Synthesis And Properties Of Nickel Phosphate Nanotubes

Metal phosphate nano-materials with abundant P-O coordination polyhedron and open frame structure, showed diversity and uniqueness in the aspects of structure and performance, and nanotubes materials with special structure and excellent performance of optics, electricity, mechanics, chemistry, magnetics and thermodynamics, so metal phosphate nanotubes materials have a broad application prospect. In this thesis, nickel phosphate nanotubes were obtained via soft template method. Furthermore, the formation mechanism and performance of nickel phosphate nanotubes were explored.(1) With CTAB as soft template and urea as assistant agent, nickel phosphate nanotubes were obtained via hydrothermal method. The effects of the reactant concentration and solution pH value on the morphology and particle size were examined, and the structure and morphology performance were tested by means of XRD, IR, SEM, TEM, et al.. The results show that nickel phosphate nanotubes seemed like tremella or coral, which consist of nanotubes with diameter of about 8 nm, length of about 200 nm, rounded channel and open end.(2) Through studying different experimental conditions, we deduced that the formation process of nanotubes was sheet-tubes-flake. Firstly, nickel phosphate formed sheet structure under the effect of CTAB, and then the sheet edge curled into a tube, finally these tubes arranged orderly themselves into flake. Nickel phosphate nanotubes show special catalytic performance. Reaction products are mainly propanal, allyl alcohol and acetone, with the molar ratio of about 5/3/2. With 4h-B-NiPO, which were prepared at the condition of molar ratio of P:Ni:urea:CTAB:H2O is 1:0.7:9:0.8:120 for 4h, as catalyst, the highest propylene oxide conversion and selectivity for propanal at 300℃ are 74.1% and 49.4%, respectively.(3) The lithium ion-doped nickel phosphate (LixNiPO) whose main components is orthorhombic NiNH4PO4·H2O were obtained via hydrothermal method. Li0NiPO looked like ball of yarn and LixNiPO(x=0.05,0.1,0.15) seemed like rose, The results show that introduction of the Li element has a great influence on their morphology, which may be due to the Li atomic radius is smaller than Ni. Li0.1NiPO and Li0.1sNiPO showed the poorer performance for isomerization reaction of propylene oxide.(4) Three different shapes of lithium phosphate catalyst were obtained, and their structure and morphology were investigated by XRD, SEM and TEM. The results show that they were of orthorhombic β-Li3PO4, and their intensity of characteristic peak change with the shape. B-Li3PO4 is stick structure, P-Li3PO4 is flake structure, and Q-Li3PO4 is hollow spheres structure. The Q-Li3PO4 shows the highest yield, the highest propylene epoxide conversion and best selectivity for allyl alcohol are 75.6%,90.1% and 89.2%, respectively.