Fabrication of onion-like carbon from nanodiamond by annealing

Carbon Nano‐Onions: A Review of Recent Progress in Synthesis and Applications

“…Briefly, the graphitization process of NDs starts at 600 °C on the surface and progressively extends into the bulk of the particle . The transformation of sp 3 to sp 2 starts by amorphous carbon, which graphitizes at temperatures between 900 and 1,100 °C . The complete transformation of the diamond core occurs at temperatures above 1,600 °C.…”

“…[57] The transformation of sp 3 to sp 2 starts by amorphous carbon, which graphitizes at temperatures between 900 and 1,100°C. [58] The complete transformation of the diamond core occurs at temperatures above 1,600°C. This annealing leads to the formation of small spherical carbon particles.…”

Understanding structure and porosity of nanodiamond-derived carbon onions

“…At temperatures between 900 and 1100°C, this amorphous layer progressively graphitizes and continuing sp 3 -to-sp 2 transformation protrudes from the outside to the core of the particles [36]. Transmission electron microscopy (TEM) investigations have shown that smaller particles can be transformed to sp 2 -hybridized carbon more readily resulting in a possible coexistence of small carbon onions with larger, partially transformed nanodiamonds [15,37,38].…”

Chromatographic Reactors

“…According to Carvill et al [64], this cycle enables the production of CO from reverse water-gas shift with purities above 99 % (contrasting with the 22 % CO product obtained in a plug flow reactor packed only with catalyst). Other benefits of using this process are the decrease of the reaction temperature and the decrease of capital costs [56].…”

“…The four steps proposed are: sorption-reaction, depressurization, purge, and pressurization. The sorption-reaction Application Reference CO oxidation [46] Dehydrogenation of ethane to ethylene [47,48,50] Dehydrogenation of methylcyclohexane to toluene [48,49] Propene metathesis [51] Steam reforming of ethanol [52] Steam reforming of methane [53][54][55][56][57][58][59][60][61][62][63] Water-gas shift [64][65][66][67][68] and the depressurization steps are the same as in the five-step cycle. In the purge step, the novelty is the use of a mixture of 5-10 % of H 2 in the steam for desorbing the CO 2 (the vent stream, with high energetic value, can be reused as fuel).…”