New Pathways for Asphaltenes Upgrading Using the Oxy-Cracking Process

Solvent deasphalting of the bottom of vacuum distillation columns (vacuum residue, VR) is a process practiced worldwide. In Northern Alberta, a solvent deasphalting plant was designed to process up to 4000 tons/day of the asphaltenic pitch. Asphaltenes oxy-cracking in liquid phase could be a new approach to asphaltenes upgrading and conversion into valuable chemicals. Oxy-cracking is a combination of oxidation and cracking in basic aqueous media at moderate temperatures (170–225 °C) and pressures (300–500 psi). This process could act very selectively producing smaller amounts of greenhouse gases like CO₂, thus being considered environmentally friendly. In this work, a mild oxy-cracking treatment of C₅-asphaltenes solid from Athabasca vacuum residue was investigated. The reaction kinetics and possible reaction mechanism for C₅-asphaltenes oxy-cracking in water under alkali conditions were studied. Products solubilized under different severities were characterized using Fourier transform infrared and nuclear magnetic resonance spectroscopies, simulated distillation, elemental analysis, and ultraviolet–visible spectrophotometry to investigate the structure of solubilized products and changes in asphaltenes structures after the reaction. A model based on sequential-parallel reactions from the asphaltenes to water-soluble products and CO₂ was found to describe the process successfully. Products of oxidized functionalities like carboxylic acids, their salts, methyl ethers and esters, and sulfur-oxidized forms plus phenolics were determined as the most significant fractions soluble in water. Solubilization of asphaltenes in water could also decrease challenges regarding facilities and pipelines plugging.