Gas phase synthesis

Siegel R W 1996 Gas phase synthesis and mechanical properties of nanomaterials Analysis 24 M10... 

Raw Material and Energy Aspects to Pyridine Manufacture. The majority of pyridine and pyridine derivatives are based on raw materials like aldehydes or ketones. These are petroleum-derived starting materials and their manufacture entails cracking and distillation of alkanes and alkenes, and oxidation of alkanes, alkenes, or alcohols. Ammonia is usually the source of the nitrogen atom in pyridine compounds. Gas-phase synthesis of pyridines requires high temperatures (350—550°C) and is therefore somewhat energy intensive. 

G s-Ph se Synthesis. A gas-phase synthesis route to making fine, pure SiC having controllable properties has been described (78,79). Methane was used as a carbon source if required, and the plasma decomposition of three feedstocks, siUcon tetrachloride [10026-04-7] SiCl, dimethyl dichi orosilane, and methyltrichlorosilane [75-79-6] CH Cl Si, into fine SiC powders was investigated. 

Another method of manufacturing SiC by the decomposition of a gas mixture containing silane, propane, and hydrogen, and hydrogen chloride has been described (80). With such a mixture, it was possible to work at a relatively lower (1200°C) temperature and it was claimed that compact, homogeneous P SiC crystals were obtained. In a variation of this gas-phase synthesis theme, SiC has been produced from the reaction of SiCl and methane (81). SiC precipitates from 1000 to 3000°C. 

Nowadays, few data have been reported in the literatnre [17] on the one-pot gas phase synthesis of MDB, nsing Ti-silicahte (TS-1) as a catalyst and... 

Apart from the widely studied silver(i) A-heterocyclic carbenes, Stoltz and Beauchamp made the first report on the gas-phase synthesis of silver(i) Fischer carbenes from the loss of N2 in various diazo malonates upon electrospray ionization and subsequent collisional activation.118 The carbenes generated were capable of undergoing multiple Wolff rearrangements and loss of CO (Scheme 18). 

The approaches used for preparation of inorganic nanomaterials can be divided into two broad categories solution-phase colloidal synthesis and gas-phase synthesis. Metal and semiconductor nanoparticles are usually synthesized via solution-phase colloidal techniques,4,913 whereas high-temperature gas-phase processes like chemical vapor deposition (CVD), pulsed laser deposition (PLD), and vapor transfer are widely used for synthesis of high-quality semiconductor nanowires and carbon nanotubes.6,7 Such division reflects only the current research bias, as promising routes to metallic nanoparticles are also available based on vapor condensation14 and colloidal syntheses of high-quality semiconductor nanowires.15... 

The gas-phase synthesis of methanol (M) from CO and H2 is a reversible reaction ... 

For the gas phase synthesis of phosgene, CO + Cl2 => C0C12, A + B => C, the tabulated data were obtained at 25°C with starting pressure of 4.0 torr for CO. and two different pressures for Cl2 t is in minutes and the partial pressures are in torr. Find the rate equation. Check the rate equation. 

Gas-phase process, of ethylene-propylene polymer manufacture, 10 711 Gas-phase reactions flow mixing for, 14 613 pressure and, 14 623 Gas-phase reactor (GPR), 20 533 Gas-phase sedimentation, 18 142 Gas-phase synthesis, in silicon carbide manufacture and processing, 22 533 Gas pipeline systems, 12 366 Gas pretreatment, 13 841 Gas processing, in petroleum refining, 18 663... 

Silicon microstructures can be categorized according to the dimensionality of the confinement. Most PL studies deal with silicon structures confined in three dimensions such dot-like structures are designated zero-dimensional (OD). An overview of size-dependent properties of silicon spheres is given in Table 6.1. Standard methods of generating such microstructures are gas-phase synthesis [Di3, Li7, Scl2], plasma CVD [Ru2, Col, Ta8] or conventional chemical synthesis [Mal5]. 

Tundo, P. and Selva, M. (2005). Continuous-flow, gas phase synthesis of 1-chlorobutane (1-bromobutane) from 1-butanol and aqueous HCl (HBr) over silica-supported quaternary phosphonium salt. Green Chem., 7,464-467. 

Timoshkin AY, Schaefer HE (2002) From parasitic association reactions toward the stoichiometry controlled gas phase synthesis of nanoparticles, A theoretically driven challenge for experimentalists. Chemical Record 2(5), 319-338... 

Recent advances in the large-scale synthesis of pyridines using conventional methods and gas phase synthesis over ZSM-5 zeolites were reviewed <98M1>. 

Powder Formation. Metallic powders can be formed by any number of techniques, including the reduction of corresponding oxides and salts, the thermal dissociation of metal compounds, electrolysis, atomization, gas-phase synthesis or decomposition, or mechanical attrition. The atomization method is the one most commonly used, because it can produce powders from alloys as well as from pure metals. In the atomization process, a molten metal is forced through an orifice and the stream is broken up with a jet of water or gas. The molten metal forms droplets to minimize the surface area, which solidify very rapidly. Currently, iron-nickel-molybdenum alloys, stainless steels, tool steels, nickel alloys, titanium alloys, and aluminum alloys, as well as many pure metals, are manufactured by atomization processes. 

Table 7.13 Some Structural Ceramics Formed in Gas-Phase Synthesis...

Table 7.14 Overall Reactions and Thermodynamic Data for the Gas-Phase Synthesis of SisN4 from Seiected Precursors...

In addition to single-component powders, gas-phase synthesis can be used to produce composite powders, such as SiC and BN. An example of an apparatus used for this particular synthesis, which is representative of the apparatuses used for most gas-phase synthesis of particles, is shown in Figure 7.38. 

A.2 Semiconductor Device Fabrication. In this section we investigate the gas-phase synthesis of compounds, primarily semiconductors, that are preferentially deposited on a surface to form a layer called a thin film. This technology can be used to form structural and protective layers of materials described in the previous section, but is used primarily to form thin films from semiconductor materials for electronic devices. Recall from Figure 6.99, for example, that most semiconductor devices are made from layers of appropriately doped compounds. In order to fabricate these devices at ever smaller scales, the layers must be formed in a carefully controlled manner. This... 

Figure 7.38 Schematic diagram of experimental apparatus used to form SiC/BN composite particles by gas-phase synthesis on a substrate (a). From Carbide, Nitride, and Boride Materials Synthesis and Processing, A. W. Weimer, ed., p. 336. Copyright 1997 by Chapman Hall, London, with kind permission of Kluwer Academic Publishers.

The direct gas-phase synthesis of ammonia from nitrogen and hydrogen (the Haber process, 1908) is presently the cornerstone of the fertilizer industry ... 

A preparative solid- gas phase synthesis of acetyl hypofluorite (1, R = Me) has been described it is based on the reaction of dilute fluorine (with air or nitrogen) with a solid complex of potassium acetate with acetic acid and can be also modified7 -9 for the preparation of acetyl... 

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