Preparation and characterization of Cs2.8H1.2PMo11Fe(H2O)O39•6H2O and investigation of effects of iron-substitution on heterogeneous oxidative dehydrogenation of 2-propanol
Preparation and characterization of Cs2.8H1.2PMo11Fe(H2O)O39•6H2O and investigation of effects of iron-substitution on heterogeneous oxidative dehydrogenation of 2-propanol
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DOI：
10.1021/cm0348996
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发表时间：
2004-07-13
影响因子：
8.6
通讯作者：
Taguchi, A
中科院分区：
文献类型：
--
作者：
Mizuno, N;Min, JS;Taguchi, A
本文报道了单铁取代磷钨酸盐的合成、表征、固载化及异丙醇氧化脱氢反应。该催化剂的结构为Cs2.8H1.2PMo11Fe（H2O）O-39.6H（2）O，并通过元素分析、X射线衍射、红外光谱、P-31 NMR和ESR谱进行了表征。在Cs2.8H1.2PMo 11 Fe（H2O）O-39.6H（2）O中，Fe 3+以反阳离子形式存在于相对畸变的八面体位置，而在Fe 3+（2.5wt%）/Cs3.0PMo 12 O 40中，Fe 3+以反阳离子形式存在于相对畸变的八面体位置。七个水分子通过在63 ℃下的热处理而解吸，并且铯氢盐在210 ℃以下是稳定的。铯氢盐用于2-丙醇非均相氧化脱氢制丙酮，本质上具有比铁浸渍的Fe 3 +/Cs3.0PMo 12 O 40和Cs3.0PMo 12 O 40催化剂更高的速率，显示在PMo 11 O 397-聚氧乙烯酸盐中的孤立铁对氧化脱氢的有效性。在流动实验中，在稳定状态下停止氧气供应的数据表明，通过2-丙醇与铯氢盐的反应生成丙酮。异丙醇氧化脱氢反应的本征速率与催化剂还原速率的相关性，速率方程为-d[2-PrOH]/dt = k·P-2-PrOH（0.80）·PO 2 -0.06，动力学同位素效应为1.6-1.9，表明催化剂还原和异丙醇的β-氢消除是反应的速率控制步骤。
Synthesis and characterization of mono-iron(III)-substituted molybdophosphate, the solidification as a heterogeneous catalyst, and the oxidative dehydrogenation of 2-propanol were reported. The catalyst was isolated as Cs2.8H1.2PMo11Fe(H2O)O-39.6H(2)O, and characterized by elemental analysis and X-ray diffraction, infrared, P-31 NMR, and ESR spectroscopy. The Fe3+ in Cs2.8H1.2PMo11Fe(H2O)O-39.6H(2)O was incorporated into the molybdophosphate framework while that in Fe3+(2.5 wt %)/Cs3.0PMo12O40 existed as a countercation in a relatively distorted octahedral site. The seven water molecules were desorbed by the thermal treatment at 63 degreesC and the cesium hydrogen salt was stable below 210 degreesC. The cesium hydrogen salt was used for heterogeneous oxidative dehydrogenation of 2-propanol to acetone and intrinsically has a higher rate than those for the iron-impregnated Fe3+/Cs3.0PMo12O40 and Cs3.0PMo12O40 catalysts, showing the effectiveness of isolated iron in the PMo11O397- polyoxometalate on the oxidative dehydrogenation. The data for the stop of the supply of the oxygen at the stationary state in the flow experiment showed that acetone was produced by the reaction of 2-propanol with the cesium hydrogen salt. The correlation between intrinsic rates of oxidative dehydrogenation of 2-propanol and reducibility of catalysts, the rate equation of -d[2-PrOH]/dt = k.P-2-PrOH(0.80).PO2-0.06, and kinetic isotope effects of 1.6-1.9 showed that the reduction of the catalyst with the beta-hydrogen elimination from 2-propanol was the rate-determining step.