Evolution of carbon structures in the pyrolysis of petroleum pitches
Okyay, Firuze (2009) Evolution of carbon structures in the pyrolysis of petroleum pitches. [Thesis]
Official URL: http://192.168.1.20/record=b1293621 (Table of Contents)
The present study focuses on the carbon structure analysis of hydrographene like materials produced during the pyrolysis of petroleum pitches under various experiment conditions and non-isothermal kinetics of pyrolysis of petroleum pitches. Non-isothermal kinetic studies of pyrolysis of the pitches based on the TGA measurements at different heating rates resulted that the average activation energy of the pyrolysis of pitch B (213.2 kJ/mol) was higher than that of the average activation energy of pitch A (185.7 kJ/mol) whereas the reaction orders of pitches A and B were 1.3 and 0.91, respectively. Experiments were carried out under an argon atmosphere at the temperature range of 500-1000±C for 30, 60 and 120 minutes in a tube furnace. FTIR, H-NMR, and C-NMR results showed that the aromatic structure of the hydrographenes were increasing with respect to increasing temperature as well as increasing time. Raman spectra results demonstrated the increase in orderness with increasing ID/IG ratio from 0.65 to 0.92 when the temperature of pitch A pyrolysis was increased from 500°C[degrees Celsius] to 900°C[degrees Celsius]. XRD patterns of the hydrographenes showed the crystallinity increased with increasing time and temperature. The calculated average numbers of graphene layers were 5 to 10 with respect to XRD patterns. The SEM images visualized the amorphous structure of hydrographenes that was highly rich in turbostratic structures. All the results of characterizations were consistent indicating the formation of highly amorphous hydrocarbon materials that contain turbostratic structures and higher heat treatments formations of aromatic structure with an increasing crystallinity and orderness. Highly amorphous hydrocarbon materials containing turbostratic structures were produced by two different types of pitches. Temperature seemed to be the dominating parameter of the pyrolysis reactions. As the pyrolysis temperature was increased aromatic structure formation was favored with an increasing crystallinity and orderness in the hydrographene materials.
Repository Staff Only: item control page