Study On Catalytic Hydrolysis Of Sodium Borohydride

With the depletion of fossil energy in the world and the intensification of environmental pollution,hydrogen energy has attracted wide attention from all over the world due to its high energy density and environmental friendliness.Currently,water,natural gas,coal and hydride are studied as the main raw materials for hydrogen production.Among the hydride hydrogen production technologies,sodium borohydride is most widely used because of its high hydrogen purity,safety and pollution-free.The choice of catalysts in the process of hydrogen liberation of sodium borohydride water is particularly critical.Because precious metals are rare and expensive,it is of great significance to study catalyst systems for non-precious metals.The paper mainly studied the effect of mixed catalysts obtained by mixing CoCl₂ with Y₂O₃,TiO₂ and Ag₂SO₄ in different ratios on the hydrogen liberation performance of sodium borohydride.The experiment firstly used the drainage method to study the different ratios of mixed catalysts?mixed catalysts accounted for the percentage of sodium borohydride:6%,8%,10%,12%,14%?on the hydrogen liberation performance of sodium borohydride water,and The optimum ratio of mixed catalyst was obtained.Secondly,under the optimal ratio,the effect of the amount of NaOH on the hydrogen liberation performance of sodium borohydride was further studied.Finally,the catalytic hydrolysis products were tested by SEM and XRD.The results show that the type,content and doping ratio of the mixed catalyst will change the hydrogen liberation performance of sodium borohydride.Among all the mixed catalyst systems,the catalyst system with the largest hydrogen release amount is 6%?CoCl₂ 30%+Ag₂SO₄ 70%?,reaching 2690 mL·g^-1;the catalyst system with the fastest hydrogen release rate is 14%?CoCl₂ 70%+Y₂O₃ 30%?,reaching 136.67 mL·min^-1·g^-1;The amount of NaOH added has a significant effect on the hydrogen liberation performance of sodium borohydride.When NaOH is present in the system,the rate of hydrogen evolution is significantly increased,and the amount of hydrogen released is significantly reduced.For the optimal ratio of CoCl₂/Y₂O₃ mixed catalyst 10%?CoCl₂ 70%+Y₂O₃ 30%?,with the increase of NaOH addition,the hydrogen release rate first increases and then decreases.When it is 0.4 g,the hydrogen release rate is the highest,reaching 391.7mL·min^-1·g^-1.Compared with the system without NaOH,the hydrogen release rate increased by 283%,but the hydrogen release amount decreased from 2555 mL·g^-1 to 2350 mL·g^-1.When the amount of NaOH added increased to 0.8 g,the rate of hydrogen evolution decreased to 287.5 mL·min^-1·g^-1;The SEM and XRD tests of the sodium borohydride hydrolyzate catalyzed by CoCl₂/Y₂O₃ showed that the content of the mixed catalyst,the doping ratio and the amount of NaOH added had no significant effect on the morphology and phase of the sodium borohydride hydrolysate.The catalyzed sodium borohydride hydrolysate is Y₂O₃-Co₂B,and the morphology is basically the same,and both of them have agglomerated granular structure.