The effect of preparation conditions on the properties of high-surface area Ni2P catalysts Original Research Article

The effect of preparation conditions on the properties of unsupported, high surface area Ni2P catalysts, prepared by adding citric acid (CA) to precursor metal salt solutions prior to drying, calcination and temperature-programmed reduction (TPR), is reported. The highest Ni2P surface area (∼220 m2/g) was obtained from a precursor solution with a P/Ni mole ratio of 2 and a CA/Ni mole ratio of 2 that was dried, calcined at 500 °C and reduced in H2 at 650 °C. Adding CA to the precursor salt solution is shown to yield amorphous precursors after calcination, rather than crystalline NiO and Ni2P4O12 that was observed in the absence of CA, and the amorphous material yielded high surface area Ni2P when reduced at temperatures above 600 °C. The high surface area Ni2P favored the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DMDBT) by the hydrogenation route, although some direct-desulfurization was observed on catalysts reduced at lower temperature in which significant metaphosphate species were identified.