Chemical carbide synthesis

Unfortunately in real situation the reactions are not carried to completion. This is why one has to solve the problem of chemical reactivity before determining the appropriate quenching rate. These remarks also apply to carbide synthesis. 

Xiang, J. Y, Liu, S. C., Hu, W. T., Zhang, Y, Chen, C. K., Wang, P. et al. (2011). Mechano-chemically activated synthesis of zirconium carbide nano-particles at room temperature A simple route to prepare nano-particles of transition metal... 

Historically, the use of acetylene as raw material for chemical synthesis has depended strongly upon the avadabihty of alternative raw materials. The United States, which until recendy appeared to have limitless stocks of hydrocarbon feeds, has never depended upon acetylene to the same extent as Germany, which had more limited access to hydrocarbons (1). During Wodd War 1 the first manufacture of a synthetic mbber was undertaken ia Germany to replace imported natural mbber, which was no longer accessible. Acetylene derived from calcium carbide was used for preparation of... 

Calcium carbide has been used in steel production to lower sulfur emissions when coke with high sulfur content is used. The principal use of carbide remains hydrolysis for acetylene (C2H2) production. Acetylene is widely used as a welding gas, and is also a versatile intermediate for the synthesis of many organic chemicals. Approximately 450,000 t of acetylene were used aimuaHy in the early 1960s for the production of such chemicals as acrylonitrile, acrylates, chlorinated solvents, chloroprene, vinyl acetate, and vinyl chloride. Since then, petroleum-derived olefins have replaced acetylene in these uses. 

Dkect synthesis is the preparative method that ultimately accounts for most of the commercial siUcon hydride production. This is the synthesis of halosilanes by the dkect reaction of a halogen or haUde with siUcon metal, siUcon dioxide, siUcon carbide, or metal sihcide without an intervening chemical step or reagent. Trichlorosilane is produced by the reaction of hydrogen chloride and siUcon, ferrosiUcon, or calcium sihcide with or without a copper catalyst (82,83). Standard purity is produced in a static bed at 400—900°C. 

There are two main processes for the synthesis of ethyl alcohol from ethylene. The eadiest to be developed (in 1930 by Union Carbide Corp.) was the indirect hydration process, variously called the strong sulfuric acid—ethylene process, the ethyl sulfate process, the esterification—hydrolysis process, or the sulfation—hydrolysis process. This process is stiU in use in Russia. The other synthesis process, designed to eliminate the use of sulfuric acid and which, since the early 1970s, has completely supplanted the old sulfuric acid process in the United States, is the direct hydration process. This process, the catalytic vapor-phase hydration of ethylene, is now practiced by only three U.S. companies Union Carbide Corp. (UCC), Quantum Chemical Corp., and Eastman Chemical Co. (a Division of Eastman Kodak Co.). UCC imports cmde industrial ethanol, CIE, from SADAF (the joint venture of SABIC and Pecten [Shell]) in Saudi Arabia, and refines it to industrial grade. 

Industrial use of HCl gas for the manufacture of inorganic chemicals includes the preparation of anhydrous NH4CI by direct reaction with NH3 and the synthesis of anhydrous metal chlorides by reaction with appropriate carbides, nitrides, oxides or even the free metals themselves, e,g, ... 

According to Ref. [12], template for synthesis of nanomaterials is defined as a central structure within which a network forms in such a way that removal of this template creates a filled cavity with morphological or stereochemical features related to those of the template. The template synthesis was applied for preparation of various nanostructures inside different three-dimensional nanoporous structures. Chemically, these materials are presented by polymers, metals, oxides, carbides and other substances. Synthetic methods include electrochemical deposition, electroless deposition, chemical polymerization, sol-gel deposition and chemical vapor deposition. These works were reviewed in Refs. [12,20]. An essential feature of this... 

With reference to the homogeneous catalyst systems thus far reported for the synthesis of hydrocarbons/chemicals from carbon monoxide and hydrogen, only the anionic rhodium systems of Union Carbide show any appreciable shift activity. With neutral species of the type M3(CO)12 (M = Ru or Os), only small quantities of carbon dioxide are produced under the synthesis conditions (57). 

Carbenium ions, 42 115, 143 acid catalysis, 41 336 chemical shift tensors, 42 124-125 fragments in zeolites, 42 92-93 history, 42 116 superacids, 42 117 Carbide catalysts, 34 37 Carbidic carbon, 37 138, 146-147 Carbidic intermediates, 30 189-190, 194 Fischer-Tropsch synthesis, 30 196-197, 206-212... 

Figure 3.35 Classification of chemical vapor infiltration processes. From Carbide, Nitride, and Boride Materials Synthesis and Processing, A. W. Weimer, ed. p. 563. Copyright 1997 by Chapman Hall, London, UK, with kind permission of Kluwer Academic Publishers.

Catalyst preparation is crucial in successful Fischer-Tropsch synthesis. Appropriate catalyst composition and delicate pretreatment and operating conditions are all necessary preconditions to achieve the desired results. Catalyst disintegration brought about by oxidation and carbide formation is a serious problem that can be prevented only by using catalysts with adequate chemical and mechanical stability under appropriate operating conditions. 

Wohler was also a co-discoverer of beryllium and silicon, as well as the synthesis of calcium carbide, among others. In 1834, WOhler and Liebig published an investigation of the oil of bitter almonds. They proved by their experiments that a group of carbon, hydrogen, and oxygen atoms can behave like an element, take the place of an element, and can be exchanged for elements in chemical compounds. Thus the foundation was laid of the doctrine of compound radicals, a doctrine which had a profound influence on the development of chemistry. 

The purpose of this chapter is to present systematic experimental procedures to deposit thin films of carbides and nitrides. Strong relationships between synthesis methods and conditions, and product structures, crystallinity, purity and phase were observed. Thin films of W, Cr, and Mo carbides and nitrides were synthesized in two different ways (1) chemical... 

An investigation of bulk (a-WC, a-W2C) and supported tungsten carbide was carried out using the formation of alcohols in Fischer-Tropsch synthesis as a chemical probe. The active phases were characterized by X-ray photoelectron spectroscopy. 

---