Vapor phase synthesis of Al-doped titania powders

1994 ◽  
Vol 9 (5) ◽  
pp. 1241-1249 ◽  
Author(s):  
Kamal M. Akhtar ◽  
Sotiris E. Pratsinis ◽  
Sebastian V.R. Mastrangelo
Keyword(s):  
Vapor Phase ◽  
Flow Reactor ◽  
Particle Surface ◽  
Particle Morphology ◽  
High Concentration ◽  
Phase Synthesis ◽  
Transmission Electron ◽  
Significant Enrichment ◽  
Vapor Phase Synthesis ◽  
Doped Titania

The role of aluminum as dopant in gas phase synthesis of titania powders was experimentally investigated in an aerosol flow reactor between 1300 and 1700 K. Titania was produced by vapor phase oxidation of titanium tetrachloride in the presence of dopant aluminum trichloride vapor. The presence of aluminum altered the particle morphology from polyhedral to irregular crystals. Energy dispersive analysis and transmission electron microscopy indicated that the powders were mixtures of crystalline titania and amorphous alumina. Analysis by XPS indicated significant enrichment of aluminum on the particle surface. Some aluminum titanate (up to 17% by volume) was formed at 1700 K when a high concentration of AlCl3 was used (AlCl3/TiCl4 ≥ 0.07). Measurements of lattice parameters by x-ray diffraction indicated that aluminum formed a solid solution in titania. While titania synthesized in the absence of aluminum was about 90% anatase, the introduction of aluminum resulted in pure rutile at AlCl3/TiCl4 = 0.07. The effects of aluminum on titania phase composition and morphology are explained by the creation of oxygen vacancies in the titania crystallites and by the enhancement of the sintring rate of titania grains.

Vapor Phase Synthesis of II-IV Semiconductor Nanoparticles in a Counterflow Jet Reactor

2000 ◽  
Vol 616 ◽  
Author(s):  
D. Sarigiannis ◽  
J.D. Peck ◽  
T.J. Mountziaris ◽  
G. Kioseoglou ◽  
A. Petrou
Keyword(s):  
Vapor Phase ◽  
Room Temperature ◽  
Steady State Mode ◽  
Znse Nanoparticles ◽  
Phase Synthesis ◽  
The Past ◽  
Transmission Electron ◽  
Vapor Phase Synthesis ◽  
Znse Thin Films ◽  
Counterflow Jet Reactor

AbstractThe vapor-phase synthesis of polycrystalline ZnSe nanoparticles is reported. The particles were grown at room temperature and at a pressure of 125 torr in a counterflow jet reactor and were collected by impact on a Si watler. The precursors used in this study were vapors of (CH3)2Zn:[N(C2H5)3)]2 and H2Se gas diluted in hydrogen. These precursors have been used in the past for Metalorganic Vapor Phase Epitaxy (MOVPE) of ZnSe thin films. The particles were characterized by Transmission Electron Microscopy (TEM). electron diffraction. and Raman spectroscopy. The reactor was operated in a continuous, steady-state mode using a gas delivery system that is typical flor MOVPII systems.

Novel two-step vapor-phase synthesis of UV–Vis light active Fe2O3/WO3 nanocomposites for phenol degradation

2016 ◽  
Vol 23 (20) ◽  
pp. 20350-20359 ◽  
Author(s):  
Davide Barreca ◽  
Giorgio Carraro ◽  
Alberto Gasparotto ◽  
Chiara Maccato ◽  
Cinzia Sada ◽  
...  
Keyword(s):  
Vapor Phase ◽  
Phenol Degradation ◽  
Phase Synthesis ◽  
Vapor Phase Synthesis

Vapor-Phase Synthesis and Surface Passivation of ZnSe Nanocrystals

2006 ◽  
Vol 8 (3-4) ◽  
pp. 533-542 ◽  
Author(s):  
Christos Sarigiannidis ◽  
Maria Koutsona ◽  
Athos Petrou ◽  
T.J. Mountziaris
Keyword(s):  
Vapor Phase ◽  
Surface Passivation ◽  
Phase Synthesis ◽  
Vapor Phase Synthesis ◽  
Znse Nanocrystals

Elemental vapor-phase synthesis of nanostructured zinc oxide

2009 ◽  
Vol 45 (11) ◽  
pp. 1246-1251 ◽  
Author(s):  
A. N. Red’kin ◽  
Z. I. Makovei ◽  
A. N. Gruzintsev ◽  
E. E. Yakimov ◽  
O. V. Kononenko ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Vapor Phase ◽  
Phase Synthesis ◽  
Nanostructured Zinc Oxide ◽  
Vapor Phase Synthesis

scholarly journals Vapor phase synthesis of glycerol carbonate over honeycomb monolith coated with zirconia based base catalysts

2018 ◽  
Vol 53 (1) ◽  
pp. 21-28
Author(s):  
VT Vasantha ◽  
SZ Mohamed Shamshuddin ◽  
M Shyamsundar ◽  
Reena Saritha Serrao ◽  
Joyce Queeny D’Souza
Keyword(s):  
Catalytic Activity ◽  
Vapor Phase ◽  
Glycerol Carbonate ◽  
Phase Synthesis ◽  
Base Catalysts ◽  
Catalytic Materials ◽  
Bed Temperature ◽  
Surface Basicity ◽  
Catalytic Material ◽  
Vapor Phase Synthesis

