Perchlorosilanes and Perchlorocarbosilanes as Precursors to Silicon Carbide

2006 ◽  
Vol 911 ◽  
Author(s):  
Vladimir Sevastyanov ◽  
Yurij Ezhov ◽  
Roman Pavelko ◽  
Nikolaj Kuznetsov
Keyword(s):  
Thermal Decomposition ◽  
Silicon Carbide ◽  
Low Temperature ◽  
Gas Phase ◽  
Thermodynamic Modeling ◽  
Reaction System ◽  
Reaction Products ◽  
Gaseous Species ◽  
Phase Synthesis ◽  
Key Features

AbstractHomologues with the general stoichiometry a(SiCl4) : bSi : cC : d(SiC) are shown to be potential precursors for the low-temperature gas-phase synthesis of silicon carbide. Thermal decomposition of these precursors yields the chemically stable gaseous species SiCl4 and condensed Si, C, SiC, SiC+Si, or SiC+C. Thermodynamic modeling of the thermal decomposition of octachlorotrisilane, Si3Cl8, is used to analyze the key features of the thermolysis of perchlorosilanes with the general stoichiometry a(SiCl4) : bSi. The equilibrium compositions of reaction products in the Si3Cl8+CO system are determined. This reaction system enables low-temperature (400 – 1200 K) synthesis of silicon carbide.

scholarly journals Low-temperature electrocatalytic conversion of CO2 to liquid fuels: effect of the Cu particle size

2018 ◽  
Author(s):  
Antonio De Lucas-Consuegra ◽  
Juan Carlos Serrano-Ruiz ◽  
Nuria Gutierrez-Guerra ◽  
José Luis Valverde
Keyword(s):  
Particle Size ◽  
Low Temperature ◽  
Gas Phase ◽  
Electrocatalytic Activity ◽  
Water Electrolysis ◽  
Proton Exchange ◽  
Liquid Fuels ◽  
Main Reaction ◽  
Membrane Electrode ◽  
Reaction Products

A novel gas-phase electrocatalytic system based on a low-temperature proton exchange membrane (Sterion) was developed for the gas phase electrocatalytic conversion of CO2 to liquid fuels. This system achieved gas-phase electrocatalytic reduction of CO2 at low temperatures (below 90 ºC) over a Cu cathode by using water electrolysis-derived protons generated in-situ on an IrO2 anode. Three Cu-based cathodes with varying metal particle sizes were prepared by supporting this metal on an activated carbon at three loadings (50, 20, and 10 wt%; 50%Cu-AC, 20%Cu-AC, and 10%Cu-AC, respectively). The cathodes were characterized by N2 adsorption–desorption, temperature-programmed reduction (TPR), and X-ray diffraction (XRD) whereas their performance towards the electrocatalytic conversion of CO2 was subsequently studied. The membrane electrode assembly (MEA) containing the cathode with the largest Cu particle size (50%Cu-AC, 40 nm) showed the highest CO2 electrocatalytic activity per mole of Cu, with methyl formate being the main product. This higher electrocatalytic activity was attributed to the lower Cu–CO bonding strength over large Cu particles. Different product distributions were obtained over 20%Cu-AC and 10%Cu-AC, with acetaldehyde and methanol being the main reaction products, respectively. The CO2 consumption rate increased with the applied current and the reaction temperature.

Materialographic Microstructural Analysis during the Process Development for the Gas Phase Synthesis of Silicon Carbide

2017 ◽  
Vol 54 (9) ◽  
pp. 636-654
Author(s):  
J. Edelbauer ◽  
C. Sinz ◽  
O. Lott ◽  
A. Nagel ◽  
W. Rimkus
Keyword(s):  
Silicon Carbide ◽  
Gas Phase ◽  
Process Development ◽  
Microstructural Analysis ◽  
Phase Synthesis ◽  
Gas Phase Synthesis

scholarly journals Low-Temperature Electrocatalytic Conversion of CO2 to Liquid Fuels: Effect of the Cu Particle Size

