Transition metal phosphides (TMP) have excellent capacity and good application prospect for hydrodesulfurization (HDS), which follows the order of Fe2P&lt;CoP&lt;MoP&lt;WP&lt;Ni2P. Oleylamine (OA) can act as surfactant, solvent, reducing agents and stabilizers since it has a high boiling point and controllable complexation property with metals. The liquid phase synthesis in OA is a potential approach providing fine control over the morphology and phase of Nickle Phosphide nanoparticles. This work presents systematic studies done of the influence of synthesis parameters on the phase and size of the NiP particles. Ni acetylacetonate (Ni(acac)2) and (TOP) were reflux in OA with the protection of N2 atmosphere. Figure 1 presents the altered parameters in the synthesis protocol. The default set of parameters (stated in figure 1 caption) leads to spherical Ni2P phase particles with a diameter of about 10 nm. Increasing the OA volume, decreasing T1, or changing the refluxing time do not have detectable influence on the Ni2P nanoparticles phase and size. The first addition of TOP is crucial for morphology control. The subsequent injection of TOP at T1 does not change the particle size. The introduction of TOP only at T1 leads to the formation of hollow Ni2P particles with diameters larger than 20 nm due to the Kirkendall-type mechanism. When T2 increases from 250 oC to 350 oC, there was no obvious change of the nanoparticle size, but the phase evolves from Ni12P5 to Ni2P, and then to Ni5P4, so the T2 is crucial for the phase transformation. Further study will focus on the first step of particle formation to decrease the Ni2P particle size, and silica coating parameters will be investigated to prevent sintering for the application of Ni2P nanoparticles during the HDS reaction.

Morphology and phase control of Ni2P nanoparticles

2019 Fall National Meeting

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