Direct Sonochemical Synthesis of Manganese Octahedral Molecular Sieve (OMS-2) Nanomaterials Using Cosolvent Systems, Their Characterization, and Catalytic Applications
Direct Sonochemical Synthesis of Manganese Octahedral Molecular Sieve (OMS-2) Nanomaterials Using Cosolvent Systems, Their Characterization, and Catalytic Applications
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DOI：
10.1021/cm203366m
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发表时间：
2012-02-28
影响因子：
8.6
通讯作者：
Suib, Steven L.
中科院分区：
文献类型：
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作者：
Dharmarathna, Saminda;King'ondu, Cecil K.;Suib, Steven L.
采用直接声化学法快速合成了锰钾矿型锰八面体分子筛（OMS-2）材料。在非热条件下产生了288 +/- 1 m（2）/g的非常高的表面积和1-7 nm范围内的小颗粒尺寸。不需要进一步的处理如煅烧来获得纯的锰钾矿相。共溶剂系统被用来减少反应时间，并获得更高的表面积。使用水/丙酮混合相溶剂系统，反应时间减少了50%。在环境温度下超声处理2小时后，用5%丙酮获得锰钾矿相。反应时间，温度和丙酮浓度被确定为最重要的参数，在纯锰钾矿相的形成。采用X射线衍射（XRD）、氮气吸附、扫描电子显微镜（SEM）、透射电子显微镜（TEM）和傅里叶变换红外光谱（FTIR）等手段对材料进行了表征。使用超声化学方法合成的OMS-2材料（K-OMS-2（SC））具有更大量的缺陷，因此与使用回流方法合成的OMS-2（K-OMS-2（REF））和商业MnO 2相比，显示出优异的苯甲醇氧化催化性能。
A rapid, direct sonochemical method has successfully been developed to synthesize cryptomelane-type manganese octahedral molecular sieve (OMS-2) materials. Very high surface area of 288 +/- 1 m(2)/g and small particle sizes in the range of 1-7 nm were produced under nonthermal conditions. No further processing such as calcination was needed to obtain the pure cryptomelane phase. A cosolvent system was utilized to reduce the reaction time and to obtain higher surface areas. Reaction time was reduced by 50% using water/acetone mixed phase solvent systems. The cryptomelane phase was obtained with 5% acetone after 2 h of sonication at ambient temperature. Reaction time, temperature, and acetone concentration were identified as the most important parameters in the formation of the pure cryptomelane phase. OMS materials synthesized using the above-mentioned method were characterized by X-ray diffraction (XRD), nitrogen sorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transformation infrared spectroscopy (FTIR). OMS-2 materials synthesized using sonochemical methods (K-OMS-2(SC)) possess greater amounts of defects and hence show excellent catalytic performances for oxidation of benzyl alcohol as compared to OMS-2 synthesized using reflux methods (K-OMS-2(REF)) and commercial MnO2.