Hideshi Maki

Formation and catalytic characterization of various rare earth phosphates

Various rare earth phosphates [rare earth elements: R = La, Ce, Pr, Nd, Sm, Yb, and Y; phosphates: Monazite-type, Xenotime-type, Rhabdophane-type, and Weinshenkite-type orthophosphates RPO4, polyphosphate R(PO3)3, and ultraphosphate RP5O14] were synthesized by heating the mixtures of each rare earth oxide and diammonium hydrogenphosphate or phosphoric acid. The compositions of rare earth phosphates were determined by XRD, FT-IR, and TG–DTA. Catalytic properties were studied as one of properties of various rare earth phosphates. Specific surface areas of samples were measured by the BET method. Acid strengths and amounts of acidic sites were measured using several indicators by n-butylamine titration. Acidic properties were also confirmed by adsorption of ammonia. Various rare earth phosphates were characterized by catalytic activities on dehydration reaction of 2-propanol, cracking/dehydrogenation reaction of cumene, and isomerization reaction of butene. The characterization of catalysts was discussed with regard to type of rare earth elements, type of phosphates, and type of phosphorus resources.

Dopamine selective molecularly imprinted polymers via post-imprinting modification

A novel synthetic dopamine receptor bearing bidentate binding sites were prepared by covalent imprinting using a disulfide linkage which is cleaved and oxidized to a non-covalent sulfoxide recognition group. The used templates have dopamine-like structures connected to an allyl moiety via a disulfide and to a 4-vinylphenyl group via a cyclic boronic diester. After the polymerization, the ester bonds were hydrolyzed and the disulfide bond was reduced to remove the template moiety from the polymer matrix, followed by the oxidation to transform the thiol residues into sulfonic acid (post imprinted process). The imprinted polymer adsorbed dopamine selectively in aqueous solution with the two-point interaction, i.e. the formation of cyclic boronic diester and electrostatic interaction with the sulfonic acid residue.

Syntheses of various rare earth phosphates from some rare earth compounds

Abstract Each rare earth compound (rare earth element; R=La, Ce, and Nd, anion; oxide, carbonate, chloride, nitrate, sulfate, oxalate, and fluoride) was mixed with (NH4)2HPO4 or H3PO4 in P/R=1, 3, and 5, and heated in air. The resulting salts were analyzed by TG-DTA, XRD and FT-IR. CePO4·nH2O was not formed in the system of CeO2–H3PO4. However, this phosphate was synthesized in the systems of Ce(NO3)3·6H2O–(NH4)2HPO4, Ce2(CO3)3·8H2O–, CeCl3·7H2O–, and Ce(NO3)3·6H2O–H3PO4. The crystallinity of CePO4·nH2O was high in the systems of CeCl3·7H2O–, and Ce(NO3)3·6H2O–H3PO4. In P/Ce=1, formation of CeO2 was observed in the systems of Ce2(CO3)3·8H2O–, CeCl3·7H2O–, and Ce2(C2O4)3·9H2O–(NH4)2HPO4.

Addition of Urea or Biuret on Synthesis of Rhabdophane-Type Neodymium and Cerium Phosphates

Urea or biuret was added to the thermal synthetic system of Rhabdophane-type neodymium and cerium phosphates. The mixture of a rare earth compound, a phosphorus compound, and an additive [CO(NH2)2 or NH(CONH2)2] was heated at 150°C or 300°C for 20 hr, and the thermal products were analyzed by the XRD, FT-IR, and BET methods. H3PO4 and (NH4)2HPO4 were used for phosphorus compounds, and for rare earth compounds, Nd2O3, Nd(NO3)3 · 6H2O, NdCl3 · 6H2O, Nd2(CO3)3 · 8H2O, CeO2, Ce(NO3)3 · 6H2O, CeCl3 · 7H2O, and Ce2(CO3)3 · 8H2O were used. Urea and biuret worked not only as a dispersing agent but also as a reactant. By the addition of biuret, the thermal products changed from cerium oxide to Rhabdophane-type cerium phosphate in the system using CeCl3 · 7H2O and (NH4)2HPO4. Addition of urea or biuret influenced the specific surface area of Rhabdophane-type neodymium and cerium phosphates. Furthermore, to increase the reactivity of the raw solid materials, mechanical treatment was performed. The mixture of diammonium hydrogenphosphate and a rare earth compound was ground with water and then heated. The influence of the addition of urea or biuret was also studied in these systems.

Nickel-Aluminum Layered Double Hydroxide Coating on the Surface of Conductive Substrates by Liquid Phase Deposition.

The direct synthesis of the adhered Ni-Al LDH thin film onto the surface of electrically conductive substrates by the liquid phase deposition (LPD) reaction is carried out for the development of the positive electrode. The complexation and solution equilibria of the dissolved species in the LPD reaction have been clarified by a theoretical approach, and the LPD reaction conditions for the Ni-Al LDH depositions are shown to be optimized by controlling the fluoride ion concentration and the pH of the LPD reaction solutions. The yields of metal oxides and hydroxides by the LPD method are very sensitive to the supersaturation state of the hydroxide in the reaction solution. The surfaces of conductive substrates are completely covered by the minute mesh-like Ni-Al LDH thin film; furthermore, there is no gap between the surfaces of conductive substrates and the deposited Ni-Al LDH thin film. The active material layer thickness was able to be controlled within the range from 100 nm to 1 μm by the LPD reaction time. The high-crystallinity and the arbitrary-thickness thin films on the conductive substrate surface will be beneficial for the interface control of charge transfer reaction fields and the internal resistance reduction of various secondary batteries.

9Be and 31P NMR analyses on the influence of imino groups on Be2+ complex stabilities of a series of cyclo‐μ‐imido triphosphate anions

The complexation behaviors of Be2+ with cyclo‐μ‐imido triphosphate anions, cP3O9−n(NH)n3− (n = 1, 2), have been investigated by both 9Be and 31P NMR techniques at −2.3 °C in order to clarify the coordination structures of the complexes. The spectra showed that cP3O9−n(NH)n (n = 1, 2) ligands form ML, ML2, and M2L complexes with Be2+ ions, and the formation of complexes coordinating with nitrogen atoms of the cyclic framework in the ligand molecule has been excluded. These complexation trends are very similar to those of Be2+‐cP3O6(NH)33− system, which has been reported by us. The peak deconvolution of 9Be NMR spectra made these beryllium complexes amenable to stability constant determinations. The stability constants of the complexes increase with an increase in the protonation constants of the ligands as the number of imino groups, which constitute the ligand molecules, is ascended. This increase is primarily attributable to the lower electronegativity of nitrogen atoms than oxygen atoms, which are directly bonded to central phosphorus atoms; moreover, tautomerism equilibrium in the entire of the imidopolyphosphate molecule is also responsible to the higher basicity. 31P NMR spectra measured concurrently have verified the formation of the complexes estimated by the 9Be NMR measurement. Intrinsic 31P NMR chemical shift values of the phosphorus atoms belonging to ligand molecules complexed with Be2+ cations have been determined. Not only the protonation constants but also the stability constants of all Be2+ complexes increase approximately linearly with an increase in the number of imino groups. Copyright

Stabilities of the Divalent Metal Ion Complexes of a Short-Chain Polyphosphate Anion and Its Imino Derivative

The stability constants of ML-type complexes of the two linear triphosphate ligand anion analogues triphosphate (

On the Protonation Behavior of Several Simple Thiophosphate Anions

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