Study On The Fabrication Of MOFs Solid-loaded Ruthenium-based Catalysts And Their Catalysed Hydrogen Producing Capability Of Ammonia Borane

As oil reserves are depleted and GHG emissions keep rising,interest in hydrogen energy is growing.Hydrogen is essentially the most abundant element throughout entire universe,making up about 75%of the mass of all known matter,and is considered to be one of the most plentiful elements available on the surface of the Earth.With its advantages such as high energy density and zero emissions,it is widely considered to be one of the most progressive sources of clean energy.However,effective storage and controlled release of hydrogen is a challenge.Catalytic hydrogen production using hydrogen storage chemicals has attracted attention as a convenient,inexpensive and efficient way to solve the problem of hydrogen storage and transportation.Considered as an important energy storage material,ammonia borane has many advantages,including good robustness within the natural environment,high hydrogen content,non-toxicity and environmental friendliness.Hydrogen release from AB with a hydrogen content of 19.6 wt%can be achieved by hydrolysis,alcoholysis,or pyrolysis.And hydrolysis is a low-pollution and mild method for hydrogen production.However,in the absence of catalyst,the hydrolysis reaction rate of AB is slow at 298 K.So far,noble metal catalysts have been extensively studied,but their high cost and limited storage make it difficult to be widely used.Therefore,reducing the amount of noble metals and combining noble and non-precious metals in the form of alloys can greatly improve the efficiency of noble metals and prepare cheap and efficient catalysts,which are essential for hydrolysis reactions.In addition,the introduction of core-shell and alloy structures can obtain higher surface area than monomers and improve the catalytic activity of catalysts.Metal organic backbone materials（MOFs）are topological structures formed by interconnecting metal nodes and organic ligands.MOFs are versatile and distinctive materials due to their multiple active sites.MOFs have ligand-unsaturated sites,known as open metal sites,which can aid in better metal-reactant interactions as well as tunable structures and properties,and have attracted attention as new functional materials.In current multiphase catalytic applications,MOF materials are used as carriers for loading metal nanoparticles.In this paper,based on the structural and physical properties of MOFs materials,a series of highly efficient catalysts M@MOF loaded with metals from MOFs materials were designed and prepared,and these catalysts were compared to study their catalytic activities,influencing factors and stability.The research of this thesis includes.1.Low-cost and efficient preparation of catalysts is a key challenge for the widespread application of hydrogen materials for water storage,such as for hydrogen production by hydrogen hydrolysis of ammonia borane.Highly dispersed Ru,Mo and Sn trimetallic alloy nanoparticles supported by MOF-801 were synthesized via a simple liquid impregnation reduction method.The catalysts were described by XRD,ICP-AES,TEM,XPS and EDS.The catalyst Ru Mo Sn@MOF-801 was tested for its catalytic activity in the formation of aqueous hydronium from ammonia-borane solution at ambient air temperature.The obtained values indicate that the combined Ru₁Mo_0.5Sn_0.1@MOF-801 catalyst demonstrated the best catalytic activity and the excellent catalytic activity of the catalyst Ru Mo Sn@MOF-801 was successfully achieved due to the strong bimetallic synergy of the Ru Mo Sn nanoparticles in the catalyst,the uniform distribution of the nanoparticles and the bifunctional effect,with an Ea of35.6 k J/mol and a TOF value of 245.4 mol H₂ min^-1（mol Ru）^-1.Notably,the catalyst achieved satisfactory hydrogen production from ammonia borane and showed a durable stability after 5cycles.2.Ru Fe@MIL-69 composites with different Ru/Fe ratios were successfully synthesized by liquid impregnation,and the results showed that different loadings had different effects on the experimental results The catalyst activity was measured by hydrogen production from the hydrolysis of ammonia borane,and the results showed that the hydrogen release rate was the fastest when the Ru/Fe ratio was 1:0.1,i.e.,the catalytic hydrolysis activity of the metal ratio was the highest under this condition.The hydrolysis experiments at different temperatures showed a TOF of 262.7 mol H₂ min^-1（mol Ru）^-1 at Ru₁Fe_0.1@MIL-69 Ea 27.0 k k J/mol.The increased catalytic activity can be attributed to the synergistic effect between the metal particles and the bifunctional interaction between the Ru Fe bimetal and the MIL-69 carrier.In addition,the catalyst showed good stability after five cycles.3.The porous octahedral copper-based metal-organic backbone MOF-199 was prepared by a simple liquid impregnation method and used as a high-performance catalyst for the hydrolysis of ammonia borane at room temperature.The catalytic activities of Ru@MOF-199,Ru Mo@MOF-199,Ru P@MOF-199 and commercial Ru/C were compared,and it was found that Ru Mo P@MOF-199 had a very high turnover rate of 735.6 mol H₂ min^-1（mol Ru）^-1 and a low activation energy of 46.9 k J mol^-1.Due to the synergistic effect,functional effect,size effect and support effect,the Ru Mo P NPs loaded on MOF-199 can kinetically promote the oxidative degradation of the attacked H-OH and improve the catalytic performance.In addition,the catalyst showed satisfactory durability for hydrolytic dehydrogenation of AB after five cycles.The novel structural features and efficient performance will be an important reference for the development of high-performance catalysts.