锰酸锂的制备、表征及甲醛降解性能研究

Preparation,characterization and catalytic degradation performance of formaldehyde of lithium manganate

目的:在不同水热温度下制备锰酸锂,对其结构进行详尽表征,并对其低浓度甲醛降解性能进行探索。方法:采用抗坏血酸、LiOH、KMnO_(4)为原料合成了锰酸锂,并通过X射线衍射(XRD)、氮气吸脱附、X射线光电子能谱(XPS)、透射电子显微镜(TEM)等对材料进行表征;并将四种催化剂应用于低浓度甲醛降解测试。结果:随水热温度从150℃升到230℃,锰酸锂的结晶性提高;LiMn_(2)O_(4)-210比表面积最大且表面氧与氧缺陷占比最高;TEM结果表明LiMn_(2)O_(4)-150为无定型结构,LiMn_(2)O_(4)-170与LiMn_(2)O_(4)-190结晶度较差,LiMn_(2)O_(4)-210和LiMn_(2)O_(4)-230的产物为八面体结构。结论:LiMn_(2)O_(4)-210具有最高的甲醛降解率,10 h内的甲醛降解率可达97%。

Aims:Lithium manganates were prepared at different hydrothermal temperatures and were characterized to explore the catalytic degradation performance of low-concentration formaldehyde.Methods:Ascorbic acid,LiOH and KMnO_(4) were used to synthesize lithium manganates.All catalysts were characterized by X-ray diffraction(XRD),nitrogen adsorption and desorption,X-ray photoelectron spectroscopy(XPS)and Transmission electron microscope(TEM),etc.The degradation performance of low-concentration formaldehyde was tested.Results:The crystallization of lithium manganate increased with hydrothermal temperatures.LiMn_(2)O_(4)-210 had the largest specific surface area and the highest proportion of surface oxygen and oxygen defects.TEM results showed that LiMn_(2)O_(4)-150 had an amorphous structure;and the crystallization of LiMn_(2)O_(4)-170 and LiMn_(2)O_(4)-190 was poor.LiMn_(2)O_(4)-210 and LiMn_(2)O_(4)-230 had an octahedral structure.Conclusions:LiMn_(2)O_(4)-210 has the best degradation performance of formaldehyde.The formaldehyde degradation rate within 10 h can reach 97%.