Catalysts ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 340 ◽  
Author(s):  
Antonio de Lucas-Consuegra ◽  
Juan Serrano-Ruiz ◽  
Nuria Gutiérrez-Guerra ◽  
José Valverde
Keyword(s):  
Particle Size ◽  
Low Temperature ◽  
Gas Phase ◽  
Electrocatalytic Activity ◽  
Water Electrolysis ◽  
Proton Exchange ◽  
Liquid Fuels ◽  
Main Reaction ◽  
Membrane Electrode ◽  
Reaction Products

A novel gas-phase electrocatalytic system based on a low-temperature proton exchange membrane (Sterion) was developed for the gas-phase electrocatalytic conversion of CO2 to liquid fuels. This system achieved gas-phase electrocatalytic reduction of CO2 at low temperatures (below 90 °C) over a Cu cathode by using water electrolysis-derived protons generated in-situ on an IrO2 anode. Three Cu-based cathodes with varying metal particle sizes were prepared by supporting this metal on an activated carbon at three loadings (50, 20, and 10 wt %; 50% Cu-AC, 20% Cu-AC, and 10% Cu-AC, respectively). The cathodes were characterized by N2 adsorption–desorption, temperature-programmed reduction (TPR), and X-ray diffraction (XRD) and their performance towards the electrocatalytic conversion of CO2 was subsequently studied. The membrane electrode assembly (MEA) containing the cathode with the largest Cu particle size (50% Cu-AC, 40 nm) showed the highest CO2 electrocatalytic activity per mole of Cu, with methyl formate being the main product. This higher electrocatalytic activity was attributed to the lower Cu–CO bonding strength over large Cu particles. Different product distributions were obtained over 20% Cu-AC and 10% Cu-AC, with acetaldehyde and methanol being the main reaction products, respectively. The CO2 consumption rate increased with the applied current and reaction temperature.

scholarly journals Different pathways of the formation of highly oxidized multifunctional organic compounds (HOMs) from the gas-phase ozonolysis of <i>β</i>-caryophyllene

2016 ◽  
Vol 16 (15) ◽  
pp. 9831-9845 ◽  
Author(s):  
Stefanie Richters ◽  
Hartmut Herrmann ◽  
Torsten Berndt
Keyword(s):  
Double Bond ◽  
Gas Phase ◽  
Organic Compounds ◽  
Atmospheric Pressure ◽  
Reaction System ◽  
Peroxy Radical ◽  
Closed Shell ◽  
Atmospheric Conditions ◽  
Reaction Products ◽  
Product Analysis

Abstract. The gas-phase mechanism of the formation of highly oxidized multifunctional organic compounds (HOMs) from the ozonolysis of β-caryophyllene was investigated in a free-jet flow system at atmospheric pressure and a temperature of 295 ± 2 K. Reaction products, mainly highly oxidized RO2 radicals containing up to 14 oxygen atoms, were detected using chemical ionization – atmospheric pressure interface – time-of-flight mass spectrometry with nitrate and acetate ionization. These highly oxidized RO2 radicals react with NO, NO2, HO2 and other RO2 radicals under atmospheric conditions forming the first-generation HOM closed-shell products. Mechanistic information on the formation of the highly oxidized RO2 radicals is based on results obtained with isotopically labelled ozone (18O3) in the ozonolysis reaction and from hydrogen/deuterium (H/D) exchange experiments of acidic H atoms in the products. The experimental findings indicate that HOM formation in this reaction system is considerably influenced by the presence of a double bond in the RO2 radicals primarily formed from the β-caryophyllene ozonolysis. Three different reaction types for HOM formation can be proposed, allowing for an explanation of the detected main products: (i) the simple autoxidation, corresponding to the repetitive reaction sequence of intramolecular H-abstraction of a RO2 radical, RO2  →  QOOH, and subsequent O2 addition, next forming a peroxy radical, QOOH + O2  →  R′O2; (ii) an extended autoxidation mechanism additionally involving the internal reaction of a RO2 radical with a double bond forming most likely an endoperoxide and (iii) an extended autoxidation mechanism including CO2 elimination. The individual reaction steps of the reaction types (ii) and (iii) are uncertain at the moment. From the product analysis it can be followed that the simple autoxidation mechanism accounts only for about one-third of the formed HOMs. Time-dependent measurements showed that the HOM formation proceeds at a timescale of 3 s or less under the concentration regime applied here. The new reaction pathways represent an extension of the mechanistic understanding of HOM formation via autoxidation in the atmosphere, as recently discovered from laboratory investigations on monoterpene ozonolysis.

