Graphitic dehydrogenation reactions

This mechanism involves the formation of ring-ring aromatics, interconnected by aliphatic chains, which after successive dehydrogenation reactions progressively organize ordered graphite structures. Vlasov and Warnatz (2002) propose a competitive role for the polyyne molecules as important soot precursors. The polyyne pathway is derived from the works of Krestinin (2000) and assumes that these species grow rapidly with successive additions of C2H radicals... 

Further dehydrogenation reactions, amorphous carbon and graphitization,... 

Steinfeldt et al. used microchannel reactors to compare the gas-phase oxidative dehydrogenation reaction of propane to propene (C3H6) [17]. The microchannels were made of SS and titanium plates that were stacked tightly together in a graphite housing that provided the inlet and the outlet ports for the reactants and products. 

Coking on the metal is proposed to occur through a series of fragmentation and dehydrogenation reactions, and the products of these reactions combine to form graphitic coke (19). An additional suggested mechanism is polymerization of adsorbed carbonaceous deposits on the metal surface (18,19). 

Besides ODH processes, a few reports about non-oxidative dehydrogenation (DH) over carbon catalysts also exist. At the reaction temperature of 823-873 K, propane is reported to react to propylene and hydrogen in high yield (30-40 %) over ordered mesoporous carbon, which was shown to be much more active than graphitic and/or nanostructured carbon (CNTs) [66], On the other hand, a hybrid catalyst system for... 

In a comparative study carbon nanofilaments showed higher activity than soot and graphite in the formation of styrene in oxidative dehydrogenation.382 In addition, activity increased with time, indicating stability toward burning. Strongly basic, possibly quinoidic, surface sites were identified after the catalytic reaction. 

Carbon black is formed by pyrolysis of hydrocarbons. The process of carbon formation is complex, involving cracking, dehydrogenation and subsequent accretion into large molecular species. It is probable that there is a stage in the reaction sequence at which liquid droplets are formed, which then undergo partial graphitization with additional... 

In this experiment the metal-free carbon nanotubes acted directly as a support and active phase for the liquid-phase ODH of dihydroanthracene to anthracene at low temperature. The results are compared with those obtained on other catalysts. Oxidative dehydrogenation of dihydroanthracene in the liquid-phase was carried out over different CNT-based materials. The results are presented in Table 7.3. The test was also performed on an exfoliated graphite material for comparison. The results clearly showed that the reaction was chemically selective whatever... 

In the combustion of methane, oxidation is accompanied by a thermal decomposition. Reactions of hydrocarbon radicals lead to unsaturated compounds such as gaseous olefins and acetylene which are then cyclized into condensed aromatic hydrocarbons. The aromatic compounds are subjected to further dehydrogenation in the reaction zone to produce carbon particles. This carbon black is a random aggregate of crystalline graphite embedded at a certain proportion in an amorphous matrix. Some hydrogen is always present in this carbon deposit. 

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