Synthesis Of Pt Based Catalysts For Hydrolysis Of Ammonia Borane

Hydrogen energy has the advantages of environmental friendliness and high calorific value.It is one of the new energy sources that is most likely to solve environmental problems and energy crisis.At room temperature,the hydrolysis of AB can realize the rapid release of hydrogen under the catalysis of catalyst.Therefore,the development of efficient and low-cost catalysts for hydrolysis of AB has become a hot research filed.In this paper,carbon nanotubes?CNTs?were used as the support to fabricate Pt/CNTs and PtCoO_x/CNTs catalyst by atomic layer deposition?ALD?,and the catalytic activity of the catalyst for the hydrolysis of AB was investigated.The experimental and characterization results show that the Pt CoO_x/CNTs bimetallic catalyst has higher catalytic activity in the hydrolysis of AB.The modification of Co nanoparticles can improve the electronic environment around Pt nanoparticles.The cleavage of O-H bond in water is the rate determing step of AB hydrolysis.The synergistic effect of Pt-Co can improve the hydrolysis rate by promoting the cleavage of O-H bond.In addition,PtCoO_x/CNTs catalysts show higher selectivity for cinnamyl alcohol in selective hydrogenation of cinnamaldehyde,which indicates that Pt-Co synergistic effect not only has higher activity in the hydrolysis of AB,but also has potential application in partial selective hydrogenation.The morphology and structure of the supports have a great influence on the catalytic activity of the catalyst.In view of this,dendritic fibrous nano-silica?DFN?with open structure and high specific surface area was ssynthesized,and the structure and morphology of DFN were optimized by adjusting the crystallization time and emulsion basicity.On this basis,PtCo/DFN catalyst was prepared by using the optimized DFN as the support and loaded with different mass ratio of Pt Co bimetallic nanoparticles,and applied to the hydrolysis of AB.The experimental results show that PtCo/DFN bimetallic catalyst has higher catalytic activity.When the mass ratio of Pt and Co is 1:2,the catalyst shows the best activity in the hydrolysis of AB.At the same time,the catalytic activity of the bimetallic catalysts can be well retained even after 6catalytic cyclesIt is considered as an effective way to improve the catalytic activity and stability of catalysts.In this experiment,using ALD combined with template sacrifice method,the Rh@TiO₂ confined catalyst can be synthesized,and the activity of the catalyst was systematically studied in terms of calcination temperature and TiO₂ tube thickness.When the calcination temperature is 425?,TiO₂ nanotubes are 11.4 nm,the catalyst shows the best catalytic activity:the activation energy of the catalytic reaction is 28.1KJ mol^-1,and the conversion frequency?TOF?is 334.1 mol _H2 molRh^-1 min^-1.In addition,we found that the catalytic activity of the catalyst can be significantly improved by adding a proper amount of NaOH into the catalytic system.The stability experiment of the catalyst shows that the Rh@TiO₂ confined catalyst has good stability,and the catalyst can still maintain high activity after 6 stability tests.At the same time,the synthesis strategy of this catalyst can also be extended to the preparation of other confined metal or metal oxide?Pd@TiO₂,NiO@TiO₂?catalysts.