Hydrogen Generation From Catalytic Hydrolysisi Of Alkaline Sodium Borohydride In A Micro-scale Fluidized Bed

In recent years, with the rapid development of the global economy, the demand on energy is soaring. Due to energy shortage and environmental deterioration et. al,a new kind of renewable clean energy is potential to meet the demands of the quick development of global economy. In the process of hydrogen development and utilization, the storage and transportation problems of hydrogen hindered its large-scale application. As a result, sodium borohydride hydrogen generation system is drawing much attention of researchers at home and abroad for its superiorities.In the earlier stage, research emphasis of hydrogen production technology from hydrolysis of sodium borohydride concentrated on the hydrogen generation catalysts. study about the hydrogen generation reaction is rare. Reactors, the place where the hydrogen generation reaction takes place, play a dominate role that can affect the efficiency and safety of the hydrogen generation process. Taking all above into consideration, a new type of reactor was introduced in this paper. Firstly, fluidization characters of the micro-scale fluidization bed were studied, and then the investigations into hydrogen generation from catalytic hydrolysis of alkaline sodium borohydride solution in the micro-scale liquid-solid fluidization bed were done.In this paper, a set of micro-scale fluidized bed hydrogen generation equipment were put up, and at the later stage, it were used as the hydrogen generation reactor. The walnut shells are applied as the raw material to prepared the supporter of the catalyst of the hydrogen generation reaction, the walnut shell activated carbon supported Co-B catalyst were made by impregnation reduction method. This catalyst can not only realizing resource utilization of the abandoned biomass, but showed relatively high catalytic activity, and this catalyst is easy to prepare and its cost is low. Some test methods were applied to represent the characters of the catalyst.Additionally, in this paper, quartz sand and walnut shell activated carbon of different diameters is applied to investigate the fluidization characters of the micro-scale liquid-solid fluidized bed, the flow pattern in the micro-scale liquid-solid fluidized bed were defined by the cold model experiments and also compared with the flow pattern in the regular size liquid-solid fluidized bed. There showed three flow patterns in the micro-scale fluidized bed. The flow velocity range of each flow pattern is slightly influenced by the filling height, whereas, with the decrease of the particle diameter and density, the flow velocity ranges of the particulate fluidization decreases. With the increase of the filling height, expansion ratio decreases, but the uniformity efficiency increases; with the decrease of the particle diameter and density, the effect of flow velocity on filling height gets significant and the uniformity efficiency increases. With the increase in filling height and decrease in particle diameter, the bed pressure drop increases, fluidization quality is improved. The minimum fluidization velocity has the same vary trend with particle diameter and density.In the last chapter, investigations into hydrogen generation from catalytic hydrolysis of alkaline sodium borohydride solution in the micro-scale liquid-solid fluidized bed were done. With the decrease of the reaction solution concentration, the lengths of stable hydrogen generation time gets longer fist and then gets shorter. When the concentration of NaBH4 is 2 wt.%, the stable hydrogen generation time accounts for 58.46 % of the total reaction time. The reaction solution flow velocity has little effect on the total reaction time, but it can affect the stable hydrogen generation time, with the increase of the reaction solution flow velocity, the stable time becomes longer first and then becomes shorter, when the flow velocity is 3.00×10-3 m·s-1, the longest stable hydrogen generation time can be obtained under this condition. Higher temperature can accelerate the reaction, but adverse for the stability of the hydrogen generation process, the reaction rate has the same vary trend with the temperature, and so does the total reaction time; when the temperature is 25 °C, the longest stable hydrogen generate time can be obtained. The particle diameter has little effect on the stability of the hydrogen generation process, the smaller the particle is, the faster the reaction becomes, and that is to say the total reaction time will get shorter.