Preparation Of Multi-element Co-based Catalysts And Their High-efficiency Dehydrogenation Of Hydrazine Borane

The advancement of science and technology has improved the quality of life of mankind,but at the same time,the exhaustion of fossil energy and environmental pollution have become more and more serious,which has triggered people's exploration of new energy sources.As the energy density of hydrogen is as high as 142 MJ/kg,and its combustion products are environmentally friendly,and have abundant earth reserves and various sources,it has been regarded as the most promising energy carrier to replace fossil fuels.Based on these advantages,the development of a hydrogen energy economy can not only hopefully replace fossil fuels,but also reduce the ever-increasing carbon emissions of using hydrocarbons as fuel,which is conducive to economic growth and achieves the goal of sustainable development.Among many hydrogen storage materials,hydrazine borane(N₂H₄BH₃,HB)has a hydrogen content of 15.4 wt%.It is a very promising hydrogen storage materials because it can be stored stably under mild conditions as a solid phase and has good stability in aqueous solutions.The dehydrogenation reaction of HB is closely related to the catalyst that catalyzes the reaction.Therefore,it is highly important to develop an efficient catalyst to improve the rate and conversion of the reaction for the application of HB as a hydrogen storage material.The current catalysts for HB hydrolysis and dehydrogenation mainly include precious metal catalysts,Ni-based precious metal alloy catalysts,and non-noble metal(Ni and Ni-based non-noble metal alloys)catalysts.For noble metal catalysts,the cost of the catalyst greatly limits the practical application of the catalyst,and the catalytic efficiency of most Ni-based catalysts and non-noble metal catalysts still needs to be improved for achieving industrialization.In response to the above problems,the research of this thesis mainly includes the following two aspects:1.Commercial Ti O₂(P25)has been chosen as the carrier material because it has good hydrophilicity,good dispersibility in aqueous solution,small average particle size,and large specific surface area.At room temperature,the Co Ir metal nanoparticles are loaded on the base material Ti O₂ by the co-reduction method,and for the HB dehydrogenation reaction the obtained Co_0.6Ir_0.4/Ti O₂ nanocomposite has a conversion rate of 100%and the conversion frequency(TOF)of 5625 h^-1.The TOF is better than most Ni-based noble metal alloy catalysts.2.In order to further improve the activity of the catalyst,inspired by the trimetallic catalysts,the obtained Co_0.6Ir_0.2Ru_0.2/Ti O₂ by introducing Ru into Co_0.6Ir_0.4/Ti O₂ can also catalyze the complete hydrolysis of HB,with the TOF of 10000 h^-1.Moreover,the cycle stability of the catalyst is good,and the conversion rate of HB hydrolysis reaction is still 100%after 8 cycles.