A novel synthesis of Ni2P/MCM-41 catalysts by reducing a precursor of ammonium hypophosphite and nickel chloride at low temperature

Authors: Hua Song, Min Dai, Hualin Song, Xia Wan, Xiaowei Xu

Abstract:
A novel method to prepare Ni₂P/MCM-41 catalysts at low reduction temperature based on ammonium hypophosphite and nickel chloride by temperature programmed reduction is described. The catalysts were prepared using incipient wetness impregnation of the siliceous MCM-41 support with aqueous solutions of ammonium hypophosphite and nickel chloride, followed by reducing the obtained precursor at 483–663K for 2 h in flowing H₂, to form Ni₂P catalysts. The catalysts were characterized by H2 temperature-programmed reduction (H₂-TPR), X-ray diffraction (XRD), N₂-adsorption specific surface area measurements (BET), CO uptake, transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS). With sample of initial P/Ni molar ratio >0.5, the Ni₂P was successfully obtained at lower reduction temperature, and a high initial P/Ni molar ratio favors the formation of Ni₂P at lower temperature. Using less oxidic phosphorus precursor of hypophosphite enabled the Ni₂P to be formed at low reduction temperature. Evaluation of the activity for DBT HDS of the catalysts shows that the catalyst prepared with initial P/Ni ratios of 2 exhibited the highest activity. At a reaction temperature of 613K, a pressure of 3.0 MPa, a H₂/oil ratio of 500 (V/V), and a weight hourly space velocity (WHSV) of 2.0 h⁻¹, the HDS conversion reached 99%, and no catalyst deactivation was observed within 120 h.

Keywords:
Nickel phosphide
Ammonium hypophosphite
Nickel chloride
MCM-41
Hydrodesulfurization
Dibenzothiophene

Published in: Applied catalysis A: General  (Volumes 462–463, Pages 1-310, 10 July 2013)

Publisher: Elsevier      

ISSN Information: 0926-860X

A novel synthesis of Ni2P/MCM-41 catalysts by reducing a precursor of ammonium hypophosphite and nickel chloride at low temperature

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