Development of supported nickel-based catalysts for deoxygenation of waste cooking oil to renewable fuel production
The development of renewable diesel fuel from the deoxygenation of non-edible oil is an alternative to non-renewable fuels. This study investigated the catalytic deoxygenation of waste cooking oil (WCO) over supported Ni-based catalysts. The deoxygenation of WCO was conducted using different type...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/104078/1/FS%202022%2043%20IR.pdf |
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| Summary: | The development of renewable diesel fuel from the deoxygenation of non-edible oil is
an alternative to non-renewable fuels. This study investigated the catalytic
deoxygenation of waste cooking oil (WCO) over supported Ni-based catalysts. The
deoxygenation of WCO was conducted using different types of supports: activated
carbon (AC), reduced graphene oxide (rGO), and beta zeolite (Zeo). The addition of Ni
to AC improves the physicochemical properties of the catalyst, owing to the high number
of acid-base sites, high surface area, smaller crystallite size, and high pore volume of the
catalyst. Based on the catalytic results, Ni20/AC was the most active catalyst, which
achieved 90% hydrocarbon yield and 89% selectivity towards n-(C15+C17). Furthermore,
it was stable up to the fourth cycle with consistent hydrocarbon yield (85-87%) and 66-
77% selectively towards n-(C15+C17). Further investigation was conducted to study the
effect of bifunctional catalysts (NiLa, NiCe, NiFe, NiMn, NiZn, and NiW) supported on
AC. High hydrocarbon yield above 60% with lower oxygenated species was found in the
liquid product with the product selectively toward n-(C15+C17)-diesel fractions. The
predominance of n-(C15+C17) hydrocarbons with concurrent production of CO and CO2
indicated that the deoxygenation pathway preceded via decarbonylation and
decarboxylation mechanisms. For NiLa/AC, high deoxygenation activity with better n-
(C15+C17) selectivity was obtained due to great synergistic interaction between La–Ni,
and its compatibility of acid-base sites increased the removal of oxygenates. For the
effect of La on the deoxygenation performance, it was found that a high percentage of
La species would be beneficial in the removal of C-O bonded species. Furthermore,
optimum deoxygenation activity of 88% hydrocarbon yield with 75% n-(C15+C17)
selectivity was obtained over 20% La, which strongly evinced that La leads to more
significant enhancement of deoxygenation activity. The NiLa/AC reusability study
showed consistent deoxygenation with 80% hydrocarbon yield and 60% n-(C15+C17)
hydrocarbons selectivity within six runs. As the NiZn/AC catalyst also showed high
performance in deoxygenation activity, the optimization over a series of Ni20Znx/AC
catalysts (X: 5–20 wt.%) was also studied. The Ni20Zn10/AC catalyst exhibited superior
deoxygenation activity by yielding 86% hydrocarbons and 79% of n-(C15 + C17) selectivity. High deoxygenation activity is corroborated by the higher acidity and basicity
strength of the catalyst and the oxygenate species removal that occurred via
decarbonylation pathway. The Ni20Zn10/AC catalyst showed promising catalytic stability
and reusability up to four runs with hydrocarbon yield (78 – 87%) and n-(C15 + C17)
selectivity within the range of 43 – 70%, respectively. The decrease in the n-(C15 + C17)
selectivity in the fourth cycle was due to the active metal species leaching and coking.
In conclusion, all Ni-based catalysts demonstrated significant catalytic activity and
reusability for green diesel production. |
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