Effect Of Alkali Metal Ions And Complexing Agents On The Catalytic Properties Of Prussian Blue Analogues

Styrene oxide has a wide range of applications in the field of chemical engineering and pharmaceutical because it is an important organic intermediate. Nowadays, the development of efficient, pollution-free and environmental friendly catalysts has been the main direction in the research.This paper summarized the Prussian blue analogues as catalysts at home and abroad, on the basis, mainly studied the effects of alkali metal ions and organic ligand complexes on the composition, crystallinity, morphology and catalytic properties of Prussian blue analogues, and further researched the epoxidation of styrene kinetics:(1) Firstly, we discussed the effect of alkali metal ions. The introduction of the alkali metal in PBA lattice not only adjusted the stoichiometric ratio of the two transition metals, but also changed the crystallinity and morphology of the PBA. The types of alkali metal ion have different effects on the catalytic activity of FeCoPBA catalysts. And the optimum concentration of cesium ion was 5 mM, the styrene conversion increased by approximately 10% and the styrene oxide selectivity by 8%; To rubidium ion, the optimum concentration was 10 mM, increaseing the styrene conversion and the styrene oxide selectivity by 8% and 12%, respectively. This was because alkali metal ions occupied interstitial cavities in the cubic Prussian blue analogues lattice and resulted in framework collapse of catalysts, which made it easier for substrate to get close to active center. Similarly, the alkali metal also improved the catalytic activity of CoFe (Ⅲ) PBA and CoFe(Ⅱ)PBA.(2) Secondly, the effects of complexing agents were researched. The complexing agents were coordinated with the metal of PBA, which have a great influence in the morphology of PBA. And we also studied the role of complexing agents to the catalytic activity of FeCoPBA, CoFe(Ⅱ)PBA and CoFe(Ⅲ)PBA, the results indicated that the same kind of complexing agent had different effects to FeCoPBA, CoFe(Ⅱ)PBA and CoFe(Ⅲ)PBA catalysts, however, the effect of tert-butanol was all the most significant, increasing the styrene conversion with 12%,26% and 23%, respectively. The coordination of complexing agents and the metal of PBA increased the number of active center and decreased the particle size, so utilization of the PBA catalysts were improved.(3) Finally, we investigated the kinetic behavior of CuCoPBA as heterogeneous catalysts for epoxidation of styrene. The reactants and the temperature were studied, and the reaction rate equation and apparent activation energy Ea (100.4 kJ/mol) were obtained. In addition, we proposed a possible mechanism which provided a theoretical basis for industrialization.