Determination of functional groups in Mexican vacuum residua

The aim of this work is to determine the presence of carbonyl groups in the resin and asphaltene fractions of Mexican vacuum residua. It is known that these groups are disintegrated when the crude is subjected to high temperatures, so it is possible that the vacuum residua do not contain these groups anymore or may have fewer percentages of them. To carry out this determination, the residua were first fractionated into their four principal components - saturates, aromatics, resins, and asphaltenes - commonly known as SARA fractions. The technique used is this work is based on the standard method ASTM D4124-01 (2001), which has two different methods for the separation, the short and the large method; in the present work the short method was used. Furthermore, the fractions were analyzed using the Fourier-transform infrared (FTIR) spectroscopy technique to determine the different chemical compounds in each fraction. The results reveal the presence of the carbonyl groups in the resins and asphaltene fractions, as expected.