钛醇盐电化学合成的研究

Direct Electrochemical Preparation of Titanium Alkoxides

采用钛金属为“牺牲”阳极,首次在无隔膜电解槽中,电化学一步法制备了纳米TiO_2前驱体钛醉盐Ti(OEt)_4,Ti(ORr-i)_4,Ti(OBu)_4.产物通过元素分析、红外光谱(FT-IR)、拉曼光谱进行表征.电化学一步法直接制备纳米材料前驱体钛醇盐,克服了传统化学方法合成金属醇盐步骤多、产率低、纯度达不到要求及后续分离繁琐等缺点.本文同时讨论了影响电合成钛醇盐的关键因素及可能的反应机理,实验表明钛在醇溶液中呈点蚀行为,钛醇盐卤化物Ti(Ⅲ)(OR)_nBr_m在阳极形成,然后被氧化为Ti(Ⅳ)(OR)_nBr_m,这种物质在阴极上ROH参与下被还原生成钛醇盐Ti(OR)_4,钛阳极表面拉曼光谱证实了上述观点.防止阳极钝化,温度控制在50～60℃之间,采用有机胺溴化物为导电盐,可以提高电合成收率.

Titanium alkoxides were directly prepared using titanium as sacrificing anode in absolute alchol. Titanium alkoxides were characterized by FT - IR spectra, Raman spectra and element analysis. The influence of temparture, conductive additives, and traces of water on the product yield was also investigated. The results showed that the direct electrochemical perparation of titanium alkoxides had high current efficiency and electrolysis yield. These titanium alkoxides have high purity and can be directly used as precursor of nanometer oxides. The experiments showed that the controlling temperature under 50 - 60℃, selecting R4NBr as conductive additives and preventing titanium anode from being passiviated can improve product yeild. The reaction mechanism is also expounded . Ti(Ⅲ)(OR)nBrm was formed on the anode surface , then the Ti(Ⅲ)(OR)nBrm was oxided into Ti(Ⅳ)(OR)nBrm and transilated to cathode room. On the cathode surface Ti(Ⅳ)(OR)nBrm was reduced into Ti(OR)4. The formation of titanium alkoxides on the anode surface was also investigated by in situ surface Raman spectroscopy.