Study On The Catalytic Performance Of Co-M-B (M=P,W) Catalyst For Hydrogen Production From The Hydrolysis Of Borohydride

So far,the energy crisis has become increasingly serious due to the depletion of traditional fossil fuels.In view of this situation,hydrogen energy as one of the new energy materials,has been widely concerned because of its high efficiency and pollution-free combustion products.However,the hydrogen generation is one of the most important problems that needs to be addressed.Recently,ammonia borane（NH₃BH₃）and sodium borohydride（Na BH₄）are widely used as hydrogen storage materials with good stability and high hydrogen storage capacity.Under the existence of appropriate catalysts,NH₃BH₃and Na BH₄can produce the hydrogen gas by the means of hydrolysis.Although noble metal catalysts have high catalytic performance,they are limited in wide use due to their high price and lack of resources.Therefore,it is particularly important to explore and prepare non-noble metal catalysts with high catalytic performance.In this paper,three different thin film catalysts were prepared chemical deposition method,and their catalytic performance for hydrogen production from the hydrolysis of borohydride was studied.The main research contents and results are as follows:1.Co-P-B thin film catalyst based on titanium foil（Co-P-B/Ti foil）was successfully prepared and applied to the hydrolysis of Na BH₄for hydrogen production.The synthesis conditions were optimized based on the aspects of chemical deposition time,reducing agent concentration and p H value.The results revealed that the optimal deposition time was 20min,reducing agent concentration was 0.8 mol·L^-1,and the deposition p H was 13.0,respectively.The obtained Co-P-B/Ti foil showed high catalytic performance for the hydrolysis of Na BH₄solution,its hydrogen production rate reached 5529.7 m L·min^-1·g^-1,and its apparent activation energy value was 48.4 k J·mol^-1.Moreover,the hydrogen release rate of the catalyst is 59.7%of the initial value for Co-P-B thin film catalyst after five cycles of testing.2.Co-P-B thin film catalyst deposited on foam nickel was successfully achieved,and its catalytic performance for hydrolysis of Na BH₄to produce hydrogen was studied.In this experiment,the concentration of reducing agent and p H value synthesis conditions were optimized.It can be seen that the particle size of prepared Co-P-B/foam Ni catalyst was the smallest when the reducing agent concentration and p H value were adjusted to 0.8 mol·L^-1and12.0,respectively,The hydrogen production rate of hydrolysis of Na BH₄solution was 5887.4m L·min^-1·g^-1,and the activation energy was 41.4 k J·mol^-1.In addition,the hydrogen release rate of the catalyst is still 79.3%of the initial value for Co-P-B thin film catalyst after five cycles of testing,which illustrated that it had good cycle stability.More importantly,when compared with Co-P-B/Ti foil,Co-P-B/foam Ni showed the better catalytic performance and cycle stability.It can be inferred that the substrate material with three-dimensional structure is conducive to improve the catalytic activity,which will be a good support for the preparation of thin film catalyst in the future.3.Co-W-B/foam nickel film catalyst was successfully prepared and was applied to the hydrolysis of NH₃BH₃to produce hydrogen.The results showed that Co-W-B/foam Ni catalysts displayed the good catalytic property when the deposition p H value was adjusted to 11.5.The Co-W-B catalyst exhibited an irregular spherical structure with the smallest particle size on the surface of foam Ni substrate.Its high hydrogen production rate of 12933.3 m L·min^-1·g^-1and lower apparent activation energy of 47.3 k J·mol^-1were obtained.By comparation with the reported catalysts,it can be found that the catalytic performance has surpassed most of Co-based catalysts,and even some noble metal catalysts.It may be attribute to the unique microstructure and the synergistic effect of Co,W and B for the synthsized Co-W-B/foam Ni film catalyst.