Processing of Solubilized Asphaltene in Aqueous Media

Abstract

The continuous increase of asphaltene production coupled with inefficiencies of conventional asphaltene utilization methods reveals the vital necessity of oil downstream sector to develop new technologies for asphaltene processing. In this research, a novel two-step process for asphaltene conversion in aqueous media is introduced. Through this process, asphaltenes are first solubilized in water via low-temperature oxidation; then, solubilized organic materials are converted to value added product through catalytic reaction. The main focus of this research is studying and understanding the second step of the process. In this regard, the solubilized asphaltene in water (SAW) which is the feedstock of the second reaction was produced in large scale through asphaltene oxidation in aqueous phase. After preparation and characterization of SAW, the impact of effective parameters and operational conditions on progress of SAW catalytic reaction was investigated. The catalytic activity in SAW reaction media was evaluated under two different atmospheres, i.e., in presence and absence of external hydrogen gas. The sulfided NiMo/γ-Al2O3 catalyst showed the best activity among the heterogeneous catalysts tested for SAW reaction with external hydrogen. On the other hand, the reduced form of Cu-Ce/MFI and Cu-MFI catalysts provided the best performance for SAW reaction in absence of external hydrogen. The kinetic study of SAW hydroprocessing was carried out, where the promotional effect of temperature on products yield and quality was observed. A lumped kinetic model containing 6 first order reactions was proposed, which accurately predicted the experimental results; the activation energy of SAW conversion was calculated to be 83 kJ/mol, which is a typical activation energy of biomass crudes reaction in water at sub-cooled conditions. Decarboxylation was a dominant reaction through SAW hydroprocessing, while hydrodeoxygenation, cracking and hydrogenation occurred in parallel.