The Synthesis Of MOFs Supported Metal Nanocatalyst For Hydrolytic Dedydrogenation Of Ammonia Borane

With the rapid development of society and economy,the demand for energy is growing.Traditional fossil fuels will not only bring environmental pollution but also have limited resources to meet social needs.As a green energy source in the 21st century,hydrogen energy is rich in reserves,widely sourced,environmental benignity and non-toxic.It is widely used in hydrogen-powered vehicles,hydrogen power generation,fuel cells and household hydrogen.However,one of the major problems that restricts hydrogen energy development is the storage of hydrogen.Ammonia borane with high hydrogen density,light weight and no toxicity,is regarded as the most promising solid material for hydrogen storage.It can release 3 equivalents of hydrogen by hydrolysis in the presence of a suitable catalyst.Therefore,it is particularly important to develop high-performance and low-cost catalysts applied to ammonia borane for hydrogen production.In this paper,bimetallic and trimetallic nano particles were used as active components,and metal organic framework MIL-101 was used as carrier to prepare high performance supported metal nanocatalyst for hydrolytic dehydrogenation of ammonia borane.The research mainly includes two parts:1.Catalysts of different non-noble metals Co,Cu,Fe,Ni composite with Ag then loaded onto MIL-101 were prepared by a simple liquid phase impregnation reduction method.The catalytic activity of AgCo@MIL-101 was found to be the best in the hydrolysis of ammonia borane.The phase composition,morphology,specific surface area metal state and metal loading of the catalyst were characterized by XRD,BET,TEM,XPS and ICP-MS.The catalytic properties of catalysts by different metal precursor concentrations,types,molar ratios and different supports were investigated.The experimental results showed that Ag0.3Co0.7@MIL-101 prepared by a chloride precursor with a concentration of 0.6M exhibited the highest catalytic activity.The TOF value was 12.4 molH2/(min·molcat)for ammonia borane hydrolysis at room temperature,and the activation energy of the reaction was 34.53 kJ/mol.The catalyst maintained 58%of its initial catalytic activity after repeated use for five cycles.2.CuFeCo@MIL-101 catalyst was prepared by liquid phase reduction method with ternary non-noble metal Cu-Fe-Co as active component.The morphology,composition,specific surface area,metal state and metal loadings of the catalyst were characterized.With the optimal experimental conditions of the above experiments,the catalytic performance of the three-metal catalyst and the bimetallic catalyst as well as the most suitable molar ratio between the three metals were researched.Cu0.6Fe0.08Co0.32@MIL-101 showed the best catalytic performance at room temperature with a high TOF value of 23.2 molH2/(min·molmetal),and an activation energy of 37.1 kJ/mol.The catalyst maintained 60%of its initial catalytic activity after seven cycles.