Jellyfish-like few-layer graphene nanoflakes: high paramagnetic response alongside increased interlayer interaction

Jellyfish-like graphene nanoflakes (GNF), prepared by hydrocarbon pyrolysis, are studied with electron paramagnetic resonance (EPR) method. The results are supported by X-ray photoelectron spectroscopy (XPS) data. Oxidized (GNFox) and N-doped oxidized (N-GNFox) flakes exhibit an extremely high EPR response associated with a large interlayer interaction which is caused by the structure of nanoflakes and layer edges reached by oxygen. The GNFox and N-GNFox provide the localized and mobile paramagnetic centers which are silent in the pristine (GNF p ) and N-doped (N-GNF) samples. The change in the relative intensity of the line corresponding to delocalized electrons is parallel with the number of radicals in the quaternary N-group. The environment of localized and mobile electrons is different. The results can be important in GNF synthesis and for explanation of their features in applications, especially, in devices with high sensitivity to weak electromagnetic field.

ISOLATION OF 1,3-BUTADIENE FROM THE BUTYLENE DIVINYL FRACTION OF HYDROCARBON PYROLYSIS

Disclosed is a variant of qualified use of butylene divinyl fraction

Unsteady-State Mathematical Modeling of Hydrocarbon Feedstock Pyrolysis

Hydrocarbon feedstock pyrolysis is an important method for obtaining monomers that are then used to produce various polymer materials. During this process, a mixture of hydrocarbons is heated at a high temperature and in the absence of oxygen. Because of the side reactions of polymerization and polycondensation, coke products are formed and settle on the inner walls of the coil. This decreases the technical efficiency of the hydrocarbon pyrolysis furnace during its operation, making the process unsteady. In the present research, we developed an unsteady-state mathematical model of hydrocarbon feedstock pyrolysis in order to improve the monitoring, forecasting, and optimization of this technological process. This model can calculate the rate of coke deposition along the length of the coil, considering the technological parameters and the composition of the supplied raw materials (the calculated value of coke deposition rate equals 0.01 mm/day). It was shown that with an increase in the propane/butane ratio from 4/1 to 1/4 mol/mol, the ethylene concentration decreases from 3.45 mol/L to 3.35 mol/L.

THE PYROCARBON FORMATION MECHANISM DURING THE HYDROCARBON PYROLYSIS PROCESS

Experimental results confirming the mechanism of pyrocarbon formation through the steps of high-molecular pyrolysis products forming in the gas phase are presented. Adsorption of high-molecular pyrolysis products on the active centers of the substrate localized at the boundaries of the contacts of its crystallites and their subsequent carbonization is confirmed. The decreasing in the length of the substrate crystallites contact boundaries leads to the increase in the content of high-molecular compounds in the gas and to the decrease in the hydrogen concentration is shown. The relation between the composition of the exhaust gas and the surface of the sealing material creates the prerequisites for controlling the pyro-consolidation process according the composition of the off-gas. The composition of high-molecular liquid pyrolysis products was identified. The difference in the composition of high-molecular pyrolysis products of the propane-butane fraction and the electric cracking gas was established. The influence of raw materials and pyrolysis conditions on the group composition of high-molecular pyrolysis products formed is shown.