Abstract
Catalyst deactivation due to coke and metals deposition as a result of cracking presents a challenge in heavy oil recovery and upgrading. This is particularly pronounced for in situ upgrading techniques, in which pelleted catalyst is packed around the perimeter of the horizontal producer well of the Toe-to-Heel Air Injection (THAI) process. The fixed bed of catalyst is virtually impossible to regenerate in place, promoting investigation of alternative contacting via the dispersion of nanoparticles. The catalysts studied were finely crushed micro-particulates with average size of 2.6μm and also a catalyst prepared upon a bacterial support. The latter has advantages in terms of ease of preparation of catalysts from recycled metal sources. Heavy oil of API gravity 13.8° and viscosity 1091mPas was used as feed and upgrading was performed in a batch reactor at 425°C, with a catalyst-to-oil ratio of 0.02 (g/g), and at an initial pressure of 20bar. The activity of the Pd/biomass catalyst was evaluated against a number of other catalysts: Pd/Al2O3, Pd/C, Al2O3 and Co–Mo/Al2O3. By using the Pd/biomass catalyst, the produced oil gravity increased by 7.8° API, and its viscosity was reduced to 7mPas. This effect corresponded to an increase in the amount of low-boiling distillate (IBP – 200°C) from 34.6vol.% (original feedstock) to 53–62vol.%, potentially reducing the amount of diluent needed for pipeline transport of bitumen. The coke yields were (wt.%): 13.65 (Al2O3), 9.55 (Pd/Al2O3), 6.85 (Pd/C) and 3.87 (Pd/biomass). The Pd/biomass catalyst showed significantly reduced coke yield compared to thermal cracking and upgrading using Pd/C and Pd/Al2O3 catalysts, which could greatly enhance catalyst survivability in the field.
Highlights
Transportation fuels account for roughly 40% of energy used globally, and 70–80% in advanced economies
In situ catalytic upgrading with nanoparticles in the to-Heel Air Injection (THAI) process was tested in a batch reactor at temperature of 425 °C, using a short residence time of 10 min
Nanoparticles of palladium (5 wt.%) supported on bacterial biomass, carbon, and alumina were compared with typical refinery Co–Mo/Al2O3 catalyst
Summary
Transportation fuels account for roughly 40% of energy used globally, and 70–80% in advanced economies. Reserves are the main source of these fuels. As a consequence of the declining reserves of light oils, attention has shifted to large deposits of untapped heavy oil and bitumen as potential alternatives, as they account for about 70% of world’s total 9–13 trillion barrel oil resources [1].
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