In this article the synthesis, characterization and catalytic activity studies of zirconia based base catalysts such as Mg(II)/ZrO2, Ca(II)/ZrO2 and Ba(II)/ZrO2 coated on honeycomb monoliths is reported. Honeycomb monoliths were coated with Mg(II)/ZrO2, Ca(II)/ZrO2, Ba(II)/ZrO2 and characterized for their physico-chemical properties such as surface basicity, crystallinity and morphology by using relevant techniques. The catalytic activity of these catalytic materials was evaluated in vapor phase synthesis of glycerol carbonate. The reaction conditions were optimized by varying reaction parameters such as nature of catalytic material, molar ratio of the reactants, catalyst bed temperature, feed-rate of the reactants and time-on-stream to obtain highest possible yield of glycerol carbonate with greater selectivity. The catalytic materials were found to be highly efficient in the synthesis of glycerol carbonate with a possible highest yield up to ~98%. These catalytic materials can be easily reactivated and reused in this reaction.Bangladesh J. Sci. Ind. Res.53(1), 21-28, 2018

scholarly journals Tuning Pt-CeO2 interactions by high-temperature vapor-phase synthesis for improved reducibility of lattice oxygen

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Xavier Isidro Pereira-Hernández ◽  
Andrew DeLaRiva ◽  
Valery Muravev ◽  
Deepak Kunwar ◽  
Haifeng Xiong ◽  
...  
Keyword(s):  
High Temperature ◽  
Co Oxidation ◽  
Vapor Phase ◽  
Ambient Pressure ◽  
Lattice Oxygen ◽  
Single Atom ◽  
Stable Form ◽  
Phase Synthesis ◽  
Vapor Phase Synthesis ◽  
High Temperature Vapor

Abstract In this work, we compare the CO oxidation performance of Pt single atom catalysts (SACs) prepared via two methods: (1) conventional wet chemical synthesis (strong electrostatic adsorption–SEA) with calcination at 350 °C in air; and (2) high temperature vapor phase synthesis (atom trapping–AT) with calcination in air at 800 °C leading to ionic Pt being trapped on the CeO2 in a thermally stable form. As-synthesized, both SACs are inactive for low temperature (<150 °C) CO oxidation. After treatment in CO at 275 °C, both catalysts show enhanced reactivity. Despite similar Pt metal particle size, the AT catalyst is significantly more active, with onset of CO oxidation near room temperature. A combination of near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and CO temperature-programmed reduction (CO-TPR) shows that the high reactivity at low temperatures can be related to the improved reducibility of lattice oxygen on the CeO2 support.

Vapor phase synthesis of fine particles

1997 ◽  
Vol 25 (5) ◽  
pp. 1008-1016 ◽  
Author(s):  
A.C. Da Cruz ◽  
R.J. Munz
Keyword(s):  
Vapor Phase ◽  
Fine Particles ◽  
Phase Synthesis ◽  
Vapor Phase Synthesis

Particle Morphology of Various SiC-Based Nanocomposite Powders Made by the Aerosol-Assisted Synthesis Method

2008 ◽  
Vol 8 (2) ◽  
pp. 907-913 ◽  
Author(s):  
Cezary Czosnek ◽  
Jerzy F. Janik
Keyword(s):  
Synthesis Method ◽  
Particle Morphology ◽  
Nanocrystalline Silicon ◽  
Carbide Powder ◽  
Excess Carbon ◽  
Phase Synthesis ◽  
Aerosol Generation ◽  
Vapor Phase Synthesis ◽  
Nanocrystalline Silicon Carbide ◽  
Nanocomposite Powders

Herein, we present a part of a study on the preparation of SiC-based composite nanopowders by the two-stage Aerosol-Assisted Vapor Phase Synthesis (AAVS) method from organosilicon precursors (neat hexamethyldisiloxane, neat tetramethoxysilane, ethanol solutions of polydimethylsiloxane). Upon generation, liquid aerosol droplets were transported in a stream of argon through a ceramic reactor tube maintained at 1200 °C. The resulting solid by-products were collected on a nylon filter as bulk powders. Each raw powder was, subsequently, pyrolyzed in a furnace reactor heated to 1650 °C under a flow of argon. After the final pyrolysis at 1650 °C, mostly nanocrystalline silicon carbide powder with small quantities of free excess carbon was obtained from the neat hexamethyldisiloxane system, composite powder of not fully converted silica and SiC was prepared from the neat tetramethoxysilane system, and C-rich/SiC composite was made from the ethanol/polydimethylsiloxane solution system. The prevailing phase of the SiC component was the regular β-SiC polytype. Most of the powders were composed of spheroidal particles – morphology imprinted during aerosol generation at 1200 °C and not much affected by the second-stage bulk pyrolysis at 1650 °C. The specifics of spheroidal morphology were characteristic of the applied precursor system.

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