The Preparation Of Amorphous Alloy Catalyst And Its Catalytic Performance Of Sodium Borohydride Hydrolysis To Produce Hydrogen

With the development of global industrial economy,the cincerns over the environment pollution and the depletion of fossil fuels supplies and global warming attributable to the greenhouse effect caused by a steep increase in carbon dioxide and other gases have made hydrogen one of the most promising future energy resources.Hydrogenation by hydrolysis has received great attention due to its mild reaction conditions,high hydrogen purity,and no harm to the environment.As a metal hydride,sodium borohydride has become one of the hot spots in the field of hydrogen production due to its large hydrogen storage density,high hydrogen production purity,low reaction temperature,safe storage and transportation,and excellent energy cycle utilization.The key technology of hydrolysis of sodium borohydride to produce hydrogen lies in catalyst.Aiming at the existing problem such as expensive of precious metal catalysts,cheap transition metal cobalt was chosen as the main active component in this work..In order to improve the catalytic performance of Co-B catalyst,a new ternary alloy catalyst was formed by doping promoter Mo and Cr in the preparation of Co-B catalyst.In this study,a series of Mo&Co-doped ternary Mo-Co-B and Cr-Co-B amorphous alloy powders,catalysts for sodium borohydride hydrolysis for hydrogen production,were prepared by chemical reduction.The structure and properties of the alloy samples were characterized by X-ray diffractometer(XRD),transmission electron microscope(TEM),scanning electron microscope(SEM)and surface area and pore size analyzer(BET).The characterization results of the catalysts were correlated with the activity of the catalysts in order to produce the best hydrogen production catalyst.Hydrogen dehydrogenation experiments of NaBH4 hydrolysis were carried out in a drainage device to test the catalytic activity and recycling performance of the catalyst.The catalytic hydrolysis kinetics of NaBH4 solution was studied by single factor experiment.The effects of reaction temperature,NaBH4 concentration,NaOH concentration and catalyst dosage on the hydrolysis of sodium borohydride were discussed.The experimental results show that the doping of Mo and CO can effectively prevent the agglomeration of Co-B nanoparticles,thus reducing the size of spherical nanoparticles and improving the specific surface area and dispersion of the particles.The doping of promoters has a significant effect on the catalytic performance of Co-B catalyst for NaBH4 hydrolysis to produce hydrogen.Through comparative analysis,under the same conditions,the hydrogen production rate increases first and then decreases with the increase of doping amount of accelerator.In the Mo-Co-B system,when n(Mo)/n(Co)was 0.05,the catalyst Mo-Co-B-3 obtained the largest specific surface area of 82.079 m2/g,showing the best catalytic activity.The hydrogen production rate reached the maximum,which was 4642.8 ml min-1·g-1,4.7 times that of Co-B catalyst.In the system of Cr-Co-B,when n(Cr)/n(Co)was 0.005,the maximum specific surface area of catalyst Cr-Co-B-2 is 66.402 m2/g,and the maximum hydrogen production rate is 2112.5 ml·min-1·g-1,which is 2.1 times of that of Co-B catalyst.