Solid acid membranes for high temperature (¿140° C) proton exchange membrane fuel cells

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Signal processing toolbox for use with MATLAB : ユーザーズガイド

A mesoporous form of titanium phosphate has been prepared by
reaction between phosphoric acid solution and either titanium propoxide or
titanium chloride in the presence of trimethylammonium surfactants. The surfactant
can be almost completely removed by extraction using acidified ethanol. The
surface area of the extracted samples depends closely on the pH of the reaction
medium, and the reaction temperature, and the highest surface areas, around
740 m2 g−1 were obtained for materials
prepared at pH 3. This surface area is partially lost when the extracted
titanium phosphate is calcined, although the mesoporous character is retained. 31P
NMR spectroscopy shows the ethanol-extracted sample to be rich in hydrogen
phosphate (HPO42− and H2PO4−)
groups, which undergo partial condensation after calcination. These hydrogen
phosphate groups are responsible for the high surface acidity determined,
and for its evolution after calcination: the total numbers of surface acidic
sites of ethanol-extracted titanium phosphate and calcined titanium phosphate,
evaluated using two-cycle adsorption of ammonia from the gas phase at
80°C, are 900 and 340 µmol g−1
respectively.

High surface area mesoporous titanium phosphate: synthesis and surface acidity determination

We introduce a novel method of inorganic synthesis using the catalytic and structure-directing properties of the demosponge enzyme silicatein-α. Recombinant silicatein-α was displayed at the surface of Escherichia coli cells by fusion to outer membrane protein A and used to biocatalytically direct the formation of layered and amorphous titanium phosphates from a small water-soluble precursor at near-neutral pH at 16 °C. Synthesis of titanium phosphates, with potential applications in catalysis and separation technology, previously has required prolonged reactions with phosphoric acid at elevated temperatures. Additionally, we use library screening to isolate a 15-mer with affinity toward the silicatein active site (Kd ca. 50 nM) and introduce this new approach to demonstrate the success of our display strategy. Considering our previous findings with native silicatein filaments, we suggest that this scalable, efficient, cell-based system may have a broad utility for the synthesis of a range of structured m...

Enzymatic Synthesis of Layered Titanium Phosphates at Low Temperature and Neutral pH by Cell-Surface Display of Silicatein-α

Two cyano-bridged Gd(III)−Cr(III) complexes [Gd(urea)4(H2O)2]2[Cr(CN)6]2 (1) and {[Gd(capro)2(H2O)4Cr(CN)6]·H2O}n (2) (capro represents caprolactam) have been synthesized and characterized structurally and magnetically. Complex 1 has a tetranuclear Gd2Cr2 square structure, in which two cis-CN- ligands of each [Cr(CN)6] link two [Gd(urea)4(H2O)2] groups and in turn, two [Gd(urea)4(H2O)2] link two [Cr(CN)6] in a cis fashion. Complex 2 is composed of 1D chains with alternating [Gd(capro)2(H2O)4] and [Cr(CN)6] moieties connected by the trans-CN- ligands of [Cr(CN)6]. The dehydration of 2 at 120 °C generates a new complex, [Gd(capro)2(H2O)2Cr(CN)6] (2‘). Magnetic studies show the existence of antiferromagnetic Gd(III)−Cr(III) interaction in these complexes. On the basis of the tetranuclear model, the magnetic susceptibilities of 1 have been analyzed giving the intermetallic magnetic coupling constant of −0.36 cm-1. Complex 2‘ exhibits a ferrimagnetic order below 2.1 K. Interestingly, 2‘ is quite soluble in wat...

Characterization of a soluble molecular magnet: unusual magnetic behavior of cyano-bridged Gd(III)-Cr(III) complexes with one-dimensional and nanoscaled square structures.

J.R. García

Papers

Formation of crystalline titanium(IV) phosphates from titanium(III) solutions

Synthesis of γ-titanium phosphate. study of the solids obtained by using water or acetone as washing agents

Hydrolytic stability of amorphous titanium and zirconium phosphates

Intercalation of α,ω-Alkyldiamines into Layered α-Titanium Phosphate from Aqueous Solutions

Direct hydrothermal synthesis of zirconium phosphate and zirconium arsenate with a novel basic layered structure in alkaline media