Formation mechanism of carbon

W.M. Pitts, The global equivalence ratio concept and the formation mechanisms of carbon monoxide in enclosure fires, Progress in Energy and Combustion Science, 21, 197-268, 1995. 

As to the formation mechanism of carbon black, there are indications that the carbon particles are formed by recombination of smaller hydrocarbons (acetylene, ethylene and their radicals as well as aromatic cracking products). 

Pitts, W.M. (1995) Gobal Equivalence Ratio Concept and the Formation Mechanism of Carbon Monoxide in Exclosure Fires. Prog. Energy Combust. ScL. 21,197-237. 

The activity of catalyst will gradually decline during application, and one of the reasons is the aggradation of carbon on catalyst surface. TPO technology is an effective way to study the formation mechanism of carbon deposition. For example, TPO is used to study Pt/Al203 catalyst for the mechanism of carbon deposition. TPO shows two peaks after the carbon deposition on surface of Pt/A Os, that is, Toi 440°C, To2 530°C. After the catalyst was deposited with carbon, it was partially oxidized (that is, the oxidation of deposition carbon of the first peak at 440°C), where the adsorption amount of H2 almost equals the fresh catalyst, and the activity of the catalyst is almost recovered. This proves that the carbon deposition takes place on surface of Pt metal, from which it can be inferred that the oxidation peak at high temperatures corresponds to the oxidation of carbon deposited on support. 

Kusunoki, M. et al., A formation mechanism of carbon nanotube films on SiC(OOOl). Applied Physics Letters, 2000. 77(4) 531-533. 

G. A. White We have done some experimental work on impregnating catalyst with potash, and, in fact, potash has been used in related fields to inhibit carbon formation primarily from hydrocarbons. We find that the mechanism of carbon formation from hydrocarbons is quite different from that from syngas. So an agent that is effective in reducing the formation of carbon from one source can be quite different with that from another source. You have to be a little bit specific in terms of the feed material from which you are trying to prevent carbon formation. 

The mechanism of carbon dioxide reduction in aqueous and nonaqueous solutions was investigated by several authors. It is now generally accepted that the reduction of carbon dioxide to formate ions is a multistep reaction with the intermediate formation of free radicals CO2 and HCO2 either in the solution or adsorbed on the electrode ... 

Mechanism of carbon monoxide formation under the conditions of smelting reduction... 

As mentioned above, the formation of peroxynitrite might be measured by luminol-amplified CL [67]. CL response was greatly augmented by bicarbonate and inhibited by SOD. Radi et al. [67] proposed the following mechanism of carbonate-enhanced luminol CL stimulated by peroxynitrite ... 

To further explore possible mechanisms of carbon-carbon bond formation, we have examined the reaction of Cp2Fe2(C0K with LiAlHi, (LAH). This reaction yields hydrocarbon products up to butane.— The results of this study are reported herein. 

Fig. 3.3. Possible mechanisms of carbon-metal double-bond formation by a-abstraction.

The mechanism of carbon tetrachloride hepatotoxicity generally is viewed as an example of lethal cleavage, where the CCh— Cl bond is split in the mixed-function oxidase system of the hepatocytes. After this cleavage damage may occur directly from the free radicals (-CCl and -Cl) and/or from the formation of toxic metabolites such as phosgene." ... 

The trimethyloxonium cation was proposed to be an intermediate in one of the proposed mechanisms of carbon-carbon bond formation in MTG chemistry on HZSM-5 (Scheme 2) (142). Chang and co-workers demonstrated that this cation could be ion exchanged into HZSM-5 from cold aqueous (CH3)30+BF4 (143). Munson and Haw (144) demonstrated that... 

In a study conducted by the Armour Research Foundation (Ref 41) a-Pb azide crystals wrapped in a thin A1 foil were subjected to fast and thermal neutrons in the heavy water pile at Argonne National Laboratory. With a thermal flux rate of about 10l4n/cm2/sec the crystals were irradiated for 8, 17 and 170 hours. The crystals decompd to a brown powder which was identified as Pb carbonate by X-ray techniques and infrared absorption spectra. From a mass spectrographic analysis of the isotopes of carbon and oxygen in the decompn products, it was determined that the mechanism of carbonate formation is a reaction with the atmosphere by broken surface bands produced by the neutrons. Subsequently, Raney (Ref 60) reported... 

One of the major problems in C02 reforming is the formation of carbon deposits [2, 3], In the C02 reforming reaction, the possible routes of carbon formation include methane decomposition (Equation 9.6) and/or CO disproportionation (Equation 9.7). The clarification of this issue is necessary because it will help to understand the mechanism of carbon formation in this reforming reaction. Such insight will also be beneficial not only for the design of reactors but also for the... 

