水合肼制氢Ni-Pt/La_2O_3催化剂研制及其反应动力学研究

PREPARATION OF Ni-Pt/La_2O_3 CATALYST AND ITS KINETICS STUDY OF HYDROUS HYDRAZINE FOR HYDROGEN GENERATION

综合采用共沉淀和置换法制备了一种La_2O_3负载纳米级Ni-Pt合金催化剂Ni-Pt/La_2O_3.经优化制备工艺,该催化剂在323 K可100%催化N_2H_4·H_2O分解制氢,反应速率340 h-1,其催化性能优于已报道的多数催化剂.此外,还对N_2H_4·H_2O催化分解制氢反应动力学进行了研究,得到其反应动力学方程为:r=-d[N_2H_4·H_2O]/dt=2435exp(-51.32/(RT))[N_2H_4·H_2O]^(0.3)[NaOH]^(0(0.12))[Ni]^(1.03).研究结果对于促进N_2H_4·H_2O分解制氢体系的实际应用奠定了基础.

Safe and efficient hydrogen storage remains a grand challenge in the widespread implementation of hydrogen fuel cell technology. Recently, chemical hydrogen storage has emerged as a promising alternative for vehicular and portable applications. A number of hydrogen-rich materials have been experimentally demonstrated to deliver large amounts of hydrogen under mild conditions with controllable kinetics. Among these materials of interest, hydrous hydrazine（N_2H_4·H_2O） is a promising but yet not fully explored candidate. The development of highly efficient catalyst and its reaction kinetics law are the key issues of N_2H_4·H_2O-based hydrogen generation（HG）systems. Herein, a supported Ni-Pt/La_2O_3 catalyst was prepared by a combination of co-precipitation and galvanic replacement methods. Via optimizing preparing processes, the developed catalyst enabled a complete decomposition of N_2H_4·H_2O to generate H_2 at a reaction rate of 340 h-1at 323 K, which outperforms most reported N_2H_4·H_2O decomposition catalysts. Phase/structural analyses by XRD, TEM and XPS were carried out to gain insight into the catalytic performance of the Ni- Pt/La_2O_3 catalyst. In addition, the effects of temperature, concentration of N_2H_4·H_2O and Na OH, and amount of catalyst on the N_2H_4·H_2O decomposition were investigated over the Ni-Pt/La_2O_3 catalyst. The kinetic rate equation may be represented by the expression： r =-d[N_2H_4·H_2O]/dt = 2435exp（-51.53/（RT））[N_2H_4·H_2O]^（0.3）[Na OH]^（0（0.12））[Ni]^（1.03）. The obtained results should lay the experimental and theoretical foundation for developing practical application of N_2H_4·H_2O-based HG system.