Efficient Ni₂P/SiO₂ Catalysts with Enhanced Performance for the Hydrogenation of 4,6-Dimethyldibenzothiophene and Phenanthrene

Highly dispersed Ni2P catalysts (Ni2P/SiO2-DPx) were prepared by reducing the passivation-free precursors, which were obtained through the phosphidation of nickel phyllosilicate with sodium hypophosphite. The strong metal–support interaction of nickel phyllosilicate and the mild phosphidation conditions prevented the agglomeration of Ni particles and resulted in a smaller Ni2P particle size. The superior catalytic performance of the as-prepared Ni2P/SiO2-DP catalysts was evaluated in hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene and the hydrogenation of phenanthrene, in comparison with Ni2P/SiO2-IM and CoMoS/γ-Al2O3 prepared from a conventional incipient wetness impregnation method. The passivation-free Ni-P/SiO2-DPx precursors showed great storage stability, and Ni2P/SiO2-DP derived from the stored Ni-P/SiO2-DP precursors exhibited negligible loss of HDS activity. This method provides a potential preparation strategy for the industrial applications of transition metal phosphides without the temperature-programmed reduction and the subsequent passivation process

In-Depth Understanding of Highly Active Silicotungstic Acid Catalysts for Ethanol Dehydration to Ethylene under Industrially Favorable Conditions

A series of SiO2-supported silicotungstic acid (STA/SiO2) catalysts were prepared by the incipient impregnation method and utilized in dehydration of ethanol to ethylene. The catalysts were characterized through X-ray diffraction (XRD), N2 physical adsorption, transmission electron microscopy (TEM), X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), pyridine-adsorbed FTIR (Py-FTIR), Raman spectroscopy, and thermogravimetry/differential scanning calorimetry (TG/DSC). The influence of loading amount and calcination temperature on the properties and catalytic activities were investigated. The yield of ethylene was 93.9% at an ethanol conversion of 96.9% over the 36-STA/SiO2(250) catalyst at 240 °C and 1.0 MPa. The kinetics study indicated that diethyl ether was an intermediate under the investigated reaction conditions. A consecutive slow decrease in ethanol conversion and ethylene yield was observed after the 800-h run, which was due to the decreased Brønsted amount caused by carbon deposition, rather than the change of crystal phase or leaching of active sites

Aqueous Phase Hydrodeoxygenation of Phenol over Ni₃P‑CePO₄ Catalysts

Unsupported Ni₃P-CePO₄ catalysts were prepared by coprecipitation, followed by drying, calcination, and temperature-programmed reduction. The prepared catalysts were characterized by XRD, N₂ adsorption–desorption, TEM, STEM-EDS elemental mapping, XPS, NH₃-TPD, FT-IR of adsorbed pyridine, and H₂-TPR. Their catalytic performances in hydrodeoxygenation (HDO) were investigated using an aqueous solution of phenol (5.0 wt %) as the feed. CePO₄ was generated in coprecipitation and stable in the subsequent drying, calcination, and temperature-programmed reduction (final temperature 500 °C). It is shown that the addition of CePO₄ resulted in enhanced HDO activity, and a maximum activity appeared at a Ce/Ni ratio of 0.3. The presence of CePO₄ improved the dispersion of Ni₃P significantly, leading to enhanced hydrogenation activity. CePO₄ served as the major dehydration sites as well because of its surface acidity (mainly Lewis acid). In addition, the kinetics of the aqueous phase HDO of phenol and cyclohexanol catalyzed by Ni₃P and by Ni₃P-CePO₄ with Ce/Ni ratio of 0.3 were investigated