An in situ method for the preparation of nickel phosphide (Ni 2 P) on silica, alumina, and amorphous silica-alumina (ASA) supports is described. The synthesis avoids the use of nickel and phosphorus salts by employing the reaction between nickel hydroxide (Ni(OH) 2) and hyphosphorus acid (H 3 PO 2), allowing the impregnation of nickel hypophosphite (Ni(H 2 PO 2) 2) onto the oxide supports in the absence of salt byproducts. Temperature-programmed reduction (TPR) in flowing hydrogen at 573-773 K yields phase pure Ni 2 P on the supports with small average particle sizes (3-4 nm) as measured using transmission electron microscopy. The conversion of Ni(H 2 PO 2) 2 to Ni 2 P and related reactions were probed using TPR with on-line mass spectral analysis of the gas effluent. Unsupported Ni(H 2 PO 2) 2 reacts in flowing hydrogen to produce PH 3 and H 2 O at 468 and 482 K, respectively; the reaction is shifted to increasingly higher temperatures for Ni(H 2 PO 2) 2 supported on SiO 2 , Al 2 O 3 and ASA. The hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) properties of the Ni 2 P catalysts were probed using a mixed feed containing carbazole and benzothiophene. While Ni 2 P/SiO 2 catalysts prepared by the different methods exhibited similar HDN and HDS activities, the in situ prepared Ni 2 P/Al 2 O 3 and Ni 2 P/ASA catalysts were substantially more active than their ex situ counterparts prepared from hypophosphite-and phosphate-based precursors.

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The kinetics of realgar (As2S2) oxidation was studied under isothermal and non-isothermal conditions. The obtained values of the activation energy indicate that the process occurs in the kinetic domainwith the realgar particles being converted to As2O3 and As4O6 (g). The very fast reaction rates were limited by the chemical reaction. The kinetic equation was found to be: ?ln (1??) = 4.56 x 103 x e(?8780/T) x t. The proposed reaction mechanism and chemical transformation investigated by ICP?AES, EDXRF and thermal analysis are discussed.