Partial Hydrogenation of Anthracene with In Situ Hydrogen Produced from Water-Gas Shift Reaction over Fe-Based Catalysts

Abstract

Partial hydrogenation of anthracene under CO-H2O, N2-H2O, and H2-H2O over Fe-based catalysts was studied at 400 °C and 10 MPa. Results show that the Fe-based catalysts display obvious catalytic activity for anthracene hydrogenation under CO-H2O instead of hydrogenation under N2-H2O and H2-H2O. The activity follows in the order of Fe(NO3)3·9H2O > Fe naphthenate > FeSO4·7H2O. Even though the amount of molecular hydrogen remains higher than that of in situ hydrogen, the anthracene conversion with in situ hydrogen is remarkably higher. It demonstrates that the in situ hydrogen is more active than molecular hydrogen for PAH hydrogenation. To further reveal the exact fate of these Fe-based catalysts, the decomposed products under CO-H2O, N2-H2O and H2-H2O were characterized by TG, XRD, and TEM. Results indicate that the Fe3O4 species play a key role in hydrogenation of anthracene under CO and H2O. Higher catalytic activity for Fe(NO3)3·9H2O is due to its complete decomposition at 350 °C to acquire higher concentration of active Fe3O4 species. The possible form of in situ hydrogen during this process is also discussed. Given that heavy oil contains abundant polyaromatics, these results are meaningful for enhancing hydrogen shuttling to heavy oil by producing natural hydrogen donors and, thus, benefiting the high-efficient upgrading.