Turbostratic carbons

The composition varies with the heat treatment and the end point according to x-ray diffraction studies it is a form of carbon that reconverts to weU-ordered graphite on heating to 1800°C. Before the use of x-rays, chemists used the Brodie reaction to differentiate between graphitic carbons and turbostratic carbons. Turbostratic carbons yield a brown solution of humic acids, whereas further oxidation of graphite oxide produces mellitic acid (benzenehexacarboxyhc acid) [517-60-2] ... 

A method for physically separating turbostratic carbon and graphite involves shaking a sample into suspension in ethylene bromide of sp gr 2.17 and centrifliging. The method is unreflable except where fine carbon and coarse graphite are admixed it can be an aid in quaUtative examination. 

Figure 1. Oxygen-containing groups on turbostratic carbon plane edges (modified...

Polished and depolished, inert (turbostratic carbon, glass and silica) and metallic ((200) oriented copper polycrystals, and Ni-25 at.%... 

Not only are the layer planes small and defective, they are also stacked with twists and tilts between them. This twisting of the layers with respect to each other gives rise to the term turbostratic carbon for these materials. The turbostratic, well-oriented, substrate-nucleated pyrocarbons are ideal candidates for graphitization, and the highly oriented pyrolytic graphite (HOPG) used for X-ray and neutron monochromators is produced from these precursors. ... 

Charlier et al. [48] used the tight-binding model to study distorted stacking of graphene layers, termed pregraphitic or turbostratic carbon. The turbostratic structure was obtained by generating an amorphous cluster of graphene plates that... 

Reaction temperatures of 250-400 °C are usually taken for oxidation with dioxygen or air. Significant quantities of surface oxides ofmosdy acidic character are produced in a few hours. The required temperatures are the lower, the smaller the particle size of the carbon is. Clean surfaces of turbostratic carbons of high surface area such as activated carbons and carbon blacks will also be oxidized at room temperature. When the carbons are freed from surface complexes by heating to 900-1000 °C in vacuo or under an inert gas, they will adsorb some... 

New methods for improving the sustainability of the methane thermocatalytic decomposition process have been developed. Studies indicate that the presence of small amounts of moisture and H2S (<3 v.%) in the hydrocarbon feedstock is not detrimental for the catalyst activity and process efficiency. This implies that commercial hydrocarbon fuels could potentially be employed as feedstocks for the process. A bench-scale thermocatalytic reactor was designed, fabricated and operated using methane and propane as feedstocks. The TCR produced hydrogen-rich gas free of CO/CO2 impurities the gas was directly fed to PEM fuel cell. Material characterization studies indicated that depending on operational conditions, carbon could be produced in several valuable forms including turbostratic carbon, pyrolytic graphite, spherical carbon particles, or filamentous carbon. 

As mentioned previously, carbon blacks can be produced with a carbon source by either its incomplete combustion with a limited amount of oxygen or its thermal decomposition in the absence of oxygen [14]. Furnace blacks are typically produced by burning natural gas and liquid aromatics in a furnace with a limited and controlled amount of oxygen at about 1673 K. The ensuing cracking and polymerization of hydrocarbons followed by their dehydrogenation lead to the formation of turbostratic carbon particles. Immediately after the reaction zone, the carbon black is quenched to 473 to 523 K with a water spray to impede... 

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