Advanced studies of catalytic upgrading of heavy oils

Abstract

Heavy oil and bitumen are known to constitute high-boiling molecules which gives them characteristic high viscosity, high density/low API gravity, low yields of fuel distillates, and high heteroatom content compared to light oil. Upgrading therefore refers to the breaking down of heavy oil into oil with similar characteristics as light crude oil. The toe-to-heel air injection (THAI) and its catalytic add-on CAPRI (CAtalytic upgrading PRocess $In-situ$) were developed to achieve this objective down-hole. In this study, the CAPRI process was explored with the objective of controlling catalyst deactivation due to coking while increasing the extent of upgrading. The effects of reaction temperature and weight hourly space velocity on the extent of upgrading were studied in the range of 350-425$^o$C and 9.1-28 h$^-$$^1$, respectively. In order to control premature deactivation of the catalysts due to coke and metal deposition, the following were investigated activated carbon guard-bed on top of the catalyst bed, hydrogen-addition, steam environment as a source of hydrogen-donor, and nanoparticulate catalyst. It was found that high reaction temperature of 425$^o$C and lower WHSV (9.1 h$^-$$^1$) improved the cracking as well as increase API gravity (~3-7$^o$), viscosity reduction of (81.9 %), demetallisation (9.3-12.3 %), desulphurisation (5.3-6.6 %), and higher yield of fuel distillates, respectively compared to upgrading at 350 and 400$^o$C. In spite of the improvement in produced oil at 425 $^o$C, the carbon-rejection was high (51-56.6 wt.%) compared to (42-47.8 wt.%) and (48-50.3 wt.%) when reaction was carried out at 350 and 400$^o$C for 25 hours operations