丙烷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 Mo 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能的影响 .实验结果表明 ,在 773K和n(C3H8) ∶n(O2 ) ∶n(N2 ) =3∶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AgMoO2 PO4中的Mo O物种 (多钼酸根 ) ,此时催化剂对丙烷选择氧化具有较高的催化活性 .催化剂中Mo O物种的转化是由MoO3 中Mo O物种和AgMoO2 PO4中Mo O物种的结构特性决定的 .AgMoO2 PO4中的Mo O物种具有较强的参与MarsvanKrevelen氧化 还原循环的能力 ,可能是丙烷选择氧化反应的活性物

钼基催化剂氧化还原性质对丙烷选择氧化制丙烯醛反应的影响

制备了Ag0 3 MoP0 6Ox 和Ce0 1Ag0 3 MoP0 6Oy 催化剂 ,并用XRD ,TPR ,LRS ,XPS和EPR对催化剂进行了表征 ,考察了催化剂的氧化还原性质及其对丙烷选择氧化制丙烯醛反应的催化性能 .结果表明 ,由于Ce和Mo发生相互作用 ,调变了催化剂的可还原性和配位不饱和Mo的量 ,使Ce0 1Ag0 3 MoP0 6Oy 催化剂对反应中间产物丙烯和正丙醇转化为丙烯醛具有较高的能力 ,从而提高了催化剂的活

Effect of redox properties on selective oxidation of propane to acrolein over molybdate-based catalyst

The Ag-0.3 Mo0.6Ox and Ce0.1Ag0.3MoP0.6Oy catalysts were prepared and characterized by XRD, TPR, LRS, XPS and EPR techniques. And the catalytic performance of the catalysts for selective oxidation of propane to acrolein was studied. The results showed that the higher propane conversion with higher selectivity for acrolein was obtained on Ce0.1Ag0.3MoP0.6Oy catalyst, In addition, the possible intermediates, propene and propanol, were favorable for the transformation to acrolein on Ce0.1Ag0.3MoP0.6Oy catalyst. After Ce was doped in Ag0.3MoP0.6Ox, the CeO2 and Ce2MoO6 could be measured. The addition of Ce to Ag0.3MoP0.6Ox improved the reducibility and the concentration of Mo5+ owing to the formation of redox couple Mo6+ + Ce3+ === Mo5+ + Ce4+, leading to the higher propane conversion and the higher selectivity for acrolein

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 MoO3 and AgMoO2PO4 phases. The Mo-O species was monitored by in-situ confocal microprobe LRS in different atmosphere. 3C(3)H(8)-lO(2)-N-2 flow, only the Raman hands of Mo-O species in AgMoO2PO4 were detected at 773 K. In O-2 flow, the Mo-O species in MoO3 and in AgMoO2PO4 could be detected at all the investigated temperatures. In 7C(3)H(8)-43N(2) flow, the intensity of Raman bands belonging to Mo-O species in both MoO3 and AgMoO2PO4 gradually decreased and finally disappeared as temperature increasing. At that time, the catalyst was exposed to 3C(3)H(8)-lO(2)-4N(2) flow, the Raman bands belonging to Mo-O species in AgMoO2PO4 was detected. Subsequently, the catalyst was switched to O-2 flow, the Raman bands of Mo-O species in MoO3 and in AgMoO2PO4 were detected again, The results of catalytic test showed higher conversion of propane with higher selectivity for propene in 3C(3)H(8)-IO2-4N(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 AgMoO2PO4 might be active species for Oxidative dehydrogenation of propane