FTIR Spectroscopy

An Analect RFX-65 spectrometer equipped with a liquid nitrogen-cooled mercury cadmium telluride (MCT) detector was used to obtain FTIR spectra of asphaltene and wax solutions. Cyclohexane was used to dissolve waxes (5-15g/L) and spectra were obtained in a KCl cell with a 0.25 mm spacer. Methylene chloride was used to dissolve asphaltenes (5-15g/L) and spectra were obtained in a CaF2 cell with a 0.2008 mm spacer.

Background spectra of pure cyclohexane or methylene chloride were integrated and subtracted from the sample spectra. Two hundred and fifty-six scans were taken of each sample recorded from 4000 to 400 cm-1 at a resolution of 4 cm-1. Peak positions and areas were determined using available software packages. Areas under absorption bands of interest were converted to functional group concentrations via Beer’s law.