Synthesis Of Porous Metal-organic Framework (MOFs) And MOFs-derived Carbon Supported Transition Metal Nanocatalysts And Their Catalytic Performance For Dehydrogenation Of Ammonia Borane

With the increasingly scarce energy supply,solving the energy problem has become a major challenge for almost all the countries at present,and hydrogen energy is one of the new energy sources that many countries prioritize and vigorously advocate.From the point of view of the current research status,the preparation of searching for more effective safety cheap way is the key solution.Chemical hydrogen storage materials,as the carriers of hydrogen storage,the first advantage is to have a relatively high rate of hydrogen storage,the second is to ensure the safety of the hydrogen controlled release,the third is convenient transportation,and other advantages.So it has attracted a lot of researchers to make futher studies.During the experiment,the MOFs are selected as the carrier,which is a kind of porous material with orderly structure,and it not only has good chemical properties,but also has been widely used in the field of optics,such as gas sensing,photoelectric converter,microstructure preparation and other applications such as LED lamps.In this dissertation,we focus on the synthesis and characterization of transition metal catalysts,their application for dehydrogenation of ammonia borane?AB?and related experimental mechanism,the paper can be divided into four parts:?1?The first part is the Rh-based nanocatalysts catalyzed the hydrolysis of ammonia borane at 298K.The use of precious metal is under control due to big expense and finite abundance,so we introduce cheap metals Co into the Rh-based nanocatalysts for the first time.The highly dispersed CoRh nanoparticles have been successfully fixed on ZIF-67through an in situ co-reduction.The Co_0.75Rh_0.25/ZIF-67 nanocatalyst exhibited the noticeable excellent catalytic performance toward hydrolytic dehydrogenation of AB,with a TOF value of 100.21mol _H2.mol^-1_catalyst.min^-1 and 100%H₂ selectivity,which is higher than a majority of the reported catalysts.?2?The second part is the non-noble metal NiCo-based nanocatalysts catalyzed the hydrolysis of ammonia borane at 298K.For the first time,we Choose to use ZIF-67 derived nitrogen-doped porous carbon?NPC-n?as the support anchored NiCo nanoparticles.Compared with Ni_0.8Co_0.2/NPC-800,Ni_0.8Co_0.2/NPC-1000 and Ni_0.8Co_0.2/ZIF-67,the Ni_0.8Co_0.2/NPC-900 nanocatalysts exhibited the noticeable excellent catalytic performance toward hydrolytic dehydrogenation of AB,with a TOF value of 48.5 mol_H2.mol catalyst^-1.min^-1,100%H2 selectivity and good durability.The catalytic activity of NiCo nanoparticles supported on ZIF-67 derived nitrogen-doped porous carbon?NPC-900?has been significantly improved,which may be explained by the high specific surface area of nitrogen-doped porous carbon with high graphitization level.The use of nitrogen-doped porous carbon?NPC?to prepare nanocatalysts with excellent catalytic properties may open up a new way to prepare NPC loading metal nanoparticles for other applications?3?The third part is that the synthesis of ternary NiCoP nanoparticles supported on ZIF-67-derived oxygen-doped porous carbon?OPC-300?have successfully been used to catalyze AB hydrolysis at room temperature for the first time.The firstly obtained Ni_0.66Co_0.19P_0.15/OPC-300 nanocatalysts shows a high TOF value of up to 95.24mol _H2?mol^-1_cat?min^-1 in NaOH?0.4M?solution at 298K,which is the best catalytic activity at room temperature among these reported first-row late transition metals NP systems up to now.After 5 cycles,it still maintained 85.0%catalytic activity and 100%H₂ selectivity.These catalysts not only improved the catalytic performance of noble-metal-free catalysts for AB hydrolysis,but also forcefully promote the available application of AB as a promising chemical hydrogen storage in the coming clean energy economy.Additionally,this facile method maybe open up a new applied avenue of TMPs in the future.?4?The fourth part is that the mechanism of the hydrolysis of ammonia borane catalyzed by the nanocatalysts was systematically explored,and the key role of nanocatalysts in the process of catalytic hydrolysis was further revealed,which is served as the theoretical basis to search effective nanocatalysts.