Thirunavukkarasu Kandasamy, Thirumoorthy Krishnan, Libuda Jörg, Gopinath Chinnakonda S
Catalysis Division, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008, India.
J Phys Chem B. 2005 Jul 14;109(27):13272-82. doi: 10.1021/jp050478v.
Nitric oxide (NO) reduction with carbon monoxide (CO) on the Pd(111) surface was studied under isothermal conditions by molecular beam techniques as a function of temperature, NO:CO beam composition, and beam flux. Systematic experiments were performed under transient and steady state conditions. Displacement of adsorbed CO by NO in the transient state of the reaction was observed at temperatures between 375 and 475 K for all the NO:CO compositions studied. NO accumulation occurs on Pd(111) surface under steady state conditions, below 475 K, due to stronger chemisorption of NO. The steady state reaction rates attain a maximum at about 475 K, nearly independent of beam composition. N2 was found to be the major product of the reduction, along with a minor production of N2O. The production of N2 and N2O indicates molecular and dissociative adsorption of NO on Pd(111) at temperatures up to 525 K. Postreaction TPD measurements were performed in order to determine the nitrogen coverage under steady-state conditions. Finally, the results are discussed with respect to the rate-controlling character of the different elementary steps of the reaction system.
采用分子束技术，在等温条件下研究了一氧化氮（NO）与一氧化碳（CO）在钯（111）表面的还原反应，该反应是温度、NO:CO束流组成和束流通量的函数。在瞬态和稳态条件下进行了系统实验。对于所有研究的NO:CO组成，在375至475K的温度范围内，观察到在反应的瞬态中NO取代了吸附的CO。在稳态条件下，低于475K时，由于NO更强的化学吸附作用，NO在钯（111）表面发生积累。稳态反应速率在约475K时达到最大值，几乎与束流组成无关。发现N2是还原反应的主要产物，同时还有少量N2O生成。N2和N2O的生成表明在高达525K的温度下，NO在钯（111）上发生了分子吸附和解离吸附。进行了反应后程序升温脱附测量，以确定稳态条件下的氮覆盖度。最后，针对反应体系不同基元步骤的速率控制特性对结果进行了讨论。
