【摘要】 采用溶剂热合成法制备了Co-ZIF-9催化剂,系统考察了碳化温度对其在硼氢化钠水解制氢反应中催化性能的影响。借助XRD、TEM、TG和XPS等表征技术,从晶体结构、微观形貌、热稳定性及电子结构等方面深入解析催化剂构效关系。?研究发现,随温度升高,Co-ZIF-9金属-有机框架拓扑解构,钴物种原位还原形成纳米晶粒,但晶粒尺寸增长与团聚导致活性位点可及性下降。当碳化温度为300℃时,催化剂实现活性组分分散与结构稳定的最佳平衡,产氢速率高达703.3 mL·min^-1·g^-1。NaOH浓度会影响水解反应的碱性环境和中间体吸附能,8 wt.%浓度时反应动力学条件最优。基于Arrhenius方程的动力学分析表明,该反应遵循零级动力学模型,其反应活化能约为35.3 kJ·mol^-1。本研究成果为MOF基催化剂的可控碳化制备及水解制氢性能优化提供了理论依据。更多还原

【Abstract】 Co-ZIF-9 catalyst was prepared by the solvothermal synthesis method,and the influence of the carbonization temperature on its catalytic performance in the hydrogen production reaction by the hydrolysis of sodium borohydride was systematically investigated.With the aid of characterization techniques such as XRD,TEM,TG and XPS,the structure-activity relationship of the catalyst was deeply analyzed from aspects such as the crystal structure,microscopic morphology,thermal stability and electronic structure.It was found that with the increase of the temperature,the topology of the metal-organic framework of Co-ZIF-9 was deconstructed,and the cobalt species were in-situ reduced to form nanocrystallites.However,the growth and agglomeration of the crystallite size led to a decrease in the accessibility of the active sites.When the carbonization temperature was 300 ℃,the catalyst achieved the best balance between the dispersion of the active components and the structural stability,and the hydrogen production rate was as high as703.3 mL·min^-1·g^-1.The concentration of NaOH will affect the alkaline environment of the hydrolysis reaction and the adsorption energy of the intermediate.When the concentration is 8 wt.%,the reaction kinetic conditions are the most optimal.The kinetic analysis based on the Arrhenius equation shows that this reaction follows a zero-order kinetic model,and its reaction activation energy is approximately 35.3 kJ·mol^-1.The research results of this study provide a theoretical basis for the controllable carbonization preparation of MOF-based catalysts and the performance optimization of hydrogen production by hydrolysis.更多还原