Continuous selective deoxygenation of palm oil for renewable diesel production over Ni catalysts supported on AlO and LaO-AlO

The present study provides, for the first time in the literature, a comparative assessment of the catalytic performance of Ni catalysts supported on γ-Al 2 O 3 and γ-Al 2 O 3 modified with La 2 O 3 , in a continuous flow trickle bed reactor, for the selective deoxygenation of palm oil. The catalysts were prepared via the wet impregnation method and were characterized, after calcination and/or reduction, by N 2 adsorption/desorption, XRD, NH 3 -TPD, CO 2 -TPD, H 2 -TPR, H 2 -TPD, XPS and TEM, and after the time-on-stream tests, by TGA, TPO, Raman and TEM. Catalytic experiments were performed between 300-400 °C, at a constant pressure (30 bar) and different LHSV (1.2-3.6 h −1 ). The results show that the incorporation of La 2 O 3 in the Al 2 O 3 support increased the Ni surface atomic concentration (XPS), affected the nature and abundance of surface basicity (CO 2 -TPD), and despite leading to a drop in surface acidity (NH 3 -TPD), the Ni/LaAl catalyst presented a larger population of medium-strength acid sites. These characteristics helped promote the SDO process and prevented extended cracking and the formation of coke. Thus, higher triglyceride conversions and n -C 15 to n -C 18 hydrocarbon yields were achieved with the Ni/LaAl at lower reaction temperatures. Moreover, the Ni/LaAl catalyst was considerably more stable during 20 h of time-on-stream. Examination of the spent catalysts revealed that both carbon deposition and degree of graphitization of the surface coke, as well as, the extent of sintering were lower on the Ni/LaAl catalyst, explaining its excellent performance during time-on-stream. Highly selective and stable Ni supported on La 2 O 3 -Al 2 O 3 catalyst on the deCO/deCO 2 reaction paths for the production of renewable diesel.