氧化镁负载的钼钒磷酸铜催化剂的积碳行为

Carbon Deposition Behavior over Copper Salts of Molybdovanadophosphoric Acid Catalyst Supported by Magnesia

研究了氧化镁负载的钼钒磷酸铜催化剂在正己醇氧化反应中的积碳行为.结果表明,积碳主要以CHx形式存在于催化剂表面,积碳的形成没有导致催化剂的失活.XRD,IR和XPS等光谱表征结果说明积碳后催化剂结构没有发生改变,并且载体表面的钼钒磷酸铜有利于积碳的消除.TPO研究结果表明,积碳在催化剂上有两种存在位置:一种沉积在钼钒磷酸铜表面,这种位置的积碳在低温下容易被烧除;另一种沉积在载体氧化镁的表面,需要高温才能烧除.随着反应时间的增加,积碳量达到定值.

MgO supported copper salt of molybdovanadophosphoric acid H4PMo11 VO40 catalysts were prepared in alcohol by impregnation and the carbon deposition over these catalysts during the n-hexanol oxidation reaction was studied. The coke predominantly deposited on the catalyst surface in the form of CH,, and it was not found that it caused the deactivation of the catalyst. The XRD, IR, XPS characterizations reveal that the Keggin structure of the CPMV was unaffected by carbon deposition. Moreover, it was shown that the supported CPMVs over the MgO surface can be beneficial to eliminate the coke. The temperature （TPO） study showed that coke was formed over the catalyst on two different sites： （1） deposited on the CPMVs which can be burn off at a low temperature; （2） deposited on the MgO which could only be removed at higher temperature. The coke content reached constant with the reaction time increasing.