MoVO_(x)复合金属氧化物的快速合成及其催化甘油氧化性能研究

Fast synthesis of MoVO_(x) composite metal oxides and study on their catalytic performance for glycerol oxidation

采用亚临界水热法快速合成了MoVO_(x)复合金属氧化物。考察了亚临界水热温度、n(Mo)∶n(V)对MoVO_(x)复合金属氧化物晶相组成、形貌、比表面积、氧化还原能力的影响。研究表明,在亚临界水热体系下可制备以V_(0.95)Mo_(0.97)O_(5)为主要晶相的MoVO_(x)样品;当制备温度为240℃、n(Mo)∶n(V)为1∶0.8时,V_(0.95)Mo_(0.97)O_(5)晶相质量分数可达到99.10%,且形貌为片状和棒状堆积结构;而当制备温度为280℃时,样品则呈现出明显的八面体结构。将所得MoVO_(x)样品用于催化甘油氧化反应,考察了其催化性能,结果表明,片状和棒状结构的比表面积高于八面体结构,片状和棒状的高比表面积结构可以很好地将催化剂内的氧化还原中心暴露出来,因此催化性能较高。在制备温度为200℃、n(Mo)∶n(V)=1∶0.8条件下制备的MoVO_(x)催化甘油氧化时,对丙烯醛和丙酮的选择性高达81.10%。

MoVO_(x) composite metal oxides are rapidly synthesized through using subcritical hydrothermal method.The influences of subcritical hydrothermal temperature and n(Mo)∶n(V)on the crystal phase composition,morphology,specific surface area,and redox ability of MoVO_(x) composite metal oxides are investigated.It is found from research that MoVO_(x) samples with V_(0.95)Mo_(0.97)O_(5) as the main crystal phase can be prepared in a subcritical hydrothermal system.As the preparation temperature is 240℃and n(Mo)∶n(V)is 1∶0.8,the mass fraction of V_(0.95)Mo_(0.97)O_(5) crystal phase can reach 99.10% and the morphology presents sheet and rod like stacking structure.As the preparation temperature is 280℃,the sample exhibits a clear octahedral structure.The obtained MoVO_x sample is applied to catalyze glycerol oxidation reaction to investigate its catalytic performance.It is indicated by the results that the specific surface area of the sheet and rod structures is higher than that of the octahedral structure.The high specific surface area structures of the sheet and rod structures can effectively expose the redox centers within the catalyst,resulting in higher catalytic performance.When MoVO_(x) prepared at a preparation temperature of 200℃ and n(Mo)∶n(V)=1∶0.8 is used to catalyze glycerol oxidation,the total selectivity of acrolein and acetone is as high as 81.10%.