The surface interaction of O2 and NO with manganous oxide
The surface interaction of O2 and NO with manganous oxide
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DOI：
10.1016/0021-9517(73)90308-4
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发表时间：
1973-12
影响因子：
7.3
通讯作者：
H. Yao;M. Shelef
中科院分区：
文献类型：
--
作者：
H. Yao;M. Shelef
采用体积法、重量法和电子顺磁共振法研究了O2和NO与负载型和非负载型MnO接触过程中的表面相互作用。在25 ° C下，氧和MnO之间的相互作用被限制在完全覆盖的表面。单层覆盖的实现是非常快的。氧的化学吸附解离和每个分子吸附四个Mn2+的自旋中心被湮灭的氧化Mn3+。在400 ° C下，Mn 3+离子与Mn 2+和Mn 4+离子不成比例。在− 78 ° C时，类似的过程仅发生在暴露表面的一部分上。在25 ° C时，NO与MnO表面的相互作用导致Mn2 O3表面上的Mn 3+离子被氧化成Mn 3+离子，同时NO也被化学吸附在Mn2 O3表面上。MnO的氧化并不局限于表面，而是比表面与O2的相互作用慢得多。吸附在Mn_2O_3上的NO可直接脱附。MnO氧化的气态产物主要是N2O和少量的N2。相比之下，NO在MnO 2表面上的化学吸附非常小。
Surface interactions occurring during the contact of O2and NO with supported and unsupported MnO were studied by volumetric and gravimetric methods and electron paramagnetic resonance. At 25 °C the interaction between oxygen and MnO is confined to the surface at complete coverage. The attainment of the monolayer coverage is very fast. The oxygen chemisorbs dissociatively and for every molecule adsorbed four Mn2+spin centers are annihilated by oxidation to Mn3+. At 400 °C the Mn3+ions disproportionate to Mn2+and Mn4+ions. At −78 °C similar proeesses take place only on a part of the exposed surface. At >70 °C the incorporation of oxygen into the bulk takes place.The interaction of NO with the surface of MnO at 25 °C leads to the oxidation of the manganous ions to Mn3+and the simultaneous chemisorption of NO on the resulting Mn2O3surface. The oxidation of MnO is not confined to the surface but takes place much slower than the surface interaction with O2. The NO adsorbed on Mn2O3can be desorbed as such. The gaseous product of the MnO oxidation is largely N2O with small amounts of N2. In contrast the chemisorption of NO on MnO2surfaces is very small.