Effect of Pd promotion and catalyst support on the Ni-catalyzed deoxygenation of tristearin to fuel-like hydrocarbons

The incomplete reduction and poor dispersion of Ni sites restrict the catalytic performance of Ni catalysts in the decarboxylation/decarbonylation (DCX/DCN) of triglycerides to fuel-like hydrocarbons. In this study, by employing Pd as promoter and/or using multifunctional supports, the activity of N...

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Bibliographic Details
Published in:Renewable energy 2022-08, Vol.195, p.1468-1479
Main Authors: Wang, Fei, Pace, Robert, Ji, Yaying, Jiang, Jianchun, Jiang, Xiaoxiang, Krystianiak, Anna, Heintz, Olivier, Caboche, Gilles, Santillan-Jimenez, Eduardo, Crocker, Mark
Format: Article
Language:English
Subjects:
Chemical Sciences
Decarbonylation
Decarboxylation
Deoxygenation
Hydrodeoxygenation
Nickel
Palladium
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Summary:The incomplete reduction and poor dispersion of Ni sites restrict the catalytic performance of Ni catalysts in the decarboxylation/decarbonylation (DCX/DCN) of triglycerides to fuel-like hydrocarbons. In this study, by employing Pd as promoter and/or using multifunctional supports, the activity of Ni catalysts in tristearin deoxygenation was greatly improved. Notably, 25%Ni/Al2O3 and 0.75%Pd/Al2O3 displayed conversion values ≤ 2%. In contrast, 25%Ni-0.75%Pd/Al2O3 afforded 100% conversion, 100% yield of diesel-like hydrocarbons and a selectivity to C17 – the main product of DCN/DCX – of 67%. The fact that the performance of the Ni–Pd catalyst is vastly superior to that of the corresponding monometallic formulations is clearly indicative of a promotion effect resulting from the interaction between the two metals. Pd addition promoted Ni reduction, thereby increasing the number of active sites. The effect of different supports (Al2O3, SiO2–Al2O3, ZrO2, and Ce0.8Pr0.2O2) of Ni–Pd catalysts were studied, and the use of SiO2–Al2O3 was observed to enhance catalyst performance by further promoting Ni reduction as well as through its high surface area and strong acidity. Moreover, using SiO2–Al2O3 as the support partially changes the deoxygenation pathway from DCX/DCN to hydrodeoxygenation, which is attributed to the ability of strong acid sites to catalyze the dehydrogenation of an alcohol intermediate to the corresponding alkene. [Display omitted]
ISSN:0960-1481
1879-0682
DOI:10.1016/j.renene.2022.06.065