scholarly journals Structural and Electrochemical Properties of Nesting and Core/Shell Pt/TiO2 Spherical Particles Synthesized by Ultrasonic Spray Pyrolysis

Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 11 ◽  
Author(s):  
Milica G. Košević ◽  
Milana M. Zarić ◽  
Srećko R. Stopić ◽  
Jasmina S. Stevanović ◽  
Thomas E. Weirich ◽  
...  
Keyword(s):  
Spray Pyrolysis ◽  
Oxygen Reduction ◽  
Hollow Spheres ◽  
Ultrasonic Spray Pyrolysis ◽  
Ex Situ ◽  
Spherical Particles ◽  
Core Shell ◽  
Ultrasonic Spray ◽  
Solid Spheres

Pt/TiO2 composites were synthesized by single-step ultrasonic spray pyrolysis (USP) at different temperatures. In an in-situ method, Pt and TiO2 particles were generated from tetra-n-butyl orthotitanate and chloroplatinic acid, and hydrothermally-prepared TiO2 colloidal dispersion served as Pt support in an ex-situ USP approach. USP-synthesized Pt/TiO2 composites were generated in the form of a solid mixture, morphologically organized in nesting huge hollow and small solid spheres, or TiO2 core/Pt shell regular spheroids by in-situ or ex-situ method, respectively. This paper exclusively reports on characteristic mechanisms of the formation of novel two-component solid composites, which are intrinsic from the USP approach and controlled precursor composition. The generation of the two morphological components within the in-situ approach, the hollow spheres and all-solid spheres, was indicated to be caused by characteristic sol-gel/solid phase transition of TiO2. Both the walls of the hollow spheres and the cores of all-solid ones consist of TiO2 matrix populated by 10 nm-sized Pt. On the other hand, spherical, uniformly-sized, Pt particles of a few nanometers in size created a shell uniformly deposited onto TiO2 spheres of ca. 150 nm size. Activities of the prepared samples in an oxygen reduction reaction and combined oxygen reduction and hydrogen evolution reactions were electrochemically tested. The ex-situ synthesized Pt/TiO2 was more active for oxygen reduction and combined oxygen reduction and hydrogen reactions in comparison to the in-situ Pt/TiO2 samples, due to better availability of Pt within a core/shell structure for the reactions.

LPG Synthesis from Syngas over Cu/ZnO-Pd-β Catalysts Prepared by Ultrasonic Spray Pyrolysis

2015 ◽  
Vol 659 ◽  
pp. 252-256
Author(s):  
Sudarat Chaiwatyothin ◽  
Wittawat Ratanathavorn ◽  
Tharapong Vitidsant ◽  
Prasert Reubroycharoen
Keyword(s):  
Spray Pyrolysis ◽  
Fixed Bed ◽  
Ultrasonic Spray Pyrolysis ◽  
Product Distribution ◽  
Fixed Bed Reactor ◽  
Spherical Particles ◽  
Gaseous State ◽  
X Ray ◽  
Ultrasonic Spray ◽  
Co Conversion

Synthesis of nanoCu/ZnO catalyst for LPG production was prepared by ultrasonic spray pyrolysis (USP). Hollow spherical particles were obtained by USP technique using an aqueous solution of Cu (NO3)3.6H2O and Zn (NO3)3.3H2O with different concentration of 0.05, 0.1 and 0.5 molar under the pyrolysis temperatures of 600, 700 and 800°C. Mists of the solution were generated from the precursor solution by ultra sonic vibrators at frequency of ~1.7 MHz. The physicochemical properties of catalysts were characterized by X-ray diffraction, temperature-programmed reduction, scanning electron microscope, nitrogen adsorption-desorption, and energy dispersive X-ray spectrometer. The results showed that increasing in precursor concentration resulted in a large particle and particles size distributed in a range of 0.63-1.21 μm. Particles prepared at pyrolysis temperature 700°C exhibited homogeneous in size and shape compared to other temperature. The catalytic activity of nanoCu/ZnO-Pd-β catalysts was performed in a fixed-bed reactor for synthesizing LPG. The reaction took place at 260°C, 3.0 MPa, and the ratio of H2/CO = 2/1. All the products from the reactor were in gaseous state, and analyzed by on-line gas chromatography. The results showed that %CO conversion was high but decreased rapidly with increasing reaction time. Cu/ZnO catalyst prepared by co-precipitation gave higher %CO conversion than that prepared by ultrasonic spray pyrolysis. Moreover, hydrocarbon product distribution for Cu/ZnO catalyst produced at concentration 0.1 M 700°C by ultrasonic spray pyrolysis gave the highest LPG selectivity.

scholarly journals Synthesis of Silica Particles Using Ultrasonic Spray Pyrolysis Method

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 463
Author(s):  
Srecko Stopic ◽  
Felix Wenz ◽  
Tatjana-Volkov Husovic ◽  
Bernd Friedrich
Keyword(s):  
Spray Pyrolysis ◽  
Sol Gel ◽  
Ultrasonic Spray Pyrolysis ◽  
Silica Particles ◽  
Cement Industry ◽  
Submicron Particles ◽  
Spherical Particles ◽  
Spray Pyrolysis Method ◽  
X Ray ◽  
Ultrasonic Spray

