Carbon Nanofiber-Assisted Modulation of Ni–CeO₂ Interaction for Hydrogen Production via Acetic Acid Steam Reforming

The strong metal-support interaction (SMSI) plays a crucial role in heterogeneous catalytic reactions. In this study, we introduced a carbon nanofiber-assisted method to adjust the Ni-CeO₂ interaction. The catalysts' physicochemical properties were characterized using various techniques and their performance was evaluated in acetic acid steam reforming. Our results showed that adding carbon nanofibers (CNFs) improved the dispersion of Ni and CeO₂ precursors, enhancing the Ni-CeO₂ interaction. This led to increased CeO₂ reduction and highly dispersed Ni⁰ on the catalyst surface, boosting its activity in the steam reforming reaction. The enhanced metal-support interaction caused electrons on the Ni⁰ surface to migrate partially to the CeO₂ surface, increasing oxygen vacancies in the CeO₂ lattice and thereby promoting H₂O dissociation and gasification of reaction intermediates. DFT calculations indicated that Ni adsorbed at the top site could promote oxygen vacancy formation, increasing the energy of the Ni 3d occupied states and enhancing the adsorption and dissociation ability of reactants. SMSI also caused some Ni atoms to migrate into the CeO₂ lattice after the reaction, improving the catalyst's sintering resistance. Ni/CeO₂ prepared at a carbon/CeO₂ ratio of 3:1 showed optimal catalytic activity, achieving an 85.2% H₂ yield at 700 °C and a 5.11 wt % coke amount, attributed to SMSI. In situ DRIFTS results revealed that the steam reforming of acetic acid involves steps like dehydrogenation, deoxygenation, and decarbonylation. Carbon deposition mainly resulted from ketene condensation at low temperatures (300-400 °C), while the oxygen vacancies generated by SMSI promoted intermediate gasification and inhibited carbon deposition.