding is evident.

Incorporation of Cadmium Ions and Cadmium Sulfide Particles into Sol-gel Zirconium Phosphate. Synthesis, thermal behavior and X-ray characterization

The inorganic ion-exchanger α-zirconium phosphate was synthesized by the sol-gel method and its properties relating to the exchange of Cd2+ and the intercalation of CdS particles were studied. The Cd2+-exchange process is a fast process and the material obtained exhibits an increased interlayer distance d with respect to its precursor (9.56 vs. 7.56 Å). The resulting Cd-containing material was exposed to aH2S gas flow to give CdS particles in the exchanger. The zirconium phosphate containing CdS particles still possesses a layered structure, with a pattern almost identical to that of the initial ion-exchanger precursor. Moreover, the material may exchange further Cd2+ and hence lead to a higher CdS particle content. The thermal behavior of this ion-exchangers containing Cd2+ or CdS particles was studied.

Intercalation of 2,2′-bipyridyl, 2,4′-bipyridyl and 4,4′-bipyridyl into γ-zirconium phosphate. physical–chemical characterization and solvent effect on the intercalation

Abstract The uptake into γ-zirconium phosphate by batch method of 2,2′-bipyridyl, 2,4′-bipyridyl, and 4,4′-bipyridyl in ethanol:water solutions of various solvent ratios has been studied. The obtained materials were examined by powder X-ray diffraction (PXRD), thermogravimetric and differential thermal analysis (TG-DTA) techniques, and UV-vis, IR and Raman spectroscopy. It has been found that the ligand content into the exchanger depends on batch temperature, ligand:exchanger ratio in the contact batch, ethanol:water solvent ratio, and isomeric nitrogen position in the diamines. The highest uptake was obtained for the ligand 2,2′-bipyridyl with an ethanol:water ratio of 1:9.

γ-Zirconium Phosphate Rhodium Intercalation Compounds: Preparation, Chemical and Thermal Characterization

Rh{sup 3+}/H{sup +} ion exchange in {gamma}-zirconium phosphate and in its intercalation compounds with organic diamine (2,2{prime}9bipyridyl, 1,10-phenanthroline, and 2,9-dimethyl-1,10-phenanthroline) has been investigated. Fully exchanged rhodium-zirconium phosphate has the composition {gamma}-Zr(PO{sub 4}) (H{sub 0.86}Rh{sub 0.38}PO{sub 4}) {center_dot} 2.3 H{sub 2}O and an interlayer distance of 15.2 {angstrom}. The exchange of Rh{sup 3+} in intercalation compounds leads to phases in which the molar ratio Rh{sup 3+}/diamine within the layers is about one. In some cases, a partial leaching of organic ligand during the Rh{sup 3+}/H{sup +} exchange has been observed. All the materials produced were characterized by their chemical compositions, X-ray powder diffraction patterns, and coupled TG/DTA analysis. In the presence of Rh{sup 3+} ions, the temperature of thermal deintercalation of diamine is lower than that observed in the pure intercalation compounds.

Synthesis and characterization of sol-gel zirconium phosphate with template surfactants by different methods

Long chain trimethylammonium salts can be successfully used as guest molecules to produce mesoporous layered materials when intercalated in sol-gel zirconium phosphate, an inorganic ion-exchanger. The obtained materials are very similar independently of the chain length and the synthesis method batch (B) or direct intercalation (DI). They show a good thermal stability, and a very high interlayer distance if compared with their precursor. By the thermal characterization it can be observed that the surfactant is lost in two or three steps depending on its position in the host. The layered structure with the expanded interlayer distance is maintained up to 300°C. From the IR spectra the different surfactant release models for (B) and (DI) are confirmed.

γ-Zirconium and γ-titanium phosphate palladium intercalation compounds: synthesis and characterization by X-ray diffraction and thermal analyses

