Infrared spectroscopy of some carbon-based materials relevant in combustion: Qualitative and quantitative analysis of hydrogen

A detailed procedure for the quantitative analysis of aromatic and aliphatic hydrogen based on infrared spectroscopy was set up and implemented on some carbon-based materials produced from organic precursors (naphthalene pitch) and/or relevant in combustion field (asphaltenes, carbon particulate matter, carbon black), spanning in the H/C atomic ratio range from 0.1 to 1. The quantitative FT-IR analysis involved the spectral deconvolution in the CH vibrations regions and the calibration factors of diverse standard species having spectral characteristics suitable for the detailed peak-to-peak analysis of the CH stretching (3100–2800 cm⁻¹) and aromatic CH bending (900–700 cm⁻¹) regions. The good agreement between the H/C atomic ratio obtained by quantitative FT-IR analysis and elemental analysis showed a reasonable reliability of the procedure. The major value of the developed FT-IR quantitative technique relies also on the capacity of discriminating between the different kinds of aliphatic and aromatic hydrogen. The quantitative and detailed analysis of hydrogen in form of CH₃, CH₂ and CH groups and in form of solo, duo and trio/quatro aromatic hydrogens showed to be useful also for inferring the structure of the aromatic moieties constituting the CC backbone of carbon materials.