This study employs a series of bimetallic IrRu/Al₂O₃ catalysts with differing Ir:Ru compositions for lean NO_x reduction by CO (CO-SCR). Catalytic activity assessments reveal that bimetallic IrRu/Al₂O₃ catalysts exhibit drastically enhanced de-NO_x activities in the low-temperature region, compared with monometallic Ir/Al₂O₃ or Ru/Al₂O₃ catalysts. Furthermore, additional characterization and kinetic studies are used to elucidate the origin of the superior catalytic activity observed on bimetallic IrRu/Al₂O₃ catalysts. DRIFTS analyses show different adsorption affinities of the catalysts towards NO and CO, with CO for Ir and NO for Ru, respectively. The possibility of NCO intermediate formation is ruled out, which implies that the reduction of NO_x proceeds through the dissociation of NO and the subsequent recombination of surface N species. Kinetic studies show that a monometallic Ir/Al₂O₃ catalyst favorably adsorbs CO, which acts as an inhibitor for facile NO adsorption and dissociation. However, bimetallic IrRu/Al₂O₃ catalysts exhibit higher affinity towards the adsorption of NO which, in terms of catalytic activities, would prove to be beneficial. Calculation of the activation energies for NO consumption and CO oxidation suggests that the rate determining step shifts from the dissociation of NO on a monometallic Ir/Al₂O₃ catalyst, to the removal of surface O with CO on bimetallic IrRu/Al₂O₃ catalysts. It is anticipated that the facile uptake of surface O through a CO oxidation reaction prevents the catalyst surface from being predominantly covered by CO or O species which could act as a poison, and leads to enhanced adsorption/dissociation of NO, resulting in a higher catalytic activity on the bimetallic IrRu/Al₂O₃ catalysts.

中文翻译：

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IrRu / Al2O3催化剂在低温下通过CO还原贫NOx的动力学和DRIFTS研究

这项研究使用了一系列具有不同Ir：Ru组成的双金属IrRu / Al ₂ O ₃催化剂，用于通过CO（CO-SCR）还原稀薄的NO _x。催化活性评估表明，与单金属Ir / Al ₂ O ₃或Ru / Al ₂ O ₃催化剂相比，双金属IrRu / Al ₂ O ₃催化剂在低温区域表现出显着增强的de-NO _x活性。此外，还进行了其他表征和动力学研究，以阐明在双金属IrRu / Al ₂ O ₃上观察到的优异催化活性的起源。催化剂。DRIFTS分析显示催化剂对NO和CO的吸附亲和力不同，CO分别对Ir和NO对Ru的吸附。的NCO中间形成的可能性被排除了，这意味着NO的还原_X通过NO的解离和面N物种的后续重组进行。动力学研究表明，单金属Ir / Al ₂ O ₃催化剂可很好地吸附CO，CO可作为便捷的NO吸附和离解的抑制剂。然而，双金属IrRu / Al ₂ O ₃催化剂对NO的吸附表现出更高的亲和力，就催化活性而言，这将被证明是有益的。NO消耗和CO氧化的活化能的计算表明，速率确定步骤从单金属Ir / Al ₂ O ₃催化剂上的NO分解，转变为双金属IrRu / Al ₂ O ₃上的CO去除表面O。催化剂。可以预料的是，通过CO氧化反应容易吸收表面O，可防止催化剂表面主要被可能起毒作用的CO或O所覆盖，并导致NO的吸附/离解增加，从而提高催化活性。活性对IrRu / Al ₂ O双金属的影响_3种催化剂。