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首页> 外文期刊>Applied Surface Science >Catalytic Properties Of Molecular Sieves Mcm41 Type Doped With Heteropolyacids For Ethanol Oxidation
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Catalytic Properties Of Molecular Sieves Mcm41 Type Doped With Heteropolyacids For Ethanol Oxidation

机译：杂多酸掺杂的分子筛Mcm41型对乙醇氧化的催化性能

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Keggin type heteropolyacids (HPAs) have been used in acid-catalysed reactions as well as oxidation reactions both in the heterogeneous and homogeneous systems. In order to be more effective for catalytic reactions, HPAs are usually impregnated on different porous materials with high surface area. The structure and texture of H_3PMo_(12)O_(40) and H_4PVMo_(11)O_(40) supported on A1-MCM41 and Fe-MCM41 were studied by XRD, low-temperature nitrogen adsorption and thermal analysis. Catalytic properties of prepared samples were studied by using a reactant pulse method at different temperatures. The ethanol conversion proceeds by two main pathways: an oxidehydrogenation reaction on redox catalytic centers, and a dehydration reaction on acidic centers, respectively. The favourable effect of HPAs deposition on Al-MCM41 and Fe-MCM41 supports for oxidehydrogenation pathway to acetaldehyde results from the examination of apparent activation energies E_a and reaction rate values. An evidenced decreasing of E_a was obtained for acetaldehyde formation in the case of Fe-MCM41-supported HPM (25 kJ/mole) comparatively with pure HPM (56.6 kJ/mole). For all reaction temperatures, the reaction rates of acetaldehyde formation are with one order of magnitude higher for supported samples than unsupported ones.
机译：Keggin型杂多酸（HPA）已用于异相和均相系统中的酸催化反应和氧化反应中。为了对催化反应更有效，通常将HPA浸渍在具有高表面积的不同多孔材料上。通过XRD，低温氮吸附和热分析研究了负载在A1-MCM41和Fe-MCM41上的H_3PMo_（12）O_（40）和H_4PVMo_（11）O_（40）的结构和织构。采用反应脉冲法在不同温度下研究了制备样品的催化性能。乙醇的转化通过两个主要途径进行：分别在氧化还原催化中心上进行氧化物氢化反应和在酸性中心上进行脱水反应。 HPAs沉积对Al-MCM41和Fe-MCM41的有利作用支持了从表观活化能E_a和反应速率值的检查结果得出的乙醛的氧化加氢途径。 Fe-MCM41负载的HPM（25 kJ / mol）与纯HPM（56.6 kJ / mol）相比，乙醛形成的E_a降低。在所有反应温度下，负载样品的乙醛形成反应速率要比不负载样品高一个数量级。

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