室温去除甲醛用锰铁氧化物催化剂制备及表征

The preparation and characterization of manganese-iron oxide catalyst for formaldehyde removal at room temperature

采用甲醛去除性能动态测试装置研究Mn/Fe物质的量比、水热温度、水热时间、焙烧温度、焙烧时间等工艺因素对锰铁氧化物催化剂室温甲醛去除性能的影响。采用X-射线衍射仪、扫描电子显微镜、能谱分析仪、透射电子显微镜、傅里叶变换红外光谱仪分析锰铁氧化物催化剂结构、形貌、微区成分、表面官能团等。结果表明,影响锰铁氧化物催化剂室温甲醛去除率强弱的顺序为:焙烧温度>煅烧时间>Mn/Fe物质的量比>水热时间>水热温度;催化剂的最佳制备工艺为:Mn/Fe物质的量比1.8∶1,水热温度140℃,水热时间8.0 h,焙烧温度150℃时,焙烧时间4.5 h,该条件下制备催化剂的室温甲醛去除率为96.14%,经6次循环使用后活性仅下降5.06%;锰铁氧化物样品由MnO2、Fe2O3和非晶相组成,样品呈球形,平均粒径6.73 nm,表面官能团主要有OH伸缩吸收、NH弯曲振动、CH弯曲振动等。

The effects of the technologic factors of mole ratio of iron to manganese,hydrothermal temperature and time,calcination temperature and time on the formaldehyde removal efficienvy at room temperature of manganese-iron oxides catalyst were investigated by using the dynamic test device for formaldehyde removal performance.The phase structure,morphology,micro area composition,surface functional groups of manganese-iron oxides were analyzed by using the X-ray diffraction,scanning electron microscope,energy spectrum analysis,transmission electron microscope,Fourier transform infrared spectroscopy.The results indicated that the sequence in terms of influence degree on the formaldehyde removal rate at room temperature of the manganese-iron oxides was calcination temperature,calcination time,mole ratio of iron to manganese,hydrothermal time and temperature.The optimal preparation technology of sample was that the mole ratio of iron to manganese was 1.8∶1,and hydro-thermal synthesized at 140℃for 8.0 h,then calcined at 150℃for 4.5 h.The formaldehyde removal efficiency at room temperature of the sample prepared under the optimal conditions was 96.14%and only down 5.06%after six cycles.The manganese-iron oxides sample was composed of MnO2,Fe2O3 and amorphous phase,the particles of the specimen were spheroid whose average size was 6.73 nm,which contained the surface functional groups of OH telescopic absorption,NH bending vibration,CH bending vibration.