Abstract
• A tandem vapor-phase hydrotreating process was employed to upcycle waste cooking oil. • A 100% hydrodeoxygenation efficiency was observed. • A 7.4-fold yield increase in C 5 -C 19 n-alkanes was obtained over Ni/Al 2 O 3 -SiO 2 compared with that of non-catalytic. • The hydrodeoxygenation mechanism induced by Ni/Al 2 O 3 -SiO 2 in the tandem conversion process was proposed. • The flexibility and practicability of this tandem hydrotreating process was evaluated. This study is focused on producing biofuels from waste oils via a tandem vapor-phase hydrotreating process in a pressurized two-stage fixed bed reactor over a bifunctional Ni/Al 2 O 3 -SiO 2 catalyst under 0.25 MPa H 2 . A 100% hydrodeoxygenation efficiency both in liquid and gas products was observed, yielding 83.9 wt% C 5 -C 19 n-alkanes which corresponds to a 7.4-fold increase compared with that obtained from non-catalytic conversion. The hydrodeoxygenation mechanism of waste cooking oil in the catalytic tandem hydrotreating process induced by Ni/Al 2 O 3 -SiO 2 was proposed. The hydropyrolysis temperature in the first reactor, hydrogenation temperature in the second reactor, reaction pressure, catalyst to waste cooking oil mass ratio, and gas hourly space velocity (GHSV) was optimized at 550 °C, 300 °C, 0.25 MPa, 3, and 56 s −1 , respectively. The application potential of this cascade vapor-phase hydrotreating process was evaluated by employing different waste oils such as palm kernel oil, woody oil ( swida wilsoniana ), soapstock, and waste lubricating oil as feedstock, giving C 5 to C 19 n-alkane yields ranging from 21.6 to 87.5 wt%. This work provides a novel and promising approach to upcycle waste oils into upgraded biofuels compared with conventional catalytic pyrolysis.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call