Instituto de Catálisis y Petroleoquímica, CSIC, Cantoblanco, 28049 Madrid, Spain.
Phys Chem Chem Phys. 2011 Jul 28;13(28):12892-9. doi: 10.1039/c1cp20287a. Epub 2011 Jun 20.
The Temporal Analysis of Products (TAP) technique has been used to investigate the mechanism involved in the catalytic decomposition of NH(3) over a series of catalysts consisting of activated carbon supported Ru (promoted and non-promoted with Na) and over an activated carbon supported Ir. An extensive study of the role played by both the support and the promoter in the "side reactions" and in the stability and surface lifetime of the NH(x) species has been performed. It was suggested that the N(2) produced during the first steps of the reaction over the activated carbon supported Ru catalysts promoted with Na forms a Na-N-Ru complex at the promoter-transition metal crystallite interface. This study also suggests that the Na promoter prevents the diffusion of hydrogen from the metal to the support via spill-over. A similar effect was observed after the thermal treatment at high temperature of the carbon catalyst support. Finally large differences in multi-pulse TAP results have been detected between Ru and Ir catalysts implying that the NH(3) decomposition reaction mechanism must be different on both metals.
时间分辨产物分析（TAP）技术已被用于研究一系列由活性炭负载的 Ru（经 Na 促进和未促进）和活性炭负载的 Ir 组成的催化剂上 NH3 催化分解涉及的反应机理。对载体和促进剂在“副反应”以及 NH(x)物种的稳定性和表面寿命中所起的作用进行了广泛的研究。研究表明，在活性炭负载 Ru 催化剂上反应的最初步骤中生成的 N2 与 Na 形成 Na-N-Ru 复合物，位于促进剂-过渡金属晶相界面。这项研究还表明，Na 促进剂通过溢流阻止了氢从金属向载体的扩散。在高温下对碳催化剂载体进行热处理后，也观察到了类似的效果。最后，在 Ru 和 Ir 催化剂之间检测到多脉冲 TAP 结果的巨大差异，这意味着 NH3 分解反应机理在这两种金属上必须不同。
