CO Oxidation over Nonstoichiometric Nickel Manganite Spinels
CO Oxidation over Nonstoichiometric Nickel Manganite Spinels
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DOI：
10.1006/jcat.2000.3110
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发表时间：
2001-03
影响因子：
7.3
通讯作者：
C. Laberty‐Robert;C. Márquez-Álvarez;C. Drouet;P. Alphonse;C. Mirodatos
中科院分区：
文献类型：
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作者：
C. Laberty‐Robert;C. Márquez-Álvarez;C. Drouet;P. Alphonse;C. Mirodatos
通过在623 K空气中煅烧混合尖晶石，合成了非化学计量比的镍锰尖晶石氧化物NixMn 3 − xMn 3δ/4 O 4 +δ（1≥x≥0）。这些材料被证明是高活性的CO氧化，一些转换被观察到在室温下的最活跃的固体（x=1.0）。CO和O2与这些氧化物的相互作用进行了研究，通过原位红外光谱在稳态和瞬态反应条件下。提出了一个详细的机制，其中CO与配位不饱和阳离子反应，得到羰基络合物，然后与表面氧活化的阴离子空位反应。吸附的和气态的CO2也经历与晶格氧或表面氢氧化物基团的慢得多的副反应，以产生更稳定的碳酸氢盐和碳酸盐物质，这导致催化剂失活。预处理的显着效果解释的基础上观察到的动力学和提出的机制
Nonstoichiometric nickel-manganese spinel oxides, NixMn3−x ▭3δ/4O4+δ (1≥x≥0), have been synthesized by calcination in air of mixed oxalates at 623 K. These materials are shown to be highly reactive for CO oxidation, some conversion being observed at room temperature for the most active solid (x=1.0). The interaction of CO and O2 with these oxides has been studied by in situ IR spectroscopy under steady-state and transient reaction conditions. A detailed mechanism is proposed wherein CO reacts with coordinatively unsaturated cations to give carbonyl complexes which in turn react with surface oxygen activated on anionic vacancies. Adsorbed and gaseous CO2 also undergo much slower side reactions with lattice oxygen or surface hydroxide groups to give more stable hydrogen carbonate and carbonates species, which lead to catalyst deactivation. Marked effects of pretreatment are explained on the basis of the observed kinetics and the proposed mechanism