CuO@NiO Nanoparticles Derived from Metal–Organic Framework Precursors for the Deoxygenation of Fatty Acids

Abstract

Hierarchical mesoporous CuO@NiO nanoparticles were synthesized using metal−organic frameworks (MOFs) as the precursor. We investigated the physicochemical properties of the MOF-derived CuO@NiO (M-CuO@NiO) and its activity for the deoxygenation of fatty acids. High-resolution transmission electron microscopy (HRTEM) revealed that M-CuO@NiO possessed a homogeneous alloy configuration with well-dispersed CuO and NiO. X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and temperature-programmed desorption (TPD) suggested that M-CuO@NiO retained the rich oxygen vacancies, excellent stability, and strong acidity, which are beneficial to the deoxygenation of fatty acids. The conversion of stearic acid (∼99.9%) and a selectivity of 94.4% to C8-C18 alkanes demonstrated the high activity of M-CuO@NiO, which is comparable to that of the noble catalyst Pt/C. In addition, a conversion of >99% for other fatty acids (lauric acid, palmitic acid, and oleic acid) and the selectivities of >90% for saturated fatty acids (lauric acid and palmitic acid) and 76.7% for oleic acid to C8-C18 alkanes indicate consistently high activity of M-CuO@NiO toward different fatty acids. Finally, we proposed the mechanistic pathways for the deoxygenation of stearic acid to C8-C18 alkanes. Overall, conclusions from this study support that M-CuO@NiO is a promising catalyst for the low-cost production of green diesel.

In Situ Electrochemical Reconstitution of CF–CuO/CeO2 for Efficient Active Species Generation

“…The full-scan XPS spectra reveal that the Cu, Ce, and O elements dominate the surface of samples (Figure a). The Cu 2p XPS spectrum of CF–CuO/CeO 2 shows that the peaks at 932.37 and 952.22 eV are attributed to Cu 2p 3/2 and Cu 2p 1/2 of Cu + /Cu 0 , while the other two peaks at 934.24 and 954.21 eV correspond to Cu 2p 3/2 and Cu 2p 1/2 of Cu 2+ , respectively (Figure b). − After the oxidative activation, the peaks of Cu + /Cu 0 have disappeared, while the new peaks associated with the CuOOH phase appeared at 935.69 and 955.95 eV, which is consistent with the result of XRD patterns. − For the Cu 2p XPS spectra of reductive-activated CF–CuO/CeO 2 , the obviously weakened Cu 2+ peaks (934.24 and 954.21 eV) and the dominant Cu + peaks (932.71 and 952.52 eV) further indicate that the Cu + phase is one of the reductive-active sites. , In the Ce 3d XPS spectra of these samples (Figure c), the peaks at about 882.46 and 898.37 eV correspond to Ce 3d 5/2 and Ce 3d 3/2 of Ce 4+ species, while the peaks at about 885.07 and 900.96 eV can be ascribed to Ce 3d 5/2 and Ce 3d 3/2 of Ce 3+ species, respectively. After oxidative activation, the peak position of Ce 4+ species hardly shifted, indicating that CeO 2 exists stably on the catalyst surface.…”

“…As shown in Figure S4a, the diffraction peaks at 43.97, 51.14, and 74.65° correspond to the Cu foam, and CuO shows the diffraction peaks at 36.18, 39.39, and 49.86° which belong to the (11-1), (111), and (20-2) planes (JCPDS card no. 48-1548). − The diffraction peaks located at 22.91, 29.68, and 33.14° are assigned to (110), (111), and (200) facets of the standard CeO 2 (JCPDS card no. 34-0394) in the CF–CuO/CeO 2 sample. , As shown in XRD patterns of the oxidative-activated CF–CuO/CeO 2 (Figure S4b–d), the diffraction peaks at 25.95, 32.75, and 34.76° are associated with (002), (0-11), and (020) planes of the CuOOH phase (JCPDS card no.…”

MOF-Derived Co3O4 Nanoparticles Catalyzing Hydrothermal Deoxygenation of Fatty Acids for Alkane Production

“…Particularly, because pores are created by the decomposition of the ligands and framework, the pore size distributions of all three catalysts indicate that pores are around 3–5 nm, which is much smaller than those in ordinary metal oxides. 17 …”

“…All experiments in this study were performed in a 1.67 mL volume microreactor produced by Swagelok, which was assembled according to the reactor used by Fu et al 19 and in our previous study. 17 Specifically, 15 mg of catalyst, 500 μL of water, 15 mg of methanol, and 0.176 mmol of stearic acid were charged into a microreactor and sealed. The tube furnace was first heated to the specified temperature, and then the reactor was placed in the tube furnace for a certain period of time.…”

“…Such an operation has been shown to be feasible in our previous research. 17 After the reaction, the reactor was taken out and quickly put into water to stop the reaction. Subsequently, the compound in the reactor was flushed out with chloroform and made the solution to constant volume with chloroform and water in the volumetric flask, respectively.…”