Green Diesel Production over Nickel-Alumina Nanostructured Catalysts Promoted by Copper

Mantha Gousi, Eleana Kordouli, Kyriakos Bourikas, Emmanouil Symianakis, Spyros Ladas, Christos Kordulis and Alexis Lycourghiotis
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Mantha Gousi: Department of Chemistry, University of Patras, GR-26504 Patras, Greece
Eleana Kordouli: Department of Chemistry, University of Patras, GR-26504 Patras, Greece
Kyriakos Bourikas: School of Science and Technology, Hellenic Open University, Tsamadou 13-15, GR-26222 Patras, Greece
Emmanouil Symianakis: Surface Science Laboratory, Department of Chemical Engineering, University of Patras, GR-26504 Patras, Greece
Spyros Ladas: Surface Science Laboratory, Department of Chemical Engineering, University of Patras, GR-26504 Patras, Greece
Christos Kordulis: Department of Chemistry, University of Patras, GR-26504 Patras, Greece
Alexis Lycourghiotis: Department of Chemistry, University of Patras, GR-26504 Patras, Greece

Energies, 2020, vol. 13, issue 14, 1-17

Abstract: A series of nickel–alumina catalysts promoted by copper containing 1, 2, and 5 wt. % Cu and 59, 58, and 55 wt. % Ni, respectively, (symbols: 59Ni1CuAl, 58Ni2CuAl, 55Ni5CuAl) and a non-promoted catalyst containing 60 wt. % Ni (symbol: 60NiAl) were prepared following a one-step co-precipitation method. They were characterized using various techniques (N 2 sorption isotherms, XRD, SEM-EDX, XPS, H 2 -TPR, NH 3 -TPD) and evaluated in the selective deoxygenation of sunflower oil using a semi-batch reactor (310 °C, 40 bar of hydrogen, 96 mL/min hydrogen flow rate, and 100 mL/1 g reactant to catalyst ratio). The severe control of the co-precipitation procedure and the direct reduction (without previous calcination) of precursor samples resulted in mesoporous nano-structured catalysts (most of the pores in the range 3–5 nm) exhibiting a high surface area (192–285 m 2 g −1 ). The promoting action of copper is demonstrated for the first time for catalysts with a very small Cu/Ni weight ratio (0.02–0.09). The effect is more pronounced in the catalyst with the medium copper content (58Ni2CuAl) where a 17.2% increase of green diesel content in the liquid products has been achieved with respect to the non-promoted catalyst. The copper promoting action was attributed to the increase in the nickel dispersion as well as to the formation of a Ni-Cu alloy being very rich in nickel. A portion of the Ni-Cu alloy nanoparticles is covered by Ni 0 and Cu 0 nanoparticles in the 59Ni1CuAl and 55Ni5CuAl catalysts, respectively. The maximum promoting action observed in the 58Ni2CuAl catalyst was attributed to the finding that, in this catalyst, there is no considerable masking of the Ni-Cu alloy by Ni 0 or Cu 0 . The relatively low performance of the 55Ni5CuAl catalyst with respect to the other promoted catalysts was attributed, in addition to the partial coverage of Ni-Cu alloy by Cu 0 , to the remarkably low weak/moderate acidity and relatively high strong acidity exhibited by this catalyst. The former favors selective deoxygenation whereas the latter favors coke formation. Copper addition does not affect the selective-deoxygenation reactions network, which proceeds predominantly via the dehydration-decarbonylation route over all the catalysts studied.

Keywords: green diesel; renewable diesel; Ni catalyst; biofuel; hydrodeoxygenation; Cu-promotion effect (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (7)

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