Highly stable Mo-based bimetallic catalysts for selective deoxygenation of oleic acid to fuel-like hydrocarbons

Abstract

To develop efficient, economical and environmentally friendly Mo-based bimetallic Al/MCM-41 catalysts for catalytic oleic acid pyrolysis into hydrocarbon-like upgrading biofuel, a series of metal-modified Mo-based catalysts was successfully synthesized. The effects of different metal oxide types (Zr, Zn, Pt, Cu, Co, Ce, Ni) and Ce to Mo mixed ratios were compared and characterized by XRD, BET, NH3-TPD, XPS, SEM and TEM technologies. Simultaneously, the deoxygenation effect and reusability properties were also evaluated by Py-GC/MS and TGA. The results showed that the molybdenum-based bimetallic catalyst exhibited superior deoxygenation activity (Ce>Cu>Zn>Ni>Zr∼Pt>Co) in the decarbonylation and decarboxylation pathways. Higher deoxygenation activity was related to rich surface Ce-□-Mo synergistic oxygen vacancies, suitable metal-Lewis and Brønsted acidity and excellent textural properties. A higher Ce content was beneficial to HC and aromatic formation due to a higher specific surface area and mesoporous volume, and a higher Mo content facilitated olefin and alkane conversion due to a higher Brønsted acid intensity and smaller pore size. The 3Ce-1Mo/Al-MCM-41 exhibited excellent catalytic activity and promising reusability by yielding 97.72% hydrocarbons, 75.33% aromatic content and 57.92% MAHs due to the synergistic effect between Ce and MoOx, rich surface Ce-□-Mo synergistic oxygen vacancies and suitable metal-Lewis and Brønsted acid intensities that contributed to better reaction activity and coke resistance and activated the CO of oleic acid. The slight reduction in HCs was mainly due to the loss of active metal sites and coke deposition. Furthermore, the synergistic effect of Ce and MoOx species obviously advanced the reaction activity and coke resistance.