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采用15N同位素标记法研究了NO催化还原反应机理及其含量对反应选择性影响,为实现NO3-选择性还原为N2提供参考数据。结果表明,NO通过吸附在催化剂Pd-In活性中心而参加还原反应,形成中间体N2O以及终产物N2和NH3,其含量控制着还原反应选择性。当NO含量较高时,主导反应是NO分子间相互作用还原为N2;当NO含量较低时,其与吸附氢作用形成NH3的反应明显增强。这主要是与Pd-In催化活性中心对NO吸附存在一个饱和阈值有关。引入NO对亚硝酸根(15NO2-)中15N还原为N2的原子转化率提高作用不明显,可能是因为引入的NO是通过取代NO2-还原产生的进而吸附在催化剂活性中心的NO而参加反应的。
15N isotope labeling method was used to study the mechanism of NO catalytic reduction reaction and the effect of its content on the selectivity of the reaction, which provided reference data for the realization of NO3-selective reduction to N2. The results showed that NO participates in the reduction reaction by adsorbing on the Pd-In active site of the catalyst to form the intermediate N2O and the final products of N2 and NH3, and the content controls the selectivity of the reduction reaction. When the NO content is higher, the dominant reaction is the reduction of the intermolecular interaction of NO to N2. When the NO content is low, the reaction with hydrogen to form NH3 is obviously enhanced. This is mainly related to the presence of a saturation threshold for NO adsorption on Pd-In catalytic centers. The effect of introducing NO on the atomic conversion of 15N reduction to N2 in nitrite (15NO2-) is not obvious, probably because the introduced NO participates in the reaction by substituting the NO2-reduction and then adsorbing NO at the active site of the catalyst .