Study on supercritical water behavior of bitumen

Bitumens were mainly obtained as a residue of the petroleum refining process and generally they are used for paving roads, roofing, coating, insulation, etc. In fact, bitumens are of great importance to the chemical industry because of their great variety of special properties, which has favored the development of a wide field of applications. They can be considered as colloidal systems in which micelles of high-molecular-weight organic molecules (asphaltenes) are dispersed in an oily phase (maltenes) consisting of low-molecular-weight saturated and aromatic hydrocarbons together with resins. The development of process has been proposed to recover chemical resources from bitumens that can accomplish the destruction of the bitumens into harmless to produce useful compounds. It was well known that water at hydrothermal condition is considered a promising and an environmentally acceptable solvent for a wide variety of chemical reactions such as organic syntheses and decomposition of hazardous waste into harmless compounds. In these works, water at supercritical conditions was applied as a solvent for degradation of swelled biomass resources and solid waste polymers or upgrading of bitumen without catalyst. The experiments were conducted using a batch-type reactor at temperature of 673 K. The chemical species in the aqueous products were analyzed by gas chromatography mass spectrometry and gas chromatography flame ionization detector. The effect of pressure and reaction time on the decomposition process was presented. Ultimate analysis of solid residue was also conducted using a CHN analyzer. Moreover, this method could become an efficient method for upgrading bitumen into harmless and high yield of valuable chemical intermediates on the basis of the experimental results.