Mechanism of ion exchange in crystalline zirconium phosphates. I. Sodium ion exchange of .alpha.-zirconium phosphate

Abstract

The sodium ion-hydrogen ion, hydrogen ion-sodium ion exchange titration curves of «-zirconium phosphate crystals, ( 04)2• 20, exhibit a hysteresis loop. This results from the presence of different phases in the forward and backward titrations. When the crystals are titrated with sodium hydroxide two solid phases are present up to 50% of exchange. They are the unexchanged «-zirconium phosphate and a half-exchanged phase whose formula is ZrCNaPChXHPCh) -5H20. This latter phase is the only one present at exactly 50% of exchange but at higher levels of exchange another two-phase region is obtained. The two phases are the half-exchanged crystals and a fully exchanged phase of composition Zr(NaP04)2.3H20. The interconversion of the half and fully exchanged phases is reversible. However, when the half-exchanged phase takes up protons it forms an unexchanged phase which is more highly hydrated than the original «-zirconium phosphate. Dehydration of the exchanged phases leads to the formation of several new phases. The phase changes during exchange and dehydration are explained on the basis of the swelling and contraction of the layers in the «-zirconium phosphate crystals.

Zirconium Phosphate Catalysts in the XXI Century: State of the Art from 2010 to Date

“…Cr(III) immobilized on m-ZrP Oxidation of allylic and benzylic compounds [39] Conversion of fructose into HMF [40] Fe(III) immobilized on window-type organic zirconium phosphonate Formaldehyde decomposition [41] Fe(Salen) and Cu(Salen) complexes supported on microcystalline ZrP Cyclohexene oxidation [42,43] Rh(III) and Ir(III) complexes intercalated into ZrP Visible light driven H 2 production [44] ClRh(PPh 3 ) 3 immobilized on ethoxysilane-modified ZrP Olefin hydrogenation [45] Co-Ru immobilized on ZrP/SiO 2 Fischer-Tropsch reaction [46] Pd NPs supported on ZrP Synthesis of 1,6-hexanediol from HMF [47] Heck reaction [48] Pd NPs supported on zirconium phosphonates Suzuki-Miyaura coupling reaction [49] Pd fluorinated complexes intercalated into microcrystalline ZrP Sonogashira and Heck reactions [50] TiO 2 pillared ZrP Degradation of methyl orange [51] TiO 2−x clusters grafted on ZrP nanosheets Degradation of methylene blue [52] Ag@AgCl/nanosized ZrP Degradation of Rhodamine B [53] Vanadium phosphorus oxide supported on ZrP dehydration of glycerol [54] 1-butyl-3-methylimidazolium chloride intercalated into layered θ-ZrP synthesis of propylene carbonate from CO 2 and propylene oxide [55] Mo et al immobilized Fe(III) ions on a new window-type porous organic zirconium phosphonate hybrid material having the formula Zr 5 (HPO 4 ) 6 [O 3 PCH 2 N(CH 2 CH 2 COOH)CH 2 PO 3 ] (ZrNCP), based on b-alanine-N,N-dimethylidenephosphonate groups bonded to adjacent inorganic layers, thus creating windows and, therefore, porosity [41]. Moreover, the presence of both nitrogen atoms and carbonyl groups in the organic chains allowed the coordination of metal ions with the wall of pores by ion exchange.…”

Síntese e caracterização de alfa-fosfato de zircônio(IV) contendo agregados de cobre metálico

“…Isto pode ser atribuído à baixa cristalinidade dos sólidos. Como observado em trabalhos anteriores, a troca com cobre não ocorre facilmente na estrutura do α-ZrP porque o íon cobre não pode passar pelas estreitas cavidades interplanares; entretanto, a incorporação desse metal torna-se significativa, à medida que o material se torna menos cristalino e essas distâncias se tornam maiores [14][15][16] .…”

Synthesis and characterization of a new crystalline tin(IV) arsenophosphate ion exchanger

“…In contrast, a-ZrP and like compounds exhibit two plateaus, indicating the formation of mono-and disodium phases. The exchange of hydrogen ions in these materials in two stages is not due to the presence of protons at two different acidic sites but attributed to the two-phase changes involved in Na+ + H+ process (8). All the hydrogen ions present in the SnP, SnAsP, and SnAs are supposed to be available for exchange to take place in a single step.…”