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- Lu, Xinnan, et al.
(författare)
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Ni2P Nanoparticles Embedded in Mesoporous SiO2 for Catalytic Hydrogenation of SO2 to Elemental S
- 2021
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 4:6, s. 5665-5676
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Tidskriftsartikel (refereegranskat)abstract
- Highly active nickel phosphide (Ni2P) nanoclusters confined in a mesoporous SiO2 catalyst were synthesized by a two-step process targeting tight control over the Ni2P size and phase. The Ni precursor was incorporated into the MCM-41 matrix by one-pot synthesis, followed by the phosphorization step, which was accomplished in oleylamine with trioctylphosphine at 300 °C so to achieve the phase transformation from Ni to Ni2P. For benchmarking, Ni confined by the mesoporous SiO2 (absence of phosphorization) and 11 nm Ni2P nanoparticles (absence of SiO2) was also prepared. From the microstructural analysis, it was found that the growth of Ni2P nanoclusters was restricted by the mesoporous channels, thus forming ultrafine and highly dispersed Ni2P nanoclusters (<2 nm). The above approach led to promising catalytic performance following the order u-Ni2P@m-SiO2 > n-Ni2P > u-Ni@m-SiO2 > c-Ni2P in the selective hydrogenation of SO2 to S. In particular, u-Ni2P@m-SiO2 exhibited SO2 conversions of 94% at 220 °C and ∼99% at 240 °C, which are higher than the 11 nm stand-alone Ni2P particles (43% at 220 °C and 94% at 320 °C), highlighting the importance of the role played by SiO2 in stabilizing ultrafine nanoparticles of Ni2P. The reaction activation energy Ea over u-Ni2P@m-SiO2 is ∼33 kJ/mol, which is lower than those over n-Ni2P (∼36 kJ/mol) and c-Ni2P (∼66 kJ/mol), suggesting that the reaction becomes energetically favored over the ultrafine Ni2P nanoclusters.
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| 2. |
- Lu, Xinnan, et al.
(författare)
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Nickel Phosphide Nanoparticles for Selective Hydrogenation of SO2 to H2S
- 2021
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 4:7, s. 6568-6582
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Tidskriftsartikel (refereegranskat)abstract
- Highly mesoporous SiO2-encapsulated NixPy crystals, where (x, y) = (5, 4), (2, 1), and (12, 5), were successfully synthesized by adopting a thermolytic method using oleylamine (OAm), trioctylphosphine (TOP), and trioctylphosphine oxide (TOPO). The Ni5P4@SiO2 system shows the highest reported activity for the selective hydrogenation of SO2 toward H2S at 320 degrees C (96% conversion of SO2 and 99% selectivity to H2S), which was superior to the activity of the commercial CoMoS@Al2O3 catalyst (64% conversion of SO2 and 71% selectivity to H2S at 320 degrees C). The morphology of the Ni5P4 crystal was finely tuned via adjustment of the synthesis parameters receiving a wide spectrum of morphologies (hollow, macroporous-network, and SiO2-confined ultrafine clusters). Intrinsic characteristics of the materials were studied by Xray diffraction, high-resolution transmission electron microscopy/scanning transmission electron microscopy-high-angle annular dark-field imaging, energydispersive X-ray spectroscopy, the Brunauer-Emmett-Teller method, H-2 temperature-programmed reduction, X-ray photoelectron spectroscopy, and experimental and calculated P-31 magic-angle spinning solid-state nuclear magnetic resonance toward establishing the structure-performance correlation for the reaction of interest. Characterization of the catalysts after the SO2 hydrogenation reaction proved the preservation of the morphology, crystallinity, and Ni/P ratio for all the catalysts.
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