Effect of CO addition on upgrading bitumen in supercritical water

• Upgrading of bitumen was examined with and without CO in supercritical water (SCW).
• CO facilitated extraction of oil.
• Coke formation in SCW with CO was suppressed.
• Extract oil was lightest at 693 K with CO.
• Distribution of oil in the reactor and temperature are important for upgrading.

Upgrading of bitumen was performed in a semi-batch type reactor in supercritical water (SCW) and in mixtures of SCW with CO or H2 from 673 to 723 K at 30 MPa. The extracted oil yield was in the order SCW + CO > SCW + H2 > SCW at 673 K. CO and H2 facilitated the extraction of the oil from inside the reactor to the outside the reactor. The coke yield in SCW + CO was lower than the yields in SCW and SCW + H2, indicating that hydrogenation of bitumen through the water-gas shift reaction probably occurred. Furthermore, the lightest extracted oil was obtained at 693 K in SCW + CO. The distribution of oil between the water-rich phase and oil-rich phase in the reactor governed the stability of the coke precursor in the oil-rich phase and the temperature determined the oil decomposition rate and the coke formation rate. The optimal upgrading condition was dependent on these factors.

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