Catalyst regeneration using CO2 as reactant through reverse-Boudouard reaction with coke

The possibility of CO2 recycling into standard refinery can largely mitigate greenhouse gas emissions. It was previously demonstrated that alumina modified by either potassium or lithium in the presence of vanadium was able to promote the reaction of CO2 with coke in the presence of O-2 during the regeneration step of a spent catalyst. Herein, vanadium-sodium and vanadium-calcium on alumina were used to achieve that reaction. These catalysts showed slightly lower conversion compared to previously catalysts. However, regardless of the type of group I and II elements, all catalysts showed very similar apparent activation energy (Ea(app)) for the coke oxidation with CO2 reaction (CO2+coketo2.6pcEaapp</mml:mover>CO+coke<mml:mo>-O), i.e., in the range of 188-193 kJ.mol(-1). In contrast without vanadium, Ea(app) was in the range of 242-253 kJ.mol(-1). Therefore, CO2 is activated in a site composed of V-O-(group I or II) in the coke proximity. Moreover, these results clearly support that vanadium plays the main role in the type of activation complex, independently of the group I and II metal used and most probably in the dissociative step of CO2. (c) 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.