采用XRD,LRS,FT-IR,UV-DRS和TPR研究了MoO3在载体Ga2O3上的分散情况.结果表明:MoO3的分散状态受Ga2O3表面结构的影响,MoO3在Ga2O3上的分散容量约为8.4μmol/m2;低于该分散容量时,Mo6+主要以高分散态存在于Ga2O3表面,而高于该分散容量时,除有分散态的Mo-O物种外,还有残余的MoO3晶相出现.TPR结果表明:MoO3低于分散容量时,体系中只观察到两个有关钼物种的还原峰(400℃和850℃);高于分散容量时,又出现一个新还原峰(550℃).400℃处的峰为分散态钼物种中的Mo6+还原为Mo4+;550℃处的峰为MoO3晶相中的Mo6+还原为Mo4+;850℃处的峰为Mo4+还原为Mo0.结合嵌入模型对这些实验事实进行了解释.
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