非水四乙基氯化铵体系中电溶解耦合铪醇盐合成的电化学机理与动力学

Electrochemical mechanism and kinetics of electrodissolution-coupled hafnium alkoxide synthesis in tetraethylammonium-chloride-based anhydrous system

作为一种具有广泛应用前景的高效电合成技术,耦合电溶解的铪醇盐合成(EHS)基于铪溶解/乙醇脱氢的同时非均相反应以及溶液中Hf^(4+)阳离子和烷氧阴离子的自发结合反应。为了阐明EHS过程的机制和动力学,通过电化学测试、扫描电镜、气相色谱和微观动力学模拟等手段,探究阳极铪溶解和阴极乙醇脱氢的电化学行为。结果表明,优选的支持电解质四乙基氯化铵(Et_(4)NCl)展现了钝化膜击穿与铪溶解协同的剧烈点蚀机制以及两段脱氢机制。为量化钝化膜击穿和铪点蚀的动力学参数,提取与钝化速率、钝化膜击穿敏感性和点蚀速率相关的3个指标,并通过建立微观动力学模型评估基于Et_(4)NCl体系的EHS工艺,其电能消耗为1.53~1.83 k W·h/kg Hf(OC_(2)H_(5))_(4)。

Electrodissolution-coupled hafnium alkoxide synthesis(EHS)is a promising pathway for efficient electro-synthesis.It employs simultaneous heterogeneous reactions of Hf dissolution and ethanol dehydrogenation,and spontaneous solution-based combination reaction between Hf^(4+) cations and alkoxy anions.To elucidate the mechanism and kinetics of EHS process,the electrochemical behaviors of anodic Hf dissolution and cathodic ethanol dehydrogenation were explored through electrochemical measurements,SEM observations,gas chromatography,and micro-kinetics modeling.The results indicated the supporting electrolytes of tetraethylammonium chloride(Et_(4)NCl)to be preferable,which facilitated a passive-film-punctured pitting mechanism for Hf dissolution and a two-stage dehydrogenation mechanism.Three indicators related to passive rate,sensitivity towards puncture of the passive film,and pitting rate were extracted to quantify the kinetics of passive puncture and Hf corrosion.Micro-kinetics models were developed to evaluate the Et_(4)NCl-based EHS process,which achieved electric energy requirements of 1.53-1.83 kW·h/kg Hf(OC_(2)H_(5))_(4).