Vanadium–potassium–alumina catalyst: A way of promoting CO2 and coke reaction in the presence of O2 during the FCC catalyst regeneration

• Spent catalyst was regenerated in the presence of CO2.
• CO2 and coke reaction occurs in the presence of O2.
• A synergetic effect between V and K was observed for CO2 activation.
• The FCC catalyst regeneration simultaneously produces CO and mitigates CO2 emissions.

CO2 recycling in refineries is of primary importance nowadays, particularly the fluid cracking process which is responsible for about 30% of CO2 emissions in the refinery, as spent catalyst undergoes coke regeneration in air. The possibility of performing this step in the presence of CO2/O2, instead of air can remarkably mitigate greenhouse gas emissions and simultaneously produce a huge amount of CO for sequential uses. Herein, we report that alumina (usually present in 20–40 wt.% in the catalyst composition) modified by both potassium (5 wt.%) and vanadium (1 wt.%) was able to perform this goal under regular regeneration conditions, i.e. at 700 °C. The apparent activation energy values for CO2 and coke reaction on alumina, alumina with potassium and with both potassium and vanadium were 349, 249 and 192 kJ/mol respectively. In the presence of 13CO2 and O2 the primary observed product was 13CO, followed by 12CO and then by 12CO2. These results unambiguously demonstrate that the stage of catalyst regeneration can be kept under heat balance and simultaneously produce a huge amount of CO and, therefore mitigate CO2 emissions.

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