scholarly journals Different Pathways of the Formation of Highly Oxidized Multifunctional Organic Compounds (HOMs) from the Gas-Phase Ozonolysis of β-Caryophyllene

2016 ◽  
Author(s):  
Stefanie Richters ◽  
Hartmut Herrmann ◽  
Torsten Berndt
Keyword(s):  
Double Bond ◽  
Gas Phase ◽  
Organic Compounds ◽  
Atmospheric Pressure ◽  
Reaction System ◽  
Peroxy Radical ◽  
Closed Shell ◽  
Atmospheric Conditions ◽  
Reaction Products ◽  
Product Analysis

Abstract. The gas-phase mechanism of the formation of highly oxidized multifunctional organic compounds (HOMs) from the ozonolysis of β-caryophyllene was investigated in a free-jet flow system at atmospheric pressure and a temperature of 295 ± 2 K. Reaction products, mainly highly oxidized RO2 radicals, containing up to 14 oxygen atoms were detected using chemical ionization – atmospheric pressure interface – time-of-flight mass spectrometry with nitrate and acetate ionization. These highly oxidized RO2 radicals react with NO, NO2, HO22 and other RO2 radicals under atmospheric conditions forming the first-generation HOM closed-shell products. Mechanistic information on the formation of the highly oxidized RO2 radicals are based on results obtained with isotopically labeled ozone (18O3) in the ozonolysis reaction and from H/D exchange experiments of acidic H atoms in the products. The experimental findings indicate that HOM formation in this reaction system is considerably influenced by the presence of a double bond in the RO2 radicals primarily formed from the β-caryophyllene ozonolysis. Three different reaction types for HOM formation can be proposed allowing to explain the detected main products, i.e. (i) the simple autoxidation, corresponding to the repetitive reaction sequence of intramolecular H-abstraction of a RO2 radical, RO2 &amp;rightarrow; QOOH, and subsequent O2 addition forming a next peroxy radical, QOOH + O2 &amp;rightarrow; R'O2, (ii) an extended autoxidation mechanism additionally involving the internal reaction of a RO2 radical with a double bond forming most likely an endoperoxide, and (iii) an extended autoxidation mechanism including CO2 elimination. The individual reaction steps of the reaction types (ii) and (iii) are uncertain at the moment. From the product analysis it can be followed that the simple autoxidation mechanism accounts only for about one third of the formed HOMs. Time-dependent measurements showed that the HOM formation proceeds at a timescale of 3 s or less under the concentration regime applied here. The new reaction pathways represent an extension of the mechanistic understanding of HOM formation via autoxidation in the atmosphere, as recently discovered from laboratory investigations on monoterpene ozonolysis.

Synthesis and Coating of Aluminum NanoCrystals

2012 ◽  
Vol 1405 ◽  
Author(s):  
Dan A. Kaplowitz ◽  
Jason Jouet ◽  
Michael R. Zachariah
Keyword(s):  
Melting Point ◽  
Low Temperature ◽  
Energy Release ◽  
Gas Phase ◽  
Decomposition Temperature ◽  
Aluminum Surface ◽  
Phase Synthesis ◽  
Aluminum Nanocrystals ◽  
Combustion Tests ◽  
Free Environment

ABSTRACTWe show a low temperature gas-phase synthesis route to produce faceted aluminum crystals in the aerosol phase. Use of triisobutylaluminum whose decomposition temperature is below the melting point of elemental aluminum enabled us to grow nanocrystals from its vapor. Combustion tests show an increase in energy release compared to commercial nanoaluminum. Production of aluminum in an oxygen free environment resulted in a bare aluminum surface that was passivated in separate experiments with nickel and iron by decomposition of their carbonyl precursors.

