Controlled Synthesis And Catalytic Properties Of Lithium Phosphate Micro/Nano Particles

The aim of this study is to prepare a series of Li3PO4 particles through different synthesis methods and Li3PO4 particles with small size via simple chemical methods for industrial application. Furthermore, the formation mechanism of lithium phosphate hollow structure was explored.1. Li3PO4 diamond particles were prepared via urea homogeneous precipitation. The effects of the reactant concentration and surfactant on the morphology and particle size were examined and the catalytic performance of product was measured. The results show that the size of particles change from large to small as the concentration of reactants increases, the particle dispersivity is better when adding CTAB. Propylene epoxide conversion and selectivity for allyl alcohol at 320℃ are 65.4% and 56.8%, respectively.2. Li3PO4 flaky particles and spherical particles were prepared by a simple hydrothermal method. The effects of the reactant solvent and surfactant on the morphology and particle size were examined and the catalytic performance of product was measured. The results show that the size of particles with mesoporous structure change from 5μm to 1μm when adding surfactant, and the particle dispersivity is well. The large particles are covered with small 100nm-200nm particles. Ethanol-water (the volume ratio of 1 to 1) solvent is favorable for micro-directional spherical particles stacked by flaky particle. The Li3PO4 catalyst prepared with ethanol-water (the volume ratio of 1 to 1) solvent shows the highest propylene epoxide conversion and best selectivity for allyl alcohol are 65.4% and 56.8%, respectively.3. Hollow Li3PO4 spherical particles were prepared via chemical precipitation method. The effects of the reactant concentration and surfactant on the morphology and particle size were examined and the catalytic performance of product was measured. The results show that the hollow structure become obvious gradually as the molar ratio of material increases. When molar ratio of LiOH and Na3PO4 is 4:1, the hollow structure is the most obvious with the maximum specific surface area. And the Li3PO4 catalyst shows the highest propylene epoxide conversion and selectivity for allyl alcohol at 280℃ are 95.5% and 94.1%, respectively. In the spectra of the inactivated LisPO4 catalyst there is a peak near 2848-2988cm-1which can be attributed to the C-H bond stretching vibration. It proves the existence of organic carbon deposits in the inactivated Li3PO4 catalyst.4. The formation mechanism of the hollow Li3PO4 spherical particles was inveastigated. The results show that the hollow degree and particle size of product change as the reactant solution concentration changes. The hollow degree changes as the reaction time and the reaction temperature change. By comparing the different morphologies and crystallization the formation of the hollow structures is based on Ostwald ripening process. And in the process the size of particles and hollow structures were affected by the reactant concentration, reaction time, reaction temperature and other conditions.