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Abstract
Ruthenium catalysts have been prepared by incipient wetness impregnation of ruthenium(III) nitrosylnitrate, Ru(NO)(NO3)3 onto high surface area titanate supports obtained by hydrothermal treatment of TiO2 P25 in concentrated alkaline solutions. These Ru-containing catalysts were evaluated in the catalytic wet air oxidation of p-hydroxybenzoic acid (p-HBZ), a model compound representative of phenolic pollutants present in olive mills wastewaters, at 413 K and 50 bars of air. Two different titanates morphologies were tested as supports for this reaction: hydrogenotitanate nanotubes (HNT) obtained with concentrated NaOH and hydrogenotitanate nanowires (HNW) formed in the presence of highly concentrated KOH solution. The HNT and HNW supports and their corresponding supported Ru catalysts were characterized by means of N2 adsorption–desorption, XRD, UV and TEM analyses. Results showed that the use of high surface area titanate supports led to catalysts much more active than similar Ru catalysts supported on conventional TiO2 supports.
Introduction Protonated titanate nanotubes synthesized by the hydrothermal method have become the target of many studies in recent years because of its unique combination of physicochemical and structural properties [ 1
difference of MnO x -based catalysts. In this study, protonated titanate is employed as a novel support for Mn species and MnO x /titanate is tested as a possible catalyst for the NH 3 -SCR reaction. The improved activity of MnO x /titanate compared to MnO x
] H.-J. Feng , F.-M. Liu , Materials Science (cond-mat.mtrl-sci), Apr 23 2007, http://arxiv.org/pdf/0704.2695, 7 pages. Influence of Barium Titanate over V-LDEC Separation 58 Journal of Planar Chromatography 29 ( 2016
, ZJ 2001 Sol-gel synthesis of free-standing ferroelectric lead zirconate titanate nanoparticles . J Am Chem Soc 123 : 4344 – 4345 10.1021/ja001893y . 9. Ren , ZH , Xu , G , Liu , Y
Abstract
Because of unique dielectric, piezoelectric, thermoelectric, optical and ferroelectric properties of titanates of alkaline earth metals, they have become an object of many scientific research. This article is concerned with mechanochemical synthesis of calcium titanate as an alternative technique to hydrothermal, sol–gel, thermal methods. The aim of this study was to verify the mechanochemical conditions of CaTiO3 formation with the use of three calcium oxide precursors—CaO, CaCO3 and Ca(OH)2. The differences in processes of calcium titanate synthesis are presented.
Abstract
In this article, mechanochemical synthesis of barium titanate from different raw materials was studied. The prepared nanodispersed powders were investigated by means of XRD, DTA-TG, DSC, FTIR, Raman, UV–VIS, ESR spectroscopy, and low-temperature adsorption of nitrogen. Barium titanate possessing high specific surface area was produced directly during dry milling from the mixtures of barium oxides and titanium dioxide low-temperature forms (amorphous and anatase).
Abstract
Embedding of barium titanate into porous oxide matrices via sol–gel synthesis and introduction in structured slurry based on fumed oxides has been carried out. Prepared compositions have been studied using XRD, DTA-TG, FTIR, TEM, and adsorption of nitrogen. It has been established that simultaneous formation both barium titanate crystal structure and porous structure of matrices occurs. Crystallites of barium titanate, which arise in pores, possess lesser size in comparison with that for bulk BaTiO3.
Abstract
Preliminary examinations regarding formation of bismuth titanates in a part of Bi2O3—TiO2 system rich with TiO2 have been carried out. Bismuth titanates have been synthesized from mixtures of Bi2O3 and TiO2 (anatase) by the conventional solid-state method at the temperatures ranged from 1273 to 1473 K. Differential thermal analysis (DTA), powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) have been used to study the formation of bismuth titanates. The following compounds have been achieved: Bi4Ti3O12, Bi2Ti2O7 and Bi2Ti4O11. Existence of controversial bismuth titanate of formula Bi2Ti3O9 in the Bi2O3—TiO2 system has not been confirmed.
Abstract
A series of rare-earth-doped sodium titanates with the chemical formula R x H y Na4 − (x+y)TiO4·nH2O (where R = Ce3+, Nd3+ and Sm3+) were grown employing solid-state fusion reaction technique. The physico-chemical investigations indicated that the new materials were self engineered into large particles enough to be used in sorption process and having crystalline structures containing localized Na+ ions. Equilibrium studies revealed that an enhancement in sorption efficiency of sodium titanate after rare-earth doping. The neodymium-rich sodium titanate exhibited a better exchange affinity for Cs+ compared to the other studied series. Data on the kinetics of cesium exchange fit well to pseudo-second order and intra-particle diffusion models. In a separate experiment, it was reported that the R-HNaTi series showed responsible sorption affinity toward Ce, Nd and Sm ions in their solution mixture with insignificant selectivity trend which reflects the high stability of titanate matrices.