Preparation of Ni2P Supported on Al2O3 and B2O3 Mixed Oxides by Temperature-Programmed Reduction of Phosphate Precursors with Low P/Ni Ratios
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2020-11
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Two types of mixed oxides of B2O3 and Al2O3 were prepared. Aluminum borates (ABx, x represents the B/(B + Al) ratio) were prepared by low-temperature thermal decomposition of aluminum nitrate and H3BO3 sustained by the simultaneous oxidation of an organic agent (glycerol), while B2O3-Al2O3 with B/(B + Al) ratio of 0.3 was obtained by incipient wetness impregnation of H3BO3 on a commercial γ-Al2O3 support. Tetrahedrally, pentahedrally, and octahedrally coordinated Al3+ cations were all present in AB0.3 with ratios of 10.9/21.3/67.8, while no pentahedrally coordinated Al3+ was observed in B2O3-Al2O3. B2O3 was enriched in the surface of AB0.3. The Ni2P phase was obtained by temperature-programmed reduction of a phosphate precursor with a P/Ni ratio as low as 1.2 supported over both AB0.3 (Ni-P(1.2)/AB0.3) and B2O3-Al2O3 (Ni-P(1.2)/B2O3-Al2O3). This suggests that the surface B2O3 inhibits the reaction between nickel phosphates and Al2O3, and thus facilitates the formation of Ni2P. The hydrodesulfurization (HDS) of dibenzothiophene (DBT) over the supported Ni2P catalysts occurred mainly by the direct desulfurization pathway, and Ni-P(1.2)/B2O3-Al2O3 was much more active than Ni-P(1.2)/AB0.3. These features make B2O3-Al2O3 a promising support for Ni2P catalysts. The HDS of DBT followed a pseudo-first-order kinetics over Ni-P(1.2)/B2O3-Al2O3, whereas over Ni-P(1.2)/AB0.3 it can be described by pseudo-zero-order kinetics. The pseudo-zero-order kinetics suggests a strong adsorption of DBT on Ni-P(1.2)/AB0.3, which could be responsible for its lower activity. © 2020, Springer Science+Business Media, LLC, part of Springer Nature
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63 (15)
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1379 - 1387
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Springer
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Al2O3; B2O3; Mixed oxide; Ni2P; Hydrodesulfurization; Dibenzothiophene