Solvent-Dependent, Low-Temperature Solution Phase Synthesis of FePt Nanowires

2008 ◽  
Vol 8 (7) ◽  
pp. 3379-3385 ◽  
Author(s):  
Kai-Ming Chi ◽  
Pei-Yu Chen
Keyword(s):  
Thermal Decomposition ◽  
Low Temperature ◽  
Reaction Temperature ◽  
Average Diameter ◽  
Solution Phase ◽  
Synthetic Approach ◽  
Phase Synthesis ◽  
Solution Phase Synthesis ◽  
Temperature Solution

Preparation of FePt nanowires by thermal decomposition of the solution mixture of equimolar Fe(CO)5 and Pt(acac)2 in n-octylamine will be presented in this account. The nanowires with the average diameter about 2 nm and the length of several hundred nanometers were characterized by TEM, EDS, XRD. It is believed that FePt nanowires were generated via the catalytic solution-liquid-solid (S-L-S) synthetic approach. This process is strongly dependent on the solvent and barely on the reaction temperature and the concentrations of precursors.

Iminyl radicals in gas-phase synthesis. I. Generation of nitriles by pyrolysis of aryl azines

1976 ◽  
Vol 29 (10) ◽  
pp. 2281 ◽  
Author(s):  
KJ Bird ◽  
AWK Chan ◽  
WD Crow
Keyword(s):  
Thermal Decomposition ◽  
Gas Phase ◽  
Low Pressure ◽  
Unimolecular Decomposition ◽  
Alkyl Aryl ◽  
Phase Synthesis ◽  
Gas Phase Synthesis ◽  
Intermolecular Reaction ◽  
Aryl Ketones ◽  
Aryl Aldehyde

Low-pressure gas-phase pyrolysis of aryl aldehyde azines leads to formation of the corresponding aryl cyanides in varying yield, together with small amounts of the corresponding stilbenes. In the case of benzaldehyde azine, stilbene formation is shown to be an intermolecular reaction. Certain substituent groups show some thermal decomposition, but this can be avoided by the use of the wines of alkyl aryl ketones; excellent nitrile yields are then obtained. The reaction is postulated as proceeding by unimolecular decomposition of the iminyl radicals formed by cleavage of the central N-N bond; thermochemical estimates are discussed. Azines from furan- and thiophen-2-carbaldehydes produce 1,2-di(2-furyl)ethylene-and 1,2-di(2- thienyl)ethylene respectively as well as the expected nitriles. As in the azines of alkyl aryl ketones, however, no alkenes are formed on pyrolysis of the azines from 2-acetylfuran and 2-acetylthiophen.

scholarly journals Alternative mechanisms of the primary act of gas-phase monomolecular thermal decomposition of N-methyl-N’-methoxydiazene-N-oxide according to the data of quantum chemical calculations

2021 ◽  
Vol 2052 (1) ◽  
pp. 012030
Author(s):  
E V Nikolaeva ◽  
G M Khrapkovskii ◽  
I V Aristov ◽  
D L Egorov ◽  
A G Shamov
Keyword(s):  
Thermal Decomposition ◽  
Gas Phase ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Density Functional ◽  
Thermal Destruction ◽  
Reaction Products ◽  
Density Functional Methods ◽  
Functional Methods ◽  
Basic Functions

Abstract The mechanisms of the primary act of thermal decomposition of the simplest representative of the series of alkoxy-NNO-azoxy compounds – N-methyl-N’-methoxydiazene-N- oxide are studied using quantum-chemical density functional methods PBE, B3LYP, wB97XD with different sets of basic functions, as well as the composite G4 method. It is shown that the most probable channel of its thermal destruction, leading to the formation of experimentally observed reaction products, is isomerization because of rotation of the OCH3 group around the NO bond with the subsequent transfer of the CH3 group between oxygen atoms. In this case, the transfer of the CH3 group is the limiting reaction of the thermal decomposition of N-methyl-N’-methoxydiazene-N-oxide as a whole.

scholarly journals Low temperature gas-phase technology cladding powdered silicon carbide

2020 ◽  
Vol 98 (2) ◽  
pp. 76-82
Author(s):  
P.A. Abdurazova ◽  
◽  
M.S. Sataev ◽  
Sh.T. Koshkarbaeva ◽  
K.A. Amanbaeva ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Low Temperature ◽  
Gas Phase ◽  
Powdered Silicon
Sign in / Sign up

Export Citation Format

Share Document