丙烯氨氧化催化剂物化性能研究──Ⅰ．程序升温脱附

Study on the Physico-Chemical Properties of the Catalyst in Ammoxidation of Propene──Ⅰ.Temperature-programmed Desorption

应用程序升温脱附技术（ＴＰＤ）研究新鲜、失活和再生三种丙烯腈催化剂上ＮＨ３、Ｏ２和丙烯吸附后的脱附行为。结果表明，三种催化剂表面都只有一种酸中心；存在三种氧物种可能是：Ｏ~－、弱结合的表面晶格氧Ｏ^（２－）和强结合的体相晶格氧Ｏ^（２－）；新鲜和再生催化剂表面都有三个吸附丙烯活性中心，而失活催化剂只有一个较弱的与主产物关系不甚密切的吸附中心。新鲜催化剂对ＮＨ３、Ｏ２和丙烯的吸附强度较弱，但吸附中心密度较大，因此性能较好；失活催化剂对ＮＨ３、Ｏ２和丙烯的吸附强度增强，密度减小，尤其对丙烯的吸附明显减少导致其失活；再生催化剂的表面化学行为与新鲜催化剂还有一定差距，其再生工艺需进一步优化。

The desorption behaviours of ammonia, oxygen and propylene adsorbed on the fresh,deactivated and regenerated catalysts were studied with TPD(Temperature Programmed Desorption) method. The results indicate that there is one acidic site and three kinds of oxygen species: O￣-, weakly-binded surface lattice oxygen O￣(2-) and strongly-binded bulk lattice oxygen O￣(2-) in catalysts. There are three kinds of adsorption site of propylene on the surface of fresh and regenerated catalyst. For the deactivated catalyst, there is only one weaker adsorption site of propylene which has minor effects on ammoxidation reaction. The adsorption site strength of ammonia, oxygen and propylene in the fresh catalyst is weaker,and the adsorption site density is greater, so its catalytic activity is better. In the deactivated catalyst, the adsorption site strength is strengthened and the adsorption site density, especially the adsorption of propylene, is decreased obviously, so its catalytic activity becomes worse.There is a difference on the surface chemical characteristics between the regenerated catalyst and the fresh catalyst,so the condition of regeneration should be optimized.