Vibrational spectroscopy for pitch characterization

Vibrational spectroscopy is the collective term used to indicate two analytical techniques. i.e. infrared (IR) and Raman spectroscopy. IR and Raman spectroscopy measure vibrational energy levels which are associated with the chemical bonds in the sample. Regarding sp2-rich carbons while Raman spectroscopy can provide information on the aromatic carbon network constituting the specimen [1], IR spectroscopy is useful to characterize the remaining part mainly constituted of sp3 carbons, heteroatoms and hydrogen functionalities. In this paper the two techniques have been coupled to fully characterize the molecular structure of solid petroleum and coal tar pitch samples with different softening points (RÜTGERS Basic Aromatics GmbH Castrop-Rauxel, Germany). The quantitative FTIR method set up and applied in previous work [2,3] was applied to determine the aliphatic and aromatic hydrogen content of pitch. FTIR analysis has also been used to evaluate sp2-bonded carbon through the quantification of aromatic hydrogen (SOLO; DUO; TRIO e QUATRO) and aliphatic hydrogen in the CH, CH2, and CH3 forms. Through a careful deconvolution procedure Raman spectroscopy was used to derive the mean cluster size of the aromatic moieties.