Structural Characterization of Large Polycyclic Aromatic Hydrocarbons. Part 1: The Case of Coal Tar Pitch and Naphthalene-Derived Pitch

Abstract

The different thermal behaviors and solubilities of large and structurally different polycyclic aromatic hydrocarbon (PAH) mixtures featuring coal tar pitch (CP) and naphthalene synthetic pitch (NP) samples could be read in light of their different molecular weight (MW) distribution and spectroscopic features. The number-average MW obtained by mass spectrometry for CP (417 Da) and NP (691 Da) resulted to be lower in comparison to the values evaluated by size-exclusion chromatography (SEC) (796 and 824 Da for CP and NP, respectively) because of the different response of the detector of mass spectrometry to low-and high-MW components. Hence, SEC showed to be more suitable for the analysis of PAH mixtures overlapping and covering a higher mass range in comparison to mass spectrometry. Insights into structural PAH features were given by means of spectroscopic analysis [infrared (IR), ultraviolet−visible (UV−vis), and fluorescence], allowing for the discrimination between different families of PAHs as ortho-fused PAHs and rylenes interspersed with aliphatic (mainly naphthenic) groups, mainly featuring CP and NP, respectively. Besides showing the different aromaticity and aliphatic/aromatic hydrogen distribution, the improvement of Fourier transform infrared (FTIR) and UV−vis absorption analysis put also in evidence the contribution of carbon-rich particle impurities and PAH aggregates in CP and NP, respectively.

Assessing the Potential of Biochars Prepared by Steam-Assisted Slow Pyrolysis for CO2 Adsorption and Separation

“…The intensity of the three peaks is almost the same, indicating a high substitution degree in the aromatic network of this sample. 30 , 31 …”

Ambient aerosol composition by infrared spectroscopy and partial least squares in the chemical speciation network: Multilevel modeling for elemental carbon

“…Symmetric CH 2 stretches in normal and branched alkanes are usually confined to a fairly narrow wavenumber range at 2850 § 10 cm ¡1 , this being 10-20 cm ¡1 higher than the wavenumbers used in the calibration (Mayo 2004a). Interestingly, CH 2 symmetric stretching at 2830 cm ¡1 has been assigned to saturated fiveand six-member ring species (e.g., 1,2,3,4-tetrahydronapthelene) in combustion soot and condensed polycyclic aromatics rich in naphthalenic moieties (Russo et al 2014;Gargiulo et al 2015). Alternatively, a C-H stretch associated with amines may be assigned to 2830 cm ¡1 with frequency lowering attributed to the Bohlmann effect .…”

Fabrication and characterization of carbon nanofibers from polyacrylonitrile/pitch blends

“…In order to have a better understanding of rheology behavior of the blends, miscibility property will be investigated using differential scanning calorimeter (DSC) and Fourier transform infrared spectroscope (FTIR). Miscibility behavior of pitch and polymer blends is a delicate issue because of the complex chemistry of pitch material . Pitch such as A240 is a reactive and isotropic pitch material with partial solubility in N , N ‐dimethylformamide (DMF).…”