酸碱性和氧化还原性对负载型钒基催化剂丙烷氧化脱氢性能的影响

Effects of acid base and redox properties on catalytic performance of supported V base catalysts for oxidative dehydrogenation of propane

用ＸＲＤ、Ｒａｍａｎ、ＴＰＲ和Ｐｙ－ＩＲ表征乙酰丙酮络钒法制备的不同氧化物和磷酸盐负载的钒氧化物催化剂，结果表明，钒氧化物在载体ＭｇＯ、Ａｌ２Ｏ３、Ｍｇ３（ＰＯ４）２、ＡｌＰＯ４和Ｚｒ３（ＰＯ４）４上是高分散的，没有生成明显的Ｖ２Ｏ５晶相；催化剂的可还原性与相应载体氧化物或磷酸盐的金属还原电位序有较好的对应关系，同时与其丙烷氧化脱氢活性也存在较好的平行关系，表明钒氧化物与载体的阳离子形成Ｖ－Ｏ－Ｍ桥键，该桥键氧较易移去，可能是丙烷氧化脱氢的活性氧物种；催化剂表面酸性位有利于丙烷Ｃ－Ｈ键的活化，但导致深度氧化产物增多。

The vanadia base catalysts supported on MgO, Al 2O 3, Mg 3(PO 4) 2,AlPO 4, and Zr 3(PO 4) 4 are characterized by X Ray diffraction pattern and Raman spectroscopy.The results show that vanadia are highly dispersed on the supports.The reducibilities of the catalysts are parallel to their activities for propane oxidative dehydrogenation, suggesting that the bridge lattice oxygen (V O M) may be the active oxygen species in the oxidative dehydrogenation of propane.The surface acid sites are favourable for activation of 2° C H bond in propane molecular, but will lower the selectivity to propene at the same time.