Carbon-, nitrogen-, and sulfur-containing species account for most of the mass of aerosol particles. In spite of years of effort by many investigators, the exact chemical forms of carbon, sulfur, and nitrogen in these particles are not known nor are the formation mechanisms of these species known with certainty. There are many reasons for this situation, including the complexity of the system and the dependence of the apparent chemical composition on the analytical methods used. For example, wet chemical analyses of sulfur and nitrogen species report only ions in solution. These ions, however, may be originally water soluble (e.g., sulfate and ammonium from ammonium sulfate), or they may be ionic products of hydrolyzable species such as amides (1). Of course, insoluble species will not be detected by wet chemical techniques. 

The methods of synthesis of fluorapatite have been widely dis cussed (J ). It is for example possible to obtain fluorapatite by substituting the hydroxyl ion for the fluoride ion, either in a-queous solution at room temperature, or through a solid state reaction at 800°C. It can also be prepared by the action of 6-tricalcium phosphate on calcium fluoride at about 800°C. Its solubility and thermal stability have already been established. While much is known about fluorapatite, many questions still exist concerning the mechanism of their formation, their composition and the structure of some of them. Two of these problems are dealt with here. First, we discuss the formation mechanism of fluorapatite by a solid state reaction between calcium fluoride and apa-titic tricalcium phosphate. Then we present the preparation and the structure of a carbonated apatite rich in fluoride ions. 

Needless to say that a deep understanding of both the formation mechanism of the SEI layer and the underlaying question of carbon s surface chemistry in a particular electrolyte solution is of utmost importance for battery developers. Clearly, the surface chemistry of graphite electrodes plays a key role in their performance.259 312 325 343-352 A lot of work was devoted to decipher this very complicated surface chemistry. It is therefore not surprising that the advancement in the understanding of surface chemistry of carbon electrodes in nonaqueous electrolytes correlates well with the worldwide production rate of lithium-ion batteries. 

The study of carbon electrodeposition from carbonate and halide- carbonate melts was devoted a cycle of works [1 - 6]. It was found that under certain conditions carbon solid phase was formed on cathode with 100 % current yield. The questions of product morphology, structure and dispersity had remained not opened because of absence at that time analysis technical equipment with high-resolution. Different schools of the electrochemists offered various mechanisms of carbon phase formation ... 

Animal and bacterial enzymes that utilize or synthesize carbamyl phosphate have activity with acetyl phosphate. Acyl phosphatase hydrolyzes both substrates, and maybe involved in the specific dynamic action of proteins. Ornithine and aspartic transcarbamylases also synthesize acetylornithine and acetyl aspartate. Finally, bacterial carbamate kinase and animal carbamyl phosphate synthetase utilize acetyl phosphate as well as carbamyl phosphate in the synthesis of adenosine triphosphate. The synthesis of acetyl phosphate and of formyl phosphate by carbamyl phosphate synthetases is described. The mechanism of carbon dioxide activation by animal carbamyl phosphate synthetase is reviewed on the basis of the findings concerning acetate and formate activation. 

In the discussion of the subject Balandin mentions (15) that Fischer previously postulated that methylene radicals may be produced as an intermediate in the formation of hydrocarbons by his method (116). This mechanism of carbon deposition on platinum supported on oxides of nickel and chromium (oxidized nichrome) through the intermediate formation of methylenes was thought by Balandin to be similar to the mechanism of dehydrogenation over this type of catalyst in that both occur on the boundaries of platinum-nickel and of platinum-chromia and were brought in agreement by him with his multiplet theory (26). 

Mechanism of Carbon-Black Formation in Relation to Compounded-Rubber Properties... 

Mechanism is generally employed as a word to describe the individual rearrangement of atoms as molecules react to form new compounds and products. The mechanism of carbon black formation is used in this context as it appears in the title of this presentation. 

Progress is achieved through change which is understood. So, in this instance, scientific knowledge must surpass the art, and a knowledge of the Mechanism of Carbon Black Formation in Relation to Compounded Rubber Properties prevails. 

The Mechanism of Carbon Black Formation and the Manufacturing Process... 

There are a great many published reports describing studies of carbon black formation in flames. Many of these deal with gaseous fuels in either pre-mixed flames or diffusion flames. The principal objectives are to develop a better knowledge of combustion through an understanding of the kinetics and mechanism of carbon formation,... 

A thorough familiarity of these works and the theories presented is essential for effective studies of the mechanism of carbon black formation however, a review of these works here is well beyond the scope of this paper. A number of extensive review articles and books are recommended (2, 1 >, L7, Z5, M, 12, 13, 42) <... 

---