丙烯选择氧化反应中钼基催化剂动态结构的研究

 用原位共焦显微拉曼光谱技术考察了丙烷选择氧化反应中Ag－Mrno－P－O催化剂的结构，讨论了催化剂动态结构的成因及其对催化剂性rn能的影响．实验结果表明，在773K和n（C3H8）∶n（O2）∶n（N2）＝rn3∶1∶4的反应条件下，Ag－Mo－P－O催化剂中的Mo－O物种可转化为ArngMoO2PO4中的Mo－O物种（多钼酸根），此时催化剂对丙烷选择氧化具rn有较高的催化活性．催化剂中Mo－O物种的转化是由MoO3中Mo－O物种和rnAgMoO2PO4中Mo－O物种的结构特性决定的．AgMoO2PO4中的Mo－O物种具rn有较强的参与MarsvanKrevelen氧化－还原循环的能力，可能是丙烷选rn择氧化反应的活性物种．

Dynamic Structure of Mo-O Species in Ag-Mo-P-O Catalyst for Oxidative Dehydrogenation of Propane

In order to understand the relationship between catalytic performance and structure of Ag Mo P O caalyst for oxidative dehydrogenation of propane, the dynamic structure of Mo O species in the catalyst was studied by in situ confocal microprobe LRS and XRD. The catalyst was mainly composed of MoO 3 and AgMoO 2PO 4 phases. The Mo O species was monitored by in situ confocal microprobe LRS in different atmosphere. 3C 3H 8 1O 2 4N 2 flow, only the Raman bands of Mo O species in AgMoO 2PO 4 were detected at 773 K. In O 2 flow, the Mo O species in MoO 3 and in AgMoO 2PO 4 could be detected at all the investigated temperatures. In 7C 3H 8 43N 2 flow, the intensity of Raman bands belonging to Mo O species in both MoO 3 and AgMoO 2PO 4 gradually decreased and finally disappeared as temperature increasing. At that time, the catalyst was exposed to 3C 3H 8 1O 2 4N 2 flow, the Raman bands belonging to Mo O species in AgMoO 2PO 4 was detected. Subsequently, the catalyst was switched to O 2 flow, the Raman bands of Mo O species in MoO 3 and in AgMoO 2PO 4 were detected again. The results of catalytic test showed higher conversion of propane with higher selectivity for propene in 3C 3H 8 1O 2 4N 2 flow at 773 K. The transformation of Mo O species is due to the intrinsic properties of Mo O species. The Mo O species of AgMoO 2PO 4 might be active species for oxidative dehydrogenation of propane.