Reaction of Phosphoric Acid with Thermal Residues and Bitumens

The purpose of the work was to study the effect of the addition of small quantities of phosphoric acid (or P2O5), on the physical and chemical behaviour of petroleum residues and bitumens. Phosphoric acid (and P2O5) reacts only with thermal products such as visbreaker (VB) residues and bitumens, and do not react with straight run (SR) products. The unstable constituents of VB residues, i.e. carbonaceous material and part of the asphaltenes, contain significant amounts of free radicals which easily share electrons with phosphorous. The resulting condensed particles are higher molecular wighht, polar material no longher soluble in the bitumen, and flocculate. This reaction confirms the presence of stable free radicals in thermal bitumens and residues, suggests a way to neutralize their destabilizing effect.