A comparative study of fixed-bed and dispersed catalytic upgrading of heavy crude oil using-CAPRI

CAtalytic upgrading PRocess In-situ (CAPRI) incorporated with Toe-to-Heel Air Injection (THAI) for heavy oil and bitumen recovery and upgrading was studied for fixed-bed and dispersed catalysts. The extent of upgrading was evaluated in terms of API gravity, viscosity reduction, impurity removal, and true boiling point (TBP) distribution. The test was carried out using Co-Mo/Al2O3 at temperature of 425 °C, pressure 20 bar, and residence time of 10 min. The dispersed catalyst was tested in a batch reactor. However, the residence time, catalyst-to-oil (CTO) ratios as well as the Reynolds numbers of both contacting patterns were kept the same to ensure dynamic similitude. It was found that the produced oil from dispersed ultrafine Co-Mo/Al2O3 catalyst (dp = 2.6 μm) exhibited superior light oil characteristics and quality than that produced with the fixed-bed of pelleted Co-Mo/Al2O3 (1.2 mm diameter × 2–5 mm length). The API gravity of the feed oil was 13.8° and the produced oil showed an increase of 5.6° in the fixed bed and 8.7° with the dispersed catalyst. Unlike the fixed-bed of pelleted Co-Mo/Al2O3 which may suffer from diffusion limitations, rapid deactivation, and channelling effect, the ultrafine particles presented high surface area to volume ratio, reducing the chances of pore plugging, have more accessible reaction sites per unit mass, and lead to enhanced cracking of macromolecules. Moreover, the reduction of sulphur of 38.6% and (Ni + V) content of 85.2% in the produced oil show greater heteroatom removal compared to 29% (sulphur) and 45.6% (Ni + V) observed in the product from the fixed-bed.