γ-Zirconium and γ-titanium phosphates (γ-ZrP, γ-TiP) with layered structure are well known as ion exchangers as well as agents intercalating organic bases. In the latter case, the intercalation compounds may exchange transition metal ions coordinated by the ligands, giving rise to in situ formed complexes. We prepared phases derived from γ-ZrP, containing organic diamines (γ-ZrPL) (L = ligand), such as 2,2′-bipyridyl (bipy), 1,10-phenanthroline (phen), and 2,9-dimethyl-1,10-phenanthroline (dmp). These materials exchange Pd2+ ions when they are in batch contact with a PdCl2 solution and this produces solids with Pd2+/L = 1. The X-ray diffraction (XRD) patterns of some materials containing Pd2+ showed an increase of 2 A in d002. The differential thermal analysis (DTA) curves of the Pd2+ materials showed a lowering of diamine temperature decomposition (100°C) with respect to those of their precursors. In the case of γ-TiP, we also obtained intercalation compounds with the above-mentioned diamines. Similar experiments showed that γ-TiPL exchanges very few Pd2+ ions, except for the one derived from γ-TiPdmp. The thermogravimetric (TG) curves show the same lowering of ligand temperature decomposition for all materials except γ-TiPPdphen. The XRD patterns for all γ-ZrPPdL and γ-TiPPdL materials show peaks at dhkl = 7.89, 8.59–8.04, and 9.31 A, for compounds containing Pdbipy, Pdphen, and Pddmp, respectively. Due to the correspondent complexes into the exchanger, these peaks disappeared when the materials, except for those containing the Pddmp complex, were stirred into CH2Cl2.

Thermal behaviour of copper-dimethyl-phenanthroline species in α-and ψ-zirconium phosphates

Two methods are described in order to obtain copper-2,9-dimethyl-1, 10-phenanthroline (dmp) coordination compounds intercalated between the layers of α-Zr(HPO4)2·H2O and ψ-Zr(H2PO4)(PO4)·2H2O: the direct intercalation of Cu-dmp complex species or the formation ‘insitu’ of coordination compounds. With the first exchanger both methods lead to similar products with X-ray diffraction patterns practically identical. They contain Cu(II–I)-dmp complex species that confer to the solids an initially green colour slowly turning to yellow with time or temperature when the reduction of Cu(II) to Cu(I) is complete. With λ-ZrP(H2PO4)(PO4)·2H2O, only the direct insertion is successful. TG/DTA experiments permit a better understanding of what is occurring in the materials during the copper reduction step, in correspondance of which, a strong endothermic peak and a gain in weight can be observed. They also show how the difference in the structure and chemical formula of the two exchangers affect the thermal behaviour of the two series of compounds.ZusammenfassungEs werden zwei Methoden zur Einlagerung von Kupfer-2,9-dimethyl-1, 10-phenanthrolin (DPM) Einlagerungsverbindungen zwischen die Schichten von α-Zr(HPO4)2 H2O und γ-Zr(H2PO4)(PO4)·2H2O beschrieben: die direkte Einlagerung von Cu-DMP-Komplexen oder die “in situ” Bildung von Koordinationsverbindungen. Mit dem ersten Austauscher führen beide Methoden zu ähnlichen Produkten mit praktisch identischen Röntgendiffraktionsbildern. Sie enthalten Cu(II–I)-DMP-Komplexe, welche den Feststoffen anfänglich eine grüne Farbe verleihen, die mit der Zeit oder der Temperatur allmählich ins Gelbe übergeht, wenn die Reduktion von Cu(II) zu Ci(I) vollständig vollzogen ist. Bei γ-ZrP(H2PO4)(PO4)·2H2O hat man nur mit der direkten Einlagerung Erfolg. TG/DTA-Versuche ermöglichen ein besseres Verständnis des Geschehens in den Substanzen während des Schrittes der Kupferreduktion, in deren Zusammenhang ein starker endothermer Peak und eine Gewichtszunahme beobachtet werden kann. Diese Experimente zeigen auch, wie der Unterschied von Struktur und chemischer Formel der zwei Austauscher das thermische Verhalten der zwei Verbindungsgruppen beeinflu\t.

Compounds of γ-zirconium hydrogen phosphate with cadmium ions: Synthesis, thermal behavior and X-ray characterization

Abstract The materials obtained by exchanging Cd2+ ions into γ-zirconium phosphate and γ-zirconium phosphate-L materials ( L = organic diamines ) have been investigated. The kinetic uptake of the Cd2+ ions by the starting materials, the thermal behavior and the structural characterization of the obtained compounds has also been examined. γ-Zirconium phosphate intercalated with CdS particles has also been prepared and characterized. Its property to exchange further cadmium ions, and thus, insert more CdS particles between the layers of the exchanger has been investigated.

Selective isomerization of α-pinene

Abstracta-Pinene isomerization was studied in gaseous and liquid phases on g-zirconium phosphate and rhodium g-zirconium phosphate. The first showed higher activity but lower reaction selectivity than the second, that led to tricyclic terpenes formation.