Silica has sparked strong interest in hydrometallurgy, catalysis, the cement industry, and paper coating. The synthesis of silica particles was performed at 900 °C using the ultrasonic spray pyrolysis (USP) method. Ideally, spherical particles are obtained in one horizontal reactor from an aerosol. The controlled synthesis of submicron particles of silica was reached by changing the concentration of precursor solution. The experimentally obtained particles were compared with theoretically calculated values of silica particles. The characterization was performed using a scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS). X-ray diffraction, frequently abbreviated as XRD, was used to analyze the structure of obtained materials. The obtained silica by ultrasonic spray pyrolysis had an amorphous structure. In comparison to other methods such as sol–gel, acidic treatment, thermal decomposition, stirred bead milling, and high-pressure carbonation, the advantage of the ultrasonic spray method for preparation of nanosized silica controlled morphology is the simplicity of setting up individual process segments and changing their configuration, one-step continuous synthesis, and the possibility of synthesizing nanoparticles from various precursors.

Synthesis of ZnO/TiO2 spherical particles for blue light screening by ultrasonic spray pyrolysis

2020 ◽  
Vol 24 ◽  
pp. 101126 ◽  
Author(s):  
Ratanathavorn Wittawat ◽  
Rungruang Rittipun ◽  
Modsuwan Jarasfah ◽  
Bouhoad Nattaporn
Keyword(s):  
Spray Pyrolysis ◽  
Blue Light ◽  
Ultrasonic Spray Pyrolysis ◽  
Spherical Particles ◽  
Ultrasonic Spray

Magnetic-luminescent spherical particles synthesized by ultrasonic spray pyrolysis

2015 ◽  
Vol 2 (7) ◽  
pp. 076103 ◽  
Author(s):  
Norma L Michel ◽  
Dora L Flores ◽  
Gustavo A Hirata
Keyword(s):  
Spray Pyrolysis ◽  
Ultrasonic Spray Pyrolysis ◽  
Spherical Particles ◽  
Ultrasonic Spray

Synthesis, morphology, and formation mechanism of mullite particles produced by ultrasonic spray pyrolysis

1996 ◽  
Vol 11 (7) ◽  
pp. 1706-1716 ◽  
Author(s):  
Dj. Janaćković ◽  
V. Jokanović ◽  
Lj. Kostić-Gvozdenović ◽  
Lj. Živković ◽  
D. Uskoković
Keyword(s):  
Spray Pyrolysis ◽  
Silicic Acid ◽  
Formation Mechanism ◽  
Ultrasonic Spray Pyrolysis ◽  
Spherical Particles ◽  
Mullite Phase ◽  
Ultrasonic Spray ◽  
Solution Preparation ◽  
Subsequent Phase ◽  
Mullite Powder

Submicrometer spherical particles of mullite powder were synthesized by ultrasonic spray pyrolysis of emulsion and solutions, using tetra-ethyl-orthosilicate (TEOS) or silicic-acid and Al(NO3)3 · 9H2O as initial compounds. Crystallization of mullite phase was determined by differential thermal (DT), thermogravimetric (TG), infrared (IR), and x-ray analyses. The synthesis of mullite from TEOS emulsion occurs by crystallization of γ–Al2O3 (or Al, Si-spinel) from the amorphous phase and its subsequent reaction with amorphous SiO2, as well as by crystallization of pseudotetragonal mullite below 1000 °C and its subsequent phase transformation into orthorhombic mullite. In the powders produced from silicic acid solutions, synthesis of mullite occurs only by crystallization of γ–Al2O3 between 900 and 1000 °C and its further reaction with amorphous SiO2 between 1100 and 1200 °C. Particle formation mechanism depended directly on the initial emulsion or solution preparation, i.e., on the phase separation in the emulsion and on the silicic-acid crosslinking conditions.

scholarly journals Synthesis of Core-Shell Si/Carbon Nanofibers on Silicon Substrates by Ultrasonic Spray Pyrolysis

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Jianhui Zhang ◽  
Naoki Kishi ◽  
Tetsuo Soga ◽  
Takashi Jimbo ◽  
Takayoshi Tanji
Keyword(s):  
Spray Pyrolysis ◽  
Carbon Nanofibers ◽  
Substrate Surface ◽  
Ultrasonic Spray Pyrolysis ◽  
Core Shell ◽  
Silicon Substrates ◽  
The Core ◽  
Ultrasonic Spray ◽  
Transmission Electron ◽  
Solid Liquid

We synthesized the core-shell Si/carbon nanofibers with diameters of 200–300 nm using ultrasonic spray pyrolysis with a phosphorus/ethanol mixture. High-resolution transmission electron microscopy (HRTEM) and energy-dispersive spectroscopy (EDS) investigations confirmed the core-shell structure, which consisted of a core of Si and a shell of amorphous carbon. The phosphorus atoms corroded the entire silicon substrate surface, and the Si-P liquid-catalyzed the solid-liquid-solid mechanism is proposed to explain the growth of the core-shell Si/carbon nanofibers.

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