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[Display omitted] • The coke resistance of Ni-based catalysts is improved profoundly by adding Er. • 99.3 % deoxygenation ratio and 64.7 % yield of biofuels is achieved on Ni-Er/50S-Al. • Er promotes the evenly distribution of Ni with smaller particle size. • More surface oxygen vacancies are critical for deoxygenating JO when REEs added. • The strong acidity leads to more coke form with Y added. Herein, three kinds of rare earth elements (Ce, Er and Y) were added to Ni-based catalysts to regulate the deoxygenation ability and coke resistance towards jatropha oil (JO) conversion. Among them, the catalysts with lanthanide metals (Ce and Er) added exhibit positive effects. Conversely, the addition of Y is counterproductive. The one with Er added displays the best catalytic performance, achieving the highest deoxygenation ratio (99.3 %) and product yield (64.7 %), and the resultant biofuel has the highest calorific value (46.02 MJ/kg). The stability of the Ni-Er/50S-Al catalyst is significantly improved due to the enhanced coke resistance compared with the one without Er added. Smaller Ni particle sizes with better dispersion, higher amount of surface Ni0 and surface oxygen vacancies are accomplished by adding Er, which contributes to the enhanced catalytic performance. The addition of Y weakens coke resistance, caused by strong acidity and big Ni particles. This study provides an effective idea for rationally designing catalysts with improved coke resistance and converting vegetable oils into biofuels. [ABSTRACT FROM AUTHOR]

Tungsten carbide-based materials have good deoxygenation activity in the conversion of biomass. In this paper, catalysts with different nickel–tungsten carbide species were prepared by tuning the reduction temperature and Ni loading, and the effects of these different tungsten carbide species in the conversion of jatropha oil were studied. XRD, XPS, TEM, HRTEM, Raman, H2-TPR, ICP-AES were used to characterize the catalysts. The results suggested that metallic W was gradually carburized to W2C species, and W2C species was further carburized to WC species with the increase in reduction temperature and Ni loading. The obtained 10Ni10W/AC-700 catalyst exhibited outstanding catalytic performance with 99.7% deoxygenation rate and 94.5% C15-18 selectivity, which were attributed to the smallest particle size, the best dispersion, the most exposed active sites, and the synergistic effect of Ni, W2C and WC species. [ABSTRACT FROM AUTHOR]

Pure Ni12P5/SiO2 and pure Ni2P/SiO2 catalysts were obtained by adjusting the Ni and P molar ratios, while Ni/SiO2 catalyst was prepared as a reference against which the deoxygenation pathways of palmitic acid were investigated. The catalysts were characterized by N2 adsorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission election microscopy (TEM), infrared spectroscopy of pyridine adsorption (Py-IR), H2-adsorption and temperature-programmed desorption of hydrogen (H2-TPD). The crystallographic planes of Ni(111), Ni12P5(400), Ni2P(111) were found mainly exposed on the above three catalysts, respectively. It was found that the deoxygenation pathway of palmitic acid mainly proceeded via direct decarboxylation (DCO2) to form C15 on Ni/SiO2. In contrast, on the Ni12P5/SiO2 catalyst, there were two main competitive pathways producing C15 and C16, one of which mainly proceeded via the decarbonylation (DCO) to form C15 accompanying water formation, and the other pathway produced C16 via the dehydration of hexadecanol intermediate, and the yield of C15 was approximately twofold that of C16. Over the Ni2P/SiO2 catalyst, two main deoxygenation pathways formed C15, one of which was mainly the DCO pathway and the other was dehydration accompanying the hexadecanal intermediate and then direct decarbonylation without water formation. The turn over frequency (TOF) followed the order: Ni12P5/SiO2 > Ni/SiO2 > Ni2P/SiO2. [ABSTRACT FROM AUTHOR]

[Display omitted] • 10Ni-ZrO 2 exhibits high activity for the deoxygenation of methyl laurate. • 100% yield of alkanes and 87.6% selectivity to C 11 are obtained. • The Ni loading directs the formation of SOV and exposed lattice planes of t-ZrO 2. • The content of Ni0, SOV and Ni-O-Zr interfaces contribute to catalytic performance. • The exposed lattice planes of t-ZrO 2 play an important role in product distribution. A series of Ni-ZrO 2 catalysts with different Ni loading were prepared and evaluated for methyl laurate conversion. Characterizations show that the 10Ni-ZrO 2 bears the smallest Ni crystal size; the highest atomic content of surface Ni0, surface oxygen vacancy and Ni-O-Zr interfaces; then exhibits the highest activity and stability towards methyl laurate conversion with nearly 100% yield of alkanes and 87.6% selectivity to undecane at 280 °C, 2 MPa H 2. The t-ZrO 2 (1 1 2) lattice plane can motivate the deoxygenation while the t-ZrO 2 (0 0 2) promotes cracking reactions, resulting in low selectivity to undecane. Moreover, 10Ni-ZrO 2 performs wide applicability for transforming crude oils into alkanes. [ABSTRACT FROM AUTHOR]