铂基催化剂用于柴油烃氧化(英文)

The catalytic performance of Pt-based catalysts for the total oxidation of hydrocarbons was investigated.The activity of supported Pt catalysts(Pt/Al2O3,Pt/ZrO2,Pt/TiO2,and Pt/H-ZSM-5)depends on the metal oxide support.Pt/Al2O3 showed the highest catalytic activity when the catalysts were aged at 750°C for 50 h in air.The activity of Pt/Al2O3 was dependent on the valence state of the Pt surface.Pt/Al2O3 with the Pt surface in the metallic state was more active than with the surface in the cationic state.The surface density of acid and basic sites on the Al2O3 support controlled the valence state of the Pt surface and stability of the Pt particles in the highly dispersed state,respectively.

Synthesis and Optical Investigations on (Ba,Sr)TiO₃Borosilicate Glasses Doped with La₂O₃

In this research paper we are reporting synthesis, structural and optical investigations of barium strontium titanate borosilicate glasses with addition of La2O3. Glasses were synthesized by conventional rapid melt quench method. Infrared absorption spectra, for various (Ba,Sr)TiO3 borosilicate glass samples having glass system 64[(Ba1-xSrx)TiO3]-35[2SiO2-B2O3]-5[K2O]-1[La2O3] (x = 0.3, 0.5, 0.6, 0.8 and 1.0), were recorded over a continous spectral range from 450 - 4000 cm-1. IR spectra were analyzed to determine and differentiate the various vibrational modes in the structural changes. Raman spectroscopy of all glass samples were also carried out wavenumber range form 200 - 1500 cm-1. These two complementary spectroscopic techniques revealed that the network structure of the studied glasses is mainly based on BO3, pentaborate groups linked to BO4 tetrahedra and units placed in different structural groups, the BO3 units? are dominanting. The recorded IR and Raman spectra of different glasses are used to clarify the optical properties of the prepared glass samples correlating with their structure and compositions. UV-Vis spectroscopy was carried out in range of 200 - 800 nm. The optical band gap was found between 2.023 - 3.320 eV.

Preparation,crystallization,microstructure and dielectric properties of lead bismuth titanate borosilicate glass ceramics

Various bulk and transparent glasses were prepared by rapid melt quenching technique in the glass system 55[(Pb_(x)Bi_(1-x))TiO_(3)]-44[2Si_(O)2B_(2)O_(3)]-La2O3(x=0-0.7).The X-ray diffraction(XRD)studies of the glass samples confirmed the amorphous nature.The differential thermal analyses(DTA)were carried out from room temperature to 900℃with a heating rate of 10℃/min.The DTA patterns of the samples showed one or more exothermic sharp peaks shifting towards lower temperature side with increasing concentration of bismuth oxide(BiO).On the basis of DTA results,the solid solution of bismuth titanum oxide(Bi_(2)Ti_(2)O_(7))/lead bismuth titanium oxide(Pb3Bi4Ti6O21)was precipitated in borosilicate glassy matrix as a major phase.The glasses were subjected to 4 h and 8 h heat treatment schedules to convert into glass ceramics.XRD analysis of these glass ceramic samples showed that the major crystalline phase of the entire glass ceramic samples with 0≤x≤0.5 is found to have cubic crystal structure,while it is tetragonal for glass ceramic sample with x=0.7.The scanning electron microscopy(SEM)micrographs indicated the uniform distribution of Bi_(2)Ti_(2)O_(7)and Pb3Bi4Ti6O21 crystallites in the glassy matrix.

Electrocatalytic evolution of oxygen on NiCu particles modifying conductive alumina/nano-carbon network composite electrode

In this paper, a novel electrically conductive alumina/nano-carbon network (NCN) composite material was used as an electro- catalyst carrier. A NiCu/Al2O3 /NCN composite electrode was prepared by electrodepositing NiCu particles onto the surface of the conductive alumina/NCN composite. Morphology, composition, crystalline structure and electrochemical properties of the NiCu/Al2O3 /NCN composite electrode were investigated. The results showed that NiCu particles can be deposited onto the surface of the alumina/NCN composite by a coelectrodeposition method. NiCu particles in the form of solid solution with face-centered cubic (fcc) structure were relatively uniformly distributed over the carbon layer of the conductive ceramic between alumina grains. As-resulted NiCu/Al2O3 /NCN composite electrode had a remarkably enhanced electrochemical activity and high stabilization for oxygen evolution reaction, which indicated its potential application with enhanced performance to oxygen evolution reaction (OER). Moreover, based on the electrochemical measurement, the mechanism of the OER on the NiCu/Al2O3 /NCN composite electrode was discussed.