Effect Of Cobalt Based Catalyst Supported On Porous Materials On Hydrolysis Of Sodium Borohydride

Sodium borohydride has a mass storage capacity of up to 10.6 wt%and negligible hydrolysis by-products,making it an important material for hydrogen storage and transportation as well as rapid preparation.The process of sodium borohydride hydrolysis requires catalysts to accelerate the reaction to meet the hydrogen production requirements.In this paper,two loaded cobalt-based catalysts were designed and prepared to address the problems of agglomeration and deactivation of sodium borohydride hydrogen production catalysts in the process,and the microstructure of the catalysts and their catalytic performance were investigated and the reaction mechanism of sodium borohydride catalyzed hydrolysis was discussed.The Co O@Co catalysts were prepared by de-templating a flake Co O carrier with 30-50 nm pores and loading the porous Co O carrier with cobalt nanoparticles of about 20 nm in diameter.The microstructural characterization of the Co O@Co catalysts showed that the Co metal nanoparticles had good dispersibility.The prepared Co₃O₄@Co catalyst exhibited a catalytic hydrogen production rate（HGR）of 2608 m L_H2·(g_cat·min)^-1 at 30℃,and maintained 83.6%activity after five rounds of catalytic cycling.The catalytic activity and cycling stability were good.The activation energy E_a was calculated using the Arrhenius equation to be 44.8 k J·mol^-1,which exhibited a low activation energy.The reaction kinetics study of Co O@Co catalyst showed that the catalytic reaction of Co catalyst for Na BH₄aqueous solution exhibited a zero-level reaction for Na BH₄.The reaction rate showed an increasing trend with the increase of catalyst addition.Spherical shell Si O₂（H-Si O₂）with a wall thickness of about 20-30 nm and a diameter of about 500-600 nm was prepared by the de-templating method using carbon nanospheres prepared by hydrothermal reaction as a template.The H-Si O₂@Co catalysts were prepared by surface amino modification using H-Si O₂ as a carrier.The catalytic hydrogen production activity of the catalyst was tested,and the H-Si O₂@Co catalyst exhibited a catalytic hydrogen production rate of 2073 m L_H2·(g_cat·min)^-1 at 30℃,and maintained 88.2%activity after five rounds of catalytic cycles.The comparison of the microscopic morphology before and after the catalytic cycle showed that the Co nanoparticles on the H-Si O₂ surface showed a certain degree of flocculation aggregation after the catalytic reaction,which was the main reason for the activity reduction.The activation energy of the reaction was calculated to be 51.7 k J·mol^-1.The reaction kinetics study showed that the catalytic hydrogen production from Na BH₄ hydrolysis showed a typical zero-level reaction.