Fabrication Of Catalysts For Hydrolysis Of Boron Compounds For Hydrogen Generation And The Study On Their Catalytic Performance

Over the past century,the use of fossil energy has promoted the rapid development of the human civilization.But at the same time also caused serious pollution to human survival environment.At present,as the main fossil energy gradually been used up and people's emphasis on environmental problems,hydrogen as a new type of energy will be acted as a sustainable energy to provide security for the future of human.But hydrogen storage is one of the bottleneck problems for hydrogen energy generally use.Currently,hydrogen storage methods mainly include physical and chemical technology.In the chemical hydrogen storage technology,fabrication suitable catalysts for hydrogen release is one of the key points for development of hydrogen storage technology application.This thesis investigates the catalytic hydrolysis of NaBH₄ and NH₃BH₃?AB?.On this basis,we designed and synthesis of a series of catalysts which is low-cost,environment friendly,with high catalytic activity and stability.According to the different hydrogen source systems,the research contents are following:1.The catalytic hydrolysis of NaBH₄The graphene oxide?GO?exhibits excellent superiority as an ideal supporting material for active sites loading and the non-noble matal alloy catalysts exhibit high activity.Herein,The Co-Sn-B/GP nanoparticle catalyst was prepared by in situ reduction of metal salts on the surface of GO.Citric acid radical was used as the complexing agent.The catalyst was added into the solution which containing 5wt.%NaOH and 5wt.%NaBH₄,a maximum hydrogen generation rate of 11,272 mL min^-1 g_Co^-1 was obtained.The rate was three times higher than that of the Co-B catalyst.The activation energy of the hydrolysis reaction was calculated to be 39.57 kJ/mol.This value of activation energy was similar as many other noble catalysts.The addition of graphene carrier makes its surface to generate more amorphous alloy,and the addition of complexing agent could prevent particles from agglomeration,all these help to improve the catalytic activity.2.The catalytic hydrolysis of NH₃BH₃For the NH₃BH₃ hydrogen source catalytic hydrolysis system,we prepared the catalyst of Ru/NC-Fe?Pt/CCF and Ru@Co/CCF via different methods.?1?We obtained a mesoporous NC-Fe material through the carbonization of a ferrocenecarboxaldehyde-based POP material,and the obtained NC-Fe was then modified with highly dispersed Ru NPs to form the Ru/NC-Fe catalyst.The Ru/NC-Fe catalyst was used for catalytic hydrogen generation from AB and showed excellent catalytic activity compared with many other noble metal-based catalysts.In this reaction,the hydrogen generation rate of 102.9 mol_H2 mol Ru^-1 min^-1 and the activation energy of 47.42 kJ mol^-1 were obtained.Moreover,the prepared catalyst can be magnetically recovered and recycled due to its ferromagnetism.?2?We fabricated of Pt-based catalysts using commercially available medical absorbent cotton as the catalyst support precursor.Under the carbonization temperature of 500?,ultrafine and well-dispersed Pt NPs modified catalyst Pt?8%?/CCF-500 was obtained,and performed excellent effect for the catalytic hydrolysis of AB as compared with many other reported noble metal-based catalysts.In this reaction,the hydrogen generation rate of 35 mol_H2 mol _Pt^-1 min^-1 and the activation energy of 39.2 kJ mol^-1 were obtained.The result indicates that the calcination temperature has a serious influence on the size of the Pt NPs.?3?In this work,the cotton was used as the starting supporting material,we fabricated the Ru@Co/CCF catalyst with low Ru loading.The obtained Ru@Co/CCF nanocatalyst showed excellent catalytic activity in the catalytic hydrolysis of AB with a turn-over frequency of 139.59mol_H mol^-1min^-1as compared with other noble metal-based catalysts.The activation energy of this reaction is 57.02 kJ mol^-1.Moreover,owing to the ferromagnetic property of the metallic Co,the Ru@Co/CCF nanocatalyst can be facilely recovered with an external magnet and reused with high catalytic stability.It is indicated that catalyzed by a noble metal nanoparticles-based catalyst,only the surface atoms of the active sites are utilized in the reactions and the noble metal atoms in the inner core are inactive.Thus,in the view of Ru metal saving and maximum utilization of Ru active sites,the inner core of the Ru NPs should be replaced by non-noble metals to fabricate functional catalysts for catalytic hydrolysis of AB.