Study On The Catalytic Performance Of Modified Cobalt-based Catalysts For Hydrogen Production From The Hydrolysis Of Sodium Borohydride

As a new type of clean energy with sustainable development,hydrogen energy has been welcomed by all countries in the world and vigorously developed.NaBH₄has a theoretical hydrogen storage up to 10.8%,recyclable by-products and no pollution,making it an ideal hydrogen storage material.It is promising to hydrolyze sodium borohydride into hydrogen by using catalyst,and the selection and preparation of catalyst are critical.In this paper,the Pr modified Co-B catalyst prepared by liquid phase coreduction method is amorphous alloy structure.The doping of Pr effectively increased the amorphous phase and dispersion of the catalyst particles.The catalyst prepared at Co:Pr=16:4 achieves the best catalytic effect,and cobalt chloride is the optimized cobalt source for synthesized catalysts.The Co-Pr-B nanoparticles are irregular flocs,and morphologic mesoporous material with a specific surface area of 63.512m²/g.In the performance tests of Co-Pr-B catalyst,hydrogen production was comparatively the best when the reaction liquid was composed of 5%Na OH and 7%NaBH₄.With the increase of reaction temperature,the hydrogen production rate of hydrolysis reaction of sodium borohydride increased continuously,and the hydrogen production rate reached 10714.3 m L·min^-1·g^-1at 25?.According to the dynamic calculation,the activation energy of the hydrolysis reaction of sodium borohydride with the Co-Pr-B catalyst for hydrogen generation was 38.89 k J/mol.Compared with the Co-B catalyst,the activation energy of the catalyst doped with rare-earth element Pr was significantly decreased.The catalytic activity of the catalyst can be maintained after 5cycles.On the basis of Co-Pr-B catalyst preparation,Co-Pr-B/TiO₂and Co-Pr-B/graphene were prepared by dip reduction method.When the Co-Pr-B nanoparticles were loaded onto the carriers,they were dispersed more evenly,which slowed down the agglomeration,enhanced the stability of the catalyst,and improved the amorphous phase.The Co-Pr-B/TiO₂catalyst was a mesoporous material,and the specific surface area increased to 83.128m²/g compared with Co-Pr-B catalyst.The larger specific surface area provided good surface support for the exposure of active sites in the catalyst.The catalyst prepared with a carrier mass of 50mg,a dipping time of 120min and catalyst load 17%showed the best catalytic performance comparatively.At 25?,the hydrogen production rate of sodium borohydrid hydrolysis with Co-Pr-B catalyst reached 12864.5 m L·min^-1·g^-1.According to the dynamic calculation,the activation energy of the hydrolysis reaction of sodium borohydride with the Co-Pr-B/TiO₂catalyst for hydrogen generation was 31.81k J/mol.Compared with Co-Pr-B catalyst,there was a significant decrease.The stability of Co-Pr-B/TiO₂catalyst was investigated.After 8 cycles,the catalyst still showed good catalytic performance.Co-Pr-B/graphene is also morphologic mesoporous material with a specific surface area of 84.210m²/g.The catalyst prepared with 3mg carrier mass,30min impregnation time and 87%catalyst load showed the best catalytic performance comparatively.At 25?,the hydrogen production rate of sodium borohydride hydrolysis with Co-Pr-B/graphene catalyst reach10981m L·min^-1·g^-1.Moreover,the catalyst still showed excellent catalytic performance after 7 cycles.