| Sodium borohydride (NaBH4) is now recognized to be one of the promising hydrogen storage materials, because of its high theoretical hydrogen storage capacity, energy density, safety and reliability. The effect of stabilizer on hydrogen generation was investigated by measuring the hydrogen generation performance of NaBH4 via catalytic hydrolysis reaction using a volumatric method. The kinetic parameters influencing the NaBH4 catalytic hydrolysis reaction without stabilizer were studied. Based on experimental results of the rate, volume of hydrogen generation and activation time, an artificial neural network model was established to evaluate the parameters (temperature, concentration of NaOH and NaBH4, and catalyst amount) that influence the catalytic hydrolysis reaction and the hydrogen generation performance of NaBH4. The hydrogen generation performance can be forecasted and optimized using the neural network model. A stabilizer-free hydrogen generator was designed for NaBH4. Catalyst with metallic particles adhered on CNTs was prepared by a dipping technique. The catalyst is characterized by transmission electron microscopy and X-ray diffraction. The effect of dipping time, activation treatment and solvent on the catalyst was studied. Subsequently, a bimetallic catalyst adhered on CNTs was synthesized.The stabilizer is experimentally demonstrated to have negative effect on the rate of hydrogen generation, volume of hydrogen generation, catalytic activation time, catalyst life, and water consumption for the NaBH4 catalytic hydrolysis reaction, which is consistent with the neural network model analysis and theoretical calculation. In order to ensure the reaction of NaBH4 catalytic hydrolysis is performed completely and rapidly, the solution ratio should be (25%~30%)NaBH4+(75%~80%)H2O, which has a hydrogen storage capacity of 5.30wt.% ~ 6.35wt.%.In a NaBH4 solution free of stabilizer, the hydrogen generation of the NaBH4 catalytic hydrolysis reaction is not a zero-order reaction, and the reaction order decreases with increasing the temperature. The reaction activation energy is measured to be 49.6kJ/mol.The NaBH4 is stored in the solid state in the sterilizer-free hydrogen generator, which makes it easier to operate, compared with the generator storing the hydrogen storage material in aqueous solution by adding stabilizer. In this way, the NaBH4 and water are separated to prevent the NaBH4 hydrolysis. The volume of hydrogen generation isincreased due to the increased ratio of NaBH4, as a result of no stabilizer. Microscopic observations showed that the metallic catalyst on CNTs was granular nano-particles. The loading capacity is found to be Ru/CNTs > Co/CNTs > Ni/CNTs. Co and Ni are partially oxidized in the catalysts of Co/CNTs and Ni/CNTs. Hydrogen generation experiments showed that the Ru/CNTs catalyst is the best.The catalytic performance is enhanced with extending the dipping time. The performance of the metal/CNTs catalyst can be improved by a pre-activation treatment of the CNTs. The performance of catalyst synthesized in ethanol is better than that synthesized in deionized water.XPS analysis showed that Ru particles in a bimetal/CNTs catalyst disperse randomly on the surface of CNTs, which could prevent Co or Ni from oxidation. The hydrogen generation performance catalyzed by bimetal/CNTs is better than that catalyzed by single metal/CNTs. It is found that the activation time is zero after 10 cycles of NaBH4 hydrolysis reaction. The volume and rate of hydrogen generation fluctuate around 450ml and 250ml/min respectively after 100 cycles, which indicates that stability of the catalyst is excellent.
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