Pyrolysis applied to the study of a Maya asphaltene

Abstract Asphaltene pyrolysis has been used to investigate the structure of a Maya asphaltene sample. A new device has been constructed to carry out out-line pyrolysis, and all pyrolysis products have been detected. As a result of the thermal decomposition of Maya asphaltene under an inert nitrogen atmosphere at 350, 400 and 450 °C, the coke, asphaltene and maltene groups of compounds have been obtained and analyzed quantitatively. The maltene group of asphaltene pyrolysis products has been separated by high performance liquid chromatography into the saturated, aromatics and polar compounds. The fractions of saturated and aromatics have been analyzed in detail by gas chromatography and mass spectrometry. The polar fraction has been studied by field desorption mass spectrometry and infrared spectroscopy. The preliminary study of asphaltene by thermogravimetric analysis (TGA) and differential thermal analyses (DTA) reflects the changes of the weight percent of solids. The saturated fraction pyrolysis products of the Maya asphaltene consist of paraffins (C 7 –C 20 ) and cyclo-paraffins (from mono- to hexacyclo-). The aromatic fraction includes from mono- to pentaaromatic and thiophenearomatic compounds. The polar fraction includes esters, ketons, amides, acids and alcohols.